ABSTRACT
Ovarian development is a key physiological process that holds great significance in the reproduction of the Chinese mitten crab (Eriocheir sinensis), which is an economically important crab species for aquaculture. However, there is limited knowledge for the regulatory mechanisms of ovarian development. To study the molecular mechanisms of its ovarian development, transcriptome analysis was performed in the ovary and hepatopancreas of E. sinensis during ovarian stages I (oogonium proliferation), II (endogenous vitellogenesis), and III (exogenous vitellogenesis). The results showed that 5,520 and 226 genes were differentially expressed in the ovary and hepatopancreas, respectively. For KEGG enrichment analysis, the differentially expressed genes in the ovary were significantly clustered in phototransduction-fly, phagosome, and ECM-receptor interaction. Significantly enriched pathways in the hepatopancreas included fatty acid biosynthesis, fatty acid metabolism, and riboflavin metabolism. Further analysis showed that 25 genes and several pathways were mainly involved in oogenesis, including the ubiquitin-proteasome pathway, cyclic AMP-protein kinase A signaling pathway, and mitogen-activated protein kinase signaling pathway. Twenty-five candidate genes involved in vitellogenesis and endocrine regulation were identified, such as vitellogenin, vitellogenin receptor, estrogen sulfotransferase, ecdysone receptor, prostaglandin reductase 1, hematopoietic prostaglandin D synthase and juvenile hormone acid O-methyltransferase. Fifty-six genes related to nutritional metabolism were identified, such as fatty acid synthase, long-chain-fatty-acid-CoA ligase 4, 1-acyl-sn-glycerol-3-phosphate acyltransferase 4, fatty acid-binding protein, and glycerol-3-phosphate acyltransferase 1. These results highlight the genes involved in ovarian development and nutrition deposition, which enhance our understanding of the regulatory pathways and physiological processes of crustacean ovarian development.
ABSTRACT
Ovarian development is a complex physiological process for crustacean reproduction that is divided into the oogonium proliferation stage, endogenous vitellogenic stage, exogenous vitellogenic stage, and oocyte maturation stage. Proteomics analysis offers a feasible approach to reveal the proteins involved in the complex physiological processes of any organism. Therefore, this study performed a comparative proteomics analysis of the ovary and hepatopancreas at three key ovarian stages, including stages I (oogonium proliferation), II (endogenous vitellogenesis) and IV (exogenous vitellogenesis), of the Chinese mitten crab Eriocheir sinensis using a label-free quantitative approach. The results showed that a total of 2,224 proteins were identified, and some key proteins related to ovarian development and nutrition metabolism were differentially expressed. The 26 key proteins were mainly involved in the ubiquitin/proteasome pathway (UPP), cyclic AMP-protein kinase A (cAMP-PKA) signaling pathway, and mitogen-activated protein kinase (MAPK) signaling pathway during oogenesis. Fifteen differentially abundant proteins (DAPs) were found to participate in vitellogenesis and oocyte development, such as vitelline membrane outer layer protein 1 homolog, vitellogenin, vitellogenin receptor, heat shock 70 kDa protein cognate 3 and farnesyl pyrophosphate synthase. Forty-seven DAPs related to nutrition metabolism were identified, including the protein digestion, fatty acid metabolism, prostaglandin metabolism, lipid digestion and transportation, i.e. short-chain specific acyl-CoA dehydrogenase, acyl-CoA desaturase, fatty acid-binding protein, long-chain fatty acid CoA ligase 4, and hematopoietic prostaglandin D synthase. These results not only indicate proteins involved in ovarian development and nutrient deposition but also enhance the understanding of the regulatory pathways and physiological processes of crustacean ovarian development.
Subject(s)
Brachyura , Proteomics , Animals , China , Female , Hepatopancreas , Ovary , VitellogenesisABSTRACT
Tamoxifen (TAM) is an antiestrogenic agent and can enter the aquatic environment in wastewater. It has been reported that TAM can induce hepatic steatosis in vertebrates, however, the effects of TAM exposure on lipid metabolism of hepatopancreas in crustaceans remains unclear. In this study, four TAM concentrations (0, 6.7, 13.4 and 20⯵gâ¯g-1 crab body weight) were injected into the swimming-leg of swimming crabs Portunus trituberculatus, as a means of evaluating the effects of TAM on the expression levels of lipid metabolism-related genes, lipid composition, and hepatopancreas histology. The results showed that the mRNA levels of three lipogenic related genes (diacylglycerol acyltransferase 1 (DGAT1), acetyl-CoA carboxylase (ACC) and fatty acyl desaturase (FAD)) decreased significantly in the 6.7⯵gâ¯g-1 and 20⯵gâ¯g-1 TAM treatments compare to the control. The mRNA levels of fatty acid synthase (FAS) decreased significantly in a dose-dependent manner as TAM concentration increased. The mRNA levels of two lipid catabolism-related genes (acyl-CoA oxidase (ACOX) and fatty acid transport protein (FATP)) were down-regulated among the three TAM treatments, while the enzyme activity and mRNA level of carnitine palmitoyltransferase I (CPT-I) was up-regulated by TAM treatments. Compared to the control, the lowest levels of total lipids and phospholipids were detected in the 6.7⯵gâ¯g-1 TAM treatment, while the 20⯵gâ¯g-1 TAM treatment had the lowest free fatty acids concentration. The 6.7⯵gâ¯g-1 TAM treatment had the lowest percentages of 16:1n-7, 18:1n-9, 18:1n-7 and total monounsaturated fatty acids (∑MUFA), whilst simultaneously recording the highest percentages of 18:2n-6 and 20:2n-6 in this treatment. Moreover, histological observations indicated that TAM caused the walls of the hepatopancreatic tubules to become brittle, with a concurrent increase in the number of blister-like cells. These results suggest that TAM damages the hepatopancreas and leads to a reduction in hepatopancreatic lipid deposition in P. trituberculatus.
