Mutagenic Effect during Combined Exposure to Ionizing and Non-Ionizing Electromagnetic Radiation.

Using the method of dominant lethal mutations, we assessed the frequency of the death of Drosophila melanogaster embryos under combined exposure to ionizing γ-radiation and non-ionizing pulsed magnetic field at various doses and modes of exposure. Mutagenic effect of combined exposure is antagonistic in nature. The antagonism is more pronounced when the following mode of exposure was used: exposure to non-ionizing pulsed magnetic field for 5 h followed by exposure to γ-radiation at doses of 3, 10, and 60 Gy. In case of reverse sequence of exposures, the antagonistic effect was statistically significant after exposure to γ-radiation at doses of 3 and 10 Gy, whereas at a dose of 20 Gy, a synergistic interaction was noted.

Destructive effects of UVC radiation on Drosophila melanogaster: Mortality, fertility, mutations, and molecular mechanisms.

The detrimental effects of ultraviolet C (UVC) radiation on living organisms, with a specific focus on the fruit fly Drosophila melanogaster, were examined. This study investigated the impact of heightened UVC radiation exposure on D. melanogaster by assessing mortality and fertility rates, studying phenotypic mutations, and investigating the associated molecular mechanisms. The findings of this study revealed that UVC radiation increases mortality rates and decreases fertility rates in D. melanogaster. Additionally, phenotypic wing mutations were observed in the exposed flies. Furthermore, the study demonstrated that UVC radiation downregulates the expression of antioxidant genes, including superoxide dismutase (SOD), manganese-dependent superoxide dismutase (Mn-SOD), zinc-dependent superoxide dismutase (Cu-Zn-SOD), and the G protein-coupled receptor methuselah (MTH) gene. These results suggest that UVC radiation exerts a destructive effect on D. melanogaster by inducing oxidative stress, which is marked by the overexpression of harmful oxidative processes and a simultaneous reduction in antioxidant gene expression. In conclusion, this study underscores the critical importance of comprehending the deleterious effects of UVC radiation, not only to safeguard human health on Earth, but also to address the potential risks associated with space missions, such as the ongoing Emirate astronaut program.

Effects of genomic instability in populations of Drosophila melanogaster from regions of Ukraine with different impact of radiation factors.

PURPOSE: To investigate differences in the gonadal dysgenesis frequency as one of the indicators of genome instability through natural populations of Drosophіla melanogaster, selected from Ukrainian regions with different radiation impacts. Follow-up study of the dynamics of this indicator under chronic exposure in laboratory conditions for 10 generations. MATERIALS AND METHODS: The study was conducted in two stages. The first one included trapping of insects in regions with different radiation loads with subsequent assessment of both the time of maturation and the index of the gonadal dysgenesis through the first (F1) generation, obtained in laboratory conditions. At the second stage, the dynamics of this indicator were investigated for the F1-descendants of each ten consequent generations, which were developed under laboratory conditions both with and without additional gamma-exposure with different characteristics of the dose rate 1.2 × 10-8, 0.3 × 10-8 and 0.12 × 10-8 Gy/sec. RESULTS: Differences in the gonadal dysgenesis frequency as one of the indicators of genome instability were revealed in F1-descendants of natural populations of Drosophіla melanogaster, selected from regions of different radiation impact. Under conditions of additional low rate chronic irradiation in laboratory conditions for 10 generations, significant differences in changes in the level and dynamics of this indicator were established depending on the accumulated dose of Drosophila populations from the city of Netishyn (Khmelnytskyi NPP) and Magarach city. There were no signs of adaptation. CONCLUSIONS: The discrepancy between the real and expected biological effects has reflected the difference in the intensity of the radiation background, which was traditionally determined by the gamma-emitters and did not take into account the wide range of other genotoxic elements from nuclear power emissions. A complex, non-monotonic type of frequency dynamics of gonadal dysgenesis could be determined by the interaction of radiation damage, protection and recovery.

Differential gene expression analysis identified determinants of cell fate plasticity during radiation-induced regeneration in Drosophila.

