• ISSN 1000-0615
  • CN 31-1283/S
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Effects of two kinds of polysaccharides on growth, serum antioxidant indices and tissue cadmium accumulation of Schizothorax prenanti
Yanhong LI, Feifei ZHANG, Yanping SHI, Maowen LIAO, Han LIU, Lin LI, Yongjia WANG, Yinglong WU
In Press  doi: 10.11964/jfc.20191012013
[Abstract](231) [FullText HTML](102) [PDF 1479KB](8)
Abstract:
The present study aimed to determine the effects of dietary 0.40% chondroitin sulfate (CS) and 0.40% acidolysis oxidated konjac glucomannan (AOKGM) added to feed for 8 weeks on growth, antioxidant indices and tissues (liver, kidney and gill) cadmium accumulation of Schizothorax prenanti. A total of 450 healthy S. prenanti individuals with similar body weight (98.00±8.54) g were randomly assigned to three groups with three replicates per group and 50 fish per replicate. After 8 weeks, the growth and the serum antioxidant indices of S. prenanti were determined. In addition, the cadmium stress test was carried out for 15 days (0, 0.10, 0.25, 1.00 mg/L), and the serum antioxidant indices and tissues cadmium accumulation of fish under cadmium stress were determined. The results were as follows: compared with the control group, specific growth rate (SGR), spleen index (SI) and head kidney index (HKI) were increased when the diets were supplemented with CS and AOKGM. Additionally, the crude lipid, crude protein and ash content of muscles were significantly increased when both polysaccharides were added. Compared with the control group, the serum superoxide dismutase (SOD) activity, total protein (TP) and nitric oxide (NO) content of the fish were significantly increased, and glucose (GLU) content of fish was significantly decreased when diets were supplemented with both polysaccharides. The glutathione peroxidase (GSH-Px) activity and cholesterol (TC) content of fish were significantly increased, and malondialdehyde (MDA) content of fish was significantly decreased when CS was added to the diet. Compared with 0 mg/L cadmium, MDA content was the highest and SOD activity was the lowest at 1.00 mg/L cadmium, GSH-Px activity was significantly decreased and NO content was significantly increased at 0.25 and 1.00 mg/L cadmium. Compared with 0 mg/L cadmium, the SOD activity significantly increased, and MDA content significantly decreased, while NO content significantly decreased at 0.10-1.00 mg/L cadmium when diets were supplemented with both polysaccharides. CS significantly increased GSH-Px activity at 0.10 and 0.25 mg/L cadmium. AOKGM significantly increased GSH-Px activity at 0.25 and 1.00 mg/L cadmium. Compared with 0 mg/L cadmium, the cadmium accumulation in liver, kidney and gill of fish significantly increased at different cadmium concentrations, while CS and AOKGM decreased the cadmium content of tissues. Taken together, the results showed that 0.40% CS and AOKGM had certain effects on the growth and antioxidant capacity of S. prenanti, and it reduced the cadmium accumulation in tissues. This study provides a new theoretical basis for the development of nutritional feed for S. prenanti.
Composition and function of the blood-spleen barrier in Quasipaa spinosa and the evolutionary level of spleen
Siyu REN, Wenhui WANG, Kaiyu WANG, Yi GENG, Defang CHEN
In Press  doi: 10.11964/jfc.20200812388
[Abstract](124) [FullText HTML](65) [PDF 2844KB](12)
Abstract:
This study aimed to explore the splenic histology and evolutionary level of Quasipaa spinosa, and also aimed to identify the existence and function of blood–spleen barrier. Histologic technology, transmission electron microscopy, immunohistochemistry, injection of trypan blue, acid phosphatase(ACP) and alkaline phosphatase(AKP) reaction were used in the study. The results showed that spleen without periarterial lymphatic sheaths (PALS) and germinal centres (GC) had two clearly distinguishable areas including the white pulp and the red pulp with fuzzy boundary. In addition to that, there was no evidence for the presence of a marginal zone, and less ellipsoids were located in the boundary region without periellipsoidal lymphatic sheaths (PELS). The white pulp was surrounded by melano-macrophage centres (MMCs) which was formed by numerous melano-macrophages and MMCs were also located in the white pulp occasionally. A few of mast cells existed in the red pulp and close to the vein. The collagen fibers existed in splenic capsule and splenic cord, especially in the wall of arteriole. The result in the detection by Alphα-naphthyl acetate esterase(ANAE) was negative. The dynamic histology of Q. spinosa after injection of trypan blue showed the blue signal was first discovered in free macrophagocyte in the red pulp after one hour post intraperitoneal injection, and then gradually congregated in splenic cord. The blue signal of diffuse distribution in reticular cells in splenic cord was weakened after twenty-four hours post intraperitoneal injection. No trypan blue was detected in the white pulp, ellipsoids and MMCs throughout the whole course of the dynamic study. Meanwhile, the result of dynamic histology post intracardiac injection was similar to that of intraperitoneal injection, except that the positive signal was discovered half an hour earlier. The result of the detection AKP and ACP on the basis of dynamic histology post intraperitoneal injection showed less ACP was detected in normal spleen, but the ACP content in splenic cords and MMCs had a trend of increasing initially and then decreasing afterwards. In contrast, the AKP remained negative in the whole study.
Research on the ethical logic of modern fisheries and aquaculture governance
Yuru HE, Shuolin HUANG, Kangcheng QIU
In Press  doi: 10.11964/jfc.20190811916
[Abstract](233) [FullText HTML](118) [PDF 1407KB](11)
Abstract:
After years of development, China's fisheries and aquaculture industry has laid a solid economic foundation by successively addressing the difficulties of catching fish, raising fish, and eating fish. The principal contradiction in this area has evolved from the issues surrounding basic livelihood (i.e. food and income) to those concerning habitat conservation, human rights, gender equality, property rights and other high-level needs. Conserving aquatic resources while maintaining fisheries justice have emerged as an irresistible trend of our time, as sustainability and responsibility become increasingly emphasized. Under this premise, fisheries and aquaculture ethics, as a form of superstructure, deserves systematic research for value identification and ranking. The study initially put forward the concept of fisheries and aquaculture ethics, that is, a set of orders and norms dealing with human-fish relations and interpersonal interactions among stakeholders, which take the rationality and legitimacy of fisheries and aquaculture as the research object and provide a judgment basis for relevant practices. Main points regarding ecological, social and industrial ethics in fisheries and aquaculture were summarized, followed by the exploration of ethics-based management theories from eco-holistic perspectives (e.g. Precautionary Principle, Ecosystem-based Management, Large Marine Ecosystems) to value-balanced perspectives (e.g. Management Strategy of Evaluation, Justification Theory). Practical guidance mainly enshrined in Code of Conduct for Responsible Fisheries was then analyzed together with ethical matrix developed for performance evalution, before specific discussion on the ethical dimension in China’s modern fisheries and aquaculture governance. China is the home of the largest number of both fishing vessels and fishermen, and is the only major country where the total output of aquaculture products exceeds that of fishing harvest, making its fisheries and aquaculture management more complicated than that of any other country in the world. Such a scenario requires a unique set of social and ecological ethics tailored for its governance. It is found that China’s traditional ecological wisdom contains rich ethical elements; and there exist ethical challenges in effectively addressing the social problems in China’s Three Fisheries and Aquaculture Issues, namely, the issues concerning the industry, villages and fishermen/aquaculture farmers. China shall further clarify the value scale and ethical foundation of fisheries and aquaculture. The study aims at promoting a sustainable conservation and development outlook in accordance with China’s conditions, in an effort to truly realize the "integration of nature and man" and coordinated development in this sector.
Review of the pilot of marine fisheries TACs in China and suggestions for the further development
Yi TANG, Lihua ZHAO
In Press  doi: 10.11964/jfc.20200212148
[Abstract](84) [FullText HTML](57) [PDF 1414KB](6)
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China has successively launched fisheries total allowable catches (TACs) pilot programs in 5 costal provinces in 2017—2018. The paper reviewed the progress of the 5 pilots based on surveys study. Some management innovations were made in the pilots: limit access to the pilot fishery by special fishing license, fishing log management, adoption of obersevers, and management involvement of fishers cooperatives. There are similar practices in different pilots regarding criteria for choice of the fish stock for pilot, limit of fishing ground use, vessels and fishing methods, supporting measures, while the following are different: single or multiple species of the target stock, limit access to the fishing ground, quotas allocation, monitoring of the catch landing. Currently there are still challengs for implementation of TACs in China with respect to multiple species fisheries, fishing monitoring system, targeted fish stock survey and monotoring, fishing limit measures, adaptive management capacity and institution structures, and legislation of liability for violation. For further development of the TACs in China, the paper suggests: consummate the legal system of TACs by revising the Fisheries Law of China, enhance fish stock survey and monitoring, develop compositive fisheries data and information system, adopt more limits for fishing operation based on license system, establish inclusive mechanism for public participation and cross-region surveillance, and adopt different models of TAC determination for single species fisheries and multiple species fisheries.
Effects of synonymous mutation on transcription and translation efficiency of Es-MSTN gene in Chinese mitten crab (Eriocheir sinensis)
Wucheng YUE, He YANG, Xing HOU, Jing'an WANG, Xiaowen CHEN, Jun WANG, Chenghui WANG
In Press  doi: 10.11964/jfc.20200512263
[Abstract](171) [FullText HTML](78) [PDF 1360KB](7)
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Synonymous mutation can induce phenotypic variation by altering gene transcription, translation and post-transcription process in recent study onuman disease.. To study the effects of synonymous mutation on gene transcription and translation, the total of 12 genotypes (GC, AT, 1T, 2T, 3T, 4A, 5T, 1C, 2C, 3C, 4G and 5G) deduced from the five SNP synonymous mutated loci in MSTN gen of Chinese mitten crab (Eriocheir sinensis) (Es-MSTN), such as SNP1(T/C)、SNP2(T/C)、SNP3(T/C)、SNP4(A/G)、SNP5(T/G), were employed by the means of site- directed mutagenesis, in vitro transcription, and gene overexpression. The result showed that the 12 alleles displayed obviously different transcriptional efficiency in vitro, there was theighest transcriptional level in the 1C allele and the lowest in the GC and AT alleles, in which the AT allele exhibited significantlyigher transcriptional level than the GC allele. The overexpression in 293T cells found that expression intensity of different mutant genotypes was significantly different at different time (24, 36, 48, 60, 72, 84, 96 and 108 h) after transfection, and the AT allele exhibited significantlyigher expression level than the GC allele. Generally, the present study indicated that these five synonymous mutationsave important effects on transcription and translation of Es-MSTN gene, suggesting that synonymous mutations would play an important role in biological process. Further studies at post-transcriptional and post-translational levels may shed light on the intrinsic relationship between gene function and phenotypic variation in E. sinensis.
Characteristics of submarine water temperature distribution of Trichiurus haumela in the East China Sea and Southern Yellow Sea with the improvement of the analysis method
Yong LIU, Jiahua CHENG
Accepted Manuscript  doi: 10.11964/20200312208
[Abstract](2) [FullText HTML](2) [PDF 9624KB](0)
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The study of the relationship between fishery organisms and water temperature is an important part of fishery scientific research, and the analysis of the suitable water temperature range of fish is an important aspect of this content. In this study, based on the distribution data of Trichiurus haumela resources obtained from a large-scale survey in four quarters from 2014 to 2015, the water temperature range analysis method was improved on the basis of previous studies to avoid some subjective factors in the analysis. a new biological subject temperature range analysis method is created and compared with the traditional frequency method and the previous biological subject method. The results show that the proportion of sites covered by the frequency method is relatively good, but the biomass coverage rate is relatively poor; in the previous biological main body method, the cumulative biomass coverage rate was the highest, and the site coverage rate was also relatively good. the disadvantage is that there are many subjective factors added in the operation process, and the distribution range is discontinuous and contains individual narrow range. In the new method, because its temperature range is relatively concentrated and short, the coverage of the site and biomass is not very high, but the biomass density in the determined temperature range is the highest, and the minimum range which can accommodate the most biomass is found. and the distribution range is continuously concentrated. The characteristics of the biological spatial distribution will directly affect the results of the temperature range analysis method, for example, the aggregation degree of the spatial distribution of the belt fish is obviously lower than that of the small yellow croaker, that is, the spatial distribution of the belt fish is relatively uniform. as a result, one of the branches of the frequency distribution is consistent with its biological main body distribution, while the small yellow croaker has no such results, and there is a great difference between its frequency distribution and biomass distribution. The analysis also found that the populations with higher biomass are generally distributed in the waters with higher water temperature, which may be related to the good nutritional status of the population and the demand for rapid growth. The uneven distribution and aggregation in biological space may be related to the food needs and predation characteristics of species. According to the temporal and spatial distribution characteristics of the high biomass population of T. haumela, it is analyzed and inferred that the population may correspond to the reproductive fish schools of spring and summer and autumn.
