Levels and fluxes in enzymatic antioxidants following gamma irradiation are inadequate to confer radiation resistance in Drosophila melanogaster

Lactobacillus reuteri's multifaceted role in mitigating ionizing radiation-induced injury in Drosophila melanogaster

The numerous beneficial probiotic properties of Lactobacillus reuteri (L. reuteri) include decreasing metabolic syndrome, preventing disorders linked to oxidative stress, improving gut flora imbalances, controlling immunological function, and extending life span. Exposure to ionizing radiation is closely associated with several disorders. We examined the protective and salvaging effects of L. reuteri on ionizing radiation-induced injury to the intestinal tract, reproductive system, and nervous system of Drosophila melanogaster. We also examined its effects on lifespan, antioxidant capacity, progeny development, and behavioral aspects to assess the interaction between L. reuteri and ionizing radiation-induced injury. The findings demonstrated that L. reuteri improved the median survival time following irradiation and greatly extended its lifespan. In addition, it raised SOD activity, reduced ROS levels in intestinal epithelial cells, and increased the quantity of intestinal stem cells. Furthermore, L. reuteri enhanced the adult male flies' capacity to move. It also successfully safeguarded the generations' growth and development. L. reuteri dramatically enhanced expression of the AMPKα gene and regulated expression of its pathway-related gene, mTOR, as well as the autophagy-related genes Atg1 and Atg5 in female Drosophila exposed to irradiation. Notably, no prior reports have been made on the possible effects of L. reuteri on injuries caused by irradiation. As a result, our research offers important new information regarding L. reuteri's possible role as a shield against ionizing radiation-induced injury.

Ionizing radiation alters functional neurotransmission in Drosophila larvae

Introduction

Patients undergoing cranial ionizing radiation therapy for brain malignancies are at increased risk of long-term neurocognitive decline, which is poorly understood and currently untreatable. Although the molecular pathogenesis has been intensively researched in many organisms, whether and how ionizing radiation alters functional neurotransmission remains unknown. This is the first study addressing physiological changes in neurotransmission after ionizing radiation exposure.

Methods

To elucidate the cellular mechanisms of radiation damage, using calcium imaging, we analyzed the effects of ionizing radiation on the neurotransmitter-evoked responses of prothoracicotropic hormone (PTTH)-releasing neurons in Drosophila larvae, which play essential roles in normal larval development.

Results

The neurotransmitters dopamine and tyramine decreased intracellular calcium levels of PTTH neurons in a dose-dependent manner. In gamma irradiated third-instar larvae, a dose of 25 Gy increased the sensitivity of PTTH neurons to dopamine and tyramine, and delayed development, possibly in response to abnormal functional neurotransmission. This irradiation level did not affect the viability and arborization of PTTH neurons and successful survival to adulthood. Exposure to a 40-Gy dose of gamma irradiation decreased the neurotransmitter sensitivity, physiological viability and axo-dendritic length of PTTH neurons. These serious damages led to substantial developmental delays and a precipitous reduction in the percentage of larvae that survived to adulthood. Our results demonstrate that gamma irradiation alters neurotransmitter-evoked responses, indicating synapses are vulnerable targets of ionizing radiation.

Discussion

The current study provides new insights into ionizing radiation-induced disruption of physiological neurotransmitter signaling, which should be considered in preventive therapeutic interventions to reduce risks of neurological deficits after photon therapy.

Insight into the evolutionary profile of radio-resistance among insects having intrinsically evolved defence against radiation toxicity

Ionizing radiation (IR) has wide-ranging applications in various fields. In agriculture, pest control is one of the important applications, because insect pests have become a threat to the global agriculture industry. IR are used routinely to prevent crop loss and to protect stored food commodities. Radio-sterilization and disinfestation treatments are commonly used procedures for insect pest control. From various studies on insect radio-sterilization and disinfestation, it has been established that compared to vertebrates' insects have high levels of radiation resistance. Therefore, to achieve adequate radio-sterilization/disinfestation; exposure to high doses of IR is necessary. However, studies over decades made a presumption that radiation resistance is general among insects. Recent studies have shown that some insect orders are having high IR resistance and some insect orders are sensitive to IR. These studies have clarified that radiation resistance is not uniform throughout insect class. The present review is an attempt to insight at the evolutionary profile of insect species studied for radio-sterilization and disinfestation treatment and are having the trait of radio-resistance. From various studies on insect radiation resistance and after phylogenetic analysis of insect species it appears that the evolutionary near species have drastically different levels of radio-resistance and trait of radiation resistance appears to be independent of insect evolution.

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.

