AUTHOR=Yang Yanan , Xu Yuanfeng , Zhang Peng , Cui Zhaoxia , Bao Chenchang 

TITLE=Comparative Genomic and Transcriptomic Analyses of CHHs and Their Putative Receptors in Scylla paramamosain, Portunus trituberculatus, and Eriocheir sinensis

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.787007

DOI=10.3389/fmars.2021.787007

ISSN=2296-7745

ABSTRACT=<p>Crustacean hyperglycemic hormone superfamily neuropeptides (CHHs) are typical crustacean eyestalk hormones that include the crustacean hyperglycemic hormone (CHH), moult-inhibiting hormone (MIH), vitellogenesis/gonad-inhibiting hormone (VIH/GIH) and mandibular organ-inhibiting hormone (MOIH), which are divided into two subfamilies: type I CHH (included CHH) and type II CHH (consisting of MIH, VIH/GIH, and MOIH). They are involved in various biological activities, such as metabolism, molting, reproduction, and osmotic regulation. Discovery of the ion transport peptide (ITP) in insects expanded the members of CHHs and revealed that CHHs are not restricted to crustaceans. In this study, we focused on three economically important crabs: the mud crab, <italic>Scylla paramamosain</italic>, the swimming crab, <italic>Portunus trituberculatus</italic>, and the Chinese mitten crab, <italic>Eriocheir sinensis</italic>. Their genomes, Pacbio full-length transcriptomic data as well as comparative RNA-seq data were obtained and used to analyze the genomic structures and expression patterns of CHHs and their putative receptors through bioinformatic methods. Two type I CHH members (<italic>CHH1</italic> and <italic>CHH2</italic>) were identified, of which <italic>CHH1</italic> had two splice variants, <italic>CHH1-v1</italic> and <italic>CHH1-v2</italic>. One copy of type II CHH (MIH) was found in <italic>P. trituberculatus</italic> and <italic>E. sinensis</italic>. While most decapods, including <italic>S. paramamosain</italic>, have two copies of type II CHHs (<italic>MIH/VIH</italic>), these <italic>MIH/VIHs</italic> are adjacent to each other on the same chromosome. Besides type I and II CHH, <italic>ITP-like peptides</italic> have also been found in the three crabs, and they are mainly expressed in the eyestalk. Four, five, and three G protein-coupled receptors (GPCRs) were identified in <italic>S. paramamosain</italic>, <italic>P. trituberculatus</italic>, and <italic>E. sinensis</italic>, respectively, which might be putative CHH receptors. These GPCRs were divided into three groups. One group was composed of two contiguous genomic position GPCRs, and they were mainly expressed in the hepatopancreas. These findings provide a basis for further studies on CHHs receptor binding tests and on CHHs/GPCRs signaling pathways.</p>