Effect and track of Mylopharyngodon piceus and Silurus asotus intestinal excreta on the recruitment of dormant Microcystis aeruginosa in aquaculture water
Wansheng ZOU, Zhi WANG, Qisheng SONG, Liangguo LIU, Qing HAN, Wenbin WANG, Pinhong YANG
In Press  doi: 10.11964/jfc.20200212150
[Abstract](159) [FullText HTML](61) [PDF 1946KB](3)
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Microcystis aeruginosa is a kind of cyanobacteria that can bloom in freshwater lakes and slow-flowing water, especially in freshwater aquaculture waters. A large amount of feces will be excreted by benthic fish in the growth process, which may provide conditions for the recovery and increment of M. aeruginosa. To explore the effects and track of the fish intestinal excreta (Mylopharyngodon piceus and Silurus asotus)on the recruitment of dormant M. aeruginosa from the sediment, and to find potential factors and mechanism, simulation experiments on the recruitment of M. aeruginosa cells from sediment were performed in the presence or absence of the fish intestinal excreta. The intestinal excreta of M. piceus or Silurus asotus were fully mixed with cells of dormant M. aeruginosa, and then they were all buried in the lake sediments. The co-culture and recruitment experiments were carried out at the gradient temperatures of 10 °C, 15 °C and 20 °C. The results showed that the recruitment rate of dormant M. aeruginosa cells in M. piceus excreta group (MP), S. asotus excreta group (SA) and M. piceus or S. asotus excreta mixture group (MP-SA) were all significantly higher than that in the control group (CK) (P < 0.05), and the recruitment rate of dormant M. aeruginosa cells in the MP group was significantly higher than those in the SA group and the MP-SA group. At 20 °C, the recruitment rate of dormant cells of M. aeruginosa in MP group was significantly higher than that in SA group, MP-SA mixed group and CK group, however, there was no significant difference in the recruitment rate between SA group and CK group (P > 0.05), and there was no significant difference between MP-SA group and CK group. From the point of view of gradient experiment temperature, the recruitment rate of dormant M. aeruginosa cells both in the control group and in the experimental group (excreta group) increased with the increase of temperature. At 10 °C, recruitment rate of dormant M. aeruginosa cells in the control group, the Mylopharyngodon piceus excreta group (MP), the S. asotus excreta group (SA) and the mixed group (MP-SA) was 14%, 45%, 36% and 28%, respectively, and at 15 °C, recruitment rate of dormant M. aeruginosa was 43%, 60%, 51%, 50%, respectively, at the experimental temperature of 20 °C, recruitment rate of dormant M. aeruginosa was 49%, 61%, 52%, 51%, respectively. For the control group and the three experimental groups (excreta group), t recruitment rate of dormant M. aeruginosa at 15 °C and 20 °C was significantly higher than that at 10 °C, but there was no significant difference in the recruitment rate of dormant M. aeruginosa cells at 15 °C and 20 °C (P > 0.05). At the same time, the main recruitment period of dormant M. aeruginosa was from day 3 to day 15. During the experiment at 10 °C, 15 °C and 20 °C, the dominant bacteria of MP group were mainly Pseudomonas, and the dominant bacteria of SA group and MP-SA group were mainly Bacillus and Firmicute, respectively. In the MP group, at 10 °C, the dominant bacteria in the sediment were Pseudomonas, Fusobacteria, Bacillus, Vibrio, Proteobacteria and Firmicute, which accounted for 33%, 13%, 9%, 7%, 4% and 4%, respectively, the proportion of dominant bacteria was 70% in total bacteria. They accounted for 61% and 54% at 15 and 20 °C, respectively. For the S. asotus excreta group (SA), at 10 °C, 15 °C and 20 °C, the dominant bacteria in the sediment were Bacillus, Bifidobacterium, lactic acid bacteria, Firmicute, Vibrio and Pseudomonas, which accounted for 64%, 50% and 42% of the total bacteria respectively. For MP-SA group, at 10, 15 and 20 °C, the dominant bacteria in the sediment were bacillus, Bifidobacterium, lactic acid bacteria, Firmicute, Proteobacteria and Pseudomonas, and their proportions in the total bacteria were 50%, 45% and 43%, respectively. The concentration of total bacteria in the sediment of each experimental group increased with the increase of temperature, and the concentration of total bacteria at 15 °C and 20 °C was significantly higher than that at 10 °C. 0-12 d was the period of bacterial proliferation. The physical and chemical indexes of the sediment-water interface (SWI) were measured and it was found that the the N/P(DIN∶SRP) ratio of MP group, SA group and MP-SA group were significantly lower than those of the control group during the period of day 3 to day 12. At the three gradient temperatures, in the same period of 0-9 d, the nitrogen-phosphorus ratio decreased the fastest in M. piceus excreta group, followed by S. asotus excreta group, the mixed group and the control group (CK). There was no significant change of nitrogen-phosphorus ratio in the whole process for the control group. In the same period, there were significant differences between the three experimental groups and the control group (P < 0.05), and there were also significant differences among the three experimental groups. During all experiments, the change trend of dissolved oxygen (DO) concentration was basically the same as that of nitrogen-phosphorus ratio, and dissolved oxygen. The results showed that the intestinal excreta of M. piceus or S. asotus could promote the recruitment of dormant M. aeruginosa, which may be the result of the decline of N/P ratio and dissolved oxygen concentration caused by flora in the excreta during the growth and proliferation period, and the effect of promoting-recruitment was more significant in the lower temperature range (10-15 °C). The results are of theoretical significance for the recruitment of dormant M. aeruginosa cells, clearing the pond of silt, and the mechanism of bloom outbreak of M. aeruginosa in spring. It also provides a new way to prevent and control the bloom of M. aeruginosa in aquaculture waters.
Nutritional physiology of Zn and its relationship with lipid metabolism for aquatic animals: A review
Guanghui CHEN, Zhi LUO
In Press  doi: 10.11964/jfc.20200612309
[Abstract](1) [FullText HTML](1) [PDF 1862KB](0)
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Zinc (Zn) is an essential trace element, and maintains the normal growth, development and nutrient metabolism of aquatic animals. To decipher the mechanism of Zn regulating nutrient metabolism in aquatic animals, the present paper summarizes the progress involved in dietary Zn requirements and the key factors influencing Zn requirements, structures and functions of key genes and proteins (such as ZnTs and ZIPs families, MTs and MTF-1) relevant with Zn homeostatic regulation, and the effects and mechanism of Zn influencing lipid deposition and metabolism. At present, although some progresses have been made in the Zn nutrition, physiology and metabolism of aquatic animals, many underlying questions remain unknown and further investigations are needed: (1) about wide-accepted evaluating standards for the optimal dietary Zn requirement; (2) about the structure and function of key genes and proteins in the regulation of Zn homeostasis, and the revelant mechanism of absorption, transport and homeostasis of Zn in aquatic animals, which provides the basis for the addition of dietary Zn sources; (3) about the signal pathways and molecular mechanism of Zn regulating nutrient metabolism, which provides the reference for the precise regulation of zinc nutrition in aquatic animals.
Isolation, identification and pathogenicity analysis luminous Vibrio campbellii from Litopenaeus vannamei
Jinjin LI, Baohua HONG, Sizhen NI, Jiawei BAO, Rongrong MA, Fei Yin, Jie HE, Huaming LUO, Chen LI, Yuanming HUANG, Dong QIAN
In Press  doi: 10.11964/jfc.20200112121
[Abstract](236) [FullText HTML](97) [PDF 1796KB](10)
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A serious diseased occurred in cultured white-leg shrimp, Litopenaeus vannamei, in greenhouse pond of mariculture farm in Taiz hou, Zhejiang province, in 2019. The diseased L. vannamei showed corkscrew swimming, anorexia, slow growth, hepatopancreas discouloured, with a mortality rate of more than 80% in 2-3 days. To study the pathogenic mechanism of PvL-1 on L. vannamei. the bacteria were isolated from moribound L. vannamei with typical symptoms by using thiosulfate citrate bile salts sucrose (TCBS) agar, with the light green colony of 3-7 mm in diameter, luminous in dark and gram negative rods. PvL-1 was identified as Vibrio campbellii with API20E biochemical bacteria identification, with similarity of 90% to reference strains CAIM249. PvL-1 belonged to the same cluster with V. campbellii CP020076 on phylogenetic analysis for fitZ, with 99.31% similarity to reference strains, and same cluster to V. campbellii EF596552, with 98.89% similarity on gapA. V. campbellii species-specific primers were used for PCR test, with 328 bp band for PvL-1 and negative for V. rotiferianus and V. harveyi. These results indicated that PvL-1 was a member of V. campbellii. PvL-1 can form typical β hemolyisis on sheep blood agar and transparent circle on the milk agar, indicated the existence of hemolytic and extracelllar protease toxin. Acute hepatopanergic necrosis, hemolysin gene, flagellate gene and other virulence genes of PvL-1 were analyzed, indicated that PvL-1 has virulence genes such as AP4, TLH, vcahHly, flaC, mukF, gloB, sodB and esrB. The healthy L. vannamei, infected with V. campbellii PvL-1, died with the similar symptoms to nature infected L. vannamei, with LD50 of 2.94×104 CFU/ind. Histopathologic examination showed that PvL-1 challenged L. vannamei hepatopancreas tubular epithelial cells massive shed and sloughing, hemocytic infiltration etc., which was similar to the native infected L. vannamei. In summary, the luminescent V. campbellii PvL-1 was isolated, with highly pathogenicity, which expanded the cognition of the luminescent V. campbellii of L. vannamei.
Annual variation of species composition and spatial structure of fish community in Shandong offshore
Xuetong LI, Kun WANG, Binduo XU, Ying XUE, Yiping REN, Chongliang ZHANG
In Press  doi: 20200312206
[Abstract](235) [FullText HTML](105) [PDF 1858KB](27)
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The coastal waters of Shandong have rich fisheries resources but have suffered from pressures including overfishing. In order to comprehensively understand the composition and structure of the fish community in Shandong coastal waters and to provide a scientific basis for the conservation of fishery resources, a fishery resources survey was conducted in Shandong coastal waters from 2016 to 2017 using bottom trawl in four seasons. A range of multivariate statistical methods including non-metric multi-dimensional scaling (NMDS) and ANOSIM were used to analyze the species composition and spatial heterogeneity of the community structure. The results showed that a total of 134 species were caught in this survey, of which 53 species had Index of relative importance IRI ≥ 1. NMDS analysis showed that the 53 species could be divided into three groups, a, b, c. Among them, Group a was characterized by the large biomass in summer and Group c in autumn. Group b was characterized by the relatively small changes of biomass throughout the year and the obvious dominance in spring and winter. Regarding the spatial structure of fish community, NMDS and ANOSIM showed that the fish community structure in Laizhou Bay (Zone A) was significantly different from that in the northern and southern adjacent waters (Zones B and C) of the Shandong Peninsula, and the differences persisted in all seasons. SIMPER showed that the species that caused the spatial heterogeneity of community structure between Zone A and Zone B & C were Cynoglossus joyneri and Lophius litulon in spring; Engraulis japonicus in summer; Chelidonichthys kumu in autumn; Acanthogobius ommaturus and L. litulon in winter.
Establishment of a dynamic energy budget (DEB) growth model for Sinonovacula constricta
Yunhui LUO, Bo WU, Shanliang XU, Jilin XU, Danli WANG
In Press  doi: 10.11964/jfc.20190911941
[Abstract](208) [FullText HTML](87) [PDF 1869KB](13)
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The purpose of this study is to establish a numerical model of dynamic energy budget for Sinonovacula constricta. According to DEB theory, the basic parameters of the model were measured and calculated by corresponding methods: shape coefficient δm, energy per unit volume of Arrhenius temperature TA, per unit time [pM], energy needed to form structural matter per unit volume [EG] and maximum stored energy per unit volume [EM]. Taking water temperature and chlorophyll concentration as forced functions, and based on the growth data of S. constricta from different seedling sources and water quality factors in ponds, STELLA 10.0 software was used to establish the DEB model of the system. The results show that the mean value is 0.3458, the average value of TA is (5 448±960) K, [pM]=17.68 J/(cm3·d), [EG]=4 050 J/cm3, [EM]= 1 840 J/cm3; and the constructed DEB model can well simulate the growth of dry weight of the soft body part and reflect the energy distribution at different time. The water temperature of the seedling released in spring was the main growth restriction factor from August 10 to September 20, and the food was the factor from September 30 to November 10. The main limiting factor was that S.constricta released in autumn showed a strong temperature limit from July 1 to September 20, while the food limit ran through the whole simulation period, with the maximum limit from March 10 to May 20. It is inferred that S. constricta released in autumn could increase the supply of food algae in spring and reach the commercial specification before high temperature in summer.
Microstructure of brain and ultrastructure optic gland of Octopus minor
Zhifa ZHU, Li BIAN, Siqing CHEN, Yamei WANG, Pengfei ZHANG, Fenghui LI, Shengnong ZHANG, Jianlong GE, Qing CHANG, Changlin LIU
In Press  doi: 10.11964/jfc.20200212169
[Abstract](168) [FullText HTML](85) [PDF 2430KB](10)
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The brain structure of Octopus minor was observed by anatomy and paraffin section. The results showed that the brain was divided into three parts according to the location of the esophagus: the supraoesophageal mass, the suboesophageal mass and the optic lobe area on both sides of the supraoesophageal mass and the suboesophageal mass. The supraoesophageal mass includes the vertical lobe, the superior frontal lobe, the inferior frontal lobe, the anterior basal lobes and the posterior basal lobes. The suboesophageal mass includes the brachial lobe, the pedal lobe, the magnocellular lobe, the chromatophore lobe, the visceral lobe, the palliovisceral lobe and the vasomotor lobe. The optic lobe area includes the optic nerve, the optic lobe, the optic gland, the olfactory lobe, the peduncle lobe and the optic tract. Paraffin section, optical microscope and transmission electron microscope were used to observe the microstructure and ultrastructure of the optic gland. The results showed that there was a layer of connective tissue wrapped outside the optic gland, which was located in the optic tract area, adjacent to the olfactory lobe and the peduncle lobe. A large number of secretory cells were observed in the inner part, with a relatively large nucleus and a diameter range of 4-8 μm. The secretory cells were rich in rough endoplasmic reticula, Golgi apparatus, secretory vesicles and vacuoles secreted by Golgi apparatus. The results showed that the structural characteristics of the optic glands of O. minor were similar to those of Sepiella maindroni and O. vulgaris.
Molecular characterization of two twist genes in barbel steed (Hemibarbus labeo) and their relationship with intermuscular bone development
Jie CHEN, Yaoping LÜ, Qingmin DAI, Le ZHANG, Luying YANG
In Press  doi: 10.11964/jfc.20190911983
[Abstract](249) [FullText HTML](128) [PDF 1838KB](29)
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There are two twist genes in vertebrates, namely twist1 and twist2, which have a regulatory effect on bone development. To explore the relationship between twist1, 2 and intermuscular bone development in barbel steed (Hemibarbus labeo), cDNAs of the twist1 and twist2 genes of H. labeo were cloned and sequenced. Sequence analysis revealed that H. labeo TWIST1 and TWIST2 were conserved in most of the teleosts, and they all had a helix-loop-helix (HLH) domain and a tryptophan-arginine (WR) domain. Phylogenetic tree analysis indicated that H. labeo twist1 and twist2 were closely related to that of zebrafish (Danio rerio). Expression of twist1 and twist2 transcripts were detected in all the tested tissues. twist1 was the highestly expressed in the brain, followed by the heart, and the lowest in the spleen. twist2 had higher expression levels in skin and gill, and the lowest expression in spleen. The transcript levels of the twist1 and twist2 gene significantly changed during the four developmental stages of intermuscular bone development, suggesting that there is a certain correlation between twist genes and intermuscular bone development. This study, for the first time, cloned the twist genes in economic fish and revealed the correlation between twist genes and intermuscular bone development. The results will provide basic data for further investigation of twist gene function and its regulation role in intermuscular bone development.
