Isolation, partial length sequence and expression of steroid inducible Hsp70 gene from Rhizopus nigricans

Previous studies have shown that filamentous fungus Rhizopus nigricans resp onds to addition of different steroids into growth medium with induction of hydroxylation system and that some steroids provoke stress response. The p urpose of this study was to investigate whether those steroids provoke indu ction of Hsp70 gene(s), well studied markers of stress response in differen t cells and organisms. The expression studies of fungal Hsp70 gene(s) using Northern blot analysis showed that fungal hsp70 mRNA was upregulated after treatment of mycelia with deoxycorticosterone and testosterone, but not af ter exposure to progesterone. In addition, expression of fungal Hsp70 mRNA was elevated after exposure of mycelia to heat shock (32 degrees C), ethano l, heavy metal (CuSO4), and oxidative stressor (H2O2), whereas treatment of mycelia with osmotic stressor (KCl) didn't have any influence on stress pr otein expression. The partial nucleotide sequence and deduced amino acid se quence homology search revealed that the cDNA clone (lambda hs20/2), isolat ed from cDNA library prepared from heat shock treated fungal mycelia, conta ined Hsp70 gene of DnaK subfamily.