Term of Award

1982

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Committee Chair

Sara N. Bennett

Committee Member 1

Wayne A. Krissinger

Committee Member 2

W. Keith Hartberg

Abstract

Conidia of wild type Neurospora crassa, 74A, were irradiated with ultraviolet light to induce mutations. In order to concentrate the numbers of conidia containing mutations which would not allow growth on mannitol, the conidia were then subjected to filtration-concentration procedures using modified Westergaard and Mitchell medium where mannitol was the sole carbon source, i.e., W-M (mannitol). Initial growth test indicated 43 of 603 (8%) of the isolated strains were unable to grow on W-M (mannitol). Ten of these mutant isolates were crossed to wild type and all produced mutant progeny. In crosses of four of the ten, the mutant allele segregated 1:1. Subsequent growth tests indicated these four isolates, as well as four others of the ten, had converted to growth on W-M (mannitol). Occurrence of adaptation, rather than genetic reversion is suggested since mutant progeny appeared in crosses made after conversion, with 1:1 segregation exhibited by progeny of two mutant isolates. Crosses to the translocated tester strains alcoy and alcoy-csp showed 1:1 segregation of progeny from one isolate, M246, and indicated linkage of mannitol non-utilization to ylo of the translocated chromosomes III and VI. Characterization of the mannitol nonutilization phenotype also included the observation of a tendency toward a non-wild type morphology. Morphologies most often noted were patchy or gumny aerial growth and also colonialism. Complementation tests of five such mutants indicated at least five distinct alleles are involved in expression of morphology.

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