Effects of four microalgae diets on growth, nutritional composition, pearl producing function, shell nacre color and trace element content of Hyriopsis cumingii
Qiang CHEN, Xiamin JIANG, Ruibing PENG, Qingxi HAN, Peng SHENG, Ruiping XUE
In Press  doi: 10.11964/jfc.20191212114
[Abstract](208) [FullText HTML](88) [PDF 1613KB](8)
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China accounts for more than 95% of global freshwater pearl production, of which 80% is Hyriopsis cumingii. In high-density H. cumingii culture, large amounts of organic manure (duck manure, bird manure, soybean milk) and chemical fertilizers are used to produce sufficient quantities of feed. This method results in a large amount of feces, pseudo feces, and residual feed being discharged, resulting in eutrophication and negative effects on the benthic environment. Water pollution can result in frequent disease outbreaks and disease control drugs can further pollute the aquatic environment. Development of intelligent culture facilities, including high-quality nutritious diets for H. cumingii, is an urgent need.  To dertimine the optimal microalgae diet for massive clam culture, this experiment was conducted to investigate the effects of different microalgae diets (Cyclotella sp., Chlorella pyrenoidosa, Scenedesmus dimorphus, Monosporidium contortum, and mixed four microalgae) on the growth, pearl producing function, nutrition composition and shell nacre color of H. cumingii, using a single factor experiment method.  The results showed that the growth of the clam was significantly different with different microalgae diets. The mussels fed Cyclotella sp. and S. dimorphus showed weight growth (WG) of 9.94 ± 0.51% and 9.42 ± 0.89%, respectively, which were significantly higher than those of the other three groups; mussels fed M. contortum had the lowest WG (5.23% ± 0.30%). Similar results were obtained for shell length growth (SLG), with mussels fed Cyclotella sp. and S. dimorphus showing the highest values (1.99% ± 0.31% and 2.07% ± 0.53%, respectively). The group fed Cyclotella sp. showed the highest shell height growth (SHG; 6.55% ± 0.62%). The highest shell width growth (SWG) was also observed in the group fed Cyclotella sp. (5.31% ± 0.71%) while the group fed M. contortum group showed the lowest SWG (3.33% ± 0.91%); there was a significant difference between these two groups. Pearl weight growth (PWG) also differed significantly among the different treatment groups. The highest PWG was observed in mussels fed Cyclotella sp. (16.23% ± 1.23%). There were no significant differences among the groups fed C. pyrenoidosa (11.40 %± 2.09%), S. dimorphus (13.40%± 2.00%), and mixed microalgae (11.80% ± 1.40%); the lowest PWG was observed in the group fed M. contortum (6.35% ± 1.90%). In summary, Cyclotella sp. and S. dimorphus were the optimal species for H. cumingii growth.  Feeding different microalgae did not have a significant effect on the shape of the pearls (probability of producing round and near-round pearls), but did have a significant effect on the probability of producing round and oval pearls. The probability of a pearl shape being round was highest in both the Cyclotella sp. and S. dimorphus groups (26.67% ± 4.71%) and was significantly higher than in the M. contortum group. However, the S. dimorphus groups was significantly more likely to have oval round shape (16.67% ± 4.71%) than the other four groups.  It is significant effect on shell nacre color. The L* values for the Cyclotella sp. (64.89±1.97) and C. pyrenoidosa (65.18±2.24) groups were lower and significantly lower than the other three groups. And with the highest L* value in the mixed algae group (68.94±1.71), which was significantly higher than the other four groups. The mixed algae group had the highest dE* value (69.08±1.68), which was significantly higher than the other four groups. The smallest dE* value was found in the Cyclotella sp. group (65.23±1.89), which was not significantly different from the C. pyrenoidosa group (65.47±2.19). There was no difference between the S. dimorphus group (67.52±2.46) and the M. contortum group (67.52±2.46), but significantly higher than the Cyclotella sp. and C. pyrenoidosa groups. The largest C* value was found in the C. pyrenoidosa group (6.03±0.98), which was slightly higher than in the Cyclotella sp. group (5.44±1.36) and significantly higher than in the S. dimorphu, M. contortum and mixed groups.  The trace element content of the mantle was significantly affected by diet. The highest Zn content was observed in mussels fed M. contortum [(170.33 ±3.86) mg/kg], followed by S. dimorphus, and Cyclotella sp. [(120.33 ± 2.05) and 122.33 ± 4.99) mg/kg) ]. The mixed algae group had lowest Fe content [(169.33± 22.13) mg/kg)], and the others had no significant difference. The content of Mg and Mn had same trend(P < 0.05), M. contortum > S. dimorphus > Cyclotella sp.= C. pyrenoidosa > mixed algae.  The Ca content of the foot was highest [(12, 637.3 ± 624.39) mg/kg] for group fed Cyclotella sp., followed by the group fed M. contortum [(8, 019 ± 513.72) mg/kg]. The Ca content of the foot for these two groups was significantly higher than that of the other groups. The highest Ca content in the mantle was observed in the mussels fed S. dimorphus [(25 049.30 ± 1 320.36) mg/kg] followed by the group fed M. contortum [(24 903.70 ± 359.06) mg/kg]. The groups fed Cyclotella sp., C. pyrenoidosa, and mixed algae showed a significantly lower Ca content in the mantle  In conclusion, Cyclotella sp. may be the best diet choice for intensive H. cumingii, and followed by S. dimorphus.
Resting metabolic rate and growth performance in Qingbo (Spinibarbus sinensis) with different body mass
Deyong PU, Xu PANG, Xiaohong LIU, Danyang XIA, Yanhong DING, Juan CHEN, Yaoguang ZHANG
In Press  doi: 10.11964/jfc.20191212116
[Abstract](189) [FullText HTML](75) [PDF 6638KB](7)
Abstract:
In order to investigate the differences of the energy metabolism and growth capacity of Qingbo (Spinibarbus sinensis) with different bogy mass, the resting metabolic rate (RMR) of this kind of fish with different body mass (10, 20, 40, 100 and 180 g groups) was firstly detected. After a 28-day feeding trial, the specific growth rate (SGR), feeding rate (FR) and the feed efficiency (FE) were tested in these groups as well. On the one hand, the RMR of S. sinensis was significantly increased with the increase of body mass, however, the RMR of unit weight was significantly decreased. Meanwhile, both SGR and FR were significantly increased, while the FE was indistinctly affected, and plasma GH hormone content was significantly negatively correlated with body mass (r = −0.753, n = 30). On the other hand, the RMR of unit mass was significantly positively correlated with SGR (r = 0.586, n = 51) and FR (r = 0.640, n = 51,), however insignificantly correlated with FE (r = 0.100, n = 51). The SGR was positively correlated with both FR (r = 0.956, n = 51) and FE (r = 0.447, n = 30), and the relation between FR and FE was not significantly correlated (r = 0.245, n = 30). All the information above suggested that, smaller S. sinensis can keep higher maintenance energy consumption and growth capacity, and this may be due to their higher digestive and assimilating ability.
Construction of a bacterial artificial chromosome (BAC) library of the female gametophytes of Saccharina japonica and map cloning and sequencing of genes neighboring with a female-specific marker FRML-1488
Pengfei LIU, Jungang GU, Yanhui BI, Zhigang ZHOU
Accepted Manuscript  doi: 10.11964/jfc.20200112143
[Abstract](8) [FullText HTML](6) [PDF 6609KB](1)
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UV sex-chromosome system exhibits unique evolution and genetic features during the haploid stage of the life cycle in some algae and bryophytes. In this study, a bacterial artificial chromosome (BAC) library of female gametophytes Saccharina japonica was constructed. The library, containing a total of 31 872 BAC clones with an average insert size of 115 kb, covering 6.57-fold of the estimated haploid genome equivalents. The specific primers of a female-specific marker FRML-1488 were to screen those BAC clones by PCR amplification. In total four positive clones were obtained, randomly selected a BAC clone (638-C12) and sequenced by Roche454 method. Finally, the insert fragment was assembled with the length of 86 996 bp, which was located in Scaffold285 and accounted for 22.4% of the length of this scaffold. Sequence analysis results showed that a large number of repetitive sequences including microsatellites and retrotransposons (Copia) were found upstream of the female-specific marker FRML-1488. Above all, the insert of BAC clone 638-C12 may be related to the U chromosome sex determining region of S. japonica. This study report of BAC library for S. japonica and sex-linked map-based cloning for the first time, contributing to a comprehensive understanding of sex chromosome structure and the sex determination mechanism of this kelp.
Indicative significance of rheotaxis behaviour of three familiar species of fish from Yuanshui River by hydropower cascade development
Bolan SONG, Xiangen SU, Tianbao LI, Liangguo LIU
Accepted Manuscript  doi: 10.11964/jfc.20200412222
[Abstract](7) [FullText HTML](6) [PDF 6094KB](0)
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The Dongting Lake water system is an important habitat and spawning ground for the fish, and it also plays a key role of the river-lake complex ecosystem in the middle reaches of the Yangtze River, which is of great significance for the maintenance or replenishment of the diversity of fish in the Yangtze River. To understand the physiological and ecological adaptation mechanism of fish movement and the evolution of their movement mode from Yuanshui River, a branch of Dongting Lake water system, we investigated the swimming ability, rheotaxis behaviour and metabolic characteristics of local fish of different species and habits by the hydropower cascade development in this study. It had an important significance to understand the impact on the diversity and biological response of fish and scientifically evaluate the ecological risk of the cascade hydropower development. The rheotaxis behaviour and swimming metabolic characteristics of three familiar fish (Carassius auratus, Siniperca knerii, Tachysurus fulvidraco) from Yuanshui River were tested using a self-manufactured apparatus for measuring swimming ability and metabolism of fish by adjusting water velocity on the laboratory. The classical increasing velocity method and video counting method were used to study these data. The results showed that the relative induction velocities of Carassius auratus(15.84±3.60 g), Siniperca knerii(27.1±7.41 g), and Tachysurus fulvidraco(17.5±4.78 g) were, respectively, 0.79±0.14 BL/s, 1.16±0.07 BL/s and 0.75±0.09 BL/s. The relative preferred swimming speed of the three fish were, respectively, 2.31±0.11 BL/s, 1.86±0.04 BL/s and 1.60±0.03 BL/s, and the critical swimming speed were, respectively, 3.43±0.37 BL/s, 2.58±0.32 BL/s and 2.68±0.13 BL/s. Under the same conditions, the preferred swimming velocity, critical swimming speed, respiratory frequency (RF) and oxygen consumption rate (OCR) of Tachysurus fulvidraco were significantly lower than those of the two other fish (P < 0.05). At different flow rates, the RF, OCR and tail beat frequency (TBF)of the three species of fish all increased significantly with the increase of flow rate, and it showed a same tendency to first increase and then decrease. The RF of all fish had peak values at the flow rate of 3 BL/s.The TBF and OCR values of Carassius auratus and Siniperca knerii peaked at the flow rate of 2 BL/s, while that of Tachysurus fulvidraco was at the flow rate of 1.5 BL/s.The rheotaxis rate of Carassius auratus increased from 64.1% under the condition of still water to 100% at the flow rate of 4 BL/s, while that of Siniperca knerii and Tachysurus fulvidraco increased respectively from 60.2% and 58.9% under the condition of still water to 100% at the flow rate of 2-3 BL/s. The swimming states of the three species of fish were obviously affected by the flow rate. Under the condition of still water, the swimming states of Carassius auratus were mainly in “moving forward against the current” and “downstream”. The Siniperca knerii under the condition of still water and most of the flowing water were in fixed station against the current. Tachysurus fulvidraco under the condition of still water and lower flowing water (<1 BL/s)were also mainly in fixed station against the current. With the increase of flow rate, the proportion of fixed station against the current decreased rapidly, and the proportion of “moving backward against the current ”increased continuously. Taken together, our findings indicated that the differences of the rheotaxis behaviour of three familiar fish from Yuanshui River were closely related to their living habits, morphological characteristics, feeding habits, feeding patterns, and their living water environment. The determination of the corresponding relationship between these parameters and the environmental conditions of the flow rate was helpful for the establishment of the simulation data model of fish swimming biology, and it also provided a reference for the study of the evolution of the environment adaptation mechanism of fish from Yuanshui River by the cascade hydropower development.
Population dynamics and stock status of Saurogobio dabryi in the downstreamof the Jialing River
Jia MA, Fubin ZHANG, Yu ZENG, Zhenyu LÜ, Jina XIAO, Xinman HE, Ming DUAN, Shaorong YANG
Accepted Manuscript  doi: 10.11964/jfc.20200312215
[Abstract](5) [FullText HTML](4) [PDF 6134KB](0)
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This research was conducted to explore the population dynamics and stock status of Saurogobio dabryi in the downstream of the Jialing River. A total of 256 individuals of S. dabryiwere collected in the lower reaches of the Jialing River (Hechuan section) from 2015 to 2016. Growth parameters and stock status of the S. dabryi population were estimated by using theFista II software. The length-weight relationship was W=7.5×10−5×L2.58 (R2=0.7311, n=256), the Von Bertalanffy growth equation was fitted as L=173.81(1−e−0.73(t+0.23)), where Loo=173.81 mm, K=0.73, t0=−0.23. The exploration rates of the S. dabryi population were 68% and 69% in 2015 and 2016 respectively, exceeding the theoretical maximum exploration rate (42%), suggested bythe Yield per Recruit model (YPR), which indicated that the S. dabryi population had been overexploited. The S. dabryi in the lower reaches of the Jialing River demonstrated allometric growth pattern, and r-selection life strategies. Recruitment to the population mainly occurred from April to June, and was unimodal. The population was dominated by younger and small sized individuals. Abundance had been declining due to overfishing and failure of natural recruitments to the population.
