Term of Award

Winter 1986

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

Sara Neville Bennett

Committee Member 1

W. Keith Hartberg

Committee Member 2

Wayne A. Krissinger

Abstract

Following ultraviolet irradiation, nine conidial separation mutants of N. crassa, wild type strain 74A, were isolated from 1481 colonies. Four of these mutants and one mutant previously isolated in this laboratory were analyzed genetically. All five mutants showed 1:1 segregation of the conidial separation trait in progeny of crosses to wild type 74a. Three of the mutants studied also carried the trait for osmotic sensitivity. This trait showed 1:1 segregation in two of the mutants, but not in the third. One of the stable mutants investigated in this study was osmotic remedial for conidial separation. Results of complementation tests indicate that these mutants not only represent separate loci for conidial separation, but are also new loci for conidial separation.

A reversion experiment was carried out using an auxotrophic strain of the mutant SS-931, which had been previously isolated in this laboratory. No revertants were recovered from 42.07 x 106 viable conidia, indicating that the reversion rate for this mutation is less than 1 / 42.07 x 106.

The mutants under investigation were also studied with light and scanning electron microscopy, and an investigation into the sensitivity of conidia of the various strains to exposure to elevated temperatures was conducted. The exposure of conidia to elevated temperatures demonstrated that the most sensitive of the strains investigated were the known osmotic sensitive mutants, and an osmotic sensitive conidial separation mutant isolated in this study.

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