Larval crowding results in hormesis-like effects on longevity in Drosophila: timing of eclosion as a model.

There is increasing evidence that stress during development can affect adult-life health status and longevity. In the present study, we examined life span (LS), fly weight, fecundity and expression levels of longevity-associated genes (Hsp70, InR, dSir2, dTOR and dFOXO) in adult Drosophila melanogaster flies reared in normal [low density (LD), ~ 300-400 eggs per jar] or crowded [high density (HD), more than 3000 eggs per jar] conditions by using the order (day) of emergence as an index of the developmental duration (HD1-5 groups). Developmental time showed a significant trend to increase while weight showed a significant trend to decrease with increasing the timing of emergence. In both males and females eclosed during first 2 days in HD conditions (HD1 and HD2 groups), both mean and maximum LSs were significantly increased in comparison to LD group. In males, mean LS was increased by 24.0% and 23.5% in HD1 and HD2 groups, respectively. In females, corresponding increments in mean LS were 23.8% (HD1 group) and 29.3% (HD2 group). In HD groups, a strong negative association with developmental time has been found for both male and female mean and male maximum LSs; no association with growth rate was observed for female maximum LS. The female reproductive activity (fecundity) tended to decrease with subsequent days of eclosion. In HD groups, the levels of expression of all studied longevity-associated genes tended to increase with the timing of eclosion in males; no differences were observed in females. On the basis of findings obtained, it can be assumed that the development in conditions of larval overpopulation (if not too extended) could trigger hormetic response thereby extending the longevity. Further studies are, however, needed to confirm this assumption.

A rapid change in P-element-induced hybrid dysgenesis status in Ukrainian populations of Drosophila melanogaster.

The Drosophila melanogaster P-transposable element is an example of mobile DNA transferred horizontally and known to have spread globally over the last 50-60 years. In Drosophila, the P-element causes a syndrome known as 'P-M hybrid dysgenesis' that obstructs normal ovary development in the female progeny of susceptible populations. Despite extensive research, the stability and global population dynamics of P-M dysgenic phenotypes remain poorly understood. Here, we report a recent and rapid transition in the P-M status of D. melanogaster populations from Ukraine. We demonstrate that these populations are currently dominated by the P'-cytotype characterized by active genomic P-elements and unknown from Ukraine just two decades ago. Our results suggest a recent invasion of the P-element in Ukraine, a pattern that matches recent discoveries from Turkey.

A HIGH FREQUENCY OF HERITABLE CHANGES IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER IN UKRAINE.

Spontaneous mutations are thought to have a stable rate for a given species. If non-adaptive, they appear at low frequencies and are governed by drift. However, environmental factors have been reported to cause spread of non-adaptive mutations in populations, governed by mechanisms, such as genetic assimilation. In the present study, we report a simultaneous appearance of a mutant and apparently non-adaptive C2 vein in Drosophila melanogaster at higher than expected frequencies in several distant populations, which excludes the role of drift or selection as the cause of the reported mutation frequencies. We discuss explanations of the phenomenon, including the role of externalfactors, such as temperature, in the possible genetic assimilation of the trait.

Mutagenesis testing using the LacZ reporter activity of the reparation gene mus209 in Drosophila melanogaster.

We studied a set of Drosophila melanogaster strains that could be potentially suitable for testing a variety of mutagenic factors. Their genomes contained insertions of the enhancer trap P{lacW} in which the activity of the LacZ reporter is under the control of the reparation genes' regulatory region. We demonstrated that the beta-galactosidase reporter, which is encoded by insertion of P{lacW} element in the gene mus209, is induced by irradiation in the cells of the salivary glands and wing imaginal discs. Despite the fact that the reporting coloration is not associated with the dose of radiation treatment, we found that the induction threshold of the reporter is different for these tissues. Thus, coloration in salivary glands is detectable after the dose of 200 rad and above, whereas the imaginal discs get colored with 500 rad and above. Thereby, multiple thresholds for induction of the reporter in the various tissues allow approximating the received dose.

TP53 codon 72 polymorphic variants (Rs1042522) frequency in the Ukrainian population. / ChASTOTA POLIMORFNYKh VARIANTIV 72 KODONU GENA TP53 (RS1042522) SERED NASELENNIa UKRAINY.

OBJECTIVE: To estimate frequencies of polymorphic variants of TP53 codon 72 in the Ukrainian population. MATERIALS AND METHODS: We determined the allele frequencies for 148 healthy people. Genotyping was performed by allele specific polymerase chain reaction. RESULTS: We identified 31 individuals (20.9 %) with Arg/Arg genotype, Arg/Pro genotype was identified for 116 indi viduals (78.4 %), whereas genotype Pro/Pro was rare and was found in one person only (0.7 %). Genotype distribu tions were not within Hardy Weinberg equilibrium (χ2 = 59,7, p < 0.0001). CONCLUSIONS: Arg and Pro allele frequencies in the population of Ukraine are 60 and 40 % respectively, which is sig nificantly differ from the frequencies described in the literature for Poland, the Czech Republic, the USA and Brazil.

The downregulation of the miniature gene does not replicate miniature loss-of-function phenotypes in Drosophila melanogaster wing to the full extent.

During maturation Drosophila wing epithelial cells undergo number of changes due to processes, which take place in the wing of the newly emerged fly, among which epithelial-to-mesenchymal transition (EMT) and apoptosis are pivotal. It is considered that neurohormone bursicon is responsible for their triggering. In turn, extracellular matrix protein Miniature is also essential for proper progress of apoptosis and, presumably, EMT. In accordance with our previously proposed hypothesis, Miniature and bursicon form stabilizing/accumulative complexes, which are able to diffuse freely within Drosophila wing, in such a way constitutively promoting enough concentrations of the maturation triggering signal. Here we tried to come to confirmation of our hypothesis from the other side, using UAS/GAL4 system and RNAi-silencing techniques.

