| Swimming crab, Portunus trituberculatus as a fashionable table delicacy is one of the mostimportant fishing and aquaculture species of crab around the coast of China. Molting too frequentlyand molting attempted are commonly found during its molting process. Molting process ofcrustaceans coordinated by endocrine cues. Molt-inhibiting hormone（MIH）, a polypeptide secretedby the X-organ-sinus gland （XO-SG） of the eyestalks, regulates molting by inhibiting the synthesisof ecdysteroids by Y-organs （YO）. The method for determination the levels of MIH mRNA in theswimming crab has been developed using relative quantification of quantitative real-time PCR（qRT-PCR）, We discovered the levels of MIH mRNA highest in the XO-SG. Referencing to themorphological observation, We divided the molt cycle into four stages that were post-molt （A andB）, inter-molt period （C）, pre-molt （D0, D1, D2, D3and D4） and molt stage （E）. As the control groupD0, the levels of MIH mRNA during a molt cycle restults were analyzed by2-△△Ctmethods,showed that MIH transcripts down-regulated0.42±0.08fold in stage A; increased1.09±0.09foldin stage B; increased1.35±0.16fold in stage C; down-regulated0.78±0.07fold in surstage D1;down-regulated0.27±0.08fold in surstage D2; down-regulated0.20±0.04fold in surstage D3/4.Data of MIH mRNA levels during a molt cycle of the swimming crab were analyzed by one-wayANOVA. MIH transcripts of each molting stages were significantly differences except surstage D2and surstage D3/4（P<0.05）. The experimental results indicated that MIH expression levels changedclear tendency with the molt cycle of swimming crab progressed, MIH transcripts increased inpost-molt（A）, achieved the crest until inter-molt （C）, then droped slowly before reaching aminimum in pre-molt （D3/4）, completed the molt cycle. During a molt cycle of the swimming crab,occurrence and advance of ecdysis was important contacting with the MIH expression levels thatregulated molting by inhibiting the synthesis of ecdysteroids by YO.The ovarian development during the entire life cycle, including crustaceans and the oviparousanimals, is closely associated with reproduction. Referencing to the morphological quantitativedetermination, we divided the second ovarian development of swimming crab into four stages thatwere I stage （GIS=0.91.5%）, II stage （GIS=1.35%）, III（GIS=612%） and IV stage（GIS=1215%）. As the control group I stage, the levels of vitellogenin （Vg） mRNA and MIHmRNA during the second ovarian development restults were analyzed by2-△△Ctmethods, showedthat Vg transcripts in the ovary increased1.68±0.37fold in stage II, increased17.15±1.12fold instage III, increased19.30±1.92fold in stage IV; Vg transcripts in the hepatopancreas increased 4.62±0.99fold in stage II, increased55.74±5.54fold in stage III, down-regulated50.42±3.21foldin stage IV; MIH transcripts in the XO-SG down-regulated0.52±0.09fold in stage II, down-regulated0.30±0.06fold in stage III, down-regulated0.11±0.02fold in stage IV. The experimentalresults indicated that Vg and MIH expression levels changed clear tendency with the secondovarian development of swimming crab progressed, Vg transcripts showed that a high positivecorrelation with the second ovarian development; MIH transcripts showed significant Negativecorrelation with the second ovarian development. |