Analytical research of spatial distribution of fish larvae and juveniles in Summer and Autumn in the eastern Chongming, Yangtze River Estuary
Huan LIU, Jinhui CHEN, Jianhui WU, Junsheng ZHONG, Mengting HAN, Chen ZHAO
In Press  doi: 10.11964/jfc.20200412230
[Abstract](154) [FullText HTML](100) [PDF 6659KB](18)
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The CEB (Chongming Eastern Beach) is located on the plume of the dilute water at the mouth of the Yangtze River. Under the action of strong currents and tides, it forms a wealth of food and provides a unique place for growth and development of fish larvae. To investigate the distribution and diversity of fish larvae, using big larval net (mesh size of 0.5 mm) to conduct 10 min horizontal trawl, while collecting real-time data of environmental parameters of the water column included temperature (SST), salinity (SSS), depth (DEP), turbidity (TUR), and chlorophyll a (Chl). A total of 10 925 fish larvae and juveniles, results showing, belonging to 52 species, 14 families, were collected. Among them, the most abundant were freshwater fish of 22 species (42%), followed by estuarine fish of 19 species, consisting 37% of total, coastal fish of 7 species (13%) and 4 species of offshore fish (8%). Whereas the most common species were Cyprinidae family, consisting of 14 species (27%); the species of the Gobiidae family were 12 species (23%); the families of the family Engraulidae and Osmeridae were both 5 species (10%). The dominant species were(Coilia mystus, 21.51%), (Colia nastus, 18.11%), (Hemiculter bleekeri, 16.34%), (Pseudolaubuca sinensis, 10.82%)and (Acanthogobius ommaturus, 9.38%), respectively. In all, the fish larvae of pre-flexion were comprised 76.49% of the total catch, 11.94% of the flexion stage, 8.01% of the post-flexion stage, 3.43% of the juvenile stage. However, the density of fish larvae in the stage of pre-flexion and flexion had a declining tendency, while the density of fish larvae in the stage of post-flexion experiencing a jumping, as the season changed. The species, bio-diversity and the density of fish larvae were higher in the summer season than in the autumn season. The Non-metric Multi-dimensional Scaling and the Cluster Analysis demonstrated that the fishes can by classified as two groups, rich in the freshwater type followed by the estuary type. Based on the results of this research and other surveys of Coilia family larvae, it shows that there is a significant difference in the spatial distribution of Coilia nasus and Coilia mystus at the larval stage of the Yangtze River. This research showed that the Gobiidae was distributed in a scattered manner, and traces of the larvae and juveniles were found in the southern branch, northern branch of the Yangtze River Estuary and Dongtan water area. Like many estuaries in the world, the Gobiidae have special living habits, which enable them to adapt to the huge runoff and sedimentation of the estuary. At present, many nets and fyke nets for eel fishing have been set up along the Yangtze River Estuary. There is no effective method to assess the damage to larvae and juveniles. In addition, the feeding of larvae and juveniles and the protection of nurseries are the key to the protection and restoration of fishery resources. The CEB of the Yangtze River estuary is a buffer water area for Chinese sturgeon juveniles to descend and migrate to the sea. The density of larvae and juveniles in this water area will significantly affect the species preservation and continuation of Chinese sturgeon. Therefore, it is urgent to develop effective and systematic long-term tracking.
Genomic analysis of Bacillus velezensis LF01 strain and the biocontrol effect of its secondary metabolites
Defeng ZHANG, Yanxia GAO, Xiaoli KE, Yajun WANG, Yan REN, Cunbin SHI
Accepted Manuscript  doi: 10.11964/jfc.20201012442
[Abstract](61) [FullText HTML](41) [PDF 8191KB](2)
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Bacillus velezensis is a novel species in the Bacillus genus which exhibits a broad spectrum of antimicrobial activities due to it produces various secondary metabolites. The current research on B. velezensis mainly focuses on its use for the promotion of the growth of animals and plants, for antagonizing pathogens, and on investigating its gene cluster which play significant roles in biological control, drug research and development, and food fermentation. The aims of this study are to explore the gene clusters related to antagonistic substances of B. velezensis LF01 strain based on the whole genome sequencing, and to evaluate the biological safety and biocontrol effect of the antagonistic substances of the LF01 strain. In this study, the whole genome of the LF01 strain was sequenced based on the third generation Nanopore sequencing platform, and its taxonomic status was identified based on ANI and DDH online analysis, and the genetic evolution at genome level. The gene clusters related to antagonistic substances of the LF01 strain was analyzed based on antiSMASH software. The hydrolysis activity of the LF01 strain to carbohydrate was analyzed based on CAZyme database. The toxicity of the antagonistic substances of LF01 strain to Oreochromis niloticus and Danio rerio was evaluated by intraperitoneal injection. The biocontrol effect of the antagonistic substances of LF01 strain to O. niloticus was evaluated by artificial infection after 5 d of feeding O. niloticus. The complete genome of LF01 strain was a total length of 3974023 bp and the GC content was 46.56%, and it contains 3843 coding genes. Compared to B. velezensis, the ANI and DDH values of LF01 strain were ≥97.66% and ≥80.10%, respectively. Furthermore, the genomic evolution analysis showed that LF01 strain was clustered with B. velezensis. These results indicated that LF01 strain was identified as B. velezensis at the genomic level. The LF01 strain contains nine gene clusters related to antagonistic substances, including bacillaene, bacillibactin, bacillomycin D, bacilysin, difficidin, fengycin, macrolactin H, plantazolicin and surfactin, which accounts for 8.83% of the total genome sequences. In addition, LF01 strain contains a large number of CAZymes related to the degradation of cellulose, hemicellulose, starch, chitin, pectin, peptidoglycan and glucan. The antagonistic substances of the LF01 strain showed high biological safety to O. niloticus and D. rerio, and they were significantly enhanced the resistance of O. niloticus against S. agalactiae infection. In conclusion, the LF01 strain contains large number of gene clusters for biosynthesis of secondary metabolites related to antagonistic substances. The antagonistic substances were found to be safe for O. niloticus and D. rerio, and feeding O. niloticus with them significantly improved the diseases resistance of fish. Therefore, the antagonistic substances of LF01 strain have a broad development and application prospect as biocontrol agents to improve bacteria diseases control in aquaculture.
Comparative analysis of skin and eye transcriptome in the Gobiopterus lacustris
Xueyou LI, Minghua XIE, Chengqin HUANG, Chun WANG, Zhongduo WANG, Yusong GUO, Zhongdian DONG
Accepted Manuscript  doi: 10.11964/jfc.20200912401
[Abstract](74) [FullText HTML](42) [PDF 6872KB](4)
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Gobiopterus lacustris is a kind of small fish with strong adaptability to salinity and easy to raise in laboratory. It is an ideal model organism and environmental indicator species, whose body is transparent and its organs can be seen through naked eyes. In order to explore the cause of the transparent body color of G. lacustris, the transcriptome analysis of skin and eye of G. lacustris was carried out. A total of 103 686 unigenes were obtained by de novo splicing. The N50 and average length were 1 456 and 2 490 bp, respectively. In Nr, Nt, Swissprot, Pfam, KOG, GO and KEGG databases, 57 380, 37 343, 51 277, 47 020, 47 555 and 25 604 unigenes were annotated respectively. KEGG enrichment showed that tyr, tyrp1 and tyrp2 were significantly down regulated in melanin production pathway. In addition, the results showed that there were 8 113 differentially expressed genes (DEGs) in the skin and eyes of G. lacustris, of which 3 174 were up-regulated in the skin and 4 939 in the eyes. The verification of 10 DEGs by qPCR confirmed that the RNA-Seq analysis was correct. This study enriches the body color research of G. lacustris, provides data for the utilization of G. lacustris genetic resources, and also provides a reference for further study on the formation mechanism of gorgeous body color of fish.
Redescription and phylogenetic analysis based on the 18S rDNA of Myxobolus tricostatus (Myxozoa: Myxobolidae)
Xinhua LIU, Meiqi WENG, Rui SONG, Yuanli ZHAO, Aihua LI, Jinyong ZHANG
Accepted Manuscript  doi: 10.11964/jfc.20200712343
[Abstract](70) [FullText HTML](40) [PDF 6437KB](2)
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Myxobolus tricostatus was found initially to infect the gills of grass carp in the late 1970s with simple and insufficient taxonomic data, so the taxonomic validity was problematic. In order to complete description and verify the validity of M. tricostatus, we redescribed M. tricostatus collected from Lake Tangxun in Wuhan city, Hubei province, using the integrative taxonomic approach of combing myxospore morphology, molecular data and ecological information of host and infection site, which has been widely accepted for the taxonomy of Myxozoa. Here, the plasmodia, tissue tropism and molecular data of M. tricostatus was firstly provided. The morphological features of the concerned species are as follows, whitish plasmodia infecting the gills measured 2.4±0.3 (2.1-2.7) mm in length and 0.8±0.1 (0.6-0.9) mm in width; mature spores encapsulated by a transparent mucous envelope were ovoid in frontal view and fusiform in sutural view, measuring 10.3±0.4 (9.4-11.0) μm long, 9.5±0.5 (8.7-10.9) μm wide, and 7.4±0.5 (6.4-8.0) μm thick; no "V"-shaped folds were observed on the posterior end of the spore; three parallel ridges could be observed in sutural view; two equal polar capsules were pyriform and coiled with 7-8 turns of polar filament. Histological observation showed that the plasmodia dwelled between the gill filaments, and no serious inflammation was found in the surrounding tissues. BLAST search indicated that M. tricostatus was most similar with M. elegans with the similarity of 89.58%, which was definitely outside the intraspecies similarity range. Phylogenetic analysis revealed that M. tricostatus branched with M. elegans from the gills of Leuciscus idus and Rutilus rutilus with high support values within the clade of cyprinidae gill-infecting Myxobolus spp. including M. enoblei, M. minutus and M. bibullatus from the gills of Catostomidae fish. The present phylogenetic results further support that host affinity and tissue tropism provides strong evolutionary signal for tissue-infecting myxobolidae. In conclusion, we provide here complete morphological, histological and molecular data to finish the description of M. tricostatus, and verify the validity of it.
Cloning and expression analysis of autophagy genes ATG13 and ATG101 in Macrobrachium nipponense under hypoxic stress
Shengming SUN, Yinxiang CHEN, Cheng ZHENG, Qianqian ZHAO, Cheng XUE
Accepted Manuscript  doi: 10.11964/jfc.20200612316
[Abstract](65) [FullText HTML](35) [PDF 7859KB](6)
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In order to study the regulation of autophagy-related gene 13 (ATG13) and ATG101 in Macrobrachium nipponense under hypoxia stress, the full-length cDNA sequences of ATG13 and ATG101 of M. nipponense were cloned for the first time by RACE PCR through cloning, expounds the cell autophagy genes ATG13 cDNA 2 043 bp (NCBI login id: MT084347), including 211 bp 5′ untranslated regions (UTR), 449 bp 3′ UTR and 1 383 bp open reading frame (ORF), which encodes 460 amino acids; ATG101 cDNA is 1 051 bp long (NCBI login id: MT084348), including the 5′ terminal non-translation region of 18 bp, the 3′ UTR of 373 bp and the open reading frame of 660 bp. The open reading frame encodes 219 amino acids. Based on bioinformatics analysis, the amino acid similarity ratio showed that the autophagy gene ATG13 of the biogas shrimp was rich in highly conserved LC3 functional domain (LIR). Phylogenetic tree analysis showed that the ATG13 gene of M. nipponense was closely related to the autophagy related genes of Penaeus vannamei. The results showed that ATG13 and ATG101 were highly expressed in hepatopancreas and brain tissues, but low in muscles. The difference of ATG13 and ATG101 expression in hepatopancreas tissues under hypoxia stress was tracked by real-time fluorescence quantitative PCR (qRT-PCR). The expression of ATG13 and ATG101 in the experimental group was significantly higher than that in the control group at 6 h and 12 h, but there was no significant difference between the experimental group and the control group at 12 h after the recovery of normoxia, which were similar with M. nipponense ATG13 and ATG101 protein expression abundance using Western Blot. The results of ultrastructure observation by transmission electron microscope (TEM) showed that autophagic vacuoles began to appear in lysosomes of hepatopancreas after 6 h and 24 h of hypoxia, suggesting that acute hypoxic stress could induce the formation of autophagosomes. The results of this study may provide a theoretical reference for understanding the regulatory mechanism of M. nipponense in response to hypoxic stress.
