De novo transcriptome analysis of eyestalk reveals ovarian maturation related genes in Macrobrachium rosenbergii

Abstract

Macrobrachium rosenbergii is a commercially important freshwater crustacean species cultured across the world. The economic benefit of M. rosenbergii industry is closely related with gamete quality which unfortunately is unstable in artificial breeding. Improving gamete quality might be achieved through a better understanding of ovarian maturation, but the molecular mechanism is still unclear. This study presented a transcriptome analysis of eyestalk between ovary undeveloped juvenile M. rosenbergii and ovary maturing adults to identify genes involved in ovarian maturation. Six cDNA libraries were constructed with three biological replicates in each group. More than 44 billion raw reads were obtained from each sequencing library using Illumina HiSeq X Ten sequencing platform and 53,878 unigenes were generated after de novo assembly. A total of 15,792 (29.3%) unigenes were annotated by searching against the public databases including NR, Swissprot, KOG, GO and KEGG databases. The comparative transcriptome analysis identified 4815 significantly differentially expressed genes (DEGs) between two groups in which 2961 genes were up-regulated and 1854 genes were down-regulated. Sixteen DEGs were identified to be candidate genes involved in ovarian maturation including neurohormones, neurotransmitter receptor, insulin-like peptides and related receptors, steroidal hormones, methyl farnesoate (MF) related genes and so on. The function of five genes was further verified using mRNA expression detecting at different ovarian developmental stages. Enrichment analysis revealed 65 significantly changed KEGG pathways, in which 2 pathways (insulin signaling pathway and TGF-beta signaling pathway) showed obvious association with ovarian maturation. Data from this study provided fundamental information about gene expression of eyestalk at different ovarian developmental stages in M. rosenbergii, which might be helpful for revealing the regulation mechanism of ovarian maturation and then further contribute to improving gamete quality in aquaculture.