Comparative Analysis of MGE 412 Patterns in 18 Isogenic Lines of Drosophila melanogaster

Comparative analysis of patterns of mobile genetic element 412 was conducted in 18 isogenic lines of Drosophila melanogaster isolated in three isogenic experiments in 1987 through 1999. Twelve extra-hot isogenization sites (in 15–18 lines) and 23 hot isogenization sites (10 lines) were found; of these, 19 occurred in the original heterogeneous line. These sites virtually do not overlap with hot induction sites of transposition. Sites of the latter group generally retain their positions during isogenization. It was shown that no more than 20% of the new sites were brought from the balancer by double recombination, while inbreeding and outbreeding caused 80% of them. Different factors were shown to have different hot isogenization sites. A similarity tree was constructed for the patterns of 18 isogenic lines. The maximum peak of the tree was very low (< 0.25), i.e., the isogenic lines are more similar to than different from one another. The tree was subdivided into subtrees. The division was in good agreement with the isogenization groups corresponding to individual isogenization experiments. Significant correlation was found between the total fragment length and the number of new sites per lines.     

Induction of MGE 412 transposition in an isogenic strain of Drosophila melanogaster by different doses of ethanol fumes

The effect of treatment of males from an isogenic Drosophila melanogaster strain by limiting doses of ethanol fumes on transpositions of MGE 412 was examined. Validity of the phenomenon of transposition induction was demonstrated. We estimated rates of induced transposition (approximately 10(-2) events per site, per sperm, per generation versus < 10(-3) in control) and showed dose dependence of the rate on the exposure time of the males to ethanol fumes. Experiments with alcohol treatment at limiting doses must end either in death of the individuals or bursts of genetic variability in their progeny. In terms of genetics of an individual, this may mean loss of vital hereditary basis followed by mass degradation of the progeny of the "hard drinkers." In terms of populations genetics, this mode of MGE transposition induction can rapidly create a burst of novel genetic variation, which, apart of great losses, may generate a number of advantageous individuals, i.e., be significant for population survival in new, stressful environments.     

Comparative analysis of MGE 412 patterns in 18 isogenic lines of Drosophila melanogaster

Comparative analysis of patterns of mobile genetic element 412 was conducted in 18 isogenic lines of Drosophila melanogaster isolated in three isogenic experiments in 1987 through 1999. Twelve "extra-hot" isogenization sites (in 15-18 lines) and 23 "hot" isogenization sites (> or = 10 lines) were found; of these, 19 occurred in the original heterogeneous line. These sites virtually do not overlap with hot induction sites of transposition. Sites of the latter group generally retain their positions during isogenization. It was shown that no more than 20% of the new sites were brought from the balancer by double recombination, while inbreeding and outbreeding caused 80% of them. Different factors were shown to have different hot isogenization sites. A similarity tree was constructed for the patterns of 18 isogenic lines. The maximum peak of the tree was very low (< 0.25), i.e., the isogenic lines are more similar to than different from one another. The tree was subdivided into subtrees. The division was in good agreement with the isogenization groups corresponding to individual isogenization experiments. Significant correlation was found between the total fragment length and the number of new sites per lines.     

Prolongation of MGE 412 transposition induction after gamma-irradiation in an isogenic line of Drosophila melanogaster]]

The dose dependence of the rate of gamma-induced transpositions and consequent dynamics of the MGE 412 pattern after gamma-irradiation were investigated in isogenic line 49 in generations F1, F12, F140, and F170. It was shown that the results on dose dependence of transpositions was very similar with the corresponding results of the classic works by Timofeeff-Ressovsky et al. (1935). It is suggested that the transcribed copies of retrotransposon 412 "cure" gamma-radiation-induced double-strand DNA breaks. The phenomenon of prolongation of MGE transposition induction during early generations after treatment was shown. In this period (F1-F12), the maximum transposition rate (lambda approximately equal to 2 x 10(-2) events per MGE copy, per haploid genome, per generation) and the maximum number of heterozygous MGE copies were achieved. In the late generations (F140 and F170), the reduced induction level (lambda approximately 10(-3) was established. In the population of effective size Ne = 2000 individuals, this corresponds to the state when lambda > 1/4Ne, i.e., when the transposition flow prevails over the MGE copy loss by genetic drift. These data together with some indirect evidence argue for the hypothesis that the spontaneous transposition rate is proportional to the average number of heterozygous MGE copies per diploid genome.     

