Vitellogenesis in the Red Crab, <i>Charybdis feriatus</i>: Contributions from Small Vitellogenin Transcripts (CfVg) and Farnesoic Acid Stimulation of CfVg Expression

Abstract

During reproductive maturation of the female red crab, Charybdis feriatus, the oocytes rapidly accumulate 110- and 78-kDa major polypeptides. Although the hepatopancreas expresses a high level of vitellogenin (CfVg) mRNA, tissue proteins and secreted proteins of the hepatopancreas consist of only small polypeptides. In addition to the 8.0-kb transcripts, many smaller mRNAs specific to the CfVg gene can be detected. These results suggest that the hepatopancreas also produces smaller CfVg transcripts for small CfVg subunits. Using an RT-PCR cloning approach, a population of the small cDNA clones were isolated. Determining the DNA sequence of these clones revealed that these transcripts were most likely the result of alternative splicing and/or alternative expression of the CfVg gene. In vitro treatment of the hepatopancreas fragments with low levels of farnesoic acid stimulated the expression of CfVg.