Comparative transcriptome analysis for identifying genes involved in reproduction of banana shrimp (Penaeus merguiensis).

Characterization of reproduction-related genes is crucial for comprehending molecular mechanisms involved in ovarian development of banana shrimp (Penaeus merguiensis). Here, genes expressed in different ovarian (immature, vitellogenic and mature) stages were characterized by RNA-Seq. In total, 12 libraries were established and 88.56 Gb (6.91-8.04 Gb/sample) clean data were obtained for overall samples. The Q30 values were between 94.14 and 94.86 %. The N50 values were 2763 bp for transcripts and 2536 bp for unigenes. A total of 2208 differentially expressed genes (DEGs) were identified, comprising 1203 up-regulated and 1005 down-regulated genes. Identified genes were annotated and functionally categorized. DEGs in protein synthesis, metabolism and biogenesis levels were abundant suggested that the development of immature ovaries to further stages requires energy and nutrient accumulation. Expression of DEGs in Cellular process, Environmental information processing, Genetic information processing, and Metabolism in immature ovaries increased in vitellogenic ovaries and decreased in mature ovaries. This reflects the rapid accumulation of various proteins during the vitellogenic stage. The identified DEGs in mature ovaries suggest that signal transduction pathways are crucial during the final ovarian maturation of P. merguiensis. Gene expression was further analyzed by qRT-PCR. PmMknk1, PmTtc3 and PmSult1C4 were upregulated in vitellogenic and mature ovaries (P < 0.05). In addition, PmCcnF, PmBmp2, PmFoxA1, PmChst5 and PmVtg were upregulated in mature ovaries (P < 0.05). This suggested their important role in ovarian development and maturation. The information is crucial for further studies on reproductive maturation of P. merguiensis.