The dynamics of vitellogenin gene expression differs between intact and eyestalk ablated kuruma prawn Penaeus (Marsupenaeus) japonicus

Abstract

In order to compare the dynamics of vitellogenin gene expression between naturally maturing prawns and prawns induced to mature artificially by eyestalk ablation, a cDNA encoding vitellogenin was cloned from a cDNA library prepared from the hepatopancreas of the kuruma prawn Penaeus (Marsupenaeus) japonicus, and a quantitative real-time reverse transcription — polymerase chain reaction (RT-PCR) system was developed. Sequence analysis revealed the likely possibility that vitellogenin cDNA from the hepatopancreas was identical to that from the ovary which had been isolated in a previous study. Based on this information, a quantitative real-time RT-PCR system was established and the dynamics of vitellogenin mRNA levels were examined. In naturally maturing prawns, vitellogenin mRNA levels were maintained at low levels during the previtellogenic stage, and thereafter, levels increased as vitellogenesis progressed but decreased during the latter stages of maturation in the hepatopancreas and ovary. In contrast, in eyestalk-ablated prawns, changes in mRNA levels differed in both tissues; an obvious increment of mRNA levels was revealed in the ovary, whereas mRNA levels were negligible in the hepatopancreas. This suggests that eyestalk ablation cannot be used to accurately simulate the natural process of vitellogenin gene expression during vitellogenesis, and that vitellogenin gene expression is regulated in a tissue-specific manner.