AUTHOR=Jiao Lefei , Dai Tianmeng , Tao Xinyue , Lu Jingjing , Zhou Qicun TITLE=Influence of Light/Dark Cycles on Body Color, Hepatopancreas Metabolism, and Intestinal Microbiota Homeostasis in Litopenaeus vannamei JOURNAL=Frontiers in Marine Science VOLUME=Volume 8 - 2021 YEAR=2021 URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.750384 DOI=10.3389/fmars.2021.750384 ISSN=2296-7745 ABSTRACT=In aquatic animals, light/dark cycle acts as an important biological factor that influences the entire life cycle. Until now, evidence regarding the regulation of physiological metabolic process under different light/dark cycles is limited in Litopenaeus vannamei. In this study, we mainly investigated the effects of different light/dark cycles (12 h light/12 h dark, 0h light/24 h dark) on the hepatopancreas metabolism and intestinal microbiota homeostasis in L. vannamei using multi-omics techniques. One interesting finding was that body color of L. vannamei became darker after 8-week dark treatment. Further hepatopancreas transcriptome analysis identified down-regulated genes involved in regulating nutrition metabolism, body color formation, diurnal rhythm, immune function, hormone levels and post-translational modifications. Intestinal microbiota analysis showed that dark treatment induced alterations in intestinal bacterial abundances in L. vannamei, such as decreased (P<0.05) relative abundance of Formosa, Demequina, Lutimonas, and increased (P<0.05) relative abundance of Ruegeria, Vibrio, Actibacter, Roseovarius, Ilumatobacter and Kriegella at genus level. Microbiota functional analysis demonstrated that dark treatment mainly increased susceptibility of pathogens, decreased nutrition metabolism and influenced circadian rhythm. This study indicated for the first time that constant darkness treatment darken body color, altered hepatopancreas metabolism and intestinal microbiota homeostasis in L.vannamei, which might give potential clues for improving the productive capacities by changing light/dark cycles in shrimp farming.