Ionizing radiation (IR) is used to treat half of all cancer patients because of its ability to kill cells. IR, however, can induce stem cell-like properties in non-stem cancer cells, potentiating tumor regrowth and reduced therapeutic success. We identified previously a subpopulation of cells in Drosophila larval wing discs that exhibit IR-induced stem cell-like properties. These cells reside in the future wing hinge, are resistant to IR-induced apoptosis, and are capable of translocating, changing fate, and participating in regenerating the pouch that suffers more IR-induced apoptosis. We used here a combination of lineage tracing, FACS-sorting of cells that change fate, genome-wide RNAseq, and functional testing of 42 genes, to identify two key changes that are required cell-autonomously for IR-induced hinge-to-pouch fate change: (1) repression of hinge determinants Wg (Drosophila Wnt1) and conserved zinc-finger transcription factor Zfh2 and (2) upregulation of three ribosome biogenesis factors. Additional data indicate a role for Myc, a transcriptional activator of ribosome biogenesis genes, in the process. These results provide a molecular understanding of IR-induced cell fate plasticity that may be leveraged to improve radiation therapy.

3.5-GHz radiofrequency electromagnetic radiation promotes the development of Drosophila melanogaster.

With the rapidly increasing popularity of 5G mobile technology, the effect of radiofrequency radiation on human health has caused public concern. This study explores the effects of a simulated 3.5 GHz radiofrequency electromagnetic radiation (RF-EMF) environment on the development and microbiome of flies under intensities of 0.1 W/m2, 1 W/m2 and 10 W/m2. We found that the pupation percentages in the first 3 days and eclosion rate in the first 2 days were increased under exposure to RF-EMF, and the mean development time was shortened. In a study on third-instar larvae, the expression levels of the heat shock protein genes hsp22, hsp26 and hsp70 and humoral immune system genes AttC, TotC and TotA were all significantly increased. In the oxidative stress system, DuoX gene expression was decreased, sod2 and cat gene expression levels were increased, and SOD and CAT enzyme activity also showed a significant increase. According to the 16S rDNA results, the diversity and species abundance of the microbial community decreased significantly, and according to the functional prediction analysis, the genera Acetobacter and Lactobacillus were significantly increased. In conclusion, 3.5 GHz RF-EMF may enhance thermal stress, oxidative stress and humoral immunity, cause changes in the microbial community, and regulate the insulin/TOR and ecdysteroid signalling pathways to promote fly development.

Effects of an electric field on sleep quality and life span mediated by ultraviolet (UV)-A/blue light photoreceptor CRYPTOCHROME in Drosophila.

Although electric fields (EF) exert beneficial effects on animal wound healing, differentiation, cancers and rheumatoid arthritis, the molecular mechanisms of these effects have remained unclear about a half century. Therefore, we aimed to elucidate the molecular mechanisms underlying EF effects in Drosophila melanogaster as a genetic animal model. Here we show that the sleep quality of wild type (WT) flies was improved by exposure to a 50-Hz (35 kV/m) constant electric field during the day time, but not during the night time. The effect was undetectable in cryptochrome mutant (cryb) flies. Exposure to a 50-Hz electric field under low nutrient conditions elongated the lifespan of male and female WT flies by ~ 18%, but not of several cry mutants and cry RNAi strains. Metabolome analysis indicated that the adenosine triphosphate (ATP) content was higher in intact WT than cry gene mutant strains exposed to an electric field. A putative magnetoreceptor protein and UV-A/blue light photoreceptor, CRYPTOCHROME (CRY) is involved in electric field (EF) receptors in animals. The present findings constitute hitherto unknown genetic evidence of a CRY-based system that is electric field sensitive in animals.

Mitochondria are specifically vulnerable to 420nm light in drosophila which undermines their function and is associated with reduced fly mobility.

