Published online by Cambridge University Press: 14 April 2009
Inositol independent (inl+) strains were obtained either as transformants following treatment of the inositol requiring (inl) strains of Neurospora crassa with the wild-type DNA or as revertants without any DNA treatment. A significant number of the inositol-independent transformants were also found to have acquired additional mutations called osmotics (os) which made them unable to grow on 1 m-NaCl medium. None of the inositol-independent revertants were found to possess such osmotic mutations and their growth remained unaffected by the presence of NaCl. Many of the osmotic mutants described here were found to be new alleles of the previously known os–1 mutation on the linkage group I of Neurospora crassa. The remainder were found to map at two new genetic loci designated as os-6 and os-7; these loci were found to be closely linked to os–1. Among the new osmotic mutants only os-1 and os-6 mutants showed intragenic complementation. The mechanism of DNA-induced mutation during transformation is discussed.