| Co-Investigator(Kenkyū-buntansha) |
FUNKENSTEIN Bruria Israel Oceanographic & Limnological Inst., Researcher, 研究員
TIETZ-DEVIR Alisa Tel Aviv University, Prof., 生命科学科, 教授
LUBZENS Esther Israel Oceanographic & Limnological Inst., Assoc.Pfor., 助教授
AIDA Katsumi Graduate Shool of Agr.Biosci.Univ.of Tokyo, Prof., 大学院・農学生命科学研究科, 教授 (50012034)
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| Research Abstract |
The endocrinological mechanisms of reproduction, especially vitellogenesis, in crustaceans have been investigated. It has been estimated that neuropeptides in the sinus gland inhibit vitellogenesis. We first extracted and purified seven structurally related neuropeptides from the sinus gland, and determined their whole amino acid sequences. They were designated as Pej-SGP-I--VII.All these peptides except for IV showed hyperglycemic acitivity, while IV had an activity to inhibit ecdysone release by Y-organ in in vitro culture system. These peptides were examined for vitellogenesis-inhibiting activity by using in vitro culture of pieces of developing ovary from the prawn Penaeus semisulcatus. The effects of these peptides on protein synthesis was examined by incorporation of ^<35>S-methionine into proteins in the ovarian pieces. The results showed that all the peptides except for IV inhibited protein synthesis. The inhibition was not confined to a specific protein but to all proteins. Ex
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periments of incorporation of ^3H-uridine showed that the inhibition occurred at the transcription level. By contrast, Pej-SGP-IV,red pigement concentrating hormone, pigment-dispersing hormone, 20-hydroxyecdysone or methyl farnesoate did not show any inhibiting or stimulating activity, suggesting the specific inhibition of six peptides.
There has been no information about the structure of yolk protein vitellin or its precursor vitellogenin in crustaceans. First, vitellin was purified from the ovary of P.semisulcatus. By SDS-PAGE,it was separated into mainly 4 subunits, 160,120,96, and 80kDa. Blotted subunit proteins were sequenced and it was found that the N-terminal sequence of larger two were identical and that of smaller two were also identical. But the sequences between the two groups were different. Internal sequences were analyzed after digestion of native vitellin with lysyl endopeptidase and sebsequent separation of the digested fragments. Thus, we have obtained a lot of partial sequences. Using these peptide sequence information, we are now cloning cDNA encoding vitellogenin to know its full sequence. Less
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