Increased blue light exposure has become a matter of concern as it has a range of detrimental effects, but the mechanisms remain unclear. Mitochondria absorb short wavelength light but have a specific absorbance at 420nm at the lower end of the human visual range. This 420nm absorption is probably due to the presence of porphyrin. We examine the impact of 420nm exposure on drosophila melanogaster mitochondria and its impact on fly mobility. Daily 15 mins exposures for a week significantly reduced mitochondrial complex activities and increased mitochondrial inner membrane permeability, which is a key metric of mitochondrial health. Adenosine triphosphate (ATP) levels were not significantly reduced and mobility was unchanged. There are multiple options for energy/time exposure combinations, but we then applied single 420nm exposure of 3h to increase the probability of an effect on ATP and mobility, and both were significantly reduced. ATP and mitochondrial membrane permeability recovered and over corrected at 72h post exposure. However, despite this, normal mobility did not return. Hence, the effect of short wavelengths on mitochondrial function is to reduce complex activity and increasing membrane permeability, but light exposure to reduce ATP and to translate into reduced mobility needs to be sustained.

Light-dependent N-end rule-mediated disruption of protein function in Saccharomyces cerevisiae and Drosophila melanogaster.

Here we describe the development and characterization of the photo-N-degron, a peptide tag that can be used in optogenetic studies of protein function in vivo. The photo-N-degron can be expressed as a genetic fusion to the amino termini of other proteins, where it undergoes a blue light-dependent conformational change that exposes a signal for the class of ubiquitin ligases, the N-recognins, which mediate the N-end rule mechanism of proteasomal degradation. We demonstrate that the photo-N-degron can be used to direct light-mediated degradation of proteins in Saccharomyces cerevisiae and Drosophila melanogaster with fine temporal control. In addition, we compare the effectiveness of the photo-N-degron with that of two other light-dependent degrons that have been developed in their abilities to mediate the loss of function of Cactus, a component of the dorsal-ventral patterning system in the Drosophila embryo. We find that like the photo-N-degron, the blue light-inducible degradation (B-LID) domain, a light-activated degron that must be placed at the carboxy terminus of targeted proteins, is also effective in eliciting light-dependent loss of Cactus function, as determined by embryonic dorsal-ventral patterning phenotypes. In contrast, another previously described photosensitive degron (psd), which also must be located at the carboxy terminus of associated proteins, has little effect on Cactus-dependent phenotypes in response to illumination of developing embryos. These and other observations indicate that care must be taken in the selection and application of light-dependent and other inducible degrons for use in studies of protein function in vivo, but importantly demonstrate that N- and C-terminal fusions to the photo-N-degron and the B-LID domain, respectively, support light-dependent degradation in vivo.

Cooperation between oncogenic Ras and wild-type p53 stimulates STAT non-cell autonomously to promote tumor radioresistance.

Oncogenic RAS mutations are associated with tumor resistance to radiation therapy. Cell-cell interactions in the tumor microenvironment (TME) profoundly influence therapy outcomes. However, the nature of these interactions and their role in Ras tumor radioresistance remain unclear. Here we use Drosophila oncogenic Ras tissues and human Ras cancer cell radiation models to address these questions. We discover that cellular response to genotoxic stress cooperates with oncogenic Ras to activate JAK/STAT non-cell autonomously in the TME. Specifically, p53 is heterogeneously activated in Ras tumor tissues in response to irradiation. This mosaicism allows high p53-expressing Ras clones to stimulate JAK/STAT cytokines, which activate JAK/STAT in the nearby low p53-expressing surviving Ras clones, leading to robust tumor re-establishment. Blocking any part of this cell-cell communication loop re-sensitizes Ras tumor cells to irradiation. These findings suggest that coupling STAT inhibitors to radiotherapy might improve clinical outcomes for Ras cancer patients.

Protective effects of crimson snapper scales peptides against oxidative stress on Drosophila melanogaster and the action mechanism.

Peptides derived from crimson snapper scales (CSSPs) were reported to possess excellent free radical scavenging activities in vitro. In present study, the anti-aging and anti-oxidative stress effects of CSSPs were evaluated in Drosophila melanogaster models. Results showed that the addition of CSSPs in the diets of normal Drosophila could effectively extend their lifespan and improve the motor ability of aged Drosophila. Moreover, CSSPs could protect Drosophila from oxidative damage induced by H2O2, paraquat and UV irradiation. The extension of lifespan was found to be associated with the effects of CSSPs in improving the antioxidant defense system of Drosophila, manifesting as the reduction of oxidation products MDA and PCO, the elevated activities of T-SOD, CAT and GSH-Px, and the upregulated expression of antioxidant related genes after CSSPs supplemented. Furthermore, CSSPs at 6 mg/mL significantly downregulated mTOR signaling pathway and activated autophagy in aged male Drosophila, and the inhibition on mTOR activation was probably mediated by the antioxidant effects of CSSPs. Our findings suggest that CSSPs have the potential in making dietary supplements against natural aging and oxidative stress in organisms.

