Noto Marine Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Ogi, Noto-cho, Ishikawa, 927-0553, Japan.
Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan.
Sci Rep. 2023 May 3;13(1):7204. doi: 10.1038/s41598-023-34159-y.
The snow crab, Chionoecetes opilio, is a giant deep-sea brachyuran. While several decapod crustaceans generally continue to molt and grow throughout their lifetime, the snow crab has a fixed number of molts. Adolescent males continue to molt proportionately to their previous size until the terminal molt at which time an allometric increase in chela size occurs and an alteration of behavioral activities occurs, ensuring breeding success. In this study, we investigated the circulating concentrations of methyl farnesoate (an innate juvenile hormone in decapods) (MF) before or after the terminal molt in males. We then conducted eyestalk RNAseq to obtain molecular insight into the regulation of physiological changes after the terminal molt. Our analyses revealed an increase in MF titers after the terminal molt. This MF surge may be caused by suppression of the genes that encode MF-degrading enzymes and mandibular organ-inhibiting hormone that negatively regulates MF biosynthesis. Moreover, our data suggests that behavioral changes after the terminal molt may be driven by the activation of biogenic amine-related pathways. These results are important not only for elucidating the physiological functions of MFs in decapod crustaceans, which are still largely unknown, but also for understanding the reproductive biology of the snow crab.
雪蟹，Chionoecetes opilio，是一种大型深海短尾十足目动物。虽然几种十足目甲壳动物通常在其一生中持续蜕皮和生长，但雪蟹的蜕皮次数是固定的。未成年雄性会按其先前的体型比例继续蜕皮，直到最终蜕皮，此时螯的大小呈比例增加，并发生行为活动的改变，从而确保繁殖成功。在这项研究中，我们调查了雄性在终末蜕皮前后体内甲基法呢酯（一种十足目甲壳动物的先天保幼激素）（MF）的循环浓度。然后，我们进行了眼柄 RNAseq，以获得对终末蜕皮后生理变化调节的分子见解。我们的分析表明，终末蜕皮后 MF 浓度增加。这种 MF 激增可能是由于编码 MF 降解酶和下颌器抑制激素的基因受到抑制，而后者负调节 MF 生物合成。此外，我们的数据表明，终末蜕皮后的行为变化可能是由生物胺相关途径的激活驱动的。这些结果不仅对于阐明 MF 在十足目甲壳动物中的生理功能（这些功能在很大程度上仍未知）很重要，而且对于理解雪蟹的生殖生物学也很重要。
