Larval stress affects adult Drosophila behavior and metabolism.

In this study, we raised the following question: "Does metamorphosis, being a "reboot" of all systems of the organism, erase the changes that occurred at earlier stages of insect development?" To answer this question, we investigated several behavioral, metabolic and neuroendocrine parameters in Drosophila melanogaster imago that had undergone heat stress at the 3rd larval instar (32 °C, 48 h). We discovered that larval stress negatively affected feeding and locomotor behavior, as well as total lipid content in adult flies. At the same time, these flies demonstrated a considerable increase in carbohydrate content and expression level of insulin/insulin-like growth factor signaling (IIS) pathway genes, dfoxo, dilp6 and dInR. The data obtained allow us to conclude that metamorphosis does not erase the effect of stress exposure at early developmental stages and causes dramatic changes in carbohydrate and lipid metabolism as well as locomotor activity of adult insects, which is at least in part due to changes in IIS activity.

Two Old Wild-Type Strains of Drosophila melanogaster Can Serve as an Animal Model of Faster and Slower Aging Processes.

BACKGROUND: Drosophila melanogaster provides a powerful platform to study the physiology and genetics of aging, i.e., the mechanisms underpinnings healthy aging, age-associated disorders, and acceleration of the aging process under adverse environmental conditions. Here, we tested the responses of daily rhythms to age-accelerated factors in two wild-type laboratory-adapted strains, Canton-S and Harwich. METHODS: On the example of the 24 h patterns of locomotor activity and sleep, we documented the responses of these two strains to such factors as aging, high temperature, carbohydrate diet, and diet with different doses of caffeine-benzoate sodium. RESULTS: The strains demonstrated differential responses to these factors. Moreover, compared to Canton-S, Harwich showed a reduced locomotor activity, larger amount of sleep, faster rate of development, smaller body weight, lower concentrations of main sugars, lower fecundity, and shorter lifespan. CONCLUSIONS: It might be recommended to use at least two strains, one with a relatively fast and another with a relatively slow aging process, for the experimental elaboration of relationships between genes, environment, behavior, physiology, and health.

Drosophila melanogaster Transcriptome Response to Different Wolbachia Strains.

Wolbachia is a maternally inherited, intercellular bacterial symbiont of insects and some other invertebrates. Here, we investigated the effect of two different Wolbachia strains, differing in a large chromosomal inversion, on the differential expression of genes in D. melanogaster females. We revealed significant changes in the transcriptome of the infected flies compared to the uninfected ones, as well as in the transcriptome of flies infected with the Wolbachia strain, wMelPlus, compared to flies infected with the wMelCS112 strain. We linked differentially expressed genes (DEGs) from two pairwise comparisons, "uninfected-wMelPlus-infected" and "uninfected-wMelCS112-infected", into two gene networks, in which the following functional groups were designated: "Proteolysis", "Carbohydrate transport and metabolism", "Oxidation-reduction process", "Embryogenesis", "Transmembrane transport", "Response to stress" and "Alkaline phosphatases". Our data emphasized similarities and differences between infections by different strains under study: a wMelPlus infection results in more than double the number of upregulated DEGs and half the number of downregulated DEGs compared to a wMelCS112 infection. Thus, we demonstrated that Wolbachia made a significant contribution to differential expression of host genes and that the bacterial genotype plays a vital role in establishing the character of this contribution.

Mechanisms of Neuroendocrine Stress Response in Drosophila and Its Effect on Carbohydrate and Lipid Metabolism.

Response to short-term stress is a fundamental survival mechanism ensuring protection and adaptation in adverse environments. Key components of the neuroendocrine stress reaction in insects are stress-related hormones, including biogenic amines (dopamine and octopamine), juvenile hormone, 20-hydroxyecdysone, adipokinetic hormone and insulin-like peptides. In this review we focus on different aspects of the mechanism of the neuroendocrine stress reaction in insects on the D. melanogaster model, discuss the interaction of components of the insulin/insulin-like growth factors signaling pathway and other stress-related hormones, and suggest a detailed scheme of their possible interaction and effect on carbohydrate and lipid metabolism under short-term heat stress. The effect of short-term heat stress on metabolic behavior and possible regulation of its mechanisms are also discussed here.

Wolbachia Effect on Drosophila melanogaster Lipid and Carbohydrate Metabolism.

The effect of maternally inherited endosymbiotic bacteria Wolbachia on triglyceride and carbohydrate metabolism, starvation resistance and feeding behavior of Drosophila melanogaster females was studied. Eight D. melanogaster lines of the same nuclear background were investigated; one had no infection and served as the control, and seven others were infected with different Wolbachia strains pertaining to wMel and wMelCS groups of genotypes. Most of the infected lines had a higher overall lipid content and triglyceride level than the control line and their expression of the bmm gene regulating triglyceride catabolism was reduced. The glucose content was higher in the infected lines compared to that in the control, while their trehalose levels were similar. It was also found that the Wolbachia infection reduced the level of tps1 gene expression (coding for enzyme for trehalose synthesis from glucose) and had no effect on treh gene expression (coding for trehalose degradation enzyme). The infected lines exhibited lower appetite but higher survival under starvation compared to the control. The data obtained may indicate that Wolbachia foster their hosts' energy exchange through increasing its lipid storage and glucose content to ensure the host's competitive advantage over uninfected individuals. The scheme of carbohydrate and lipid metabolism regulation under Wolbachia's influence was suggested.

Motus Vita Est: Fruit Flies Need to Be More Active and Sleep Less to Adapt to Either a Longer or Harder Life.