Oxidative and radiation stress induces transposable element transcription in Drosophila melanogaster.

It has been shown that stressors are capable of activating transposable elements (TEs). Currently, there is a hypothesis that stress activation of TEs may be involved in adaptive evolution, favouring the increase in genetic variability when the population is under adverse conditions. However, TE activation under stress is still poorly understood. In the present study, we estimated the fraction of differentially expressed TEs (DETEs) under ionizing radiation (144, 360 and 864 Gy) and oxidative stress (dioxin, formaldehyde and toluene) treatments. The stress intensity of each treatment was estimated by measuring the number of differentially expressed genes, and we show that several TEs families are activated by stress whereas others are repressed. The proportion of DETEs was positively related to stress intensity. However, even under the strongest stress, only a small fraction of TE families were activated (9.28%) and 17.72% were repressed. Considering all treatments together, the activated proportion was 19.83%. Nevertheless, as several TEs are incomplete or degenerated, only 10.55% of D. melanogaster mobilome is, at same time, activated by the stressors and able to transpose or at least code a protein. Thus, our study points out that although stress activates TEs, it is not a generalized activation process, and for some families, the stress induces repression.

Musashi expression in intestinal stem cells attenuates radiation-induced decline in intestinal permeability and survival in Drosophila.

Exposure to genotoxic stress by environmental agents or treatments, such as radiation therapy, can diminish healthspan and accelerate aging. We have developed a Drosophila melanogaster model to study the molecular effects of radiation-induced damage and repair. Utilizing a quantitative intestinal permeability assay, we performed an unbiased GWAS screen (using 156 strains from the Drosophila Genetic Reference Panel) to search for natural genetic variants that regulate radiation-induced gut permeability in adult D. melanogaster. From this screen, we identified an RNA binding protein, Musashi (msi), as one of the possible genes associated with changes in intestinal permeability upon radiation. The overexpression of msi promoted intestinal stem cell proliferation, which increased survival after irradiation and rescued radiation-induced intestinal permeability. In summary, we have established D. melanogaster as an expedient model system to study the effects of radiation-induced damage to the intestine in adults and have identified msi as a potential therapeutic target.

Fruit Fly, Drosophila melanogaster, as an In Vivo Tool to Study the Biological Effects of Proton Irradiation.

The clinical superiority of proton therapy over photon therapy has recently gained recognition; however, the biological effects of proton therapy remain poorly understood. The lack of in vivo evidence is especially important. Therefore, the goal of this study was to validate the usefulness of Drosophila melanogaster as an alternative tool in proton radiobiology. To determine whether the comparative biological effects of protons and X rays are detectable in Drosophila, we assessed their influence on survival and mRNA expression. Postirradiation observation revealed that protons inhibited their development and reduced the overall survival rates more effectively than X rays. The relative biological effectiveness of the proton beams compared to the X rays estimated from the 50% lethal doses was 1.31. At 2 or 24 h postirradiation, mRNA expression analysis demonstrated that the expression patterns of several genes (such as DNA-repair-, apoptosis- and angiogenesis-related genes) followed different time courses depending on radiation type. Moreover, our trials suggested that the knockdown of individual genes by the GAL4/UAS system changes the radiosensitivity in a radiation type-specific manner. We confirmed this Drosophila model to be considerably useful to evaluate the findings from in vitro studies in an in vivo system. Furthermore, this model has a potential to elucidate more complex biological mechanisms underlying proton irradiation.

Genetic mechanisms of formation of radiation-induced instability of the genome and its transgenerational effects in the descendants of chronically irradiated individuals of Drosophila melanogaster.

