Induction of ovarian maturation in Penaeus monodon by molecular signal interventional approach.
Vitellogenin (VTG) synthesis in the hepatopancreas and ovary is negatively regulated by vitellogenesis-inhibiting hormone (VIH) produced in the neurosecretory cell of X-organ/sinus gland complex of the eyestalks of penaeid shrimp. Eyestalk ablation is used commercially to induce ovarian maturation in shrimps which leads to an eventual loss of the spawner. The aim of the present study was to understand the molecular mechanism of VIH regulation in ovarian development and its inhibition of VTG gene expression by using a MEK-specific inhibitor (U0126). The real-time quantitative PCR results showed VTG mRNA level was progressively increased in the ovary and hepatopancreas of unilateral eyestalk-ablated and inhibitor-treated shrimps. Western blot analysis also showed that phosphoMEK was detected only in the unilateral eyestalk-ablated and control shrimp, whereas phospho-MEK was not detected in inhibitor-treated shrimp. DAX-1, SF-1, and StAR expression correlated with changes in VIH mRNA and altered phospho-ERK levels. This is consistent with the hypothesis that suppression of DAX-1 results in SF-1-mediated StAR protein upregulation of estradiol that is implicated in vitellogenesis. This is the first report that demonstrates the molecular mechanism of VIH suppression via MEK pathway to induce ovarian maturation in female Penaeus monodon by molecular signal intervention, a less-invasive method than traditional eyestalk ablation.
Unit of Biochemistry, Department of Zoology, University of Madras, School of Life Science, Guindy, Chennai, Tamil Nadu, India. hdrajum@yahoo.com
Halagowder
H
Devaraj
Marimuthu
M
Saravanakumar
Mani
M
Thiyagu
D000704:Analysis of Variance; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002070:Butadienes; D002352:Carrier Proteins / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D057137:DAX-1 Orphan Nuclear Receptor / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects* / Q000235:genetics; D043143:Hepatopancreas / Q000378:metabolism; D006652:Histological Techniques; D007447:Invertebrate Hormones / Q000378:metabolism*; D009570:Nitriles; D010053:Ovary / Q000254:growth & development* / Q000378:metabolism; D033561:Penaeidae / Q000254:growth & development*; D010750:Phosphoproteins / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012741:Sexual Maturation / Q000187:drug effects / Q000502:physiology*; D054339:Steroidogenic Factor 1 / Q000378:metabolism; D014819:Vitellogenins / Q000378:metabolism*; D000098682:Steroidogenic Acute Regulatory Protein
D002070:Butadienes; D002352:Carrier Proteins; D057137:DAX-1 Orphan Nuclear Receptor; D017931:DNA Primers; D004791:Enzyme Inhibitors; D007447:Invertebrate Hormones; D009570:Nitriles; D010750:Phosphoproteins; D054339:Steroidogenic Factor 1; C113580:U 0126; D014819:Vitellogenins; D000098682:Steroidogenic Acute Regulatory Protein; C073189:vitellogenesis inhibiting hormone