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Temperature-sensitive multicellular mutants of Wangiella dermatitidis
Abstract:
Three temperature-sensitive morphological mutants of Wangiella dermatitidis were isolated and characterized. The mutants grew in the yeastlike morphology at the permissive temperature (25 degrees C) but expressed a multicellular (Mc) phenotype at the restrictive temperature (37 degrees C). Cultures of Mc 2 and 3 incubated at the restrictive temperature showed rapid reductions in the percentage of budded cells in the population. In contrast, budding continued for several generations in cultures of Mc 1. Incubation of cultures of Mc 2 and 3 at the restrictive temperature for 48 h resulted in nearly total conversion of yeastlike cells to the multicellular form; about 50% of the cells of Mc 1 had converted to multicellular forms after 48 h at the restrictive temperature. Studies using radiolabeled compounds documented that DNA, RNA, and protein synthesis continued at the restrictive temperature. The results suggest that multicellularity is the result of inhibition of bud emergence and cell separation without inhibition of growth nuclear division, and cytokinesis.
Insights
Three Wangiella dermatitidis mutants developed multicellular forms at 37°C. This change resulted from inhibited cell separation and bud emergence, not growth or division, offering insights into fungal morphology.
Area of Science:
- Mycology
- Cell Biology
- Genetics
Background:
- Wangiella dermatitidis is a dimorphic fungus.
- Understanding the genetic and cellular basis of dimorphism is crucial for studying fungal pathogenesis.
Purpose of the Study:
- To isolate and characterize temperature-sensitive morphological mutants of Wangiella dermatitidis.
- To investigate the cellular mechanisms underlying the transition to multicellularity.
Main Methods:
- Isolation and characterization of three temperature-sensitive mutants.
- Incubation of mutants at permissive (25°C) and restrictive (37°C) temperatures.
- Microscopic observation of cell morphology and budding.
- Analysis of DNA, RNA, and protein synthesis using radiolabeled compounds.
Main Results:
- Mutants exhibited yeast-like morphology at 25°C and a multicellular (Mc) phenotype at 37°C.
- Mc 2 and 3 showed rapid decreases in budded cells at 37°C, with nearly total conversion to multicellular forms within 48 hours.
- Mc 1 displayed continued budding for several generations, with approximately 50% conversion to multicellular forms after 48 hours at 37°C.
- DNA, RNA, and protein synthesis remained active at the restrictive temperature.
Conclusions:
- Multicellularity in these mutants is caused by the inhibition of bud emergence and cell separation.
- Cellular growth, nuclear division, and cytokinesis are not inhibited during the transition to multicellularity.
- These findings provide insights into the regulation of cell cycle progression and morphogenesis in Wangiella dermatitidis.