Altered Development in a Temperature-Sensitive Morphological Mutant ofWangiella Dermatitidis

Abstract

A mutant strain of the polymorphic fungus Wangiella dermatitidis that exhibits a temperature-conditional developmental process at the restrictive temperature of 37 C was found to be subtly different from the wild-type parental strain at the permissive temperature of 25 C. The mutant strain grows as a budding yeast at 25 C, but exhibits multicellular-form development at 37 C, whereas the wild type grows as a yeast at either temperature. In contrast to the wild type, cells of the mutant grown at 25 C had a slightly longer mean generation time, and mother cells, but not buds, were more spherical. The growth kinetics ofthe mutant shifted from an exponential to an arithmetic mode when cells were shifted from 25 C to 37 C. Finally, the ability of a mutant yeast cell to commit to multicellular-form development was shown to depend on its cell cycle position.