Effects of cadmium on fecundity and defence ability of Drosophila melanogaster

Cadmium and phthalate impacts developmental growth and mortality of Spodoptera littoralis, but not reproductive success

Our environment is increasingly polluted with various molecules, some of which are considered endocrine disruptors. Metals and phthalates, originating from industrial activities, agricultural practices, or consumer products, are prominent examples of such pollutants. We experimentally investigated the impacts of the heavy metal cadmium and the phthalate DEHP on the moth Spodoptera littoralis. More specifically, larvae were reared in laboratory conditions, where they were exposed to diets contaminated with either two doses of cadmium at concentrations of 62.5 µg/g or 125 µg/g, two doses of DEHP at 100 ng/g and 10 µg/g, or a combination of both low and high doses of the two compounds, with a control group for comparison. Our findings indicate that cadmium delays the developmental transition from larva to adult. Notably, the combination of cadmium and DEHP exacerbated this delay, highlighting a synergistic effect. In contrast, DEHP alone did not affect larval development. Additionally, we observed that cadmium exposure, both alone and in combination with DEHP, led to a lower mass at all larval stages. However, cadmium-exposed individuals that reached adulthood eventually reached a similar mass to those in other groups. Interestingly, while our results did not show any effect of the treatments on hatching success, there was a higher adult mortality rate in the cadmium-treated groups. This suggests that while moths may prioritize reproductive success, their survival at the adult stage is compromised by cadmium exposure. In conclusion, our study demonstrates the impact of cadmium on the development, mass, and adult survival of moths, and reveals synergistic effects when combined with DEHP. These results confirm cadmium as an endocrine disruptor, even at low doses. These insights underscore the importance of understanding the toxicological effects of low doses of pollutants like cadmium and DEHP, both individually and in combination.

5-Hydroxymethylfurfural mediated developmental toxicity in Drosophila melanogaster

5-hydroxymethylfurfural is a common byproduct in food. However, its effect on growth and development remains incompletely understood. This study investigated the developmental toxicity of 5-HMF to Drosophila larvae. The growth and development of Drosophila melanogaster fed with 5-50 mM 5-HMF was monitored, and its possible mechanism was explored. It was found that 5-HMF prolonged the developmental cycle of Drosophila melanogaster (25 mM and 50 mM). After 5-HMF intake, the level of reactive oxygen species in the third instar larvae increased by 1.23-1.40 fold, which increased the level of malondialdehyde and caused changes in antioxidant enzymes. Moreover, the nuclear factor erythroid-2 related factor 2 antioxidant signaling pathway and the expression of heat shock protein genes were affected. At the same time, 5-HMF disrupted the glucose and lipid metabolism in the third instar larvae, influencing the expression level of key genes in the insulin signal pathway. Furthermore, 5-HMF led to intestinal oxidative stress, and up-regulated the expression of the pro-apoptotic gene, consequently impacting intestinal health. In short, 5-HMF causes oxidative stress, disturbs glucose and lipid metabolism and induces intestinal damage, damaging related signaling pathways, and ultimately affecting the development of Drosophila melanogaster.

Distribution and accumulation of Cadmium in different trophic levels affecting Serangium japonicum, the predatory beetle of whitefly Bemisia tabaci, biologically, physiologically and genetically: An experimental study

Cadmium (Cd) is a heavy metal that is of great concern in agroecosystems due to its toxicity to plants, herbivores, carnivores, and human beings. The current study evaluated the allocation and bioaccumulation of Cd from soil to cotton plants, cotton plants to herbivore pests, and herbivorous pests to a natural enemy predator. When soil was spiked with 100 mg/kg Cd, results demonstrated that cotton roots accumulated more Cd than the stems and leaves. The bioaccumulation of Cd was less in 4th instar larvae, pupa, and adults of Serangium japonicum than in Bemisia tabaci adults. The bioaccumulation in S. japonicum elongated the immature development period and reduced adult longevity, oviposition days, fertility, and total pre-oviposition duration. The net reproduction of S. japonicum was also reduced, as was female mature weight and feeding potential; as a result, Cd exposure could reduce the future population size compared to uncontaminated populations. There was decreased activity of the antioxidant enzymes (SOD, CAT, and POD) and energy-conserving lipids (glycogen, triglyceride, and total cholesterol) in Cd-contaminated S. japonicum compared to controls. The detoxifying enzyme activity of GST and P450 increased while AChE activity did not change. The qRT-PCR research showed that SOD1, CAT, POD, glycogen, and triglyceride gene expression was higher than in controls, whereas detoxification gene expression did not change. Our results indicate that Cd exposure has a physiological trade-off between its adverse effects on life history traits and elevated detoxification and antioxidation of S. japonicum, which could result from gene expression alteration. Further studies are needed to assess whether Cd exposure causes irreversible DNA damage in S. japonicum.

