Primary study on the regulation of G-protein coupled receptors and signal pathways in the larval settlement and metamorphosis of the blue mussel Mytilus galloprovincialis

To investigate the internal mechanism of the larval settlement and metamorphosis of the blue mussel Mytilus galloprovincialis,the roles of G-protein coupled receptors (GPCRs) and signal pathways were primarily studied by using their activators and inhibitors together with the inducing control of natural inducer-biofilms.The results showed that the activator of GPCRs (GppNHp) and the inhibitor (GDP-β-S) did not have inductive and inhibitive activities,respectively.This indicated that other cellular action or processes not related to GPCRs may be involved in the larval settlement and metamorphosis of the blue mussel M.galloprovincialis.Six kinds of neuro-pharmaceutical agents except IBMX,which are related to the AC/cAMP pathways and theoretically have inductive activities,did not have active effects at the concentrations of 10^-8-10^-3 M after 48 and 72 h and even presented relatively high neuro-pharmaceutical toxicities.IBMX presented certain inductive activity at the concentration of 10^-4M after 72 h,whereas this was significantly lower and hysteretic compared to that of biofilms which had very high activity after 48 h.Two kinds of activators related to PI/DAG/PKC pathway did not have inductive activity after 48 h and 72 h,but the inhibitor,H-7 showed significant inhibitive effect at the low concentration of 10^-6 M.This inhibitive effect of H-7 disappeared after 72 h and the inhibitive concentration increased to 10^-5 M.By comparing the effective concentrations and time,PI/DAG/PKC signal pathway was confirmed to involve in and regulated the larval settlement and metamorphosis of M.galloprovincialis,whereas AC/cAMP signal pathway may be the minor pathway or just the experimental false result due to the toxicity of the agents.Moreover,the present study utilized biofilms but not artificial inducers which can demonstrate the internal mechanism of larval settlement and metamorphosis under natural conditions.This can also benefit the study of the developmental biology of this species and realize the technique development of anti-biofouling by cutting the signal pathway.