Complementation of the sor-4 gene of Neurospora Crassa /

Abstract

The study of catabolite repression in Neurospora crassa examines regulation of genetic expression in the presence of various carbon sources. Certain mutant strains of N. crassa do not display preferential expression of genes for metabolizing preferred carbon sources. An example is the sorbose resistant sor-4 strain. A cotransformation experiment was devised to determine if the gene relieving the sor-4 mutant strain of catabolite repression was complementary to ere-I, a gene thought to be involved in the events leading to catabolite repression. Neurospora crassa conidia were converted to spheroplasts in order to render them competent to take up DNA. Conidia from wild type (74A) and mutant (sor-4) strains were transformed with both the cre-l gene and a gene encoding resistance to Hygromycin B, an antibiotic used as a selectable marker. The transformed colonies were further examined for morphology, and it was determined that the sor-4 colonies were not converted back to wild type phenotype. Although resistance to the antibiotic was conferred on both wild type and mutant cells, a Southern blot showed that copies of cre-l were not integrated into the genome of sor-4 Neurospora crassa. Cotransformation did not give evidence of complementation of the cre-l gene and the sor-4 mutation.