AUTHOR=Zhao Yan-Fei , Wen Qi-Qiao , Ao Chun-Mei , Wang Wei , Shi Li-Li , Wang Cheng-Gui , Chan Siuming-Francis 

TITLE=Ecdysis Triggering Hormone, Eclosion Hormone, and Crustacean Cardioactive Peptide Play Essential but Different Roles in the Molting Process of Mud Crab, Scylla paramamosain

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.855391

DOI=10.3389/fmars.2022.855391

ISSN=2296-7745

ABSTRACT=<p>Molting behavior in insects is controlled by the ecdysis triggering hormone (ETH), eclosion hormone (EH) and the crustacean cardioactive peptide (CCAP). At present, the regulation of molting behavior in crustaceans remains unclear. Here, we studied the roles of <italic>ETH</italic>, <italic>EH</italic>, and <italic>CCAP</italic> in the molt regulation of the crab, <italic>Scylla paramamosain</italic> from their expression pattern and <italic>in vivo</italic> assays. The results showed that transcripts of <italic>ETH</italic>, <italic>EH</italic>, and <italic>CCAP</italic> were mainly localized in thoracic ganglia and fluctuated periodically with the molting cycle. When <italic>ETH</italic> or <italic>CCAP</italic> was knockdown at early premolt stage (D0), molting of crabs was interrupted and all animals died at late premolt stage (D2). While the <italic>EH</italic> gene was knock-down, most crabs were dead before D2. Injection of synthetic peptide for ETH or CCAP rescued <italic>ETH</italic>- or <italic>CCAP</italic>-gene knock-down crabs separately. However, none of peptides could rescue <italic>dsEH</italic>-injected crabs. At D0 stage, knockdown of <italic>ETH</italic> down-regulated the transcriptions of <italic>EH</italic> and <italic>CCAP</italic>; while <italic>ETH</italic> was up-regulated when <italic>EH</italic> was knockdown. At D2 stage, <italic>ETH</italic> transcripts levels were reduced with the injection of <italic>dsEH</italic> but increased with the same dose of <italic>dsETH</italic> as crabs at D0 stage. Co-injection of ds<italic>ETH</italic> and ds<italic>EH</italic> down-regulated <italic>ETH</italic> at D2 stage. Results showed that <italic>ETH</italic>, <italic>EH</italic>, and <italic>CCAP</italic> play essential but different roles in molt regulation in mud crab. In summary, the result of this study contributes to the discovery of different molecular mechanisms between Insecta and Crustacea and may provide insight to develop fishery drugs that helps aquacultured crustaceans to molt successfully.</p>