Establishment and application of SYBR Green I real-time fluorescence quantitative PCR for detection of Anguillid herpesvirus
Yingying LI, Jinxian YANG, Xi CHEN, Qiang CHEN, Tieying SONG, Junqing GE
Accepted Manuscript  doi: 10.11964/jfc.20200712326
[Abstract](53) [FullText HTML](29) [PDF 6251KB](5)
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China owns the largest eel culture industry in the world. Since 1990s, "mucus sloughing and hemorrhagic septicemia disease" has become one of the main epidemic diseases of cultured juvenile eel, with typical symptoms of "mucus sloughing", "red head" and "hemorrhagic septicemia", and high morbidity and mortality. The disease could also be found in adult eels with typical symptoms of "hemorrhagic septicemia", resulting in a huge number of deaths, and enormous economic losses to the industry. Cultivation experience showed that the disease might be caused by viral pathogen. We had Anguillid herpesvirus 1 (AngHV) isolated from the clinical samples of the disease. Further pathogenicity and epidemiological analysis showed that AngHV was the pathogenic agent of eel "mucus sloughing and hemorrhagic septicemia disease". A rapid and sensitive detection method for AngHV is of great significance for the early diagnosis, prevention and control of AngHV disease. Real-time fluorescence quantitative PCR (qPCR) method has been widely used in pathogen detection. To establish SYBR Green Ⅰ qPCR method for detection of AngHV, the sequence of AngHV ORF49 was amplified by PCR and cloned into pET-32a vector to construct the standard plasmid pET-32a-ORF49. Primers were designed according to ORF49 sequence, and a SYBR Green Ⅰ qPCR method was developed for AngHV detection using serially diluted standard plasmid as templates, then the sensitivity, repeatability, specificity and application effects of the method were evaluated. The results showed that the cycle threshold value(CT) of the qPCR assay had a well linear relationship with the copy number of the standard plasmid, the correlation coefficient (R2) of the obtained standard curve was 0.999, and the amplification efficiency was 100.855%. The melting curve analysis showed that there was only one melting peak with Tm values of 88.34-88.95 °C. Amplication specificity analysis indicated that the method could specifically detect AngHV, and had no amplification of Cyprinid herpesvirus 3 (CyHV-3), Rana Grylio virus (RGV) and Eel iridovirus (EIV). The coefficient of variation within and between groups was less than 1% and 2%, respectively, which indicated that the method was repeatable. The qPCR method could detect a minimum of 10 viral copies with higher sensitivity than conventional PCR method, which has detection limit of 1 000 copies. Application analysis indicated that AngHV could be detected in the main tissues of AngHV infected Anguilla Anguilla with 5.70×107 copies in gill, 1.91×106 copies in mucus, 1.31×106 copies in fin, 3.31×104 copies in heart, 1.75×104 copies in intestine, 1.25×104 copies in kidney, 6.51×103 copies in skin, 6.26×103 copies in muscle, 6.13×103 copies in brain, 2.48×103 copies in liver and 1.81×103 copies in spleen. The amounts of virions in gills, fins and skin mucus were significantly higher than those in other tissues. The positive detection rate of the qPCR method for the 25 suspected eel "mucus sloughing and hemorrhagic septicemia disease" samples was 96%, while that of the conventional PCR method was only 76%. In conclusion, the established SYBR Green I qPCR method has high sensitivity, strong specificity and good repeatability, and can be used for rapid and quantitative detection of AngHV, which would be helpful for the prevention and control of eels "mucus sloughing and hemorrhagic septicemia disease".
Isolation, identification and pathogenicity of Flavobacterium psychrophilum from Oncorhynchus mykiss
Jingru CHAI, Di WANG, Tongyan LU, Yongsheng CAO, Shaowu LI
Accepted Manuscript  doi: 10.11964/jfc.20200512260
[Abstract](60) [FullText HTML](34) [PDF 6861KB](6)
Abstract:
As the causative agent of bacterial cold-water disease (BCWD), Flavobacterium psychrophilum mainly infects juvenile salmonids and causes great economic loss in salmonid aquaculture worldwide. F. psychrophilum is characterized by a broad geographical distributions and hosts, inducing typical clinical signs of caudal peduncle erosion, skin ulcerations, pale gills, enlarged spleen, ascites and spiral swimming behavior in diseased fish. Although studies have been carried out on the epidemiology and pathogenicity of this bacterium in many countries, there are still lack of any reports on F. psychrophilum strains isolated in cultured salmonids in China. In the present study, two pathogenic bacterial strains (CH06 and CH07) were isolated from the muscle lesions of diseased rainbow trout (Oncorhynchus mykiss) using a polyphasic approach. The results indicated that CH06 and CH07 isolates had an egg-like appearance on TYES agar, producing flexirubin-like pigments, and positive for oxidase and catalase. It can hydrolyze gelatin and casein, cannot hydrolyze starch or use fructose, galactose and esculin. The results of 16S rRNA alignment suggested that the homology of CH06 and CH07 isolates with the F. psychrophilum reference strain NBRC 15942 strain were 99.35% and 99.42%, respectively. Based on the biochemical and molecular characteristics results, CH06 and CH07 isolates were identified as F. psychrophilum. The multiplex PCR method was used to identify the serotypes of CH06 and CH07 isolates as type 1 (Fd type). MLST analysis indicated that the genotypes of CH06 and CH07 isolates were ST-12 and ST-78, respectively, both belonging to CC-ST10. The artificial infection results indicated that CH06 and CH07 isolates were highly pathogenic to juvenile rainbow trout with the LD50 values of 7.1 × 105 and 1.1 × 105 CFU/mL, respectively. The dosage of the challenge was inversely proportional to the time when the clinical signs appeared. F. psychrophilum was successfully re-isolated from muscle, spleen of artificial infected fish. Histopathological changes showed that the hepatocytes of the diseased fish were swollen and vacuoles degenerated. Some hepatocytes were lysed and necrotic and the nucleus was dissolved. The spleen was congested and hemorrhagic with reduced amounts of the lymphocytes and increased amounts of the red blood cells and the hemosiderin. The muscle fiber gap was widened and broken, uneven bending. Parts of the muscle cell sarcoplasmic dissolution was honeycomb-like. CH06 and CH07 isolates exhibited slightly different resistance profiles to 10 antibiotics. They were both highly susceptible to ampicillin and trimethoprim-sulfamethoxazole, while CH06 isolate was reduced susceptible to enrofloxacin and florfenicol and CH07 isolate was moderately susceptible to enrofloxacin and florfenicol. This is the first report on the biological characteristics of F. psychrophilum isolates recovered from cultured O.mykiss in China, expecting to provide scientific support towards the prevention and control of BCWD in salmonid aquaculture.
Research progress of matrix proteins in Hyriopsis cumingii
Li YUAN, Xiaojun LIU, Zhiyi BAI, Jiale LI
Accepted Manuscript  doi: 10.11964/jfc.20200612302
[Abstract](92) [FullText HTML](61) [PDF 6163KB](15)
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Shell and pearl are highly ordered biominerals formed by calcium carbonate under the control of organic matrix, composed of shell matrix proteins, sugars and lipids. Shell matrix proteins play significant roles in the formation of shells and pearls. It is very important to study the matrix proteins of Hyriopsis cumingii for revealing the formation mechanism of pearls and cultivating high quality pearls.In this paper, 26 matrix proteins related to the formation of the cuticle, prism layer and nacreous layer of H. cumingii were introduced. The structural characteristics of these matrix proteins were analyzed, including the amino acid composition, primary structure and advanced structure. The roles of these matrix proteins in biomineralization were also introduced, including participating in the deposition of calcium carbonate, the formation of organic framework, the regulation of crystal morphology, the regulation of shell coloring and the correlation with pearl weight.
Effect of dietary choline level on growth performance, body composition and serum antioxidant activity of juvenile largemouth bass (Micropterus salmoides)
Yue ZHOU, Weilong WANG, Songlin LI, Hongyu LYU, Song ZHANG, Naisong CHEN, Xuxiong HUANG
Accepted Manuscript  doi: 10.11964/jfc.20200812380
[Abstract](149) [FullText HTML](93) [PDF 6523KB](20)
Abstract:
An experiment was conducted to investigate the effects of dietary choline content on growth performance, body composition, and serum antioxidant activity of juvenile largemouth bass, Micropterus salmoides. Graded choline chloride levels of 0, 700, 1 400, 2 100 and 2 800 mg/kg were supplemented to basal diet to formulate five isonitrogen and isoenergy practical diets containing choline of 2 369.57 (control group), 2 716.90, 2 993.49, 3 443.60 and 3 799.05 mg/kg, respectively. Each diet was randomly assigned to triplicate cages of 20 fish with an initial average weight of (20.00±0.10) g for 56 days. The results showed that the weight gain rate (WGR) and specific growth rate (SGR) of the fish first increased and then decreased with the increase of dietary choline chloride, and reached the maximum when the dietary supplementation was 2 100 mg/kg, which were significantly higher than those of the control group. The survival rate (SR), hepatopancreas somatic index (HSI), viscera somatic index (VSI), and condition factor (CF) of the fish were not significantly affected by dietary choline chloride supplementation. When the dietary choline chloride supplementation reached 2 100 mg/kg or above, the lipid contents in muscle and liver of the fish were significantly decreased than those in control. Compared with the control group, the total antioxidant capacity, superoxide dismutase and catalase activities were significantly increased and the content of malondialdehyde in serum was significantly decreased in the groups which were dietary supplemented 1 400 mg/kg, 2 100 mg/kg and 2 800 mg/kg choline chloride. The maximum of lysozyme activity and minimum of aspartate aminotransferase activity appeared in the group treated with dietary choline chloride of 2 100 mg/kg the dosage was, which were significantly different from those of the control group. All these results indicated that the suitable dietary choline chloride supplementation could significantly improve growth performance, reduce liver fat content, and enhance the serum's antioxidant capacity. Regression analysis showed that the recommended amount of choline chloride in the practical diet of juvenile largemouth bass was 2 008.50 ~ 2 398.16 mg/kg (the dietary choline content was 3 432.09 ~ 3 530.23 mg/kg).
Cloning and characterization of homologue of mitotic arrest deficient 2 from Pyropia haitanensis and its expression analysis during parthenogenesis
Chenhui ZHONG, Zhongyan HUAN, Longchen TANG, Zhen LU, Qi LIN, Xinghong YAN
In Press  doi: 10.11964/jfc.20200112129
[Abstract](390) [FullText HTML](167) [PDF 2630KB](20)
Abstract:
To investigate the role and molecular mechanism of diploidization of cells during the parthenogenetic development of female gametophyte in Pyropia haitanensis, a cDNA sequence of homologue of mad2 was isolated and its expression profile at different developmental stages of parthenogenesis was characterized. In this study, the cDNA of Ph-mad2 spans 672 bp that encodes a protein of 223 amino acids (aa) with a predicted molecular weight of 23.8 ku. The deduced protein sequence of PhMAD2 has a typical HORMA domain and conservative serine and threonine phosphorylation sites. Phylogenetic analysis revealed that evolutionary status of P. haitanensis was extremely related to the fungi from Phycomycetes, such as Saprolegnia diclina and S. parasitica. Quantitative real-time PCR (qRT-PCR) analysis showed that the expressions of Ph-mad2 at reproductive cell development stage (RDS) and parthenospore development stage (PDS) with diploid carpogonium-like cells and carpospore-like cells were significantly down-regulated compared with that at vegetative cell proliferation stage (VPS) with haploid vegetative cells, while its expression profiles were up-regulated in the later stages of parthenosporophyte formation stage (PFS) and parthenosporophyte growth stage (PGS), in which the diploid carpospore-like germlings and parthenosporophytes underwent normal mitosis. These results suggested that Ph-mad2 reduction potentially prevented the formation of spindle assembly checkpoint (SAC) at mitotic cells during the early stages of parthenogenesis, and triggered their development of diploidization. These results provide important information for revealing the mechanism of spontaneous chromosome doubling in the parthenogenesis of P. haitanensis.
Community structure of epiphytic macroalgae on mussel culture rafts in Gouqi Island
Shouyu ZHANG, Xiao CUI, Zhenghua WANG, Kai WANG, Xiaopeng CHENG, Shurong LIU, Hui SHEN
In Press  doi: 10.11964/jfc.20200512257
[Abstract](485) [FullText HTML](239) [PDF 3386KB](53)
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Macroalgae that grow naturally on the artificial rafts of shellfish culture, have attracted much attention due to their high coverage, high biodiversity, and large biomass, as well as the following ecological side effects of the formation of amphipods such as gammaridea and caprellidae, and the microbial on the leaves communities. In order to understand the characteristics of the species composition, distribution pattern and seasonal variation of macroalgae in the shellfish raft culture area, the epiphytic macroalgae on the mussel rafts in Gouqi Island in spring (May), summer (August), and autumn (November) of 2018, and winter (February) of 2019 were sampled and analyzed. The results showed that 49 species of epiphytic macroalgae belonged to 11 orders, 20 families, 33 genera. In terms of seasonal variation, the number of species was the highest in autumn (29 species), the lowest in spring (20 species), with an average of 23 species; the seasonal variation of average biomass was the highest in summer (5529.40 g/m2), and the lowest in autumn (2340.45 g/m2). The annual average value was 3345.06 ± 1480.40 g/m2; the horizontal distribution of species number and biomass were gradually decreasing from the inside to outside of the culture zones; the highest index of epiphytic macroalgae diversity (H') was autumn (2.30). The lowest is summer (1.87), the annual average was 2.07 ± 0.18; there were 13 dominant species in the epiphytic macroalgae community, the highest in autumn (8 species) and the lowest in summer (5 species), with an average of 6 species. The dominant species that existed throughout the year were Jania adhaerens and Hypnea boergesenii; among the dominant epiphytic macroalgae, the maximum and minimum niche breadth occurred in autumn, they were Hypnea boergesenii (2.214) and Sargassum horneri (0.739); the maximum and minimum values of niche overlap occurred in autumn, and they were Sargassum horneri - Gracilaria textorii (0.861) and Grateloupia turuturu - Sargassum horneri (0). The present study has shown that the existence of large-scale raft culture can prolong the growth period of red algae such as Grateloupia livida and Hypnea boergesenii, and increase the habitat range of brown algae such as Sargassum horneri, thus changing the community structure of macroalgae in the culture area, which is conducive to maintaining a higher level of annual primary productivity and the production of macroalgae debris in the sea area, and provides new ideas and important scientific basis for the construction of seaweed beds in the process of marine ranch construction.
