title: Gamma-ray irradiation promotes premature meiosis of spontaneously differentiating testis-ova in the testis of p53-deficient medaka (Oryzias latipes).
abstract: In this study, the roles of p53 in impaired spermatogenic male germ cells of p53-deficient medaka were investigated by analyzing histological changes, and gene expressions of 42Sp50, Oct 4 and vitellogenin (VTG2) by RT-PCR or in situ hybridization in the testes. We found that a small number of oocyte-like cells (testis-ova) differentiated spontaneously in the cysts of type A and early type B spermatogonia in the p53-deficient testes, in contrast to the wild-type (wt) testes in which testis-ova were never found. Furthermore, ionizing radiation (IR) irradiation increased the number of testis-ova in p53-deficient testes, increased testis-ova size and proceeded up to the zygotene or pachytene stages of premature meiosis within 14 days after irradiation. However, 28 days after irradiation, almost all the testis-ova were eliminated presumably by p53-independent apoptosis, and spermatogenesis was restored completely. In the wt testis, IR never induced testis-ova differentiation. This is the first study to demonstrate the pivotal role of the p53 gene in the elimination of spontaneous testis-ova in testes, and that p53 is not indispensable for the restoration of spermatogenesis in the impaired testes in which cell cycle regulation is disturbed by IR irradiation.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Bioscience Bldg. 102, Kashiwa, Chiba 277-8562, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yasuda
authors.forename: S
authors.initials: S
authors.lastname: Oda
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Kimori
authors.forename: Y
authors.initials: Y
authors.lastname: Kamei
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
authors.forename: T
authors.initials: T
authors.lastname: Todo
authors.forename: H
authors.initials: H
authors.lastname: Mitani
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000528:radiation effects; D005720:Gamma Rays; D008297:Male; D008540:Meiosis / Q000528:radiation effects*; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D009990:Oryzias / Q000254:growth & development; D010445:Peptide Elongation Factors / Q000378:metabolism; D013091:Spermatogenesis / Q000528:radiation effects; D013093:Spermatogonia / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects; D013737:Testis / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014819:Vitellogenins / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism
chemical_list: D050814:Octamer Transcription Factor-3; D010445:Peptide Elongation Factors; D016159:Tumor Suppressor Protein p53; D014819:Vitellogenins; D029867:Xenopus Proteins; C066976:thesaurin A