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The isolation of mms- and histidine-sensitive mutants in Neurospora crassa
Abstract:
A simple method of replica plating has been used to isolate mutants of Neurospora crassa that have increased sensitivity to methyl methanesulfonate (MMS) and/or to histidine. Twelve mutants with increased sensitivity to MMS and one mutant with increased sensitivity to histidine showed Mendelian segregation of the mutant phenotypes. Three mutants were mapped to loci not previously associated with MMS sensitivity. Two other were allelic to the UV- and MMS-sensitive mutant, mei-3. Survival curves indicate that conidia (mutant or wild-type) survive on much higher concentrations of MMS at 25 degrees than at 37 degrees. In contrast, mycelial growth is more resistant to MMS at 37 degrees. The possibility of qualitatively different repair processes at these two temperatures is discussed.
Insights
Researchers isolated Neurospora crassa mutants sensitive to methyl methanesulfonate (MMS) and histidine. Temperature significantly impacts MMS survival, suggesting distinct repair mechanisms in conidia versus mycelia.
Area of Science:
- Genetics
- Molecular Biology
- Mycology
Background:
- Understanding DNA repair mechanisms is crucial for cellular health.
- Neurospora crassa serves as a model organism for genetic studies.
- Methyl methanesulfonate (MMS) is a chemical mutagen used to study DNA damage and repair.
Purpose of the Study:
- To isolate and characterize mutants of Neurospora crassa with altered sensitivity to methyl methanesulfonate (MMS) and/or histidine.
- To investigate the genetic basis of MMS sensitivity.
- To explore the influence of temperature on MMS resistance.
Main Methods:
- Replica plating was employed to screen for mutants.
- Mendelian genetics was used to analyze mutant segregation.
- Survival curves were generated to assess MMS sensitivity at different temperatures.
Main Results:
- Twelve mutants with increased MMS sensitivity and one with increased histidine sensitivity were isolated.
- Mutant phenotypes followed Mendelian segregation.
- Three novel loci associated with MMS sensitivity were identified.
- Two mutants were allelic to the known mei-3 mutant.
- Conidia showed higher survival at 25°C compared to 37°C, while mycelia were more resistant at 37°C.
Conclusions:
- The study identified new genetic loci involved in MMS sensitivity in Neurospora crassa.
- Temperature-dependent differential survival suggests distinct DNA repair pathways operating in conidia and mycelia.
- Further research into these temperature-dependent repair processes is warranted.