AUTHOR=Liu Fang , Shi Wenyuan , Ye Haihui , Liu An , Zhu Zhihuang 

TITLE=RNAi Reveals Role of Insulin-Like Androgenic Gland Hormone 2 (IAG2) in Sexual Differentiation and Growth in Hermaphrodite Shrimp

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.666763

DOI=10.3389/fmars.2021.666763

ISSN=2296-7745

ABSTRACT=<p>Insulin-like androgenic gland hormone (IAG) is the most widely known hormone that regulates sexual differentiation in crustaceans. Previously, a transcriptome study described two transcripts of IAGs (<italic>Lvit-IAG1</italic> and <italic>Lvit-IAG2</italic>) in the peppermint shrimp <italic>Lysmata vittata</italic>, a species characterized by a rare reproductive system of protandric simultaneous hermaphroditism (PSH). Herein, we explored the function of <italic>Lvit</italic>-IAG2 via RNA interference (RNAi) experiments, and then compared the functional differences between the two IAGs. We demonstrated that <italic>Lvit</italic>-IAG2 positively regulated the expression of crustacean hyperglycemic hormone (<italic>Lvit-CHH</italic>) in eyestalk ganglion but exhibited no significant effect on the expression of gonad-inhibiting hormone (<italic>Lvit-GIHs</italic>) and crustacean female sex hormone (<italic>Lvit-CFSHs</italic>). Besides, <italic>Lvit-IAG2</italic> gene knockdown caused degeneration in appendices masculinae (AM) and suppressed germ cells at the secondary spermatocyte stage. Moreover, silencing the <italic>Lvit-IAG2</italic> gene impeded ovarian development, including smaller previtellogenic oocytes, and lower expression of <italic>vitellogenin</italic> (<italic>Lvit-Vg</italic>) gene in hepatopancreas and <italic>vitellogenin receptor</italic> (<italic>Lvit-VgR</italic>) gene in the ovarian region. Notably, silencing the <italic>Lvit-IAG2</italic> gene impeded individual growth of the species. Collectively, findings from this study demonstrate that <italic>Lvit</italic>-IAG2 and <italic>Lvit</italic>-IAG1 coordinatively function to modulate sexual differentiation in <italic>L. vittata</italic>; meanwhile, <italic>Lvit</italic>-IAG2 stimulates the growth of the PSH species.</p>