Comparative transcriptome analysis reveals molecular mechanisms of the effects of light intensity and photoperiod on ovarian development in Procambarus clarkii (Girard, 1852).

Procambarus clarkii (Girard, 1852) has important economic value in China and internationally. In this research, the comparative transcriptome analysis was used to reveal molecular mechanisms of influences of photoperiod and light intensity on ovarian development in P. clarkii for the first time. Some genes (such as laminin, collagen, integrin beta, catenin) and pathways (including TGF-beta signaling pathway, focal adhesion, ECM-receptor interaction) associated with ovarian development and oocyte maturation were significantly upregulated. Some genes related to circadian clock (such as CLK, PER) were identified in this research. The results indicated that when light intensity or photoperiod increased, P. clarkii could up-regulate the expression levels of the laminin and collagen, thereby synthesizing related proteins, promoting meiosis of the oocytes, thus increasing the number of oocytes in the ovary. At the same time, P. clarkii could up-regulate the expression levels of integrin beta, integrin alpha 6, and diacylglycerol to synthesize related proteins, thereby promoting the formation of proteins and fats such as triglycerides, these proteins and fats can provide material basis for maturation and development of oocytes, resulting in oocyte maturation and ovarian development. P. clarkii could synthesize related proteins by upregulating expression levels of genes (such as catenin), these proteins or hormones can adhere to other actins (such as integrins), thereby stabilizing the morphology of the oocytes and ensuring normal development. Meantime, the increase in light intensity or photoperiod could cause release GSH and VTG, resulting in oocytes development and maturation. The data in this research can reveal molecular mechanisms of impacts of photoperiod and light intensity on oocyte maturation and ovarian development in P. clarkii, can offer crucial genomic data for studying developmental mechanisms of ovary and oocyte in crustacean.