Vitellogenesis in the red crab Charybdis feriatus: Hepatopancreas-specific expression and farnesoic acid stimulation of vitellogenin gene expression.
Vitellogenesis in the mature female crab Charybdis feriatus occurs all year round during which active synthesis of the vitellogenin (Vg) precursor occurs. Several polypeptides from the ovaries were shown to be immuno-reactive to the shrimp vitellin (Vn) antibody. N-terminal amino acid sequence determination revealed that several ovarian polypeptides and one polypeptide secreted by the hepatopancreas were identical to part of the C. feriatus Vg (CfVg) precursor. The full-length cDNA sequence encoding a protein with high amino acid sequence similarity to the Vg of the shrimp Metapenaeus ensis was cloned. In common with the shrimp M. ensis MeVg2, the crab vitellogenin gene is expressed only in the hepatopancreas. The expression level of CfVg is undetectable in the non-reproductive females, increases to maximum at the middle stages of vitellogenesis and drops to a lower level in late vitellogenesis. Expression of CfVg also extended to females that are undergoing brooding of developing larvae. Although the 8 kb transcript for the full-length cDNA was detected, smaller transcripts specific to CfVg mRNA were also detected, suggesting the occurrence of alternative splicing/expression of the CgVg gene to produce the smaller transcripts. Using a short term in vitro hepatopancreas explant culture assay, we have demonstrated that low concentrations of farnesoic acid (FA) stimulate CfVg gene expression in the hepatopancreas. Although both methyl farnesoate (MF) and juvenile hormone III also caused up-regulation of the CfVg gene, their effects are only significant at much higher concentrations.
Mak
Abby Sin Chi
AS
Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, P.R. China.
Choi
Chi Lung
CL
Tiu
Shirley Hiu Kwan
SH
Hui
Jerome Ho Lam
JH
He
Jian-Guo
JG
Tobe
Stephen S
SS
Chan
Siu-Ming
SM
D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D003386:Brachyura / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D043143:Hepatopancreas / Q000378:metabolism*; D008969:Molecular Sequence Data; D012098:Reproduction / Q000502:physiology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014818:Vitellogenesis / Q000235:genetics / Q000502:physiology*; D014819:Vitellogenins / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D005231:Fatty Acids, Unsaturated; D014819:Vitellogenins; C007702:farnesoic acid