Involvement in Meiotic Prophase of H1 Histone Kinase and p34cdc2 Homologues in Lily (Lilium longiflorum) Microsporocytes. (lily microsporocyte/p34cdc2 kinase/meiosis/pachytene)

Abstract

We have taken advantage of the synchrony of meiotic prophase I in Lilium microsporocytes to investigate the presence and involvement in four stages of meiotic prophase I (leptotene, zygotene, pachytene, and diplotene) of the p34^cdc2 H1 histone kinase, a component of MPF and a key participant in division control in other eukaryotes. H1 kinase activity showed a peak pattern during meiotic prophase I with the highest kinase activity at pachytene. A monoclonal antibody directed against a highly conserved region of p34^cdc2 (termed the ‘PSTAIR’) recognized three major protein forms by immunoblotting. The highest level of the fastest-migrating form was observed at pachytene, coinciding with the highest activity of H1 kinase. Both the proteins recognized by the anti-PSTAIR antibody and H1 histone kinase activity were retained on beads conjugated with p13^suc1, a protein known to physically associate with p34^cdc2. These observations suggest that p34^cdc2 or protein(s) highly homologous to p34^cdc2 is a component of Lilium H1 histone kinase and plays a role in regulating meiotic prophase I.