Analysis of MGE Dm412 localization pattern in Drosophila melanogaster lines undergoing long-term selection for a quantitative character]

The subpopulation composed of the mixture of Drosophila isogenic lines with interrupted wing radial vein (mutation radius incompletus, ri) was subjected to long-term selection in different directions for increase or decrease in expression of the ri gene. As a result, the lines with contrasting different values of mean character phenotype were developed. The isogenic lines of mean character phenotype were developed. The isogenic lines and F2 from their crosses with selected lines were analysed by the pattern of copia-like MGE DM412 localization. The isogenic lines were shown to have individual pattern, the selected lines differing strongly from them. Selection led to the loss of Dm412 localization sites during negative selection, while positive selection results both in loss and acquisition of sites. Correlation between the phenotype of the quantitative character and the pattern of MGE Dm412 was revealed.     

Transposition of Regulatory Elements by P-Element-Mediated Rearrangements in Drosophila melanogaster

Previously we described highly unstable mutations in the yellow locus, induced by the chimeric element and consisting of sequences from a distally located 1A unique genomic region, flanked by identical copies of an internally deleted 1.2-kb P element. Here we show that a sequence, which is part of the yellow 1A region, can be transmitted to the AS-C by successive inversion and reinversion generated by yellow- and AS-C-located P elements. The chimeric element contains a regulatory element from the 1A region that specifically blocks yellow wing and body enhancers and simultaneously stimulates yellow expression in bristles. These results suggest that P-element-generated chimeric elements may play a certain role in rapid changes of regulatory regions of genes during evolution.     

Transposition of the bobbed locus in Drosophila melanogaster

Due to the complete absence of ribosomal DNA (genetic symbol bb-), the Xbb- chromosome of Drosophila is lethal both in homozygous conditions and in compound with the Xbb- chromosome. However, in the cross between the C(1)RM/Ybb- females and the Xbb-/BSYbb+ males, characterized by the development of lethal Xbb-/Ybb- zygotes, two fertile males were detected. These males possessed all the markers of the Xbb- chromosome but lacked the Y chromosome BS marker. Genetic analysis of their progeny showed that genes responsible for restoration of viability and fertility of these exceptional males were associated with the X chromosome. The crossover tests showed that in one case these genes were tightly linked to the w locus (the bbAM1 allele), and in the second case they were located 12.6 map units to the right of the Tu locus (the bbAM7 allele). It has also been shown that the bb locus was transposed to the X chromosome within the short arm of Y chromosome. Transposition of the BSYbb+ chromosome-specific rDNA sequences to the X chromosome was confirmed by means of Southern blotting. These data indicate that replacement of the bb locus is realized by transposition rather than recombination.     

Transposition of the hobo element in Drosophila melanogaster somatic cells

Somatic mutation and recombination test on wing cells of Drosophila melanogaster showed that the recombination frequency in the somatic tissues of strains studied correlated with the presence of a full-length copy of the hobo transposable element in the genome. Transposition of hobo in somatic tissue cells at a frequency 3.5 x 10-2 per site per X chromosome was shown by fluorescence in situ hybridization with salivary gland polytene chromosomes of larvae of one of the D. melanogaster strains having a full-length hobo copy.     

Transposition of the hobo element in Drosophila melanogaster somatic cells

Somatic mutation and recombination test on wing cells of Drosophila melanogaster showed that the recombination frequency in the somatic tissues of strains studied correlated with the presence of a full-length copy of the hobo transposable element in the genome. Transposition of hobo in somatic tissue cells at a frequency 3.5 × 10^?2 per site per X chromosome was shown by fluorescence in situ hybridization with salivary gland polytene chromosomes of larvae of one of the D. melanogaster strains having a full-length hobo copy.     

Induction of male recombination in Drosophila melanogaster by chemical treatment

Acridine orange (AO), ethidium bromide (EB), ethyl methanesulfonate (EMS) and 8- ethoxycaffeine ( EOC ) were fed to larvae of Drosophila melanogaster in order to test their capacity for the induction of meiotic recombination in males. Our results show that AO and EB increase significantly the male recombination frequencies. No relationship between chromosome breakage ability and male recombination induction was found since EMS and EOC , two effective chromosome-breaking agents, were unable to increase the male recombination.     

Effect of a Dipeptide-Enriched Diet in an Adult Drosophila melanogaster Laboratory Strain

A novel ZMP analog 3 was synthesized from inosine in 10 steps, and exhibited small but significant inhibitory activity toward protein kinase C.     

