The method of penicillin selection used after UV-irradiation (lambda = 254 nm) allows one to select UV-sensitive mutants (uvs-mutants) of the phototrophous bacterium Rhodopseudomonas sphaeroides induced by nitrosomethylurea with an effectiveness greater by an order of magnitude. Over 30% of the uvs-mutants obtained using this method had an elevated sensitivity not only to far-UV (F-UV, lambda = 254 nm) but also to near-UV (N-UV, lambda greater than 280 nm) UV-irradiation. No correlation was found in the degree of sensitivity to F-UV and N-UV-irradiation of the uvs-mutants. Mutants highly sensitive to the lethal action of N-UV were isolated.

Genetic Techniques↗

PubMedDate not supplied

[Use of a pyrimidine-dependent mutant for effective labeling of the DNA OF Aspergillus nidulans].

Incorporation of the radioactive label from pyrimidines into RNA and DNA of an Aspergillus nidulans pyrimidine-dependent mutant was studied. The label from [14C2]uridine was incorporated at the highest rate into both fractions of nucleic acids from A. nidulans of the wild type and pyr-mutant. The content of the label in the DNA of the pyr-mutant was several times higher than that in the wild type DNA. Therefore, pyr-mutants can be used in order to study molecular-genetic processes in the cells of A. nidulans. The label from [3H5]deoxyuridine, [14C2]thymine, [14C2]thymidine, [14C2]cytosine and I114C2]uracil was incorporated into the pyr-mutant RNA and DNA at a much lower rate than into the wild type RNA and DNA. Apparently, these pyrimidines cannot maintain the growth of the pyr-mutant. Incorporation of the label from [14C2]uracil into the pyr-mutant DNA increased if growth of the mycelium was stimulated by low concentrations of unlabeled uridine.

Aspergillus nidulans↗