Analysis of Meiosis using Hybrid-male-sterile Animals.

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Meiosis is one of the important process for formation of the functionally reproductive cells and the major events are the piring of homologous chromosomes, genetic recombination (crossing-over) and chiasma-formation between them and segregation of chromosomes (disjunction).The failure of any one of these events leads to lack of reproductive cells and sterility. Despite the accumulation of many cytological and cytogenetical studies on meiosis, molecular analyzes of meiotic events are just underway using yeasts, but still scarece in higher organisms. Nevertheless, understanding and control of meiotic events could make uncountable contribution for breeding, fertility and sterility problems and human welfare. We have tried to analyze testicular and ovarian cells from the male-sterile animals, Yak (F1 of Bos taurus X Bos grunniens), Cerus elaphus X Cerus nippon F1 (deer), M.fascicularis X M.assamesis F1 (monkey), cytologically and molecular biologically using our antibodies to recombination … More al enzymes and various probes prepared from the meiotically active genes. Currently we have completed our studies using yaks. The hybrid-male-sterile deers are not yet in our hand, while hybrid-sterile-monkey died and the next production is questionable in Kunming Institute. The followings are our experimental results today :1.The male-sterility is caused by meiotic degradation mostly during pchytene and some at diakinesis and metaphase I.However, the similar meiotic degradation has been observed in oocytes, suggesting the reduction in number of the oocytes. The antibody prepared against RecA protein and Lim15 (lily meiotic prophase I-specific gene) protein using E.coli have positively bound to most of meiotic cells even from sterile testes, while little binding has been observed in somatic cells including the testicular and the ovarian ones.2.Acivities of DNA polymerase beta and alpha isolated from meioic prophase cells of sterile and fertile (normal ox) animal are essentially the same, based on the cellular protein.3.Isolated cDNA clones from sterile and fertile testicular meiotic prophase cells are similar in restriction maps and quantities obtained, suggesting that the normal transcription is occurring in meiotic prophase cells from the sterile males.All of these can gives us a clue to conclude the following but it is preliminary and further carefull studies should be carried out.1.So-called male-sterility is caused by the meiotic break down lead to reduction of sperm. This occurs also in female. Since female fertility is obtainable with one egg cell, the female is fertile despite the reduction in the number of oocytes.2.The molecular events so far examined indicated that there is no detectable difference between the fertiles and the steriles until either prophase or metaphase. The meiotic degradation in these hybrids may be due to apoptosis as speculated in mutant mouse, but this requirs more analysis. Less