Cadmium chloride exposure impairs the growth and behavior of Drosophila via ferroptosis

Cadmium (Cd) is a widely distributed toxic heavy metal that enters the environment via anthropogenic mobilization and accumulates in plants and animals, causing metabolic abnormalities even mortality. Although the toxic effects and stress damage of cadmium have been investigated extensively over the past few decades, research on its ability to trigger ferroptosis, growth retardation, and behavioral abnormalities is insufficient. As a result, the effects of CdCl₂ exposure on growth and development, activity and sleep, and ferroptosis in this study were examined in fruit fly (Drosophila melanogaster). When exposed to 0.5 mM CdCl₂, the entire growth period from larvae to adults was prolonged, and the rates of pupation and eclosion were decreased. Additionally, CdCl₂ exposure resulted in a decrease in body weight and individual size of fruit fly and high lethality rate. Moreover, CdCl₂ exposure altered fruit fly behavior, including decreased activity and increased sleep duration, particularly in females. Ferrostatin-1 (Fer-1) is a potent selective ferroptosis inhibitor that effectively slows lipid hydroperoxide accumulation to rescue body size reduction and restore activity and sleep in CdCl₂-exposed female flies. CdCl₂ exposure could induce ferroptosis in fruit fly mechanistically, as evidenced by inhibition of Nrf2 signaling pathway, accumulation of lipid peroxidation, impairment of GPX4 antioxidant system, and upregulation of iron metabolism. Our findings suggest that Cd exposure triggers ferroptosis, which leads to growth retardation and behavioral disorders in fruit fly.

Exposure to a sublethal concentration of CdO nanoparticles impairs the vision of the fruit fly (Drosophila melanogaster) by disrupting histamine synthesis and recycling mechanisms

While there is substantial literature on potential risks associated with exposure to emerging nanomaterials, less is known about the potential effects of hazardous metallic nanoparticles on vision, as well as the mechanisms that underpin them. The fruit fly (Drosophila melanogaster) was used as an in vivo model organism to investigate the effects of exposure to a sublethal concentration (0.03 mg CdO NPs/mL, which was 20% of the LC₅₀) on fly vision and compound eye ultrastructure. First, we observed a reduction in phototaxis response in treated flies but no change in locomotor activity. Because histamine (HA) has been linked to arthropod vision, we investigated HA synthesis, uptake, and recycling as a possible underlying mechanism for the observed adverse effect of CdO NPs on fly vision. This was accomplished by measuring the expression of the histamine decarboxylase (hdc) gene, which encodes the enzyme that converts the amino acid histidine to histamine (HA), as well as the expression of some genes involved in HA-recycling pathways (tan, ebony, Balat, CarT, and Lovit). The results showed that CdO NPs changed the expression levels of hdc, Lovit, tan, and eboney, indicating that HA synthesis, transport, and recycling were disrupted. Furthermore, less histamine immunolabeling was found in the head tissues of CdO NP-treated flies, particularly in the optic lobes. We also observed and quantified CdO NP bioaccumulation in compound eye tissues, which resulted in a number of cytological changes. Phenotypic effects (undersized eyes) have also been observed in the compound eyes of F1 flies. Considering the significance of vision in an organism's survival, the findings of this study are extremely crucial, as long-term exposure to CdO NPs may result in blindness.