The article is devoted to the study of the role of intracellular mechanisms in the formation of radiation-induced genetic instability and its transgenerational effect in cells of different tissues of the descendants of Drosophila melanogaster mutant strains whose parents were exposed to chronic radiation (0.42 and 3.5 mGy/h). The level of DNA damage (alkali-labile sites (ALS), single-strand (SSB) and double-strand (DSB) breaks) in cells of somatic (nerve ganglia, imaginal discs) and generative (testis) tissues from directly irradiated animals and their unirradiated offspring was evaluated. Confident transgenerational instability (on the level of ALSs and SSBs), observed only in somatic tissues and only at the higher dose rate, is characteristic for mus209 mutant strains defective in excision repair and, less often, for mus205 and mus210 mutant strains. The greatest manifestation of radiation-induced genetic instability was found in evaluating the DSBs. Dysfunction of the genes mus205, mus304, mei-9 and mei-41, which are responsible for postreplicative repair, excision repair, recombination and control of the cell cycle, affects transgenerational changes in the somatic tissues of the offspring of parents irradiated in both low and high dose rates. In germ cells, the key role in maintaining genetic stability under chronic irradiation is played by the non-recombination postreplication repair mus101 gene. We revealed the tissue specificity of the radiation-induced effects, transgenerational transmission and accumulation of DNA damage to descendants of chronically irradiated animals.

The role of DNA repair genes in radiation-induced adaptive response in Drosophila melanogaster is differential and conditional.

Studies in human and mammalian cell cultures have shown that induction of DNA repair mechanisms is required for the formation of stimulation effects of low doses of ionizing radiation, named "hormesis". Nevertheless, the role of cellular defense mechanisms in the formation of radiation-induced hormesis at the level of whole organism remains poorly studied. The aim of this work was to investigate the role of genes involved in different mechanisms and stages of DNA repair in radioadaptive response and radiation hormesis by lifespan parameters in Drosophila melanogaster. We studied genes that control DNA damage sensing (D-Gadd45, Hus1, mnk), nucleotide excision repair (mei-9, mus210, Mus209), base excision repair (Rrp1), DNA double-stranded break repair by homologous recombination (Brca2, spn-B, okr) and non-homologous end joining (Ku80, WRNexo), and the Mus309 gene that participates in several mechanisms of DNA repair. The obtained results demonstrate that in flies with mutations in studied genes radioadaptive response and radiation hormesis are absent or appear to a lesser extent than in wild-type Canton-S flies. Chronic exposure of γ-radiation in a low dose during pre-imaginal stages of development leads to an increase in expression of the studied DNA repair genes, which is maintained throughout the lifespan of flies. However, the activation of conditional ubiquitous overexpression of DNA repair genes does not induce resistance to an acute exposure to γ-radiation and reinforces its negative impact.

Effects of ionizing radiation at Drosophila melanogaster with differently active hobo transposons.

Purpose: The role of transposable elements in formation of radiobiological effects is understudied and contradictory. The aim of this study was to investigate the response of Drosophila melanogaster to irradiation depending on the level of activity hobo transposons and the role of hobo transposons in formation of ionizing radiation late effects.Materials and methods: The individuals of Drosophila melanogaster with different level activity of hobo-elements were exposed to acute irradiation in doses of 1-100 Gy at early ontogenesis stages. The reaction of individuals to exposure was studied using the larvae survival rate, morphological parameters of reproduction system, DNA damage rate, and mutability of mini-white locus.Results: We found the pronounced linear deferred effects of irradiation for animals with a high activity level of full-size hobo copies. The radiosensitivity of individuals with a mean level of activity transposon was whether higher or did not differ from the radiosensitivity of animals with a low activity hobo.Conclusion: The obtained results suggest that full-size hobo-elements with a high activity level (less often with a mean activity level) are responsible for delayed deleterious irradiation effects.

Effects of historic radiation dose on the frequency of sex-linked recessive lethals in Drosophila populations following the Chernobyl nuclear accident.

