ISOLATION AND GENETIC ANALYSIS OF MUTANT STRAINS OF CHLAMYDOMONAS REINHARDI DEFECTIVE IN GAMETIC DIFFERENTIATION

[摘要] Impotent mutant strains of Chlamydomonas reinhardi , mating-type ( mt ) plus, are described that have normal growth and motility but fail to differentiate into normal gametes. Procedures for their isolation and their genetic analysis are described. Five of the imp strains ( imp-2, imp-5, imp-6, imp-7 , and imp-8 ) exhibit no flagellar agglutination when mixed with mt - or mt + gametes; these strains have been induced to form rare zygotes with mt - gametes and the mutations are shown to be unlinked to the mt locus (with the possible exception of imp-7 ). Two of the strains ( imp-3 and imp-4 ) carry leaky mutations that affect cell fusion; neither mutation is found by tetrad analysis to be linked to mt or to the other. Cells of the imp-1 strain agglutinate well with mt - gametes and active agglutination continues for up to 48 hours, but cell fusion occurs only very rarely. Analysis of these rare zygotes indicates that imp-1 is closely linked to the mt + locus, and fine-structural studies reveal that imp-1 gametes produce a mutant mating structure involved in zygotic cell fusion. The development of sexuality in C. reinhardi therefore appears amenable to genetic dissection.

[学科分类] 医学（综合）