CHARACTERIZATION AND EXPRESSION ANALYSIS OF E75 DURING OVARIAN DEVELOPMENT AND JUVENILE GROWTH OF THE MUD CRAB, SCYLLA PARAMAMOSAIN ESTAMPADOR, 1950 (BRACHYURA, PORTUNIDAE)

In arthropods, E75 is an important nuclear receptor to regulate various physiological processes, such as development and reproduction. In this study, a 3551 bp cDNA of E75 (SpE75) with a typical domain organization of the nuclear hormone receptor was cloned from Scylla paramamosain. A qRT-PCR analysis revealed that, during ovarian development, the expression of SpE75 significantly increased after the onset of vitellogenesis and reached its peak value at the early vitellogenic stage. In vitro and in vivo experiments showed that 20-hydroxyecdysone significantly induced the transcriptions of the genes of both SpE75 and vitellogenin in the ovary. During juvenile crab (C1) development, the expression of SpE75 increased from 0 h (postmoult stage) to 96 h (premoult stage) and kept a low level in the fasting crabs. Together, these results indicate that SpE75 may be playing an important role in the regulation of ovarian development and somatic growth, as a component of ecdysone signalling in crustaceans.