Term of Award

Spring 2002

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)


Department of Biology

Committee Chair

Sara Neville Bennett

Committee Member 1

Wayne A. Krissinger

Committee Member 2

Oscar J. Pung


The crisp-5 (cr-5) mutant (allele 123 CJ13-6A) of Neurospora crassa was isolated in the Georgia Southern Neurospora Laboratory and was found to be linked to ad-4 in LG III. The present study mapped cr-5 to the right of ad-4 with the gene order pro-1 ad-4 cr-5 with 1.3% to 5% recombination between ad-4 and cr-5. Reciprocal crosses of cr-5 pro-la double mutant and the leu-1A marker strain supported the gene order pro-1 cr-5 leu-1, successfully bracketing the cr-5 locus. There was 12% to 18% recombination between pro-1 and cr-5 and 9% to 19% recombination between cr-5 and leu-1.

Both cr-5 and wild type 74A were grown on minimal medium in which the carbon source was 2% sucrose, 2% glucose, 2% fructose, 2% lactose, 2% mannitol. 2% glycerol, 2% sorbitol or 2% sorbose. The cr-5 mutant grew better on glucose and fructose separately than it did on sucrose. Both the mutant and wild type grew very poorly on lactose, mannitol, sorbitol and glycerol. The pattern of growth of cr-5 was different on media with lactose, mannitol, glycerol, and sorbitol. Although cr-5 grew poorly on media with some carbon sources, it was found to be a fertile female on all carbon sources tested. Neither strain tested grew on sorbose as the sole carbon source.

Observations utilizing SEM indicated that, compared to wild type 74, cr-5 has a reduced mycelium containing clusters of conidia formed by highly branched conidiophores carried on short aerial hyphae. The mutant cr-5 conidiates early and profusely.

The time and percent germination of wild type 74A and cr-5 conidia were determined. Conidia of cr-5 consistently germinated earlier than those of wild type but the percent of conidia germinating one hour after the first observation of germination was higher for wild type.

Conidia of cr-5 were tested for thermotolerance at 60oC heat shock temperature. The mutant cr-5 exhibited thermotolerance. Therefore, when performing crosses with new mutants, it would be advisable to test the heat shock effect to avoid skewed results when scoring progeny of the crosses.

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