Participation of the intracellular enzymes in the control of mutational processes : Part 4: the role of UV-specific endonuclease and medium composition in the induction of genic mutations in Escherichia coli.

The influence of UV-specific endonuclease and medium composition on the frequency and spectrum of genic mutations in Escherichia coli KI2 uvr (+) (with normal repair enzymes) and urv A6 (defective in UV-specific endonuclease) was studied. Mutations at the locus glu (gene controlling assimilation of glucose) were induced by ultra-violet irradiation and hydroxylamine treatment. To identify mutant colonies, triphenyl tetrazolium chloride (TTC) was added to the medium since it coloured the mutant colonies bright crimson and readily permitted distinction between pure mutant clones (complete mutations) and mixed clones (mosaic or sector mutations).

Linear differentation of cereal chromosomes : III. Rye, triticale and 'Aurora' variety.

The BSG test was used in an investigation of the linear differentiation in rye variety 'Zhitkinskaya', common wheat variety 'Aurora' and two secondary Triticale namely AD-196 and F-1239.Chromosomes of 'Aurora' variety and wheat chromosomes within Triticale may be easily divided into "constant" and 'variable' chromosomes as described previously (lordansky et al. 1977; Zurabishvili et al 1977).

Linear differentiation of cereal chromosomes : I. Common wheat and its supposed ancestors.

Using the Giemsa technique of differential staining (the BSG test), we have studies the karyotypes and constructed the idiograms of T. aestivum L. var.

Molecular mechanisms of the origin of chromosome aberrations and the structural organisation of eukaryotic DNA.

A new hypothesis on the appearance of exchange chromosomal aberrations has been suggested. According to this hypothesis, temporal duplex polynucleotide structure should arise during G1 and G2 phases during the correction of DNA. The size of the duplex, as a rule, should be restricted to the size of complementary nucleotide sequences in the regions of repetitions.