Haploid spore formation following arrested cell fusion in Chlamydomonas (Chlorophyta)

Sexual fusion of haploid Chlamydomonas gametes produces a diploid zygote which undergoes sporulation (maturation). The authors have used a combination of genetic and cellular approaches to evaluate the role(S) of gametic cell and nuclear fusion in the progression of sporulation. A fusion-arrested strain, zym-26-3, was obtained following ultraviolet irradiation of vegetative haploid cells of the homothallic species Chlamydomonas monoica Strehlow. Using the DNA-specific fluorochrome, DAPI, the authors determined that diploidy was rarely achieved although nuclear migration to the base of the cytoplasmic bridge connecting the gametes and attempted transit through the tubule could be easily documented.