222 genetic characters--heterozygosity, correlation coefficient of single-locus heterozygosity, genetic distance. It is shown that (1) the Moscow Russian population is more heterozygous for genes ADA than other compared groups (0.132 ± 0.0137) and (2) the relation degree of ethnic groups with Moscow population decreases in sequence: Caucasoids, Mongoloids, Negroids. The maximum distance is found between Moscow population and Negroids (D = 0.0272 -+ 0.0036).
109 Sideris, E.G., and H. Petraki, Biology Division, Nuclear Research Center Democritos and Research Laboratories 'Agios Savas' Hospital, Athens (Greece)
Sister-chromatid exchanges and chromosome structure The effect of Cu 2+ on purified DNA from eucaryotic cells and on the chromosomes of cells in culture from the V79 Chinese hamster semihaploid cell line was studied. The effect on DNA was studied by thermal transition spectroscopy. While an increase of the Cu 2÷ concentration u p to 10-5 M does not significantly alter the thermal unfolding of the DNA, higher concentrations up to 10-4 M markedly affect the conformation of the DNA. When cells of the V79 cell line were exposed to Cu 2+ in the form of nitrates parallel effects were observed on the frequency of sister-chromatid exchanges and the mitotic index. No changes were detected in cells treated with Cu z+ up to 10 -5 M. Exposure of the cells to higher Cu 2+ concentrations resulted in a sharp increase of the frequency of sister-chromatid exchanges and the mitotic index. Both effects are being attributed to the influence of Cu 2+ on the structure of the DNA molecule.
110 Sobels, F.H., Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden (The Netherlands)
Ten years' EEMS. Environmental mutagenesis: achievements and perspectives In July 1970, the EEMS was founded in Munich with about 20-30 scientists with an interest in the field of chemical mutagenesis. At present, the society has more than 700 members from 28 different countries. Growing concern about damage to D N A as an important source of human ill-health has resulted in an explosive development of the field of environmental mutagenesis which has attained a new dimension as genetic toxicology. Many new assay systems to test for the induction of genetic damage are now in operation and systematic approaches to evaluate mutagenic activity in tier systems or batteries of tests have been developed. Tremendous progress has been achieved in the recognition of carcinogens by means of short-term