Effects of Long-Term Exposure to Cadmium on Development, Reproduction and Antioxidant Enzymes of Aleuroglyphus ovatus (Acari: Acaridae)

Grain contaminated by cadmium (Cd) has become a serious food security problem, and it is necessary to determine and evaluate the toxic effect and defense mechanism of long-term heavy metal pollution in grain. In order to evaluate the effects of long-term heavy metal Cd stress on the stored grain pests, Aleuroglyphus ovatus were fed with an artificial diet supplemented with different concentrations of Cd (0, 5, 10, 20 mg/kg). The development, fecundity and detoxification enzymes of A. ovatus were analyzed and observed. In this study, the immature duration of A. ovatus was significantly prolonged under long-term Cd stress. Moreover, the survival duration of female adults was significantly shortened. The total number of eggs laid and the daily number laid per female adult decreased significantly. There were significant differences in protein content at protonymph and tritonymph stages when the concentration of Cd exceeded 10 mg/kg. The protein content of female adults was higher than that of male adults. The activity of detoxification enzymes showed differences in different conditions, such as development stage, Cd concentration and gender. These findings confirmed that A. ovatus were sensitive to Cd, and their offspring were severely affected under long-term Cd stress. Therefore, A. ovatus is a good model for evaluating the toxicity of long-term heavy metal Cd stress. The study provides the basis and enriches the research content of heavy metal pollution on mites, contributing to the harmonious and healthy development between the environment and human beings.

Analysis of Differential Gene Expression of the Aquatic Insect Protohermes costalis (Walker) (Megaloptera: Corydalidae) in Response to Cadmium Exposure

Heavy metal pollution in freshwater ecosystems is a serious threat to aquatic organisms. Species of Megaloptera are important predators of aquatic invertebrates and have been widely used as bioindicators in assessing the quality of freshwater ecosystems. In this study, we determined the differential gene expression profile of Protohermes costalis (Walker) (Megaloptera: Corydalidae) in response to cadmium (Cd) exposure by using transcriptome analysis. A total of 60,627 unigenes were obtained in the transcriptomes of 150 mg/liter (PL), 1,000 mg/liter (PH) CdCl2 treatment, and the no Cd control (PC). Differential expression gene (DEG) analysis by pairwise comparison identified 2,794 DEGs after filtering the noninsect genes and repetitive counts. 606 DEGs were shared in comparisons of PL versus PC and PH versus PC, with 165 DEGs consistently up-regulated and 441 down-regulated by both PL and PH. Six heat shock proteins (HSPs) in the HSP70 family were identified in P. costalis and PcosHSP68 was up-regulated by both PL and PH. Real-time quantitative polymerase chain reaction (RT-qPCR) confirmed that the expression levels of PcosHSP68 in PL and PH were higher than that of PC by 31 and 197%, respectively. These results showed that exposure to Cd altered the gene expression profiles of P. costalis and the transcriptome data presented in this study provide insight into future studying on molecular mechanisms of Cd toxicity to these insects.

Toxic metals that interact with thiol groups and alteration in insect behavior

Toxic metals, such as mercury (Hg), lead (Pb), cadmium (Cd), and copper (Cu), are widespread in the biosphere, and human activities have contributed to their continuous release into the ecosystems. Metal-induced toxicity has been extensively studied in mammals; however, the effects of these metals on insects' behavior have been explored to far lesser degree. As the main mechanism of toxicity, the cationic metals, explored in this review, have high affinity for thiol-containing molecules, disrupting the function of several proteins and low-molecular-weight thiol-containing molecules. Existing literature has corroborated that Hg, Pb, Cd, and Cu can disrupt locomotor and mating behaviors, but their effects on insects' memory and learning have yet to be fully characterized. Though field studies on metal-induced toxicity in insects are limited, results from Drosophila melanogaster as an experimental model suggest that insects living in contaminated environments can have behavioral foraging and reproductive deficits, which may cause population decline. In this review, we address the interaction between metals and endogenous thiol groups, with emphasis on alterations in insect behavior.

Is Turkish coffee protects Drosophila melanogaster on cadmium acetate toxicity by promoting antioxidant enzymes?

