EFFECTS OF MF AND 20E ON LARVAL SURVIVAL,METAMORPHOSIS,AND EXPRESSION OF TYPE-Ⅱ CHH GENES IN LITOPENAEUS VANNAMEI
Methyl farnesoate(MF)and 20-hydroxyecdysone(20E)play crucial roles in the molting,metamorphosis,and developmental morphogenesis of crustaceans.The synthesis and secretion of MF and 20E in vivo are regulated by type-Ⅱ crustacean hyperglycemic hormone(CHH).To investigate the impact of MF and 20E on the development of Litopenaeus vannamei larvae,different concentrations of MF and 20E were used to treat L.vannamei larvae of various developmental stages,and the survival rate and metamorphosis rate of the larvae were examined.Additionally,we conducted a comprehensive characterization of all members of the type-Ⅱ CHH subfamily and assessed their expression patterns in post-larval shrimp in response to exogenous MF and 20E using real-time quantitative PCR.Results indicate that the early-stage larvae exhibited a heightened sensitivity to both MF and 20E.The survival rates decreased in a dose-dependent manner,and both MF and 20E also led to a reduction in metamorphosis rates.The type-Ⅱ CHH subfamily of L.vannamei consists of eight molt-inhibiting hormone(MIH)genes(LvMIH1-8)and one vitellogenesis-inhibiting hormone(VIH)gene(LvVIH).In post-larval shrimp,the expression level of LvMIH3 was found the highest,followed by LvMIH1 and LvMIH7,while no significant expression of other type-Ⅱ CHH genes was observed.Additionally,the application of exogenous MF and 20E significantly upregulated the expression of LvMIH1 and LvMIH7,whereas downregulated that of LvMIH3.Our findings suggest that LvMIH1,LvMIH3,and LvMIH7 play crucial roles in mediating the signaling of MF and 20E,providing valuable insights into the regulatory mechanism of type-Ⅱ CHH in crustacean molting and metamorphosis.
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维普