Molecular Genetic Analysis of Ethanol Intoxication in Drosophila melanogaster

Recently, the fruit fly Drosophila melanogaster has been introducedas a model system to study the molecular bases of a varietyof ethanol-induced behaviors. It became immediately apparentthat the behavioral changes elicited by acute ethanol exposureare remarkably similar in flies and mammals. Flies show signsof acute intoxication, which range from locomotor stimulationat low doses to complete sedation at higher doses and they developtolerance upon intermittent ethanol exposure. Genetic screensfor mutants with altered responsiveness to ethanol have beencarried out and a few of the disrupted genes have been identified.This analysis, while still in its early stages, has alreadyrevealed some surprising molecular parallels with mammals. Theavailability of powerful tools for genetic manipulation in Drosophila,together with the high degree of conservation at the genomiclevel, make Drosophila a promising model organism to study themechanism by which ethanol regulates behavior and the mechanismsunderlying the organism's adaptation to long-term ethanol exposure.     

Transposition of the vertebrate Tol2 transposable element in Drosophila melanogaster

The Tol2 element is a transposon found from a genome of a vertebrate, a small teleost medaka fish. Tol2 encodes a gene for a transposase which is active in vertebrate animals so far tested; for instance, in fish, frog, chicken and mammals, and transgenesis methods using Tol2 have been developed in these model vertebrates. However, it has not been known whether Tol2 can transpose in animals other than vertebrates. Here we report transposition of Tol2 in an invertebrate Drosophila melanogaster. First, we injected a transposon donor plasmid containing a Tol2 construct and mRNA encoding the Tol2 transposase into Drosophila eggs, and found that the Tol2 construct could be excised from the plasmid. Second, we crossed the injected flies, raised the offspring, and found that the Tol2 construct was integrated into the genome of germ cells and transmitted to the next generation. Finally, we constructed a Tol2 construct containing the white gene and injected the transposon donor plasmid and the transposase mRNA into fertilized eggs from the white mutant. We analyzed their offspring, and found that G1 flies with wild type red eyes could be obtained from 35% of the injected fly. We cloned and sequenced 34 integration loci from these lines and showed that these insertions were indeed created through transposition and distributed throughout the genome. Our present study demonstrates that the medaka fish Tol2 transposable element does not require vertebrate-specific host factors for its transposition, and also provides a possibility that Tol2 may be used as a new genetic tool for transgenesis and genome analysis in Drosophila.     

Induction of somatic and male crossing-over by bleomycin in Drosophila melanogaster

Bleomycin (BLM) is well known as an antibiotic as well as for its antineoplastic activity. A clinical preparation of BLM was tested for its recombinogenicity in a higher eukaryotic organism, Drosophila melanogaster. Feeding of the F1 larvae on a medium with BLM increased somatic crossing-over spots on female tergites and induced recombination in male germ cells. However, nonlinear dose-response curves were obtained. Malformed tergites were also observed in females treated with BLM.     

Drosophila melanogaster P Transposable Elements: Mechanisms of Transposition and Regulation

The molecular mechanisms that control P element transposition and determine its tissue specificity remain incompletely understood, although much information has been compiled about this element in the last decade. This review summarizes the currently available information about P element transposition, P-M hybrid dysgenesis and P cytotype features, P element-encoded repressors, and regulation of transposition.     

Transposition bursts in analysis of repeated mutations in unstable strains of Drosophila melanogaster

The phenomenon of transposition memory was earlier demonstrated for the cut locus and mdg4. This work has been aimed at finding out, in what way the transposition memory can be realized. An unstable stock cmMR17ctMRpN17 was analysed which had high frequency of double cm+ct+ reversions and cmMRctMRpN repeated mutations. A series of five such transpositions could be followed. The ctMRpN17 mutation is a result of insertion at the cut locus mdg4 with the jockey element inserted within it. As seen from in situ hybridization analysis, transitions to the normal phenotype correlate, as a rule, with the excision of mdg4 and the jockey from the cut locus. Analysis of distribution of mdg1, mdg2, mdg3 and jockey on the X-chromosome of unstable revertants and repeated mutants indicated that not only transpositions of mdg4 and jockey, but also those of all mobile elements tested occur. So, we propose that the transposition memory in our genetic system is manifested in the process of transposition bursts.     

A Study of the Fertility of a Drosophila melanogaster MS Strain with Impaired Transposition Control of the gypsy Mobile Element

Molecular Biology - The flamenco locus is one of the main components of the piRNA pathway of regulation of mobile genetic elements (MGEs) in Drosophila melanogaster. Mutations at this locus lead to...