The first complete <Emphasis Type="Italic">Mag</Emphasis> family retrotransposons discovered in <Emphasis Type="Italic">Drosophila</Emphasis>

A retrotransposon of the Mag family was found in the Drosophila simulans genome for the first time. We also identified novel transposable elements representing the Mag family in seven Drosophila species. The high similarity between the 3’ and 5’ long terminal repeats in the found copies of transposable elements indicates that their retrotransposition has occurred relatively recently. Thus, the Mag family of retrotransposons is quite common for the genus Drosophila.     

The insulin-like receptor gene expression in the tissues synthesizing gonadotropic hormones at sexual maturation of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> females

The insulin/insulin-like growth factor signaling pathway is involved in the regulation of the synthesis of insect gonadotropic hormones, juvenile (JH) and 20-hydroxyecdysone (20E). We carried out the immunohistochemical analysis of the insulin receptor (InR) expression in the corpus allatum (the JH-producing gland) and in the ovarian follicular cells (a site for the synthesis of 20E precursor, ecdysone) in the process of sexual maturation of D. melanogaster females and examined the influence of exogenous JH on the InR expression in these tissues. For the first time, it was demonstrated that InR was expressed in follicular cells and that its expression in corpus allatum and follicular cells of Drosophila females was stage-specific, i.e., the expression intensity in young females greatly exceeded that in mature individuals. We also found a negative feedback loop in the regulation of JH levels by the insulin signaling pathway in Drosophila adults: the experimental increase in the JH titers in young females dramatically reduced the InR expression intensity in corpus allatum and follicular cells.     

Effect of Gonadotropic Hormones on Stress Resistance of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> Females Infected with Different <Emphasis Type="Italic">Wolbachia pipientis</Emphasis> Genotypes

The effect of gonadotropic hormones (juvenile (JH) and 20-hydroxyecdysone (20E)) on heat stress resistance was for the first time studied in wild type D. melanogaster line females infected with different genotypes of the Wolbachia pipientis alpha-proteobacterium. It was found that an experimental increase in JH level induces a decrease in the heat stress resistance, while an increase in 20E level induces its increase in sixday females both uninfected with the Wolbachia and infected with different bacterium strains (wMelCS, wMelPop, and wMel). However, the intensity of response differs: a decrease in the survival with an increase in JH level and its increase with an increase in 20E level are more pronounced in females infected with pathogenic wMelPop strain and less pronounced in females infected with the wMelCS genotype than in uninfected females and females infected with the wMel genotype. Data obtained suggest that the wMelCS genotype induces a decrease and wMelPop induces an increase in the level of stress hormone (dopamine), since previously we demonstrated that an increase in the JH level in mature females increases the dopamine level, an increase in the 20E level decreases it, and an increase/decrease in the dopamine level, in turn, leads to a decrease/increase of the Drosophila female resistance to heat stress.     

Mutation processes in natural populations of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> and <Emphasis Type="Italic">Hirundo rustica</Emphasis> from radiation-contaminated regions of Ukraine

Natural populations of Drosophila melanogaster and Hirundo rustica from regions of Ukraine exhibiting different levels of radiation contamination are investigated. Genetic monitoring was performed with respect to such parameters as the frequency of visible sex-linked mutations, frequency of gonad reduction in Drosophila, and rate of interphase manifestations of chromosomal instability in the erythrocytes of the birds. The results attest to a possible opposite dependence of the level of chromosomal instability among swallows and that of the rate of lethal mutations in the sex chromosome of Drosophila on the density of radiation contamination.     

Historical patterns of niche dynamics in Neotropical species of the <Emphasis Type="Italic">Drosophila</Emphasis> subgenus (Drosophilidae,Diptera)

Niche conservatism (NC) presence is a controversial question in evolutionary ecology. In Drosophila, little is known about which is the preponderant evolutionary pattern, since the adaptive radiation hypothesis first proposed by Throckmorton assumed niche divergence (ND) according to a niche occupancy scenario. Nevertheless, this hypothesis has not yet been straightforwardly tested. Our aim here was to test the role of NC patterns across evolution of American drosophilids belonging to the tripunctata and virilis-repleta lineages of the Drosophila subgenus, through measures of geographical, abiotic and biotic niche overlap and evaluations regarding the presence of phylogenetic signal or niche identity. We recovered phylogenetic signal attributable to phylogenetic niche conservatism when all species were analyzed together, but not in more restricted groups. Identity tests showed that niche equivalency was seldom rejected for the tripunctata lineage species. So, in general, neither the results for the Drosophila subgenus nor those for the tripunctata lineage support the hypothesis of an adaptive radiation. Notwithstanding, there were also several isolated cases supporting a scenario of ND, and ecological speciation was evident in some of the evaluated sister species pairs.     

