Abstract
Colony development by Aspergillus nidulans temporally and spatially controlled to produce asexual fruiting structures known as conidiophores approximately 18 hours after germination of the conidiospores. Mutations that delay conidiophore development by at least 24 hours result in fluffy- appearing colonies. The flbC gene had been previously identified screen for fluffy mutants that had lower than normal expression of the primary developmental regulatory gene brlA+ (WIESER et ai. 1994). A deletion of the region encoding FLBC has the same phenotype as the point mutant, flbC8, indicating that flbC8 causes a loss function. The flbC DNA sequence predicts a AA polypeptide with significant identity at carboxy terminus to the DNA-binding motif of the C2H2 zinc-finger family of transcription factors. A portion of the flbC8 sequence was found to have a single base- pair change that produces a H237Q change in the second putative zinc finger, providing another line of evidence the flbC8 mutation generates a loss function. The flbC8 mutant shows increased levels of flbC expression during development, suggesting that a negatively acting autoregulatory pathway may exist. A screen for suppressors of the flbC8 phenotype was of the asexual conducted to identify new components developmental pathway. Approximately 50,000 colonies were screened after a chemical mutagenesis of an flbC8 strain. Two different loci were identified that qualitatively suppressed the flbC8 and []flbc phenotypes. Diploid analysis of the suppressors indicated that both are recessive. Construction double mutants containing the sfcA1 mutation and flbB or flbD indicate that the sfcA1 can also suppress the respective fluffy phenotypes.
Meyer, Gregory Brian (1999). Characterization of the flbC developmental locus and a screen for loss-of-function flbC suppressors in Aspergillus nidulans. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1999 -THESIS -M477.