Reciprocal cross differences in Drosophila melanogaster longevity: an evidence for non-genomic effects in heterosis phenomenon?

Reciprocal cross effects (i.e., differences between reciprocal hybrids that are developed by reversing the strains from which the dam and the sire are taken) are commonly used as a measure of sex-linkage or maternal effects. However, the papers reporting parental effects on life span of experimental animals are scarce. In order to investigate the potential of parent-of-origin effects for the longevity of hybrids, we determined the life spans of the inbred lines of Drosophila melanogaster [Oregon-R (OR), Canton-S (CS) and Uman (Um)] that differ significantly in longevity, as well as the life span of the progeny from the reciprocal crosses among them. The hybridization caused the increase in both flies' mean and maximum life span mainly shifting the survival curves upward proportionally at all ages. This resulted in the reduction in the Gompertz intercept (frailty) whereas the Gompertz slope (the rate of aging) was predominantly unchanged. Better-parent heterosis was observed in hybrids between OR and Um inbred lines and the extent of heterosis was more pronounced in hybrids between CS and Um inbred lines if long-lived parent was used as the female parent, and short-lived parent was used as the male parent in the crossing scheme. Such discrepancy in life span between reciprocal crosses may indicate that non-chromosomal factors are significantly contributing to a heterotic response. Our data are in line with the previous reports suggesting the involvement of non-genomic factors, particularly epigenetic events attributed to hybridization, in the manifestation of heterosis.

On the persistence of P element in cultured lineages of Drosophila melanogaster.

P transposon is known to have invaded the Drosophila melanogaster genome in the 1950s as a result of horizontal transmission from D. willistoni. Part of the evidence supporting the timing of its invasion comes from analyses of cultured drosophila lineages originating from wild flies cultivated long time in laboratory before analysis. Such analyses have shown that P element was absent from the genomes of cultured lineages established from wild flies caught from the wild before the 1950s. Although the hypothesis of P element transmission has obtained multiple lines of evidence and is beyond doubt today, we decided to test whether analysis of cultured lineages can provide some temporal information on the P element population dynamics. In the present work we demonstrate that P element present the in wild-caught flies may be lost in the cultured fly lineages after some generations. This result is in accordance with the results of at least one published work and suggests that analysis of the cultured fly lineages may sometimes be unreliable in establishing historical trends in P element population dynamics, as the transposon may be occasionally lost, perhaps in the highly inbred lineages in which not all founding females carry it.

DNA methylation in Drosophila melanogaster may depend on lineage heterogeneity.

DNA methylation has been discovered in Drosophila only recently. Current evidence indicates that de novo methylation patterns in drosophila are maintained in a different way compared to vertebrates and plants. As the genomic role and determinants of DNA methylation are poorly understood in invertebrates, its link with several factors has been suggested. In this study, we tested for the putative link between DNA methylation patterns in Drosophila melanogaster and radiation or the activity of P transposon. Neither of the links was apparent from the results, however, we obtained some hints on a possible link between DNA methylation pattern and genomic heterogeneity of fly lineages.

The influence of some environmental factors on cytological and biometric parameters and chlorophyll content of Deschampsia antarctica Desv. in the maritime Antarctic.

Under the environmental conditions of the Point Thomas Oasis (King George Island, the South Shetland Islands), we studied the influence of month-long artificial treatment with fresh water, salt water, and guano solution on the biometric characteristics, chlorophyll content, as well as the nuclear area of leaf parenchymal cells and nuclear DNA content, in a maritime Antarctic aboriginal plant Deschampsia antarctica. The modeled factors induced an increase in the generative shoot height and the length of the largest leaf, but did not influence the number of flowers. Treatment with guano caused an increase in the chlorophyll a and b contents, while fresh water treatment only led to some increase in chlorophyll a. Fluctuations of physiologically significant traits, such as the nuclear area and DNA content in the leaf parenchyma cells of D. antarctica, have been traced under the influence of the studied factors. Understanding of the hierarchy of influence of these factors as well as and sensitivity of plants of this species to external agents require further investigation.

Mobile genetic elements and cancer. From mutations to gene therapy.

In the present review, an association between cancer and the activity of the non-LTR retroelements L1, Alu, and SVA, as well as endogenous retroviruses, in the human genome, is analyzed. Data suggesting that transposons have been involved in embryogenesis and malignization processes, are presented. Events that lead to the activation of mobile elements in mammalian somatic cells, as well as the use of mobile elements in genetic screening and cancer gene therapy, are reviewed.

Are Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl. migratory relicts?

It remains unclear why there are only two vascular plant species in Antarctica, Deschampsia antarctica Desv. (Poaceae) and Colobanthus quitensis (Kunth) Bartl. (Caryophyllaceae). Despite progressing climate warming, there is also just one alien plant species found in the region, introduced by humans and spreading mainly in disturbed habitats. In the present article we try to interpret the data concerning the history of the biota and glaciations of the continent, proceeding from the assumption that both plants migrated to Antarctica during the Oligocene-Pliocene, when it was less isolated and the climate was more favorable for their naturalization. Genetic evidence was also taken into consideration. Our data allow suggesting secondary dispersal in the region, due to transfer by birds with regard of climate changes. With this in mind, we believe that D. antarctica and C. quitensis are migratory relicts.