Vitellogenesis in the red crab Charybdis feriatus: Hepatopancreas‐specific expression and farnesoic acid stimulation of vitellogenin gene expression

Abstract

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.

Molecular diversity and evolution of the large lipid transfer protein superfamily

“…Additional sequences of LLTPs from arachnids may help define the context of the divergence of M-177. Importantly, the Vtg of decapodan Crustacea is not directly related to the Vtg genes of other taxons, as assumed by others (52)(53)(54)(55)(56)(57)(58)(59)(60), but is an apoB-like LLTP. This observation explains previous phylogenetic analyses on Vtgs only (57,62,69,70), in which decapodan Vtg failed to group with other invertebrate Vtgs.…”

“…In another class of arthropods, the decapodan Crustacea (e.g., lobster, crayfish, crab, shrimp), two distinct LLTPs have been identified, a CP (7,8) and a yolk protein named Vtg (52)(53)(54)(55)(56)(57)(58)(59)(60). Although both LLTPs have been identified only in distinct species, the relatively close relationship among these species as well as the divergence of the identified proteins strongly suggest that the subset of LLTPs present in decapodan Crustacea con-sists at least of one CP and one Vtg.…”

Reproductive regulators in decapod crustaceans: an overview

“…However, the multiple spatial locations of FA-O-MeT gene expression are an open area of interest to all crustacean sesquiterpenoid researchers. Recently, Mak and colleagues (Mak et al, 2005) demonstrated that FA (low concentrations) can also stimulate Charybdis feriatus Vg gene expression in the HP. Similarly, FA also consistently stimulated MeVg1 expression by the HP explants, while both FA and 20-hydroxyecdysone stimulated ovarian explants of M. ensis in vitro (Tiu et al, 2006).…”

Review of the reproductive biology of amphipods and their endocrine regulation: Identification of mechanistic pathways for reproductive toxicants

“…Experimental evidence suggests that major functions of MF in crustaceans are in the positive regulation of the molt cycle and enhancing reproductive maturation [102,104]. Methyl farnesoate has been implicated as a morphogen in postembryonic larval stages of crustacean development [104] and in reproductive maturation in decapods, in which it increases production of vitellogenin and oocytes [104,105]. Methyl farnesoate also stimulates gonadal maturation of both male and female decapods [104,106].…”