Variation in the pH of experimental diets affects the performance of Lymantria dispar asiatica larvae and its gut microbiota

To study dietary pH effects on Lymantria dispar asiatica larvae and provide a theoretical basis for its control in different forests, phosphate buffers (PBs) of pH 6, 7, and 8 were used to prepare experimental diets. The diet prepared with pH 6 PB was named as DPB6, with pH 8 PB as DPB8, and with pH 7 PB as DPB7 (control). The dietary pH was 5.00 in DPB6, 6.05 in control, and 6.50 in DPB8. After feeding on the diets with different pH values for 84 hr, fourth-instar caterpillars were randomly collected. Growth and various physiological traits were determined and 16S recombinant DNA sequencing was performed using the intestinal microflora of surviving larvae. Results showed that the mortality was 30% in DPB6, and 10% in DPB8, while no mortality was observed in control. The partial least squares discriminant analyses suggested that diets prepared with PB of different pH resulted in different food intake, amount of produced feces, weight gain, digestive enzyme activities, and antioxidant enzyme activities in larvae. Interestingly, both the highest weight gain and the lowest total antioxidant capacities were seen in control larvae. Results also showed that the larval gut microbiota community structure was significantly affected by dietary pH. Moreover, linear discriminant analysis effect size suggested that the family Acetobacteraceae in control, genus Prevotella in DPB8, and genus Lactococcus, family Flavobacteriaceae, family Mitochondria, and family Burkholderiaceae in DPB6 contributed to the diversity of the larval gut microbial community.

Radioprotective role of uric acid: evidence from studies in Drosophila and human dermal fibroblast cells

Exposure to ionizing radiation (IR) is a common phenomenon during medical diagnosis and treatment. IRs are deleterious because cellular exposure to IR can cause a series of molecular events that may lead to oxidative stress and macromolecular damage. Radiation protection is therefore essential and significant for improving safety during these procedures. Over decades several antioxidant molecules have been screened to explore their potential as radio-protectors with little success. Therefore, the current study was carried out to confirm the role of uric acid (UA)-a putative antioxidant molecule in radioprotection using radio-resistant insect Drosophila and human dermal fibroblast (HDF) cells. Here, we demonstrate the depleted levels of UA in the mutant flies of Drosophila melanogaster-rosy and by targeting xanthine oxidase (XO an enzyme involved in UA metabolism), through maintaining flies on an allopurinol mixed diet. Allopurinol is a drug that reduces UA levels by inhibiting XO; it reduces the survival percentage in D. melanogaster compared to wild type flies following gamma irradiation at a dose of 1000 Gy. Enzymatic antioxidants such as superoxide dismutase (SOD), catalase, D. melanogaster glutathione peroxidase (DmGPx) and levels of non-enzymatic antioxidants were measured to evaluate the importance of UA. The results indicate that lack of UA reduces the total antioxidant capacity. The activity of SOD was lowered in male flies. Furthermore, we show that supplementation of UA to HDFs cells in media improved their survival rate following gamma irradiation (2 Gy). From the present study we conclude that UA is a potent antioxidant molecule present in high levels among insects. Also, it appears that UA contributes to the radiation resistance of Drosophila flies. Hence, UA emerges as a promising molecule for mitigating radiation-induced oxidative damage in higher organisms.

Ambient temperature-mediated enzymic activities and intestinal microflora in Lymantria dispar larvae

To understand how ambient temperature affect the gypsy moth larvae, and provide a theoretical basis for pest control in different environments. Fourth instar gypsy moth larvae were incubating for 3 hr at 15℃, 20℃, 25℃, 30℃, 35℃, and 40℃, respectively. Afterward, digestive and antioxidant enzyme activities, total antioxidant capacity, and intestinal microflora community were analyzed to reveal how the caterpillars respond to ambient temperature stress. Results showed that both digestive and antioxidant enzymes were regulated by the ambient temperature. The optimum incubation temperatures of protease, amylase, trehalase, and lipase in gypsy moth larvae were 30℃, 25℃, and 20℃, respectively. When the incubation temperature was deviated optimum temperatures, digestive enzyme activities would be downregulated depending on the extent of temperature stress. In addition, glutathione S-transferase, peroxidase, catalase, and polyphenol oxidase would be activated under a sufferable temperature stress, but superoxide dismutase and carboxylesterase (CarE) would be inhibited. In addition, results showed that the top two abundant phyla were Proteobacteria and Firmicutes. The phylum Firmicutes abundance was decreased and phylum Proteobacteria abundance was increased by ambient temperature stress. Moreover, it suggested that gypsy moth caterpillars at different ambient temperature mainly differed from each other by Escherichia-Shigella and Bifidobacterium in control, Acinetobacter in T15, and Lactobacillus in T40, respectively.