The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

Yoshitaka Nagahama - One of the best experts on this subject based on the ideXlab platform.

Masaru Matsuda - One of the best experts on this subject based on the ideXlab platform.

  • Sex determination in the teleost medaka, Oryzias latipes.
    Annual Review of Genetics, 2005
    Co-Authors: Masaru Matsuda
    Abstract:

    AbstractAlthough the sex of most animals is determined by genetic information, sex-determining genes had been identified only in mammals, several flies, and the worm Caenorhabditis elegans until the recent discovery of DMY (DM-domain gene on the Y chromosome) in the sex-determining region on the Y chromosome of the teleost fish medaka, Oryzias latipes. Functional and expression analyses of DMY have shown it to be the master gene for male sex determination in the medaka. The only sex-determining genes found so far in vertebrates are Sry and DMY. Therefore, the medaka is expected to become a good experimental animal for investigating the precise mechanisms involved in primary sex determination in nonmammalian vertebrates. This article reviews the origin of DMY and the sexual development of gonads in the medaka. The putative functions of DMY are also discussed.

Linyan Zhou - One of the best experts on this subject based on the ideXlab platform.

Tapas Chakraborty - One of the best experts on this subject based on the ideXlab platform.

Takashi Iwamatsu - One of the best experts on this subject based on the ideXlab platform.

  • Chromosome formation during fertilization in eggs of the teleost Oryzias latipes.
    Methods of Molecular Biology, 2011
    Co-Authors: Takashi Iwamatsu
    Abstract:

    : Upon fertilization, eggs shift their cell cycle from the meiotic to the mitotic pattern for embryogenesis. The information on chromosome formation has been accumulated by various experiments using inhibitors to affect formation and behavior of chromosomes in the cycle of cell proliferation. Based on experimental results on meiosis and early stages of development of the teleost Oryzias latipes, we discuss the roles of the activities of histone H1 kinase, microtubule-associated protein kinase, DNA polymerase, DNA topoisomerase, and other cytoplasmic factors that play a crucial role in formation and separation of chromosomes.

  • Stages of normal development in the medaka Oryzias latipes
    Mechanisms of Development, 2004
    Co-Authors: Takashi Iwamatsu
    Abstract:

    Abstract Unfertilized eggs of Oryzias latipes were artificially inseminated and incubated at 26±1 °C. Careful observation of the process of embryonic development by light microscopy allowed division of the process into 39 stages based on diagnostic features of the developing embryos. The principal diagnostic features are the number and size of blastomeres, form of the blastoderm, extent of epiboly, development of the central nervous system, number and form of somites, optic and otic development, development of the notochord, heart development, blood circulation, the size and movement of the body, development of the tail, membranous fin (fin fold) development, and development of such viscera as the liver, gallbladder, gut tube, spleen and swim (air) bladder. After hatching, development of the larvae (fry) and young can be divided into six stages based on such diagnostic features as the fins, scales and secondary sexual characteristics.

  • Stages of normal development in the medaka Oryzias latipes.
    Mechanisms of development, 2004
    Co-Authors: Takashi Iwamatsu
    Abstract:

    Unfertilized eggs of Oryzias latipes were artificially inseminated and incubated at 26+/-1 degrees C. Careful observation of the process of embryonic development by light microscopy allowed division of the process into 39 stages based on diagnostic features of the developing embryos. The principal diagnostic features are the number and size of blastomeres, form of the blastoderm, extent of epiboly, development of the central nervous system, number and form of somites, optic and otic development, development of the notochord, heart development, blood circulation, the size and movement of the body, development of the tail, membranous fin (fin fold) development, and development of such viscera as the liver, gallbladder, gut tube, spleen and swim (air) bladder. After hatching, development of the larvae (fry) and young can be divided into six stages based on such diagnostic features as the fins, scales and secondary sexual characteristics.

  • Evidence for Involvement of the Exudate Released from the Egg Cortex in the Change in Chorion Proteins at the Time of Egg Activation in Oryzias latipes
    Zoological Science, 1996
    Co-Authors: Yasushi Shibata, Takashi Iwamatsu
    Abstract:

    Abstract In eggs of the medaka Oryzias latipes, we recently found that the changes in chorion proteins that occur upon fertilization could be induced in vitro by an egg exudate including cortical alveolar contents. In the present study, the time course of the changes in chorion proteins induced in vitro by egg exudate was examined by SDS-PAGE analysis and was found to be quite similar to that of in vivo chorion hardening at the time of fertilization. The activity of egg exudate was dose-dependent. Moreover, when the exudate was heated for 30 min at 60°C, it lost its activity. On the other hand, in heat-treated chorions, the intermediate proteins appeared following incubation with egg exudate, although chorion hardening did not occur. These results suggest the presence of a chorion protein-modifying enzyme(s) in the exudate re-leased from the cortex during egg activation in Oryzias latipes.