The nsdD (never in sexual development) gene encodes a putative GATA type transcription factor that has a type IVb zinc finger DNA binding domain at the C-terminus. Null mutants that the total nsdD ORF was deleted showed the typical NsdD phenotype. However, being cultured for a week or more after inoculation onto the center of the plate, a few of cleistothecia bearing mature ascospores could be found in null mutant strains. On the other hand, the nsdDl9 mutant strain which contains a nonsense mutation within the nsdD coding region never developed cleistothecia at all under the same conditions, suggesting a dominant negative effect of the truncated NSDD proteins. When NSDD was over-expressed under the niiA promoter with nitrate, the number of cleistothecium was dramatically increased, implying a positive regulatory role of NSDD on sexual development. Northern blot analysis using total RNAs from a wild-type strain grown in minimal media revealed that the nsdD gene was expressed throughout the life cycle. However, its expression was repressed under the certain conditions, such as in the presence of high concentrations of salts, under which sexual development was inhibited. It was also found that the phenotypes of reduced or delayed sexual development in veA l or nsdB5 could be suppressed when multiple copies of the nsdD gene are present, or the gene is over-expressed.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)