<Emphasis Type="BoldItalic">In situ</Emphasis> real-time evaluation of radiation-responsive promoters in the extremely radioresistant microbe <Emphasis Type="BoldItalic">Deinococcus radiodurans</Emphasis>

A third generation promoter probe shuttle vector pKG was constructed, using the green fluorescent protein as a reporter, for in situ evaluation of Deinococcal promoter activity in Escherichia coli or Deinococcus radiodurans. The construct yielded zero background fluorescence in both the organisms, in the absence of promoter sequences. Fifteen Deinococcal promoters, either harbouring Radiation and Desiccation Response Motif (RDRM) or not, were cloned in vector pKG. Only the RDRM-promoter constructs displayed (i) gamma radiation inducible GFP expression in D. radiodurans, following gamma irradiation, (ii) DdrO-mediated repression of GFP expression in heterologous E. coli, or (iii) abolition in GFP induction following gamma irradiation, in pprI mutant of D. radiodurans. Utility of pKG vector for real-time in situ assessment of Deinococcal promoter function was, thus, successfully demonstrated.     

Characterization of the complete mitochondrial genome of flower-breeding <Emphasis Type="Italic">Drosophila incompta</Emphasis> (Diptera,Drosophilidae)

Drosophila incompta belongs to the flavopilosa group of Drosophila, and has a restricted ecology, being adapted to flowers of Cestrum as feeding and oviposition sites. We sequenced, assembled, and characterized the complete mitochondrial genome (mtDNA) of D. incompta. In addition, we performed phylogenomic and polymorphism analyses to assess evolutionary diversification of this species. Our results suggest that this genome is syntenic with the other published mtDNA of Drosophila. This molecule contains 15,641 bp and encompasses two rRNA, 22 tRNA and 13 protein-coding genes. Regarding nucleotide composition, we found a high A?T bias (76.6 %). The recovered phylogenies indicate D. incompta in the virilis–repleta radiation, as sister to the virilis or repleta groups. The most interesting result is the high degree of polymorphism found throughout the D. incompta mitogenome, revealing pronounced intrapopulational variation. Furthermore, intraspecific nucleotide diversity levels varied between different regions of the genome, thus allowing the use of different mitochondrial molecular markers for analysis of population structure of this species.     

Efficacy of plants extracts from the Cerrado against adult female of <Emphasis Type="Italic">Dermacentor nitens</Emphasis> (Acari: Ixodidae)

Dermacentor nitens tick is commonly found in the equine auditory canal, where it causes economic losses due to its direct damage, causing blood spoliation, stress, transmission of pathogens, and predisposition to myasis and secondary bacterial infection in its hosts. In this study we evaluated the effect of ethanolic extracts of Cerrado plants on biological parameters of engorged females of D. nitens. Ethanolic extracts were prepared from the leaves of Schinopsis brasiliensis, Piptadenia viridiflora, Ximenia americana, and Serjania lethalis at 25–150 mg mL^?1. Groups of 10 engorged adult females were treated with these extracts and compared with a control containing distilled water and another control with organophosphate, using five replicates for each group. Compared with the control with water, S. lethalis and X. americana extracts at 100 and 150 mg mL^?1 significantly inhibited the posture ability. Differently, extracts of S. brasiliensis and P. viridiflora were the most effective in inhibiting larval hatching. Extracts of X. americana and P. viridiflora showed effective inhibition of reproductive parameters of the tick, presenting dose-dependent effect with IC₉₀ 78.86 and 78.94 mg mL^?1, respectively. Theses effective extracts contained low condensed tannin levels and their HPLC chromatograms revealed the presence of flavonoids. The efficacies of P. viridiflora and X. americana extracts were higher than 90% indicating that these extracts are promising as alternative agents for D. nitens control.     

Lactobacilli-Host mutualism: &quot;learning on the fly&quot;

Metazoans establish with microorganisms complex interactions for their mutual benefits. Drosophila, which has already proven useful host model to study several aspects of innate immunity and host-bacteria pathogenic associations has become a powerful model to dissect the mechanisms behind mutualistic host-microbe interactions. Drosophila microbiota is composed of simple and aerotolerant bacterial communities mostly composed of Lactobacillaceae and Acetobactereaceae. Drosophila mono- or poly-associated with lactobacilli strains constitutes a powerful model to dissect the complex interplay between lactobacilli and host biologic traits. Thanks to the genetic tractability of both Drosophila and lactobacilli this association model offers a great opportunity to reveal the underlying molecular mechanisms. Here, we review our current knowledge about how the Drosophila model is helping our understanding of how lactobacilli shapes host biology.     

