会計基準の変遷(3) -個別会計基準の拡大-

Abstract

To evaluate functions of vitellogenin (Vg) and heat shock protein 90 (Hsp90) during ovarian and embryonic development of Exopalaemon carinicauda, the cDNA of Vg (Ec-Vg) was cloned, and the abundances of Ec-Vg and heat shock protein 90 (Hsp90) (Ec-Hsp90) were determined during ovarian and embryonic development. During ovarian development, the concentration of Vg protein in hemolymph was markedly greater than in the ovary and hepatopancreas, and was greatest at sexual maturity. The relative abundance of Ec-Vg mRNA transcript was greatest in the hepatopancreas and almost undetectable in hemocytes. By combining mRNA transcript relative abundances with morphological results, a model was developed to explain the mRNA transcript relative abundance of Ec-Hsp90 and Ec-Vg during ovarian and embryonic development. The relative abundance of Ec-Vg mRNA transcript was greatest during the recovery period after reproduction had occurred (Stage V) and mature stage (Stage IV) in the ovary or hepatopancreas, respectively. There were marked associations of the patterns of Ec-Hsp90 and Ec-Vg mRNA transcript abundances both in hepatopancreas and ovary. During embryonic development, the relative abundance of the two mRNA transcripts were greatest at the metazoea and protozoea stages, respectively. These results indicate that Ec-Vg is produced primarily in the hepatopancreas, secreted into the hemolymph and transported into growing oocytes. It, therefore, is believed that Ec-Vg has an important function in the overall ovarian development and late embryonic development of E. carinicauda. In contrast, Ec-Hsp90 is a regulatory factor for Vg transcription and is important during early organogenesis in E. carinicauda.