Term of Award

Spring 1999

Degree Name

Master of Science

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Committee Chair

Sara Neville Bennett

Committee Member 1

Wayne A. Krissinger

Committee Member 2

Oscar J. Pung

Abstract

The osmotic-sensitive mutant of Neurospora crassa, os-1 (M16). exhibits pleiotropic characteristics of sensitivity to medium with 2% NaCl, altered non-wild type morphology, and resistance to the fungicide vinclozolin while wild type N. crassa exhibits resistance to 6% NaCl and sensitivity to vinclozolin. Revertant isolates of os-1 (M16) were obtained following UV irradiation, and four of these isolates were characterized, on media with or without 6% NaCl or vinclozolin, for the rate of hyphal elongation, biomass and quantity of conidia produced. All four isolates were classified as partial revertants because they were no longer osmotic sensitive but were still vinclozolin resistant. Based on the degree of their resistance to vinclozolin. they were categorized into two types: Three were type-H (highly vinclozolin resistant) partial revertants. and one was type-L (less vinclozolin resistant) partial revertant. Additional characterization by scanning electron microscopy of the four revertants, wild type 74, trp-l, os-l and the os-l, trp-ldouble mutant revealed the presence of poriform depressions in the cell wall of hyphal tips. The numbers and appearance of the depressions differed among the strains, but did not correlate directly to the presence or absence of osmotic sensitivity.

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