Natural populations of drosophila melanogaster from radioactively contaminated territories of Ukraine

Complete text of publication follows. Drosophila melanogaster has been used as a model object to study Chernobyl NPP after-effects on biological processes. We performed study of natural populations from sites contaminated with radionuclides. Drosophila individuals were collected in autumn 2005 and 2006 in the regions with different degrees of radioactive contamination. The flies were sampled in Polesskoe with radioactive background of 50 uR/h; near cooling pond of Chernobyl NPP (2100 uR/h); Chernobyl city (60 uR/h); Kyiv (17 uR/h), Lubny (16 uR/h); Piryatin (15 uR/h); Uman (12 uR/h); Odessa (13 uR/h). Hybridological analysis was performed using drosophila laboratory lines Canton S (wild type strain) and C(1)DX (to detect lethal mutations in sex chromosome). The flies were kept on a standard medium in laboratory conditions. Occurrence of hybrid dysgenesis was monitored by gonad reduction, isolating the gonads and evaluating visually the degree of their development. Visual mutations have not been found in all the natural populations studied. When the populations were transferred to culture breeding, an elevation of the mutation visible frequency in generations has been detected. The elevation was the highest for Chernobyl (2100 uR/h) population. All the mutations observed are typical for Ukraine. Low frequency of gonad reduction has been detected. Since the gonad reduction is one of the traits of mobile elements activity in drosophilids, a conclusion has been made about the absence of mobile elements activity in all the populations, including the laboratory wild-type line Canton S. The results of the gonad reduction analysis indirectly confirm the low frequency of visual mutations in the populations studied. To assess the spontaneous level of lethal sex-linked mutations, the male/female ratio was evaluated in the first generation and compared with the ratio in the strain Canton S (using as control) using χ2-criterion. In natural populations from Lubny and Piryatin, the level of the sex-linked lethal mutations statistically exceeded the control level during the two years monitoring. For other populations the level of the sex-linked lethal mutations was not higher than that of the control.