Metabolic profiling of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> metamorphosis: a new insight into the central metabolic pathways

Introduction

Metamorphosis is a complicated process in which cell proliferation, differentiation, and death are orchestrated to form the mature structures of insects. In Drosophila, this process is controlled by ecdysone, a steroid hormone responsible for tissue remodeling and organogenesis that gives rise to the adult fly.

Objective

By using a metabolomics approach, this study aimed to elucidate global changes in the central metabolic pathways in Drosophila throughout metamorphosis and then further examine the effects of temperature and origin on metabolic profiles.

Methods

Targeted and non-targeted metabolic profiling of time-course samples from Drosophila were constructed to cover a wide range of cellular metabolites during metamorphosis.

Results

This was the first wide-scale metabolomics study of Drosophila metamorphosis focusing on central metabolism. The abundance of detected metabolites changed drastically and correlated strongly with the development of Drosophila pupae. In non-stress conditions, temperature affected the developmental time, but the metabolic state at a certain stage of metamorphosis remained stable. Between D. melanogaster Canton S and Oregon R, similar metabolic profiles throughout metamorphosis was observed. However, there were still differences in purine and pyrimidine metabolism at an early stage in the pupal period, which was matched by differences in ecdysteroid levels.

Conclusion

This study supported the strength of metabolomics in the field of developmental biology. The results provided a general view on the metabolic profile of Drosophila during metamorphosis, which provides basic 3 knowledge for future metabolomics studies using Drosophila.

     

Pulse Generation in the Quorum Machinery of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>

Pseudomonas aeruginosa is a Gram-negative bacterium that is responsible for a wide range of infections in humans. Colonies employ quorum sensing (QS) to coordinate gene expression, including for virulence factors, swarming motility and complex social traits. The QS signalling system of P. aeruginosa is known to involve multiple control components, notably the las, rhl and pqs systems. In this paper, we examine the las system and, in particular, the repressive interaction of rsaL, an embedded small regulative protein, employing recent biochemical information to aid model construction. Using analytic methods, we show how this feature can give rise to excitable pulse generation in this subsystem with important downstream consequences for rhamnolipid production. We adopt a symmetric competitive inhibition to capture the binding in the lasI–rsaL intergenic region and show our results are not dependent on the exact choice of this functional form. Furthermore, we examine the coupling of lasR to the rhl system, the impact of the predicted capacity for pulse generation and the biophysical consequences of this behaviour. We hypothesize that the interaction between the las and rhl systems may provide a quorum memory to enable cells to trigger rhamnolipid production only when they are at the edge of an established aggregation.     

Chromosome nondisjunction in <Emphasis Type="Italic">Drosophila</Emphasis> strains mutant for tumor suppressor Merlin

The effect of mutation for gene Merlin on chromosome disjunction in Drosophila during meiosis was genetically studied. Chromosome nondisjunction was not registered in females heterozygous for this mutation and containing structurally normal X chromosomes. In cases when these females additionally contained inversion in one of chromosomes X, a tendency toward the appearance of nondisjunction events was observed in individuals containing mutation in the heterozygote. The genetic construct was obtained allowing the overexpression of protein corresponding to a sterile allele Mer ³ in the germ cell line. This construct relieves the lethal effect of Mer ⁴ mutation. The ectopic expression of this mutant protein leads to chromosome nondisjunction in male meiosis.     

Reproductive tables of predatory phytoseiid mites (<Emphasis Type="Italic">Phytoseiulus persimilis,Galendromus occidentalis</Emphasis>, and <Emphasis Type="Italic">Neoseiulus cucumeris</Emphasis>)

Feeding of predatory mites (Phytoseiulus persimilis, Galendromus occidentalis, and Neoseiulus cucumeris) on different life stages of Tetranychus atlanticus under optimal conditions was studied. Daily and total consumption of prey by predators and selection of prey of different life stages were studied for 5 days and for the entire feeding period. Average daily food consumption [number of individuals] for the entire life period of mature mite females constituted 0.43 females + 5.0 [nymphs and males] + 3.4 eggs of Tetranychus atlanticus in P. persimilis; 0.12 females + 3.70 [nymphs and males] + 3.10 eggs in G. occidentalis; and 0.19 females + 4.10 [nymphs and males] + 3.50 eggs in N. cucumeris. During the entire period of feeding, P. persimilis preferred large individuals and at the postembryonic stages selected prey to a greater extent than G. occidentalis and N. cucumeris (61.8 and 55.1%, respectively). The use of a 5-day express-method is possible for estimation of some biological characteristics of phytoseiids that previously consumed the same food for a long period. In other cases, analysis of characteristics for the entire life period is necessary.     

