[Change in the genetic structure of an experimental population of Drosophila by electrophoretic locus under the effect of ecological conditions]. / Izmemenie geneticheskoi struktury éksperimental'nykh populiatsii Drosofily po élektroforeticheskim lokusam pod vliianiemékologicheski kh uslovii.

Dynamics of the genetic structure of experimental Drosophila populations being kept over 50 generations at 25 and 17 degrees C6 and on the medium with ethanol (12%) was studied. In all experimental populations alteration in allele frequencies of Adh, Gpdh, Hex and Est-6 loci took place in the first 20-25 generations on monitoring under the influence of the temperature and ethanol. Later on, an equilibrium relation between allele frequencies will be established.

[Selected plateau during long-term selection in experimental populations of Drosophila]. / Selektsionnoe plato pri dlitel'nom otbore v éksperimental'nykh populiatsiiakh drozofily.

Drosophila subpopulations which did not any more response to the artificial selection effect were obtained as the result of long-term selection for the number of abdominal bristles and thorax length. Study on selection lines has shown that genetic variability may both decrease in the process of selection and increase temporarily. Not always does fixation of alleles controlling a quantitative character occur when the selection limits are achieved.

[Dynamics of quantitative traits of Drosophila during long-term selection]. / Dinamika kolichestvennykh priznakov drozofily pri dlitel'nom otbore.

The results of long-term mass selection for the number of abdominal bristles and thorax length in Drosophila population during over 60 generations in opposite directions are given. It is shown that effectiveness of selection depends upon additive genetic component of phenotypic variability of characters in the initial population.

[Dynamics of the genetic structure in experimental Drosophila populations for the Adh locus as affected by ethanol]. / Dinamika geneticheskoi struktury éksperimental'nykh populiatsii drozofily po lokusu Adh pod vliianiem étanola.

Electrophoresis method was used to analyze the genetic structure of four experimental Drosophila populations (the control one and those with 5, 10 and 15% of ethanol in the nutrient medium) with initial frequency of AdhF = 0.5 for 50 monitoring generations. It was established that F and S alleles had different selective values. Natural selection favoured the F-allele. Addition of ethanol to the nutrient medium increased the selection intensity in the first 15 generations but did not change the relative adaptability of three genotypes. This caused a similarity of genetic structure in experimental populations during 50 generations.

[Effectiveness of selection for thorax length in model Drosophila populations in chemical mutagen exposure]. / Effektivnost' otbora po dline grudi v model'nykh populiatsiiakh drozofily pri vozdeistvii khimicheskim mutagenom.

Artificial selection for increasing and decreasing Drosophila thorax length was carried out over 20 generations. Chemical mutagen, dimethylsulfate (DMS) was regularly applied to enhance genetic variation in selected lines. It was determined that under the influence of mutagen the efficiency of selection for decreasing thorax length was much higher, while selection course for increasing thorax length was not affected significantly. Regression coefficient of responses to selection, general for males and females, was equal to b = -0.035 +/- 0.004 for lines of negative direction of selection when the mutagen was applied and -b = -0.023 +/- 0.004 without mutagenesis; for lines of positive direction b = 0.026 +/- 0.005 and b = 0.024 +/- 0.005. Fitness component variation by artificial selection was studied. A complex correlation was detected between direction of selection, the shift value of model quantitative character and fitness component variation by selection. The main factor stimulating a sharp drop of average fitness of lines appeared to be the influence of directional artificial selection. The regular treatment by a moderate dose of the mutagen did not affect markedly the average fitness variation of selected lines.

[Comparative study of the effectiveness of selection in diploid and autotetraploid populations]. / Sravnitel'noe izuchenie éffektivnosti otbora v diploidnykh i autotetraploidnykh populiatsiiakh

The mitotic activity and ploidy of cells of three strains of cellus tissue by the addition of the culture medium of 0,01; 0,1 and 1 mg/l of phytohemagglutinin was studied. These strains derived from the leaves of haploid, diploid, and tetraploid plants of Lycopersicon, esculentum. The number of dividing cells under the influence of phytohemagglutinin increased by 1;5 and 4% for haploid, diploid and tetraploid strains respectively. The shift of the peak of the mitotic activity at early stages of subculture under the effect of phytohemagglutinin was noticed. Phytohemagglutinin did not change the frequencies of cells of different ploidy in all the strains analysed. A weak mutagenic activity of phytohemagglutinin in the concentrations used was observed. Cells with single bridges were more frequently observed among the aberrant cells.