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Polypeptide composition and biosynthesis of the yolk proteins in the firebrat, Thermobia domestica (insecta, thysanura)
Author(s) -
Rousset André,
Bitsch Colette,
Bitsch Jacques
Publication year - 1988
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.940090405
Subject(s) - vitellogenin , hemolymph , biology , yolk , vitellogenesis , biochemistry , polyacrylamide gel electrophoresis , molecular mass , gel electrophoresis , antiserum , glycoprotein , microbiology and biotechnology , embryo , antibody , oocyte , gene , genetics , enzyme , ecology
Abstract Ion‐exchange chromatography of crude ovarian extracts of the primitive insect Thermobia domestica allowed the separation, in native conditions, of major and minor vitellins of molecular weights of 300,000 and 430,000, respectively. Their polypeptide subunits were determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and immunotransfer using an antiserum prepared against major vitellin. This protein was resolved into large ( M r 166,000–212,000) and small (around M r 50,000) polypeptides. Minor vitellin, on the other hand, exclusively contained small polypeptides that are immunologically different from those of the major vitellin. Vitellogenin polypeptides from the hemolymph of mature females exhibited electrophoretic mobilities and immunological properties similar to vitellin polypeptides. Pulse‐chase experiments showed that the female fat body synthesizes radioactive and immunoprecipitable proteins, whose polypeptide pattern is close to that of the major vitellogenin. However, part of the primary vitellogenic polypeptides, at M r 210,000 and 212,000, is rapidly processed to M r 176,000 and 182,000 subunits. These two polypeptides, as well as the precursors, enter into the composition of the major hemolymph vitellogenin. Finally, processing of the still uncleaved 210,000–212,000 polypeptides takes place in the ovary, which performs the same step of vitellogenin maturation as the fat body.