Contrary to the effects of high doses of radiation, the effects of low doses of radiation are still being investigated. Low doses and their non-targeted effects in particular are of special interest for researchers. The accident that occurred at the Chernobyl Nuclear Power Plant (NPP) gives researchers the opportunity to view these effects outside of a laboratory environment. For this paper, the relationship between low historic radiation doses and the persistent genetic damage observed in populations of fruit flies (Drosophila melanogaster) around the Chernobyl NPP over 3 years will be investigated. Data from Zainullin et al. (1992) on the frequency of sex-linked recessive lethals (SLRLs) in D. melanogaster around the Chernobyl NPP. To calculate the absorbed historic external dose, a method based on the Gaussian plume model was used to find the external dose from both plume shine and ground shine. The dose attributed to the ground shine dose made a greater contribution to the overall absorbed external historic radiation dose than the plume shine dose. For earlier generations of Drosophila living in the radioactive contaminated sites, the SLRL frequencies appeared to correlate with the dose in a linear no-threshold relationship. The later descendent generations appeared to have developed a radio-adaptive-like response. This work contributes to the understanding of historic dose effects on wildlife health following the accidental release of high mount of radioactive materials into the environment.

A new role for Drosophila Aurora-A in maintaining chromosome integrity.

Aurora-A is a conserved mitotic kinase overexpressed in many types of cancer. Growing evidence shows that Aurora-A plays a crucial role in DNA damage response (DDR) although this aspect has been less characterized. We isolated a new aur-A mutation, named aur-A949, in Drosophila, and we showed that it causes chromosome aberrations (CABs). In addition, aur-A949 mutants were sensitive to X-ray treatment and showed impaired γ-H2Av foci dissolution kinetics. To identify the pathway in which Aur-A works, we conducted an epistasis analysis by evaluating CAB frequencies in double mutants carrying aur-A949 mutation combined to mutations in genes related to DNA damage response (DDR). We found that mutations in tefu (ATM) and in the histone variant H2Av were epistatic over aur-A949 indicating that Aur-A works in DDR and that it is required for γ-H2Av foci dissolution. More interestingly, we found that a mutation in lig4, a gene belonging to the non-homologous end joining (NHEJ) repair pathway, was epistatic over aur-A949. Based on studies in other systems, which show that phosphorylation is important to target Lig4 for degradation, we hypothesized that in aur-A949 mutant cells, there is a persistence of Lig4 that could be, in the end, responsible for CABs. Finally, we observed a synergistic interaction between Aur-A and the homologous recombination (HR) repair system component Rad 51 in the process that converts chromatid deletions into isochromatid deletions. Altogether, these data indicate that Aur-A depletion can elicit chromosome damage. This conclusion should be taken into consideration, since some anticancer therapies are aimed at reducing Aurora-A expression.

Evidence that the radioprotector effect of ascorbic acid depends on the radiation dose rate.

Many studies have revealed that ascorbic acid (Aa) acts as a powerful inhibitor of genetic damage. The objetive of the present study was to evaluate the radioprotector effect of Aa at two diferent radiation dose rates. The somatic mutation and recombination test in Drosophila melanogaster was used. 48 h larvae were treated for 24 h with 25, 50 and 100 mM of Aa. After pretreatment, larvae were irradiated with 20 Gy of gamma rays administered at 36 or 960 Gy/h. Toxicity, development rate and frequency of mutant spots were recorded. Results provide evidence of a radioprotective effect for all tested concentrations of Aa only when 20 Gy were delivered at 36 Gy/h and only with 25 mM using the 960 Gy/h. To consider the use of Aa as radioprotector or therapeutic agent, it is necessary to know its potential under different situations to avoid unwanted injuries.

Different radiation dose rate as radioprotection and the cross effect with chromium using in vivo somatic cells of Drosophila.

Ionizing radiation plays a key role in the adaptation of an individual organism to environmental pollution, at the same time, it has biological effects that depend on radiation intensity or dose rate (DR). Although the effect of DR has been studied in vitro, the phenomenon known as the inverse effect of DR, which indicates as it decreases that the induction of damage is greater, has not been widely studied in vivo. The present study is aimed to test 0.5 and 1 Gy in somatic cells of the wing of D. melanogaster, administered at 5.4 or 34.3 Gy/h and from 0.037 to 0.3 mM of CrO3 as conditioning treatment. No changes were found in larva-to-adult viability. A protective as well as a cross effect of pre-exposure to different DR and CrO3 concentrations against genetic damage induced by 20 Gy or 1 mM CrO3 was evident.