Deciphering the molecular regulatory mechanisms regulating the reproductive molt of Macrobrachium nipponense through transcriptome analysis of ovaries at different molting stages

The relationship between molting and reproduction has received more attention in economically important crustacean decapods. Molting and reproduction are synergistic events in Macrobrachium nipponense, but the molecular regulatory mechanisms behind them are unclear. In the current study, we performed Illumina sequencing for the ovaries of M. nipponense during molt cycle (pre-molting, Prm; mid-molting, Mm; and post-molting, Pom). A total of 66.57 Gb of transcriptome data, 105,149 unigenes were obtained by sequencing, with an alignment ratio of over 87.57% with the reference genome. DEGs were annotated through Gene Ontology (GO)and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases for gene classification and pathway analysis. Twenty-six molt-related DEGs were obtained by screening and their expression patterns at different molting periods were clustered. KEGG enrichment analysis showed that the pathways regulating M. nipponense molting mainly include mTOR signaling pathway, TGF-beta signaling pathway, insect hormone biosynthesis and Wnt signaling pathway. Our transcriptomic data suggest that these pathways crosstalk with each other to regulate the synthesis and degradation of ecdysone throughout the molt cycle. The current study has deepened our understanding of the molecular mechanisms of crustacean molting and will serve as a basis for future studies of crustacean and other molting animals.