ISOLATION OF DIFFERENTIALLY EXPRESSED CDNA CLONES FROM SALT ADAPTED ASPERGILLUS-NIDULANS

Differentially expressed cDNA clones were isolated from salt-adapted A spergillus nidulans (FGSC #359). Poly (A)(+) RNA from adapted mycelia was used to construct a lambda Uni-ZAP cDNA library. The library was s creened with mixed subtracted cDNA probes. Three-hundred and fifty-sev en positive plaques were isolated in the primary screening. Sixty-two randomly selected plaques were purified and placed into eight differen t cross-hybridization groups. A representative cDNA from each group wa s used to study expression under unadapted, salt-adapted and salt-shoc k conditions. These clones, representing eight different genes, displa yed enhanced expression under salt stress. Exploratory nucleotide sequ encing was performed, and the predicted amino-acid sequence was compar ed with known gene sequences in the data-bank. Five of the cDNA clones were identified as a mitochondrial (mt) ATPase beta subunit, a mt ATP ase subunit 9, a mt transport protein, a ubiquitin-extension protein a nd a ribosomal protein. Three cDNA clones could not be identified due to lack of adequate homology with known sequences. These results sugge st that at least five genes with known function in cellular processes like ATP generation and protein synthesis, and three other genes of un known identity, are greatly induced in salt-adapted conditions.