<正>Objective: To study the effects of the fixed-point mutant on growth cycle and ultrastructure of the Calmodulin fixed-point mutant yeast. Methods: Growth cycle and ultrastructure of the Calmodulin fixed-point mutant yeast were studied by using cytometry and scan electron microscope. Results: After culture at 30’C for 36 h

the content of aneuploidy of the temperature-sensitive recombinant yeast monoploid B（F92+） and E（F89+FH1 + ） strains were 63. 87% and 63. 55%

respectively. These were significantly different from control OP<0. 01) ; The content of the non-temperature-sensitive recombinant yeast monoploid A（F89+） and C（F141+） strains were 100. 00% and 99. 97%

respectively

which were not significantly different from control value （P>0. 05）. Observed by scan electron microscope

the control group

A and C strain’s buds were spherical or oval and those bud-necks were fairly shorter; the B and E strain’s buds were slender

some cell were abnormal and some buds might show spherical or oval. Conclusion: DN