The aim of this study was to obtain unusual mutations called conditional. The mutations manifest in some, not all representatives of a species. Collections of these mutations in chromosomes X, 2, and 3 of Drosophila m...The aim of this study was to obtain unusual mutations called conditional. The mutations manifest in some, not all representatives of a species. Collections of these mutations in chromosomes X, 2, and 3 of Drosophila melanogaster were established. Sex of fly or chromosomal rearrangement was the conditions providing ＂manifestation-non manifestation＂ of these mutations. The mutations differ from the usual by a set of properties. The salient differences in addition to conditional manifestation include： manifestation dependence on the spatial arrangement of chromosomal material in the genome, parental effects （maternal or paternal） of the mutant, capacity for transferring the genome from stable to unstable state. It is suggested that conditional mutations are mutant variants of Drosophila regulatory genes contained by the large Genomic Regulatory Network of Drosophila. Thus, the genes of this category can be detected by using special breeding procedures, mutations of these genes have unusual manifestation.展开更多
A mutation in an ontogene acts as a conditional dominant lethal: it is lethal in a certain genotype but not lethal in another. In total, 30 mutations of this type residing in the Drosophila melanogaster X chromosome h...A mutation in an ontogene acts as a conditional dominant lethal: it is lethal in a certain genotype but not lethal in another. In total, 30 mutations of this type residing in the Drosophila melanogaster X chromosome have been assayed for their ability to cause meiotic nondisjunction. The level of X nondisjunction in the females heterozygous for the mutation in ontogene appears to be very high. The share of matroclinous daughters reaches 24.7% of the overall offspring and of patroclinous males, 24.9%. Neither inversion in the opposite X chromosome nor additional Y chromosome has any effect on the X nondisjunction. The balance of the XX and X0 egg cells is disturbed: exceptional daughters are prevalent in the offspring of the females with a normal opposite X chromosome and exceptional sons, in the offspring of the females with an inverted X chromosome. In addition, 12% of the matroclinous daughters of the females with a normal opposite X chromosome are homozygous for the marker of one of the maternal X chromosomes (“equational” nondisjunction). A “fading” parental effect of the mutation in ontogene on the X chromosome nondisjunction is also observed. Under experimental conditions, the mutant ontogenes reside in meiotic densely compacted X chromosomes. We infer that the ontogenes are DNA regions with controlled compaction. It is postulated that the genetic activity of ontogenes is determined by this compaction and has a biophysical (electromagnetic) nature. In a meiotic cell, ontogenes induce physical fields providing the operation of meiotic proteins. The structure of these fields is distorted in the mutants for ontogenes, thereby decreasing the efficiency of proteins and, as a consequence, causing meiotic defects.展开更多
文摘The aim of this study was to obtain unusual mutations called conditional. The mutations manifest in some, not all representatives of a species. Collections of these mutations in chromosomes X, 2, and 3 of Drosophila melanogaster were established. Sex of fly or chromosomal rearrangement was the conditions providing ＂manifestation-non manifestation＂ of these mutations. The mutations differ from the usual by a set of properties. The salient differences in addition to conditional manifestation include： manifestation dependence on the spatial arrangement of chromosomal material in the genome, parental effects （maternal or paternal） of the mutant, capacity for transferring the genome from stable to unstable state. It is suggested that conditional mutations are mutant variants of Drosophila regulatory genes contained by the large Genomic Regulatory Network of Drosophila. Thus, the genes of this category can be detected by using special breeding procedures, mutations of these genes have unusual manifestation.
文摘A mutation in an ontogene acts as a conditional dominant lethal: it is lethal in a certain genotype but not lethal in another. In total, 30 mutations of this type residing in the Drosophila melanogaster X chromosome have been assayed for their ability to cause meiotic nondisjunction. The level of X nondisjunction in the females heterozygous for the mutation in ontogene appears to be very high. The share of matroclinous daughters reaches 24.7% of the overall offspring and of patroclinous males, 24.9%. Neither inversion in the opposite X chromosome nor additional Y chromosome has any effect on the X nondisjunction. The balance of the XX and X0 egg cells is disturbed: exceptional daughters are prevalent in the offspring of the females with a normal opposite X chromosome and exceptional sons, in the offspring of the females with an inverted X chromosome. In addition, 12% of the matroclinous daughters of the females with a normal opposite X chromosome are homozygous for the marker of one of the maternal X chromosomes (“equational” nondisjunction). A “fading” parental effect of the mutation in ontogene on the X chromosome nondisjunction is also observed. Under experimental conditions, the mutant ontogenes reside in meiotic densely compacted X chromosomes. We infer that the ontogenes are DNA regions with controlled compaction. It is postulated that the genetic activity of ontogenes is determined by this compaction and has a biophysical (electromagnetic) nature. In a meiotic cell, ontogenes induce physical fields providing the operation of meiotic proteins. The structure of these fields is distorted in the mutants for ontogenes, thereby decreasing the efficiency of proteins and, as a consequence, causing meiotic defects.
