| Research Abstract |
In this study, using specific antisera, we have detected three kinds of histone variant, that shows specific temporal and spatial distribution during microsporogenesis and pollen development, among basic proteins included in male gametic (generative and sperm) nuclei of Lilium longiflorum. One is a meiotic histone (mHl), which had been reported to be a histone Hl-like protein. It appears preceding meiotic division in microsporocytes and is preferentially localized on the centromeres/kinetochores during microsporogenesis and megasporogenesis. Using this antiserum, we were able to visualize the fusion and disjunction of centromeres of homologous chromosomes in prophase I, nonseparation of the sister centromeres at anaphase,, separation of them at anaphase II and the attachment of the centromeres to spindle microtubules. Second group is a gHl, which is also a variant of histone Hl. It is not a gametogenesis-specific protein, but abundantly accumulates in the male gametic nuclei. The analogous proteins are present in nucleoli of higher plant cells including monocotyledon and dicotyledon as well as in nucleoli of somatic and early reproductive cells of this lily. Last are male gamete-specific, core histone variants, that were designated gH2A, gH2B and gH3. They appear during the development of bicellular pollen after microspore mitosis and are specifically localized in the generative and sperm nuclei. But, they were targeted to the nucleoli in somatic cells. From these observations, it is assumed that these histone variants are closely related to specific chromatin organization and the chromatin organization of the male gametic nuclei is similar to that of nucleolus.
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