Various <Emphasis Type="Italic">Wolbachia</Emphasis> genotypes differently influence host <Emphasis Type="Italic">Drosophila</Emphasis> dopamine metabolism and survival under heat stress conditions

Background

One of the most widespread prokaryotic symbionts of invertebrates is the intracellular bacteria of Wolbachia genus which can be found in about 50% of insect species. Wolbachia causes both parasitic and mutualistic effects on its host that include manipulating the host reproductive systems in order to increase their transmission through the female germline, and increasing the host fitness. One of the mechanisms, promoting adaptation in biological organisms, is a non-specific neuroendocrine stress reaction. In insects, this reaction includes catecholamines, dopamine, serotonin and octopamine, which act as neurotransmitters, neuromodulators and neurohormones. The level of dopamine metabolism correlates with heat stress resistance in Drosophila adults.

Results

To examine Wolbachia effect on Drosophila survival under heat stress and dopamine metabolism we used five strains carrying the nuclear background of interbred Bi90 strain and cytoplasmic backgrounds with different genotype variants of Wolbachia (produced by 20 backcrosses of Bi90 males with appropriate source of Wolbachia). Non-infected Bi90 strain (treated with tetracycline for 3 generations) was used as a control group. We demonstrated that two of five investigated Wolbachia variants promote changes in Drosophila heat stress resistance and activity of enzymes that produce and degrade dopamine, alkaline phosphatase and dopamine-dependent arylalkylamine N-acetyltransferase. What is especially interesting, wMelCS genotype of Wolbachia increases stress resistance and the intensity of dopamine metabolism, whereas wMelPop strain decreases them. wMel, wMel2 and wMel4 genotypes of Wolbachia do not show any effect on the survival under heat stress or dopamine metabolism. L-DOPA treatment, known to increase the dopamine content in Drosophila, levels the difference in survival under heat stress between all studied groups.

Conclusions

The genotype of symbiont determines the effect that the symbiont has on the stress resistance of the host insect.

     

The <Emphasis Type="Italic">ecdysoneless</Emphasis><Superscript>1</Superscript> Gene Regulates Metabolism of the Juvenile Hormone and Dopamine in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

The dopamine (DA) content and the level of juvenile hormone (JH) degradation were studied in females of the wild-type Canton S strain and the ecdysoneless ¹ (ecd ¹) mutant, which does not produce ecdysone at a restrictive temperature (29°C). Exposure at the restrictive temperature considerably increased the JH-hydrolyzing activity and the DA content in five-day ecd ¹ females compared with flies of both strains growing at 19°C and Canton S females exposed at 29°C. In one-day ecd ¹ females, the level of JH degradation also increased at the restrictive temperature, but the DA content was low. The effect of ecdysone deficiency on the stress reaction in Drosophila melanogaster females was studied using changes in DA content and JH degradation as the reaction indicators. The ecd ¹ mutation did not prevent the initiation of the stress reaction in females exposed at the restrictive temperature, but changed its intensity (stress reactivity). The interaction of 20-hydroxyecdysone with JH and DA in regulating Drosophila reproduction under normal conditions and in stress is discussed.     

Ecdysone 20-monooxygenase activity in <Emphasis Type="Italic">Drosophila virilis</Emphasis> strains varying in ecdysteroid response to heat stress

The effect of various duration of heat stress (38°C) on the activity of ecdysone 20-monooxygenase converting ecdysone into 20-hydroxyecdysone has been studied in D. virilis of wild type and mutant strain females, which differ by the mode of heat stress response of ecdysone and 20-hydroxyecdysone. We are the first to show that heat stress induces activity of ecdysone 20-monooxygenase in Drosophila females and enzyme activity correlates with the level of 20-hydroxyecdysone.     

Genetic and epigenetic effects of <Emphasis Type="Italic">lgl</Emphasis> tumor suppressor mutations on longevity under temperature stress

Human populations are polymorphic for risk factor mutations predisposing to diseases and cancer. The evolutionary conservative tumor suppressor gene lethal (2) giant larvae (lgl), whose null variants are widespread in natural Drosophila populations, can be used as a model to study this phenomenon. We studied the effect of lgl deletion and insertion mutant alleles on the survival and longevity of their carriers depending on the genotype, cross direction, and exposure to permanent or impulse temperature stress. Under constant temperature stress, the viability and longevity of lgl/+ deletion heterozygotes increased compared to the control flies carrying two normal doses of this gene. This haploid effect was maternally mediated. Exposure of deletion heterozygotes at successive oogenesis stages to moderate impulse temperature stress affected progeny survival in a similar way. The effect of impulse heating at the pre-embryo stage was bidirectional: positive in the case of impulse warming of mature eggs and negative during egg differentiation. However, in both cases, deletion of one allele of the tumor suppressor gene in lgl/+ females increased survival of the next generation and delayed senescence. These data were compared to similar epigenetic transgenerational effects reported earlier for humans.