Effects of the growth, gonadal development and muscle quality on Eriocheir sinensis under the monomer culture with formula feed and frozen fish
Wei Feng, Hui Li, Yongkai Tang, Shengyan Su, Meiyao Wang, Jianlin Li, Juhua Yu
Accepted Manuscript  doi: 10.11964/jfc.20200512261
[Abstract](246) [FullText HTML](121) [PDF 2114KB](23)
Abstract:
In order to study the effect of formula feed and frozen fish on the breeding performance and nutritional status of Eriocheir sinensis, this experiment analyzed the growth performance, gonadal development and nutrient composition of monocultured Chinese mitten crab by continuous sampling, and further compared the FBI, WGR, SGR, SR and MI. The results showed that: ① In terms of survival rate, the formula feed group was significantly higher than the frozen fish group, while there was no significant difference in the FBI, WGR, SGR and MI between the two groups. At different stages of molting, the formula feed group of the body weight was smaller than the frozen fish group, and the differences between the two groups after the third molting was significant; the weight gain rate was different between the female and male crabs, and the weight gain rate of formula feed group in the female crab was significantly smaller than that of the frozen fish group after the second molting, while the male crabs in the two stages after the first and fourth molting were significantly larger than the frozen fish group. ② The hepatopancreas index was 3.59% and 4.45% under the formula feed and frozen fish groups, respectively, the gonadal index was 3.20% and 2.25%, and the hepatopancreas index and gonadal index were not significant differences under the two groups. ③ In terms of muscle amino acid content, the total amino acids, total essential amino acids and total flavor amino acids in the formula feed group was significantly smaller than that of the frozen fish group; from a single amino acid, the lysine and arginine content of the formula feed group was significantly smaller than that of the frozen fish group, and the content of proline is significantly greater in formula feed than the frozen fish group. ④ In terms of muscle fatty acid content, the highly unsaturated fatty acid and DHA+EPA content of the formula feed group was significantly higher than the frozen fish group; from the perspective of a single fatty acid, in the monounsaturated fatty acid C16:1 and C18:1n-91 content of the formula feed group was significantly smaller than the frozen fish group, but in the polyunsaturated fatty acid ARA and DHA of formula feed group was significantly higher than the frozen fish group. Studies have shown that the formula feed group is close to the frozen fish group in the growth performance and muscle quality of the Chinese mitten crab, but the gonad development and survival rate fed with formula feed are better than the frozen fish group under the monomer culture conditions, which has more development advantages on Aquaculture.
Resource status and distribution characteristics of Portunus trituberculatus before summer fishing moratorium ends in Laizhou Bay
Bingqing XU, Wei CHEN, Tiantian WANG, Yanyan YANG, Fan LI, Shude LIU
Accepted Manuscript  doi: 10.11964/jfc.20200312211
[Abstract](250) [FullText HTML](105) [PDF 2327KB](20)
Abstract:
Based on samples collected from bottom trawl surveys before summer fishing moratorium ends in Laizhou Bay from 2010 to 2017, The temporal and spatial distribution of Portunus trituberculatus were studied by silhouette width of clustering, With the released and recaptured data, Some suggestions were advised on the resource status of P. trituberculatus in Laizhou bay. The results show that resources of P. trituberculatus in the south are obviously better than those in the north from the spatial distribution, which can be clustered into near-shore group, far-shore group and deep-sea group by Rousseeuw index. Group assessment is reasonable. The average silhouette width of station clustering was 0.34, the similarity of the stations in the group was higher, and the clustering effect was better; The resources of P. trituberculatus have obvious interannual fluctuation from the temporal distribution, which can be clustered into better group, general group and worse group by Rousseeuw index. Group assessment is reasonable. The average silhouette width of year clustering was 0.15, the year similarity within the group was low, and the clustering effect was poor. In addition, according to Pearson correlation analysis of spatial grouping, we found that the resource status is closely related to the near-shore group, and according to SIMPER analysis of temporal grouping, we found that the resource status mainly depends on the near-shore resources. Therefore, the management and protection of the near-shore group is very important to the resource of P. trituberculatus before summer fishing moratorium ends in Laizhou Bay. When enhancement and releasing of P. trituberculatus, It is suggested that we should not only maintain the releasing scale, but also focus on the protection and management of resources in the early days, effectively increase the near-shore resources and further realize the significance of the enhancement of P. trituberculatus.
Multi-scale analysis on spatial heterogeneity for abundance of Antarctica krill(Euphausia superba) in the South Orkney Islands during summer 2018
Shujie WAN, Guoping ZHU
Accepted Manuscript  doi: 10.11964/jfc.20191112045
[Abstract](316) [FullText HTML](155) [PDF 1841KB](6)
Abstract:
Antarctic krill (Euphausia superba) is a key species in the pelagic ecosystems of the Southern Ocean, and is also an important fishing target in China's distant-water fisheries. A full understanding of its spatial distribution characteristics can provide theoretical support for the sustainable exploitation and conservation of E. superba resources. Based on acoustic data collected by E. superba resource survey in the South Orkney Islands during summer 2018, the survey area was divided into 7 different spatial scales and the geo-statistical method was used to research the spatial heterogeneity of abundance of E. superba in different spatial scales. The result showed that: ①as the spatial scale increased, the nugget and nugget-sill rations gradually decreased, the partial and sill decreased first, then increased and went down again, and 40′×40′ spatial scale had the biggest values; ② under different spatial scales, the semi-variogram was fitted by different models, spherical model had the best performance in 20′×20′ and 50′×50′ spatial scales, exponential model had the best performance in 10′×10′ spatial scale, Gaussian model had the best performance in 30′×30′, 40′×40′ and 60′×60′ spatial scales. And the fitted models showed the spatial auto-correlation was relatively strong; ③ the spatial structure of E. superba showed that, based on anisotropic, 50′×50′ spatial scale had the minimum difference of fractal dimension values, 60′×60′ spatial scale had the biggest difference of fractal dimension values. Based on isotropic 60′×60′ spatial scale had the minimum fractal dimension value, 50′×50′ spatial scale had the biggest fractal dimension value. It is conducted that the abundance of E. superba in the South Orkney Islands had distinct spatial heterogeneity, a number of factors contributed to this phenomenon, including external surrounding factors like ocean flow fields, the change of nutrient and thermocline caused by the exchange of water masses and internal factors like behavior character of E. superba.
Application of non-thermal sterilization technologies in raw ready-to-eat aquatic products
Biansheng LI, Yating HUANG, Zheng RUAN
Accepted Manuscript  doi: 10.11964/jfc.20190911979
[Abstract](325) [FullText HTML](132) [PDF 1171KB](13)
Abstract:
This paper reviews the biological hazards of traditional processing method of raw ready-to-eat aquatic products and the effects of seven non-thermal sterilization technologies on microbial inactivation in raw ready-to-eat aquatic products and their quality, to provide useful information for the application of non-thermal sterilization technologies in the processing of raw ready-to-eat aquatic products. Ultra-high pressure treatment, irradiation and DPCD technology have good sterilization effect, but their influence on the quality of aquatic products is different due to the different kinds of aquatic products, process parameters and other conditions. Ultra-high pressure treatment and DPCD technology will reduce the transparency and increase the hardness of fish and shrimp under high treatment intensity, and irradiation will cause peculiar smell of aquatic products under high treatment intensity. stable chlorine dioxide, ozone, acid electrolyzed water and biological preservatives have good antibacterial and bacteriostatic effect and little impact on the quality of aquatic products, they can be used to extend shelf life and maintain quality.
Characteristics of formation related genes (PyMFG) of monospores and analysis of differential expression in Pyropia yezoensis
Shanshan SONG, Hongchang DING, Xinghong YAN
In Press  doi: 10.11964/jfc.20190311710
[Abstract](379) [FullText HTML](150) [PDF 2804KB](14)
Abstract:
In our study, a complete open reading frame of PyMFG was obtained by RT-PCR based on the sequence of differentially expressed genes (Contig-21827) screened by transcriptome sequencing of Pyropia yezoensis. Sequence analysis showed that the ORF of the PyMFG was 1 224 bp in length and encoded a polypeptide fragment of 407 amino acids with a molecular weight of 46.24 ku, and theoretical pI of 9.08. Domain analysis revealed that the protein contains a conserved TEA domain and a YAP domain, which belongs to the TEA-ATTS superfamily domain. We found that the protein and fungal conidia forming proteins clustered into one large branch with close genetic relationship through multiple sequence alignment and phylogenetic analysis. In addition, the comparison of the ability of releasing monospores and qRT-PCR analysis between different strains indicated that the expression trend of PyMFG in PY26W and PY26W' was highly consistent with macroscopic statistical results, while the trend in PY26R and PY26R' were exactly existed difference. By inference, the gene type and molecular mechanism regulating the formation and release of monospores in the parental (PY26W) and partial parental strain (PY26W') and the female parental (PY26R) as well as partial female strain (PY26R') existed certain difference, leading to the divergence between the macroscopic statistical results of monospores and the qRT-PCR results.
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2021, 45(3): 0-0.  
[Abstract](0) [FullText HTML](0) [PDF 12433KB](0)
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2021, (3): 1-1.  
[Abstract](0) [FullText HTML](0) [PDF 222KB](0)
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Verification of microsatellite markers associated with growth traits in selected populations of grass carp (Ctenopharyngodon idella)
Chengchen YU, Yubang SHEN, Xiaoyan XU, Rongquan WANG, Jiale LI
2021, 45(3): 321-332.   doi: 10.11964/jfc.20200212165
[Abstract](431) [FullText HTML](258) [PDF 5363KB](65)
Abstract:
Growth traits are important economic traits in genetic breeding of aquaculture species. The combination of trait-related molecular markers and breeding can greatly accelerate the breeding process. In our previous research on the growth traits of Ctenopharyngodon idella, using the method of QTL mapping, we found two growth-related QTLs in the linkage group 1. Based on this, two pairs of the two QTL flanking markers (CID391_2, CID1512, CID973_1, and CID254_1) were used to analyze the 480 individuals of C. idella in the Yangtze River system in order to verify these microsatellite markers associated with growth traits in selected populations of grass carp. The results showed that: ① the four microsatellite markers were highly polymorphic in this population (PIC> 0.50), among which the number of observed alleles (Na) at each locus was 12 to 23, and the number of effective alleles (Ne) was 4 to 12, the observed heterozygosity (Ho) was 0.607-0.904, and the expected heterozygosity (He) was 0.751-0.902; ② by means of One-Way Analysis and multiple comparisons of the genotypes and the growth traits (body weight and body length) in the selected populations of C. idella, CID391_2 showed no significant difference between genotypes and the two growth traits in female individuals, while there was significant difference between genotypes and the two growth traits in male individuals; CID1512, CID973_1 and CID254_1 showed significant differences between each genotype and the two growth traits in female or male individuals. This study has verified microsatellite markers associated with growth traits in selected populations of C. idella. It will provide a basis for further research on QTL mapping in C. idella and the practice of molecular marker assisted selection (MAS) based on QTL mapping.
RNA sequencing to identify genes and SNP markers associated with growth traits in Ctenopharyngodon idella
Xue SUN, Shengjie LI, Peng JIANG, Jinxing DU, Jiahui ZHOU, Junjie BAI
2021, 45(3): 333-344.   doi: 10.11964/jfc.20190911988
[Abstract](438) [FullText HTML](210) [PDF 5499KB](73)
Abstract:
In order to identify genes associated with growth traits and SNP (Single nucleotide polymorphism) markers in Ctenopharyngodon idella, RNA-Seq (RNA Sequencing technology) was used to analyze the transcriptomes of liver, muscle and brain tissues of fast-growing and slow-growing C. idella groups. A total of 314.65 million clean reads were gained for the fast-growing and slow-growing groups, and 34 147 unigenes were assembled, with an average length of 1 060 bp, of which 30 751 genes were annotated. 1 013, 552, and 372 significant differentially expressed genes were screened in liver, muscle, and brain tissues, respectively, of which 4 580 SNP markers were detected. Then, the polymorphisms of 34 SNP markers was detected and validated with SNaPshot technique in the extreme populations of growth traits of C. idella (n=300), and among which, 30 SNPs (83.24%) were successfully genotyped. A general linear model was used to analyze the correlation between 30 SNPs and growth traits. The results showed that at the position of Unigene00810126-8014, the body weight, body length, body height, head length and caudal peduncle length in individuals with CC genotype had significantly higher values than TT genotype. At the position of Unigene00810126-2903, the body weight of AA genotype was significantly higher than those with GG genotype. At the position of Unigene00870394-525, individuals with the AA genotype had significantly higher values in body weight and body height than those with GG genotype. At the position of Unigene02938762-011628, TT and CC genotypes had significant differences in body mass, body length and head length traits. Besides, other SNPs loci were not significantly correlated with growth traits. The four selected markers were located at Somatolactin alpha (slα), Early growth response protein-1 (egr-1) and Myosin heavy chain (myh) genes. The average polymorphism information content (PIC), average expected heterozygosity (He) and average observed heterozygosity(Ho) of 8 EST-SNP markers in C. idella population were 0.300, 0.377 and 0.363, respectively, indicating that genetic diversity of C. idella breeding population had relatively high level. In conclusion, 1 937 differentially expressed genes and four SNP markers related to growth traits were obtained, which can be used as candidate genes and for molecular marker-assisted selection of C. idella, and can also be used in subsequent breeding work.
Genetic structure of D-loop sequence in Acanthopagrus latus
Zhenhan HE, Shan XIAO, Shaoshao WANG, Huifang CHEN, Shaoping SU, Yongzhen ZHAO, Chunling YANG, Digang ZENG, Weilin ZHU, Xiuli CHEN, Huawei MA, Weiming JIANG, Qingyun LIU, Qiangyong LI, Min PENG
2021, 45(3): 345-356.   doi: 10.11964/jfc.20191212113
[Abstract](263) [FullText HTML](130) [PDF 5643KB](15)
Abstract:
Acanthopagrus latus is a valuable marine fish and an important economic fish for marine aquaculture along the South China coast. In order to ascertain the genetic diversity and genetic differentiation status of A. latus populations distributed along the South China coast, in this study, the mitochondrial control region (D-loop) gene sequences were used to analyze the genetic diversity and population genetic structure of eight A. latus populations from the South China coast, including Xiamen, Shanwei, Yangjiang, Haikou, Sanya, and Beihai, Qinzhou, Qinzhou and Fangcheng. The results showed that 320 D-loop sequences from the eight A. latus populations were 947-958 bp in length. Totally, 29 insertion or deletion sites and 210 mutation sites (including 142 parsimony information sites and 68 single mutation sites) were detected in the D-loop sequences; overall mutation sites, haplotype number, and haplotype diversity (Hd), average nucleotide difference and nucleotide diversity (π) were 210, 268, 0.998 43, 14.790 65 and 0.01570, respectively. The results of cluster analysis showed that all populations were clustered into two groups, east and west separated by Qiongzhou Strait. The genetic differentiation coefficient (FST) between the eight populations was –0.01268-0.466 74, and gene flow (Nm) was 0.571 26~∞. The variance analysis showed that the genetic variation between groups, between populations within groups, and between individuals within populations were 33.42%, 0.32%, and 66.26%, respectively. Neutral tests showed that Tajima’s D was –1.694 77 (P = 0.010 00) and Fu ’s Fs was –23.683 39 (P = 0.00600), indicating that A. latus along the South China coast experienced a population expansion event. This study indicated that the genetic diversity of A. latus populations along the South China coast was relatively rich. This study suggested that A. latus populations can be divided into two management units by the Qiongzhou Strait, the east group and the west group for germplasm protection. Based on such monitoring results, some countermeasures and suggestions for the future restoration strategy were proposed so as to provide a theoretical basis for restoring and protecting the A. latus populations, and meanwhile it can also provide some scientific guidance for artificial breeding and value-added release in natural sea area.
