TEMPORAL AND SPATIAL-DISTRIBUTION OF MEIOTIN-1 IN ANTHERS OF LILIUM-LONGIFLORUM

Meiotin-1 is a chromatin associated, conserved protein found in meiocytes immediately preceding and during meiosis and is thought to have a role in determining the higher order structure of meiotic chromosomes [Riggs and Hasenkampf: Chromosoma 101:92-98, 1991]. In the studies reported here we utilized immunoblotting and immunocytochemical techniques to examine the temporal and spatial distribution of meiotin-1 in the anthers of Lilium longiflorum. The results with the anti-meiotin-1 immune serum were compared with those obtained using an anti-histone Hl immune serum. The anti-histone H1 immune serum gave constant immunostaining in all cell types of the anther at all of the stages tested. In contrast, the anti-meiotin-1 immune serum only gave immunostaining with the microsporocytes and to a lesser extent with the nutritive layer, the tapetum. It did not react with the cells of the anther wall. Meiotin-1 immunostaining was first present in significant quantities in the microsporocytes as they accumulated in the G1 phase before the onset of premeiotic S phase and reached peak levels in the time interval between leptotene and pachytene-the same interval when chromosome synapsis occurs and when reciprocal genetic exchange is thought to occur. Immunostaining for both meiotin-1 and histone H1 uniformly decorates the longitudinal axes of the chromosomes. Our data are consistent with the idea that the role of meiotin-1 may be to tag certain sequences or to limit the degree of chromosome condensation that occurs during meiotic prophase.