In an inbred low-activity (LA) strain of Drosophila melanogaster with a low level of fitness and a complex of inadaptive characters, in situ hybridization reveals an invariant pattern of distribution of three copia-like elements (mdg-1, mdg-3, and copia). Rare, spontaneous, multiple transpositions of mobile elements in the LA strain were shown to be coupled with a drastic increase of fitness. A changed pattern of various types of mobile elements was also observed on selecting the LA strain for higher fitness. High-fitness strains show transpositions of mobile elements to definite chromosomal sites ("hot spots"). Concerted changes in the location of three different mobile elements were found to be coupled with an increase of fitness. The mdg-1 distribution patterns were also examined in two low-fitness strains independently selected from the high-fitness ones. Fitness decrease was accompanied by mdg-1 excision from the hot spots of their location usually detected in the high-fitness strains. The results suggest the existence of a system of adaptive transpositions of mobile elements that takes part in fitness control.
The paper describes the origin and development of population genetics, its main disco veries achieved in experiments with Drosophila before 1948 breakage and summarized the results of two series of long-term studies on genetic variability in Drosophila car ried out by the authors.The conceptual contribution of two main centers or school leaded by N. Koltzov and S. Chetverikov in Moscow and Yu.Filipchenko in St.-Pelersburg is considered.The ideas and methodology of these schools were introduced into American and European genetics by Th.Dobzhansky and N. V. Timofeev-Ressovsky.A new approach to the description of the eukaryotic genome organizations is des cribed.The authors argued that main source of the origin of various hereditary changes in nature is the interaction of environment with the facultative genomic elements.Biological background and the origin of genetics.At the beginning of our century, biology in Russia was flourishing.It is noteworthy to men tion here that I. P. Pavlov in 1904 and I. I. Mechnikov in 1908 were No bel prize winners.Leading Russian biologists traditionally were interes ted in evolutionary problems [1].In his comprehensive review Vucinich [110] correctly concludes that Russian scientists «alone represented the full spectrum of attitudes and critical stances toward the scientific, socio logical and general intellectual merits of the Darwinian theory of evolu tion».Even an idea as popular in modern cellular and evolutionary bio logy as symbiogenesis was conceptually developed firstly by Russian bo tanists but almost completely ignored in the West [74].Russian evolutionary thought developed through dynamic discussion and often controversy.One group of evolutionists accepted and contribu ted widely to Darwinian theory.Among them were the eminent Russian zoologists -brothers Alexander and Vladimir Kovalevsky, Menzbir, A. N. Severtzov and his follower I. I. Schmalhausen, Dogel, Zavarzin, Shimkevitch, botanists Komarov, Sukachev, Taliev, Tsinger.At the same time there were the eminent critics of the main concepts of Darwinian theory.The most illustrious embryologist of the pre-Darwinian period, Karl von Baer (1792-1876), a distinguished member of the St. Petersburg Academy of Sciences was one such critic.We may al so include here the famous botanists: Korzhinsky who discovered, simul taneously with Hugo de Vries, mutations in plants, and also Famintsyn, Borodin.The great zoologist Lev Berg (the father of a famous populati on geneticist Raissa Berg) developed the impressive anti-Darwinian con ception of Nomogenesis.His book was translated into English and issued in the 1960s as a second edition with a preface by Th.Dobzhansky.Mo re recently Dobzhansky [20
There are "slow" and "rapid" acetylator phenotypes in mice according to N-acetyltransferase activity (E.C. 2.3.1.5) (N-AT). The results of direct, back- and reciprocal crosses of mice lines with rapid acetylation phenotype (C57BL/He) show monogenic autosomic control of acetylation locus (Ac) with rapid allele dominance and sex dependence upon N-AT activity in males. So, genetic polymorphism according to the Ac locus exists in mice as well as in some other animal species and in humans. The results obtained in this study demonstrated the correlation between the N-AT level in mice and their predisposition to malignant tumors as well as dependence of cyclophosphamide action on the N-AT activity upon the genotype of an individual, which suggests a certain role of the Ac locus in tumor development.