With their increasing use in today's industry, heavy metals cause biochemical and biophysical changes by affecting the control and regulatory systems of living things. Cadmium (Cd), a heavy metal, spreads to the environment through both natural sources and industrial activities. It is taken into the organism through water, food, skin contact or smoke. Systems and organs of living things are directly or indirectly affected by Cd toxicity. Besides their recreational usage, herbal products such as coffee are preferred in alternative medicine because of their antioxidant, anti-inflammatory, anticancer and antidiabetic effects. Turkish coffee (TK) is a drink rich in flavorings, phenolic compounds and antioxidant compounds. The study evaluated the possible antioxidant role of TK against oxidative stress induced by Cadmium acetate (CdA) in the fat tissues of old-young female individuals of Drosophila melanogaster. The female flies were fed with either a standard diet, or CdA (10-30 mg), or TK (2%), or both (CdA + TK) for 3 and 10 days. Following the completion of the feeding period, the amounts of fatbody and oxidative stress markers (oxidative stress index, malondialdehyde), activities of antioxidant enzymes (Glutathione-S-transferase, Catalase, and Superoxide dismutase) and their levels were measured. Fat body lipid droplets were high in the individuals exposed to high concentrations of CdA. It was determined that lipid droplets decreased but did not significantly alter oxidative stress in the individuals treated with TK (p = 0.05). This article may be of help in terms of the use of TK compounds as antioxidants to evaluate their effects in preventing heavy metal accumulation and stress in the aging process.

Interactions and toxicity of non-essential heavy metals (Cd, Pb and Hg): lessons from Drosophila melanogaster

Some heavy metals are essential in trace amounts, enhancing enzyme functioning and other intracellular molecules. Others are explicitly toxic at low concentrations, increasing the risk of organ-related toxicity. Non-essential metals have similar mechanisms of toxicity to essential metals. These include the modifiable change in oxidation states, interaction with sulfhydryl moieties of proteins and indirect modification of nucleic acids. Ultimately, oxidative stress is generated, and potentiation of damage ensues. The susceptibility, sensitivity, genetic resources, and cellular response of Drosophila melanogaster to heavy metal exposure and toxicity have made this insect appropriate for toxicological studies. In this review, we focus on the toxicological impacts of non-essential metals (Cd, Pb, and Hg) in Drosophila and discuss its cellular and developmental responses to increasing concentrations of these metals. We also suggest current or proposed therapeutic alternatives, as well as dimensions that may improve the studies of non-essential metal biology.

Dietary cadmium induced declined locomotory and reproductive fitness with altered homeostasis of essential elements in Drosophila melanogaster

Cadmium (Cd) exerts detrimental effects on multiple biological processes of the living organisms along with epigenetic transgenerational effect. Drosophila melanogaster offers unique opportunity to evaluate Cd toxicity when studying important life traits in short duration of time by designing distinct behavioural assays. Present study utilized this model organism to assess Cd induced lethality, retarded growth, decreased life span and altered behaviour of the animals either at larval or adult stage. Our investigations revealed reduced locomotion and reproductive fitness of the animals upon Cd exposure. Transgenerational effect on locomotion was found to be behaviour specific as larval crawling was affected, but adult fly negative geotaxis was comparable to the control. Mechanistically, decreased antioxidant enzymes activity, superoxide dismutase (SOD) and catalase (CAT) together with altered homeostasis of essential elements (Fe, Zn and Mg) may be responsible for the observed effects. Altogether our work showed extensive range of Cd altered Drosophila behaviour which warrants need to control environmental Cd toxicity.

