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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.

SUBMITTER: Yasuda T

PROVIDER: S-EPMC3481122 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Gamma-ray irradiation promotes premature meiosis of spontaneously differentiating testis-ova in the testis of p53-deficient medaka (Oryzias latipes).

Yasuda T T Oda S S Li Z Z Kimori Y Y Kamei Y Y Ishikawa T T Todo T T Mitani H H

Cell death & disease 20121004

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 w ...[more]

PMID: 23034330

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Project description:BackgroundPrimordial germ cells (PGCs) give rise to gametes that are responsible for the development of a new organism in the next generation. Two modes of germ line specification have been described: the inheritance of asymmetrically-localized maternally provided cytoplasmic determinants and the induction of the PGC fate by other cell types. PGCs specification in zebrafish appears to depend on inheritance of germ plasm in which several RNA molecules such as vasa and nanos reside. Whether the specification mode of PGCs found in zebrafish is general for other fish species was brought into question upon analysis of olvas expression--the vasa homologue in another teleost, medaka (Oryzias latipes). Here, in contrast to the findings in zebrafish, the PGCs are found in a predictable position relative to a somatic structure, the embryonic shield. This finding, coupled with the fact that vasa mRNA, which is localized to the germ plasm of zebrafish but does not label a similar structure in medaka opened the possibility of fundamentally different mechanisms governing PGC specification in these two fish species.ResultsIn this study we addressed the question concerning the mode of PGC specification in medaka using embryological experiments, analysis of RNA stability in the PGCs and electron microscopy observations. Dramatic alterations in the somatic environment, i.e. induction of a secondary axis or mesoderm formation alteration, did not affect the PGC number. Furthermore, the PGCs of medaka are capable of protecting specific RNA molecules from degradation and could therefore exhibit a specific mRNA expression pattern controlled by posttrancriptional mechanisms. Subsequent analysis of 4-cell stage medaka embryos using electron microscopy revealed germ plasm-like structures located at a region corresponding to that of zebrafish germ plasm.ConclusionTaken together, these results are consistent with the idea that in medaka the inheritance of maternally provided asymmetrically-localized cytoplasmic determinants directs cells to assume the germ line fate similar to zebrafish PGCs.

Dataset Information

Gamma-ray irradiation promotes premature meiosis of spontaneously differentiating testis-ova in the testis of p53-deficient medaka (Oryzias latipes).

Publications

Gamma-ray irradiation promotes premature meiosis of spontaneously differentiating testis-ova in the testis of p53-deficient medaka (Oryzias latipes).

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