Differences in lipid accumulation and mobilization in the hepatopancreas and ovary of female mud crab (Scylla paramamosain, Estampador, 1949) during ovarian development

The accumulation and mobilization of lipids and fatty acids are known to vary greatly between the ovary and hepatopancreas of crab broodstock during ovarian development. However, the underlying mechanism is not completely understood. In the present study, we analyzed and compared the biochemical compositions and expression profiles of lipid metabolism-related genes during each maturation stage in Scylla paramamosain. The results revealed that ovaries deposited large amounts of total lipid contents with a predominance of neutral lipids, mainly triacylglycerol (TAG), rich in high levels of saturated fatty acids throughout ovarian development. Microsomal triglyceride transfer protein (MTP), surfeit locus protein 4 (SURF4) and apolipocrustacein (ApoCr) transcription levels were significantly increased in the hepatopancreas as did transcription levels of the vitellogenin receptor (VTGR) in the ovary during ovarian development (P < 0.05). We speculated the possible mechanism by which MTP transported TAG to ApoCr, then SURF4 conveyed ApoCr from the hepatopancreas to the hemolymph during ovarian development, and finally, ApoCr was absorbed by the VTGR of oocytes, leading to a higher gonadosomatic index (GSI) and lipid deposition regulated by lipogenesis and lipolysis genes. These results are considered to provide fundamental information for further reproductive biology research on female mud crabs.