Expression pattern and localization analysis of cbx2 during embryonic and gonadal development in the medaka (Oryzias latipes)
Qinghe CHAO, Fengfeng SHEN, Zhenxi CAI, Junling ZHANG
2021, 45(3): 357-364.   doi: 10.11964/jfc.20200112133
[Abstract](326) [FullText HTML](196) [PDF 5514KB](40)
Abstract:
CBX2 (Chromobox homolog2), as a key member of the Polycomb Group protein (PcG) family, plays an important role in gonadal development. Mice lacking cbx2 showed defects in gonads (both ovary and testis) development, and some mice have exhibited male-to-female sex reversal. But little is known about the function of cbx2 in gonadal development of fish. In this study, we used Oryzias latipes, a model organism, to investigate the expression of cbx2 during embryonic and gonadal development by real-time PCR and immunohistochemistry. Real-time PCR results showed that cbx2 was highly expressed in embryos at gastrula, neurula and organogenesis stages. In bisexual gonads, cbx2 had a relatively high expression in testis. Immunohistochemistry results revealed that cbx2 mRNA was mainly localized in spermatogonia and spermatocytes in testis. And cbx2 was also predominately observed in oocytes at stages I, II and III in ovary. In order to further study the function of cbx2, we used microinjection technology to knock out cbx2. The results showed that the expression of cbx2 was significantly decreased after injecting siRNA, and thus the expression of sox9 (SRY-related HMG box 9) was down-regulated, whereas the expression of foxl2 (Forkhead transcriptional factor 2) increased. This indicated that cbx2 was not only involved in embryonic development but also played a role in gonadal differentiation and gametogenesis in O. latipes.
Comparative transcriptome analysis of the gonad of the lacustrine goby (Gobiopterus lacustris)
Zhongdian DONG, Xueyou LI, Chengqin HUANG, Hairui ZHANG, Shunkai HUANG, Ning ZHANG, Yusong GUO, Zhongduo WANG
2021, 45(3): 365-380.   doi: 10.11964/jfc.20200312214
[Abstract](89) [FullText HTML](47) [PDF 6890KB](12)
Abstract:
Lacustrine goby (Gobiopterus lacustris) belongs to a genus of gobies that are small in size and endemic to freshwater, brackish waters or coastal environments around the Indian and Pacific oceans. G. lacustris has almost transparent skin and clearly visible internal organs, making it an ideal fish model for potential research in development, reproduction and other fields. Here, we constructed gonadal transcriptomes of G. lacustris using Illumina sequencing for the first time and identified genes that may be involved in gonadal development, gametogenesis and reproduction. Row reads were assembled into 62 573 unigenes with N50 value of 3 082 bp and a mean length of 1 869 bp. 41 480, 32 848, 37 500, 35 394, 18 318, 35 394 and 27 009 unigenes were successfully annotated in NR, NT, SwissProt, PFAM, KOG, GO and KEGG databases, respectively. Gene expression patterns in the ovary and testis were compared, and 10 954 differentially expressed genes (DEGs) were identified. Among these genes, 8 571 were up-regulated in the ovary, and 2 383 were up-regulated in the testis. qPCR analysis of 14 selected genes showed patterns consistent with the transcriptome results. Numerous DEGs involved in gonadal development and gametogenesis were identified, including foxl2, dmrt1, cyp19a1a, inha, inhb, sycp2, zglp1, tdrp, zps and esra. Using GO and KEGG enrichment analyses, pathways involved regulation of gonadal development and gametogenesis, such as “ubiquitin mediated proteolysis”, “oocyte meiosis”, “progesterone-mediated oocyte maturation”, “p53 signaling pathway” and “PI3K-Akt signaling pathway”, were also identified. In addition, 38 550 simple sequence repeats were identified from 20 517 SSR containing sequences, and 192 450 single nucleotide polymorphisms were detected. This study denotes the first gonadal transcriptomic analysis of G. lacustris and provides a valuable dataset for future functional analysis of sex-associated and molecular marker-assisted selections in G. lacustris.
Sequence structure and immune function of signal transduction and transcriptional activator STAT1 of barbel chub (Squaliobarbus curriculus)
Hong LUO, Yaoguo LI, Dongfang LI, Jun ZOU, Tiaoyi XIAO
2021, 45(3): 381-395.   doi: 10.11964/jfc.20191112082
[Abstract](382) [FullText HTML](181) [PDF 6499KB](46)
Abstract:
The grass carp hemorrhage disease poses a serious threat to the long-term expansion of the aquaculture industry. The barbel chub (Squaliobarbus curriculus) could hybrid with the grass carp to produce progeny possessing resistance to GCRV infection and, therefore, are considered valuable genetic resources for studying the molecular mechanisms of grass carp hemorrhage. To investigate the immune function of barbel chub STAT1 (ScSTAT1) against GCRV infection, the RACE (rapid amplification of cDNA ends), qPCR (quantitative polymerase chain reaction) and RNAi (RNA interference) techniques were applied to obtain the full-length cDNA sequence of ScSTAT1, to detect its expression profile in healthy and GCRV-infected tissues, and to explore its basic immune function. The ScSTAT1 was 2 922 bp in length and encoded a protein of 718 amino acid residues. The ScSTAT1 contained conserved domains for STAT_int, STAT_alpha, STAT_binding and SH2. Phylogenetic analysis revealed that the ScSTAT1 was closely clustered with the homologue from Ctenopharyngodon idella, forming an extended clade with those from Mylopharyngodon piceus, Carassius auratus and Tachysurus fulvidraco. Compared to the homologues from mammals and reptiles, ScSTAT1 lacked a C-terminal TAD domain where a serine phosphorylation site is present. The expression level of ScSTAT1 was shown to be the highest in the spleen among the tissues analyzed, with the lowest level detected in the liver. Treatment of fish with LPS, Poly I:C or GCRV resulted in upregulation of expressions of ScSTAT1 in the spleen and kidney. At 12 h post GCRV infection, the ScSTAT1 expression was down-regulated in the spleen, followed by increases. At 12 h and 72 h post GCRV infection, in trunk kidney the expression levels of ScSTAT1 were significantly higher than those in the control group. In the S. curriculus fin cell (ScF) line, knockdown 60% of ScSTAT1 expression by RNA interference led to decreased expression of IRF3, IRF9 and Mx at 48 h post GCRV infection. The results of the present study proved that ScSTAT1 participated in the signal transduction of the IFN system and played a key role in immune reaction against GCRV infection. The results also provide research basis for further study on the functions of ScSTAT1 in disease resistance in fish.
Transcriptome analysis of Procambarus clarkii to screen genes related to ovary development, immunity and growth
Hongxia JIANG, Huifen LIU, Xiao MA, Limin WU, Xianghui KONG, Xuejun LI
2021, 45(3): 396-414.   doi: 10.11964/jfc.20200612284
[Abstract](465) [FullText HTML](254) [PDF 5958KB](55)
Abstract:
Procambarus clarkii is one of the freshwater lobsters which has important economic value in China. However, long-term high-density farming and inbreeding have brought many negative effects on the cultivation of P. clarkii , such as slow growth, small size, frequent diseases, and the difficulty of artificial breeding caused by the asynchrony of gonadal development, which have severely restricted the further development of P. clarkii aquaculture. In order to find candidate genes involved in ovary development, immunity and muscle growth of P. clarkii for improving the production performance of this species, the transcriptomes of ovary, hepatopancreas and muscle of P. clarkii were sequenced by a new generation of high throughput sequencing technology. After quality control and assembly, the sequences acquired were blasted against NR, Swiss-Prot, pfam, COG, GO and KEGG databases, and then cluster analyses were performed. In total, 53 006 final unigenes with an average length of 1 194 bp were obtained. Pairwise comparison of sequencing libraries of 3 tissue samples revealed that 20 382 differentially expressed genes (DEGs) were found in ovary vs. hepatopancreas group, 12 753 DEGs were found in hepatopancreas vs. muscle group, 21 629 DEGs were found in muscle vs. ovary group. Gene ontology analysis indicated that some DEGs were annotated into “reproduction”, “reproduction process”, “immune system process” and “growth” GO terms. KEGG pathway analysis showed that some DEGs were enriched in signaling pathways related to ovarian development, immunity and muscle growth. Based on GO functional classification and KEGG pathway analysis, a large number of candidate genes related to ovarian development, immunity and muscle growth of P. clarkii were screened, such as vitellogenin, vitellogenin receptor, Toll-like receptor 2, Toll-interacting protein, myostatin, 5-hydroxytryptamine receptor, etc. The results of this study enriched the gene resources of P. clarkii and could provide basic data for the further genetic breeding and immunity research of this commercial species.
Glycogen content fluctuation and association analysis with polymorphism of gys gene of Sinonovacula constricta in the Zhejiang population
Yanyuan CHEN, Sheng LIU, Jing HE, Hanhan YAO, Zhihua LIN, Yinghui DONG
2021, 45(3): 415-423.   doi: 10.11964/jfc.20200212159
[Abstract](282) [FullText HTML](141) [PDF 5666KB](27)
Abstract:
In order to explore the characteristics of glycogen content in Sinonovacula constricta, the glycogen synthase (sc-gys) gene and its feasibility in molecular marker-assisted breeding, the annual changes of glycogen content were detected in this study. The glycogen content in S. constricta was high between February to June and reached the maximum level in April during the annual cycle. The sc-gys gene has a full-length cDNA of 2 402 bp and an ORF of 2 136 bp, encoding 711 amino acids, with high similarity to orthologs of other animals showing conserved domain of Glycosyltransferase. The results of real-time quantitative PCR showed that sc-gys was mainly expressed in mantle and foot tissues. The expression level of sc-gys in April was significantly higher than that of other months, indicating its close relation to glycogen synthesis. Two SNP loci was tightly associated with glycogen content in the sc-gys exon region from “Yongle NO.1” new strain and wild population of Taizhou, and there was no linkage disequilibrium between the two SNP loci. Glycogen content of individuals with these two genotypes combinations was 11.8% higher than that of the population average. These two SNP loci and proper combination would provide candidate genetic markers for glycogen content genetic improvement of S. constricta.
Investigation into the microstructure and microchemical characteristics of the hard tissues of Acipenser sinensis
Tao JIANG, Chengyou WANG, Hao DU, Shuhuan ZHANG, Hongbo LIU, Qiwei WEI, Jian YANG
2021, 45(3): 424-432.   doi: 10.11964/jfc.20191012033
[Abstract](358) [FullText HTML](154) [PDF 5651KB](22)
Abstract:
Chinese sturgeon (Acipenser sinensis) is an endemic, endangered and protected anadromous fish in China. This fish has been listed as a Category I nationally protected species in China and a critically endangered (CR) species of the International Union for Conservation of Nature (IUCN). Due to the restrictions by several special reasons of this species, e.g., long lifespan, complex migratory process, and precarious resource situation, it is quite difficult to objectively reveal the features of life history, and characteristics of distribution, and dynamics of habitat use (e.g., spawning/nursery site) by some traditional methods. Consequently, introducing more new innovative approaches is needed to achieve new breakthrough on research of migratory ecology and conservation for this species. In the present study, microchemical characteristics of three kinds of hard tissues of A. sinensis (i.e., otolith, dorsal scute, and pectoral fin ray) were studied comparatively by electron probe microanalyses (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) with their microstructure. The results show that otoliths of A. sinensis are loose in structure and contain small sand-like microcrystalline vaterite spherulites with independent core areas. In constrast, the dorsal scute is a stratified tissue while the pectoral fin ray is a relatively compact and uniform tissue. Viewed from the microchemical results of the three hard tissues, the analytical accuracy across all samples was high for Mg, Ti, V, Mn, Cu, Zn, Co, Sr, Ba and Ca with RSD<10%. The z-Scores of habitat element ratios for Co/Ca, Sr/Ca and Ba/Ca in both pectoral fin ray (−0.97-2.16, −0.78-2.56, −0.96-2.41) and otolith (−1.7-0.74, −1.24-0.98, −1.09-1.09) are consistent, while those z-Scores in the dorsal scute (−1.95-2.32, −1.68-2.03, −1.62-2.68) are fluctuative due to its stratification. At the same time, the microchemical maps of Sr, Ca and Ba in these three hard tissues revealed that pectoral fin ray and dorsal scute were uniform color/concentration while different parts of otolith showed different colors/concentrations. Based on the aforementioned findings and we consider practical needs from no lethality, difficulty of sampling and sample preparation process, tissular microstructure composition, and environmental element bioaccumulation. In the present study, the microstructure and microchemical characteristics of three kinds of hard tissues of A. sinensis, i.e., otolith, dorsal scute, and pectoral fin ray, were studied comparatively. The present study suggested that the pectoral fin ray is the best hard tissue material for microchemical study for reconstructing the history of the migration and life cycle of A. sinensis.
