Transcriptomic analysis of differentially expressed genes in the molting gland (Y-organ) of the blackback land crab, Gecarcinus lateralis, during molt-cycle stage transitions

Abstract

A transcriptome of the Gecarcinus lateralis molting gland (Y-organ or YO) contained 48,590 contiguous sequences (contigs) from intermolt (IM), early premolt (EP), mid premolt (MP), late premolt (LP), and postmolt (PM) stages. The YO is kept in the basal state in IM by molt-inhibiting hormone (MIH)/cyclic nucleotide-dependent signaling. YO activation in EP requires down-regulation of MIH signaling and activation of mechanistic target of rapamycin (mTOR)-dependent protein synthesis. Transition of the YO to the committed state in MP requires activin/transforming growth factor-beta (TGFβ) signaling. YO repression occurs at the end of LP. A total of 28,179 contigs (58%) showed molt stage-specific changes in gene expression. The largest number of differentially-expressed genes (DEGs) were at the IM/EP (16,142 contigs), LP/PM (18,161 contigs), and PM/IM (8290 contigs) transitions. By contrast, the numbers of DEGs were 372 and 1502 contigs for the EP/MP and MP/LP transitions, respectively. DEG analysis of 23 signal transduction pathways showed significant changes in MIH, mTOR, activin/TGFβ, Notch, MAP kinase, and Wnt signaling. Down-regulation of MIH signaling genes in premolt is consistent with reduced MIH sensitivity in MP and LP. Up-regulation of mTOR signaling genes in IM and premolt stages is consistent with its role in YO activation and sustained ecdysteroidogenesis. Up-regulation of activin/TGFβ signaling genes in EP and MP is consistent with the role of a myostatin/activin-like factor in YO commitment. Notch, MAP kinase, and Wnt DEG analysis may indicate possible crosstalk with the MIH, mTOR, and activin/TGFβ pathways to integrate other inputs to control YO ecdysteroidogenesis.

Effects of temperature on juvenile Dungeness crab,Metacarcinus magister(Dana): survival, moulting, and mTOR signalling and neuropeptide gene expression in eyestalk ganglia, moulting gland (Y-organ), and heart

“…Consistent with previous findings, Y-organ Rheb mRNA levels were positively correlated with ecdysteroid titres, which indicates that Rheb is central to regulating ecdysteroidogenesis through the mTOR pathway (Chang and Mykles, 2011;Das et al, 2018;Shyamal et al, 2018). Expression patterns of the GTPase Mm-Rheb may relate to temperature-dependent mTOR activation and protein synthesis during the moult cycle of juvenile M. magister.…”

“…mTOR-dependent protein synthesis is required for increased ecdysteroid synthesis and secretion in the activated Y-organ. Transcriptional regulation of this pathway takes place not only during moult induction in G. lateralis (Abuhagr et al, 2014b(Abuhagr et al, , 2016Das et al, 2018;Shyamal et al, 2018), but also during naturally occurring moults in M. magister. However, the expression patterns differ between species (no change to up to 10-fold change), and differing degrees of post-transcriptional regulation are likely (Abuhagr et al, 2014b;2016).…”

“…mTOR activity is required for Y-organ activation, as rapamycin inhibits Y-organ ecdysteroid synthesis in vitro and lowers haemolymph ecdysteroid titre in Gecarcinus lateralis induced to moult by eyestalk ablation (Abuhagr et al, 2014b(Abuhagr et al, , 2016. Moreover, mTOR signalling genes, such as Gl-mTOR, Gl-Rheb, Gl-AKT and Gl-S6K, are upregulated in the Y-organ of G. lateralis induced to moult by multiple leg autotomy or eyestalk ablation (Abuhagr et al, 2014b(Abuhagr et al, , 2016Das et al, 2018;Shyamal et al, 2018). Rheb (Ras homolog enriched in brain) is a GTP-binding protein that binds to mTOR and other proteins to form the active mTOR Complex 1 (mTORC1; reviewed in Saxton and Sabatini, 2017).…”

V-ATPase subunit B plays essential roles in the molting process of Chinese mitten crab, Eriocheir sinensis

“…RNA interference of V-ATPase caused molting defect and developmental abnormalities in Periplaneta fuliginosa (Sato et al, 2017). However, although V-ATPase is important, studies on molting regulation in crustaceans are scarce (Das et al, 2018;Nagasawa, 2012;Roegner et al, 2018).…”

CrustyBase: an interactive online database for crustacean transcriptomes

“…Therefore, in acknowledgement to the apparent naming convention of genomics databases, this platform has been released under the name “CrustyBase”, and is accessible at https://crustybase.org . The site currently holds ten public datasets obtained from NCBI Gene Expression Omnibus records and from our own archive, including species such as the ornate spiny lobster Panulirus ornatus {Hyde, 2019 #442}, the Eastern spiny lobster Sagmariasus verreauxi {Ventura, 2015 #139;Ventura, 2015 #64}, the tropical land crab Gecarcinus lateralis [ 16 ], the whiteleg shrimp Litopenaeus vannamei [ 17 , 18 ], the oriental river prawn Macrobrachium nipponense [ 19 ], the marine copepod Temora longicornis [ 20 ], the salmon louse Caligus rogercresseyi [ 21 ] and the water flea Daphnia magna [ 22 ].…”