Proteins and pathways involved in larval attachment and metamorphosis of the three major marine biofouling invertebrates

Marine invertebrates play a crucial role in the structure and function of marine benthic ecosystems worldwide. Most of them have indirect life histories which typically involve a more or less dramatic metamorphosis, a critical developmental process which transfers a pelagic larva into a benthic juvenile. Unfortunately, relatively little attention has been paid to the molecular mechanisms controlling these critical biological processes, particularly on the regulation of protein expression/protein translational modification and the related signal transduction pathway.;In this thesis research, I investigated the protein expression and phosphorylation change during larval attachment and metamorphosis of the two marine fouling invertebrates, the polychaete Hydroides elegans and the barnacle Balanus amphitrite. Additionally, the effects of a potent antifouling compound on these biological processes have also been study at the protein level. Results suggested that: (1) in H. elegans, post-translation modification of tubulins is important for larvae to develop to a stage capable of attachment and metamorphosis; (2) In B. amphitrite, proteins involved in stress regulation and energy metabolism play crucial roles in regulating larval attachment and metamorphosis, while the antifouling compound butenolide may exert its effects by sustaining the expression levels of these proteins.;On the basis of the proteomics results, I studied the NO/cGMP/cAMP pathway in the settling larvae of B. amphitrite and the bryozoan Bugula neritina. Pharmacological treatment results indicated that in both species, NO plays an inhibitory role in regulating larval settlement. Additionally, I demonstrated that the regulatory role of NO is mediated via downstream guanylyl cyclase and cGMP in B. amphitrite. In B. neritina, both cGMP and cAMP have been proved to be the downstream mediators of NO in regulating larval settlement. Importantly, I found that NO exclusively localized at sensory related organs of B. neritina swimming larvae, suggesting the presumptive sensory functions of NO during larval attachment of this species.;Taken together, this study provided a foundation for future comparative proteomics analysis across different species of marine invertebrates, contributed new insight into the regulatory roles of NO signaling during larval attachment and metamorphosis, and suggested a mechanism that might conservatively regulate these critical processes across different phyla of marine invertebrates.