Key functional groups selection in marine ranching fishery resources from the Pearl River Estuary
Weiguo ZHOU, Dewen DING, Anning SUO, Weihong HE, Tao TIAN
2021, 45(3): 433-443.   doi: 10.11964/jfc.20191212111
[Abstract](361) [FullText HTML](208) [PDF 5685KB](37)
Abstract:
Functional groups are the foundation of the analysis of food web structure and energy flow in marine ranching ecosystems. Based on filed investigation in Wanshan Islands adjacent sea in 2016 and 2017, and historical data of fishery resources in the Pearl River Estuary, the predominance, biomass and catch rate of fishery resources were studied. The results showed that Caranx kalla, Collichthys lucidus, Metapenaeus joyneri, Eucrate crenata, Coilia mystus, Oratosquilla oratoria, Eucrate solaris and Charybdis acuta were the shared economical species from the top 30 economic species. In terms of feeding habit, seven groups were identified in Pearl River Estuary including zooplanktivores, zooplanktivores/benthivores, benthivores, benthivores/piscivores, piscivores, omnivores, and detritivores. And benthivores (34%) and zooplanktivores (20%) groups were dominant in the Pearl River Estuary. Furthermore, rare fishes, high-yield fishes and shrimp and crab were eventually selected as top economic species of key functional groups in marine ranching fishery resources including Pampus argenteus, E. moara, L. japonicas, N. albiflora, Mugil cephalus, Penaeus monodon , and Scylla serrate . The common features are: (i) native economic species; (ii) great body weight and high yield; (iii) delicious taste and high market value; (iv) capable of artificial reproduction and release; (v) different habitat water layers; (vi) mutualistic. According to tropic levels of these top economical species in food chain, we found that both Epinehelus moara and Nibea albiflora belong to the higher carnivorous species. Epinehelus moara are bottom fishes that mainly feed on small and medium-sized fish, crustaceans and cephalopods, while Nibea albiflora are middle and lower-layer fishes that mainly feed on small and medium-sized fishes (e.g., Decapterus maruadsi, Sardinella aurita ) and shrimps (e.g., O. oratoria, Alpheus japonicas ). In addition, Pampus argenteus, Lateolabrax japonicas and S. serrate belong to the intermediate carnivorous species. To be specific, Pampus argenteus are pelagic fish, mainly feeding on jellyfish, ripple worms, water fleas or other zooplankton. L . japonicas are bottom fishes that mainly feed on fishes (e.g., C.mystus , Setipinna taty ) and crustaceans (e.g., Oratosquilla oratoria. Scylla serrate ) are benthic crustacean and feed on mollusks and small crustaceans. Moreover, M. cephalus inhabits the middle and lower layers and belongs to lower carnivorous species, mainly feeding on debris or diatoms. And Penaeus monodon are bottom-layer omnivorous species that mainly feed on mollusks and zooplankton. In conclusion, we constructed seven key functional groups of marine ranching fishery resources composed of top economic species and organisms in their food chains, including P. argenteus functional groups, Epinehelus moara functional groups, L. japonicas functional groups, N. albiflora functional groups, M. cephalus functional groups, P. monodon functional groups and S. serrata functional groups. The above seven key functional groups can realize poly-dimension utilization of space-time resources in marine ranching, thus are of great importance for sustainable development of marine fisheries and healthy coastal ecosystems.
A numerical study of the effect of relative inflow distance on hydrodynamic characteristics in the single-drain rectangular aquaculture tank with arc angles
Boru XUE, Linping YU, Qian ZHANG, Xiaozhong REN, Chunwei BI
2021, 45(3): 444-452.   doi: 10.11964/jfc.20191112077
[Abstract](272) [FullText HTML](89) [PDF 5790KB](12)
Abstract:
In order to explore the influence of the position of the water inlet device on the hydrodynamic characteristics of the single-drain rectangular arc angle aquaculture tank, a new parameter, the relative inflow distance C/B (C is the horizon distance from inlet to sidewall, B is the width of the rectangular tank) was proposed in this paper, and the complex flow field of near the sewage outlet were analyzed by fluid dynamics characteristics variables, and to measure the effective utilization rate of water in aquaculture tank, the effective utilization coefficient of energy ηe is put forward. Meanwhile based on the Reynolds averaged Navier Stokes (RANS) equation and RNG k-ε turbulence model, a three-dimensional numerical model of rectangular arc angle aquaculture tank was constructed. Computational fluid dynamics simulation technology was used to calculate and analyze the flow field environment in the constructed aquaculture tank. By adjusting the layout position of the inlet system, the flow field in the tank (especially at the bottom) was optimized, and the influence of the optimization of hydrodynamic conditions on the collection and discharge performance of the aquaculture tank system was analyzed. This base case is validated against the experimental velocity measurements using Acoustic Doppler Velocimetry (ADV) at predefined locations across the central vertical plane of the tank. On this basis, the hydrodynamic conditions of the aquaculture tank system were systematically analyzed by hydrodynamic characteristics , such as the average velocity, energy efficiency, velocity distribution uniformity at the bottom of the tank and so on. The numerical simulation results show that the average velocity and energy efficiency can be significantly improved by optimizing the relative inflow distance, which is conducive to the formation of uniform and stable flow field. And increasing the relative inflow distance parameter C/B from 0.00 to 0.05 can effectively improve the flow field characteristics in the aquaculture tank, and setting the relative inflow distance parameter C/B between 0.02 and 0.04 is beneficial to obtain the best flow field conditions for the single channel rectangular arc angle aquaculture tank system.The results show that the ratio parameter C/B in the range of 0.02~0.04 could effectively improve flow field characteristics of the system so as to get better hydrodynamic conditions for circulating aquaculture, and relatively minor construction changes could improve the hydrodynamic conditions of the aquaculture system and open up new ideas for obtaining the hydrodynamic environment conducive to fish welfare and production operation.
Effects of integrated rice-crayfish co-culture on soil fertility and metal element content
Jixin YU, Wei LI, Jiashou LIU, Fei XIONG, Jing YUAN, Tanglin ZHANG
2021, 45(3): 453-461.   doi: 10.11964/jfc.20190711895
[Abstract](220) [FullText HTML](97) [PDF 5476KB](20)
Abstract:
The integrated rice-field aquaculture (IRFA) has been practiced successfully for 2000 years in China. The integrated rice-crayfish (Procambarus clarkii) co-culture (IRCC) has contributed more than 50% of the yield of IRFC, currently. Thus it is necessary to conduct researches on the IRCC, including its’ environmental impacts. As commercial feed feeding is very popular in IRCC practice, one of the potential environmental problems is the effects of feeding on the water and soil quality. Some previous studies have indicated that most nitrogen and phosphorus in the feed deposit in soil of crustacean aquaculture system. While it is not clear whether IRCC can increase nitrogen and phosphorus in soil, even some researches have been done. And it’s also not clear the effects of IRCC on the metal element contents in soil. The purpose of this study was to evaluate the impacts of IRCC in soil fertility (nitrogen, phosphorus and organic matter contents), and metal element contents on soil. Six physicochemical indicators and 11 metal elements contents of three layers of soil (0-10 cm, 10-20 cm and 20-30 cm) of the trench (TRC) and paddy (PRC) of IRCC, and rice monoculture fields (RM, as control) in Qianjiang City, Hubei Province, China, were measured, and the culture ages of the two modes were both 5 years. Contents of soil organic matter (SOM) and available phosphorus (AP) were measured by potassium dichromate heating oxidation-volumetrics, and NaHCO3 extraction, ammonium molybdate-tartaric emetic-ascrbic acid colorimetry method, respectively. Contents of total nitrogen (TN), ammonia nitrogen (\begin{document}$ {\rm{NH}}_4^ + $\end{document}-N), nitrate (\begin{document}$ {\rm{NO}}_3^ - $\end{document}-N) and total phosphorus (TP) were measured by flow injection analysis, and contents of Cr, Cu, Cd, Pb, Zn, Ni, As, Fe, Mg, Ca and Mn were measured by microwave digestion-inductively coupled plasma-mass spectrometry. The contents of Cr, Cd, Pb, Zn, Ni, As and Cu were then evaluated according to the risk screening values for soil contamination of agricultural land in <GB15618—2018>. The results showed that the TN, \begin{document}$$\end{document}AP and TP content of all layers exhibited a trend of PRC > RM > TRC, while SOM (excepting 20-30 cm layer) and NH4+-N of RM > PRC > TRC and \begin{document}$ {\rm{NO}}_3^ - $\end{document}-N of TRC > PRC > RM. The content of Cu, As, Mg and Mn of all soil layers showed a trend of TRC > PRC > RM, while Cd, Pb, Fe and Ca on the contrary, and less significant differences were noted among TRC, PRC and RM for Cr, Zn or Ni, excepting for 0-10 cm longer. According to the risk screening values for soil contamination of agricultural land in <GB15618—2018>, Cr, Cd, Pb, Zn, Ni and As contents were up to standard, while Cu content was generally out of the limits, with over-limit ratios of 14%-46%. The results indicate that integrated rice-crayfish co-culture could increase nitrogen and phosphorus contents in the paddy soil, while decrease those in the trench soil, and SOM content.
Detection, genotyping and pathogenicity of virulence genes in Aeromonas species isolated from diseased freshwater fish
Xiaofang LIU, Yan REN, Defeng ZHANG, Hua GONG, Cunbin SHI, Ouqin CHANG, Houjun PAN
2021, 45(3): 462-471.   doi: 10.11964/jfc.20200312180
[Abstract](385) [FullText HTML](156) [PDF 8633KB](27)
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Aeromonas spp. are gram-negative bacteria that can infect a variety of aquatic and terrestrial animals, including humans and cause motile aeromonad septicemia. The prevalence of Aeromonas spp. in various water and food sources poses a significant public health threat. Aeromonas spp. encompass a diversity of strains or genotypes with varying pathogenic potentials. Many strains are pathogenic, but others are avirulent and produce little harm to the host. The availability of methods to assess the pathogenic potential of Aeromonas spp. would contribute to the improved control and prevention strategies for this bacterial infection. An approach to the direct detection of potentially pathogenic Aeromonas spp. is the use of virulence determinants as genetic markers. To investigate the correlation between virulence genes and pathogenicity of Aeromonas spp., 173 strains of Aeromonas were isolated from different diseased freshwater fish from 2009 to 2018 as the research object. Virulence genes including aer, act, fla, lip, gcaT, exu, ast, alt, eprCAI and ahyB were detected and the bacterial pathogenicity with different virulence genotypes was assessed through intraperitoneal (IP) injection challenged Carassius auratus gibelio (gibel carp). Molecular identification revealed that A.veronii (119/173, 68.8%) and A.hydrophila (50/173, 28.9%) were the prevalent species based on gyrB gene sequencing. The distribution of 10 virulence genes including aer (162/173, 93.64%), act (131/173, 75.72%), ast (55/173, 31.79%), alt (58/173, 33.53%), lip (152/173, 87.86%), exu (154/173, 89.02%), fla (143/173, 82.66%), gcaT (148/173, 85.55%), eprCAI(41/173, 23.70%) and ahyB (51/173, 29.48%) were determined and these strains were sorted into 7 clusters (Ⅰ-Ⅶ) and formed 53 genotypes according to the virulence distribution profile. 8-10 virulence genes were present in 24.86% (43/173) Aeromonas strains, among which 38 strains were identified as A. hydrophila and 4 strains A.veronii. The eprCAI (0/119, 0%), ahyB (19/119, 15.13%), ast (7/119, 5.88%) and alt (24/119, 20.17%) genes were detected from the A.veronii isolates. Most of the Aeromonas strains (94.22%, 163/173) had hemolytic activity. At the challenge dose of 3.0×106CFU per fish, 3 strains of A.veronii (Ⅳ-5, Ⅴ-1 and Ⅵ genotype) and 16 strains of A.hydrophila (Ⅰ, Ⅱ-1, Ⅱ-3, Ⅱ-5, Ⅲ-1, Ⅲ-2, Ⅲ-3, Ⅲ-5, Ⅳ-1 and Ⅳ-2 genotype) were highly pathogenic and the mortality reached 80%-100%.The study suggested that A.veronii was the most prevalent species in the diseased fish. A.veronii isolates had fewer virulence genes and lower pathogenicity than A.hydrophila ones. The result may provide reference for epidemiological investigation of motile aeromonad septicemia and vaccine research.
ROUNDUP
Progress in research of antifouling technology of offshore cage netting
Jiangao SHI, Wenwen YU, Kui ZHAO, Yongli LIU, Lei WANG, Aicai XU, Liqun WANG, Xiangyu CHANG, Yue WANG, Bin SUN, Aiyan SHU
2021, 45(3): 472-485.   doi: 10.11964/jfc.20200512274
[Abstract](753) [FullText HTML](575) [PDF 6466KB](185)
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In offshore cage aquaculture, the fouling organisms attached to netting could be detrimental to cage facilities and the living environment of cage-cultured fish. Due to the wide variety of marine fouling organisms, the various changes in the marine environment, the complex structure of net cage, the safety of farmed fish, and the varying conditions of farmers, the anti-fouling work of net cage is very complicated and difficult. Therefore, the antifouling problem of netting has been a cause for concern in offshore cage aquaculture. This paper briefly introduces the classification and the product characteristics of offshore cages; based on these, it then specifies the cutting-edge of offshore cage antifouling technologies, including manual cleaning method, antifouling coating method, mechanical cleaning method, metal alloy netting antifouling method, box rotation antifouling method, biological antifouling method, and the intrinsic antifouling method of netting, etc. Meanwhile, the antifouling effects of these methods, particularly the good and bad effects compared with manual removal method, are summarized. Underpinned by our research group’s findings regarding cage antifouling, it analyses the different methods listed above and serves as reference for in-depth study of offshore cage antifouling technologies and green development of offshore cage aquaculture. On the basis of summarizing some cage antifouling methods with their advantages and disadvantages, the authors proposed some research proposals directions for cage antifouling technologies. The first is to study the antifouling mechanism of net coatings and metal alloy net, the intelligent technology of the mechanical cleaning machine and the spinning technology for composite fiber with the intrinsic antifouling function. And the second is to create collaborative anti-fouling technology (such as the combination of mechanical removal method and antifouling coating method or other antifouling methods). In China, there is great potential in offshore cage aquaculture, but there is a long way to go in the study of antifouling technologies of offshore cage netting.

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