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Isolation and characterization of temperature-sensitive mutants of Saccharomyces cerevisiae
1Department of Agricultural Chemistry, National Taiwan University, Taipei, R.O.C.
Abstract:
Temperature-sensitive (ts) mutants of Saccharomyces cerevisiae Y-196 were isolated by UV irradiation and/by EMS treatment. There were 163 ts mutants isolated from 66,957 colonies. These mutants were designated as AMY-1 to AMY-163. These ts mutants grew normally at 30 degrees C, but did not grow at 38 degrees C. In an auxanographic study, we showed that AMY-46 was an absolute ts mutant, while AMY-10, AMY-15, AMY-16, AMY-49, AMY-66, AMY-88, AMY-114, AMY-126, AMY-127, AMY-129, AMY-136, AMY-150, AMY-157, AMY-158, AMY-159, AMY-161, and AMY-162 were auxotrophic ts mutants except AMY-16 had cell size 2-42% larger than that of the wild type. Cell aggregation phenomenon was found when the ts mutants were cultivated at 30 degrees C to stationary phase then cultured at 38 degrees C for 4 hr. The budding numbers at 30 degrees C were less than that at 38 degrees C. Mutant AMY-49 had the highest budding number. There was a positive correlation between the growth rate and the average budding number. However, there was a negative correlation between the growth rate at 30 degrees C and the length of long axis of cell or the size of cell.
Insights
Researchers isolated 163 temperature-sensitive (ts) mutants of Saccharomyces cerevisiae, identifying auxotrophic strains and observing cell aggregation at elevated temperatures. These ts mutants offer insights into yeast cell growth regulation.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Temperature-sensitive (ts) mutants are crucial tools for studying essential genes and cellular processes.
- Saccharomyces cerevisiae is a widely used model organism in biological research.
Purpose of the Study:
- To isolate and characterize temperature-sensitive mutants of Saccharomyces cerevisiae Y-196.
- To investigate the growth characteristics and potential auxotrophy of these mutants at different temperatures.
Main Methods:
- Isolation of ts mutants using UV irradiation and Ethyl methanesulfonate (EMS) treatment.
- Auxanographic studies to determine auxotrophic requirements.
- Microscopic observation of cell morphology and budding under varying temperature conditions.
Main Results:
- 163 ts mutants (AMY-1 to AMY-163) were isolated from 66,957 colonies, exhibiting normal growth at 30°C but not at 38°C.
- Mutant AMY-46 was identified as an absolute ts mutant, while others displayed auxotrophic characteristics.
- Cell aggregation was observed at 38°C, with a positive correlation between growth rate and budding number, and a negative correlation between growth rate and cell size.
Conclusions:
- The isolated ts mutants provide valuable genetic resources for studying temperature-dependent cellular functions in Saccharomyces cerevisiae.
- Auxotrophy and cell aggregation are significant phenotypes observed in these mutants, suggesting roles in nutrient metabolism and cell-cell interactions.
- Further characterization of these mutants can elucidate gene functions critical for yeast viability and growth.