Antibodies directed against a meiosis-specific, chromatin-associated protein identify conserved meiotic epitopes

The molecular mechanisms by which meiotic events are regulated are at present unknown. To approach this problem, we have exploited the natural synchrony of Lilium meiocytes to compare the nuclear protein profiles of a variety of stages of meiosis. This approach has facilitated the identification of a number of nuclear proteins that appear and disappear in a stage-specific fashion. Here we report the presence of an abundant nuclear protein that first appears during premeiotic interphase, a period during which the irreversible commitment to meiosis occurs. Antibodies directed against this protein demonstrate its meiosis specificity as well as conservation of the epitope(s) in both mono- and dicotyledonous plant species. Chromatin fractionation studies indicate that this protein, which we have termed meiotin-1, is associated with strings of nucleosomes. Implications for meiotic chromatin packaging and chromosome structure are discussed.