BACKGROUND: Activity plays a very important role in keeping bodies strong and healthy, slowing senescence, and decreasing morbidity and mortality. Drosophila models of evolution under various selective pressures can be used to examine whether increased activity and decreased sleep duration are associated with the adaptation of this nonhuman species to longer or harder lives. METHODS: For several years, descendants of wild flies were reared in a laboratory without and with selection pressure. To maintain the "salt" and "starch" strains, flies from the wild population (called "control") were reared on two adverse food substrates. The "long-lived" strain was maintained through artificial selection for late reproduction. The 24 h patterns of locomotor activity and sleep in flies from the selected and unselected strains (902 flies in total) were studied in constant darkness for at least, 5 days. RESULTS: Compared to the control flies, flies from the selected strains demonstrated enhanced locomotor activity and reduced sleep duration. The most profound increase in locomotor activity was observed in flies from the starch (short-lived) strain. Additionally, the selection changed the 24 h patterns of locomotor activity and sleep. For instance, the morning and evening peaks of locomotor activity were advanced and delayed, respectively, in flies from the long-lived strain. CONCLUSION: Flies become more active and sleep less in response to various selection pressures. These beneficial changes in trait values might be relevant to trade-offs among fitness-related traits, such as body weight, fecundity, and longevity.

Easy and Effective Method for Extracting and Purifying Wolbachia Genomic DNA.

A number of methods for extracting the DNA of maternally inherited obligate intracellular bacteria Wolbachia from an insect host and its subsequent purification have been described in previous scholarship. As Wolbachia is present in the hosts' organisms in rather low quantities, these techniques used to be quite labor-intensive. For this paper, we analyzed them in detail, searched for a possibility to simplify and accelerate the protocol, and proposed an easy and effective method for isolating Wolbachia DNA from Drosophila melanogaster with a purity sufficient for genomic sequencing. Our method involves the centrifugation of homogenized flies or just their ovaries, as the most Wolbachia-enriched tissue, followed by the filtration of homogenate and extraction of DNA using a modified version of the Livak buffer protocol. The proportion of Wolbachia DNA in the total DNA was quantified based on the results of sequencing with the use of the Illumina MiSeq platform and a pipeline of bioinformatic analysis. For the two analyzed D. melanogaster lines infected with two different Wolbachia strains, the proportion was at least 68 and 94%, respectively.

New Wolbachia pipientis Genotype Increasing Heat Stress Resistance of Drosophila melanogaster Host Is Characterized by a Large Chromosomal Inversion.

The maternally transmitted endocellular bacteria Wolbachia is a well-known symbiont of insects, demonstrating both negative and positive effects on host fitness. The previously found Wolbachia strain wMelPlus is characterized by a positive effect on the stress-resistance of its host Drosophila melanogaster, under heat stress conditions. This investigation is dedicated to studying the genomic underpinnings of such an effect. We sequenced two closely related Wolbachia strains, wMelPlus and wMelCS112, assembled their complete genomes, and performed comparative genomic analysis engaging available Wolbachia genomes from the wMel and wMelCS groups. Despite the two strains under study sharing very close gene-composition, we discovered a large (>1/6 of total genome) chromosomal inversion in wMelPlus, spanning through the region that includes the area of the inversion earlier found in the wMel group of Wolbachia genotypes. A number of genes in unique inversion blocks of wMelPlus were identified that might be involved in the induction of a stress-resistant phenotype in the host. We hypothesize that such an inversion could rearrange established genetic regulatory-networks, causing the observed effects of such a complex fly phenotype as a modulation of heat stress resistance. Based on our findings, we propose that wMelPlus be distinguished as a separate genotype of the wMelCS group, named wMelCS3.

Molecular mechanisms of exceptional lifespan increase of Drosophila melanogaster with different genotypes after combinations of pro-longevity interventions.

Aging is one of the global challenges of our time. The search for new anti-aging interventions is also an issue of great actuality. We report on the success of Drosophila melanogaster lifespan extension under the combined influence of dietary restriction, co-administration of berberine, fucoxanthin, and rapamycin, photodeprivation, and low-temperature conditions up to 185 days in w1118 strain and up to 213 days in long-lived E(z)/w mutants. The trade-off was found between longevity and locomotion. The transcriptome analysis showed an impact of epigenetic alterations, lipid metabolism, cellular respiration, nutrient sensing, immune response, and autophagy in the registered effect.

Fitness Analysis and Transcriptome Profiling Following Repeated Mild Heat Stress of Varying Frequency in Drosophilamelanogaster Females.

Understanding how repeated stress affects metabolic and physiological functions in the long run is of crucial importance for evaluating anthropogenic pressure on the environment. We investigated fertility, longevity and metabolism in D. melanogaster females exposed to short-term heat stress (38 °C, 1 h) repeated daily or weekly. Daily stress was shown to cause a significant decrease in both fertility and longevity, as well as in body mass and triglyceride (fat) content, but a significant increase in trehalose and glucose content. Weekly stress did not affect longevity and carbohydrate metabolism but resulted in a significant decrease in body mass and fat content. Weekly stress did not affect the total level of fertility, despite sharp fertility drops on the exact days of stressing. However, stressing insects weekly, only in the first two weeks after eclosion, caused a significant increase in the total level of fertility. The analysis of differentially expressed genes in the fat bodies and adjacent tissues of researched groups with the use of RNA-Seq profiling revealed changes in signal pathways related to proteolysis/digestion, heat shock protein 23, and in the tightly linked stress-inducible humoral factor Turandot gene network.