Somatic mitosis in haploid and diploid strains of Cochliobolus sativus

Abstract

From examination of living and doubly stained nuclei, somatic nuclear division in a haploid and a diploid strain of Cochliobolus sativus resembles conventional mitosis in that a metaphase-plate-like configuration and an associated fusiform spindle were present. However, a spindle pole body located at the spindle poles, the nucleolus, and presumably, the nuclear envelope persisted throughout the division cycle. During division, chromosomes contracted and the spindle elongated. At anaphase, lagging chromosomes were invariably observed.Within multinucleate cells there was variation in the degree of synchrony of nuclear division. Most, however, showed partial synchrony with the gradient direction basipetal in the diploid, acropetal in the haploid. Diploid and haploid nuclei also differed in size, in the size of spindle, number and probably in the size of chromatinic elements, and sometimes in the number of nucleoli. The haploid number of chromosomes appears to be six to eight.