Effects of cadmium on oxidative stress and cell apoptosis in Drosophila melanogaster larvae

With the increase of human activities, cadmium (Cd) pollution has become a global environmental problem affecting biological metabolism in ecosystem. Cd has a very long half-life in humans and is excreted slowly in organs, which poses a serious threat to human health. In order to better understand the toxicity effects of cadmium, third instar larvae of Drosophila melanogaster (Canton-S strain) were exposed to different concentrations (1.125 mg/kg, 2.25 mg/kg, 4.5 mg/kg, and 9 mg/kg) of cadmium. Trypan blue staining showed that intestinal cell damage of Drosophila larvae increased and the comet assay indicated significantly more DNA damage in larvae exposed to high Cd concentrations. The nitroblue tetrazolium (NBT) experiments proved that content of reactive oxygen species (ROS) increased, which indicated Cd exposure could induce oxidative stress. In addition, the expression of mitochondrial adenine nucleotide transferase coding gene (sesB and Ant2) and apoptosis related genes (Debcl, hid, rpr, p53, Sce and Diap1) changed, which may lead to increased apoptosis. These findings confirmed the toxicity effects on oxidative stress and cell apoptosis in Drosophila larvae after early cadmium exposure, providing insights into understanding the effects of heavy metal stress in animal development.

Antibacterial activity of eugenol on the IS-58 strain of Staphylococcus aureus resistant to tetracycline and toxicity in Drosophila melanogaster

The indiscriminate use of antibiotics contributes significantly to the selection of bacteria resistant to several antibiotics. Among the resistance mechanisms are the Efflux Pumps which are responsible for extruding solutes from the cell cytoplasm through proteins in the cell membrane. Because of this, new strategies are needed to control multidrug-resistant pathogenic strains. In this way, the objective of this study was to evaluate the antibacterial activity of eugenol by inhibition of TetK Efflux Pump in strains of Staphylococcus aureus resistant to Tetracycline, in addition to evaluating its toxicity in Drosophila melanogaster. To determine the Minimum Inhibitory Concentration (MIC), the broth microdilution method was used. The modulated effect of antibiotic and Ethidium Bromide associated with eugenol in subinhibitory concentrations (MIC/8) was evaluated. To evaluate the toxic effect of eugenol on D. melanogaster, fumigation tests were used, in which the parameters of mortality and damage to the locomotor system were evaluated. The results showed that eugenol has no direct activity in S. aureus, with an MIC ≥1024 μg/mL. However, it demonstrated that the synergistic potential when associated with Tetracycline, reducing the MIC of the antibiotic, already associated with Ethidium Bromide, had an antagonistic effect. When the toxicity in D. melanogaster was evaluated, eugenol demonstrated a non-toxic profile, since it presented EC50: 2036 μL/mL in 48 h of exposure. In conclusion, eugenol had no relevant direct effect against S. aureus, however, it potentialized the action of the antibiotic by decreasing its MIC.

Dietary cadmium (Cd) reduces hemocyte level by induction of apoptosis in Drosophila melanogaster

Drosophila melanogaster larvae ensure continuous proliferation and differentiation of hemocytes to maintain a fixed range of different blood cell types during its various stages of development. Variation in this number is often an indicator of animal well-being, its genotype or an effect of environmental perturbation, including exposure to heavy metals. The present study investigates the effect of Cd on larval hemocytes. Embryos were allowed to grow in metal media till third instar larvae and finally circulating hemocyte were collected. The number of major hemocytes, plasmatocytes and crystal cells was determined to be lowered in Cd exposed animals. Our results also showed modulation of antioxidant biology of Cd exposed hemocytes by changing the major antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) activity, and decreasing reduced glutathione (GSH) levels in hemocytes suspended in the hemolymph. Acridine orange (AO) staining further revealed induction of apoptosis in hemocytes of metal treated larvae. Our results suggest a negative impact of Cd exposure on the hemocytes of the Drosophila larvae culminating in their lowered count by induction of apoptosis.

Chlordane exposure causes developmental delay and metabolic disorders in Drosophila melanogaster

The incidence of metabolic diseases is increasing every year, and several studies have highlighted the activity of persistent organic pollutants (POPs) in causing hyperlipidemia and diabetes, and these compounds are considered to be endocrine disrupting chemicals (EDCs). Chlordane is classified as an endocrine disruptor, but the mechanism of how it functions is still unclear. This study investigates the effects of chlordane exposure on Drosophila larvae. Drosophila was cultured in diet containing 0.01 μM, 0.1 μM, 1 μM, 5 μM, and 10 μM chlordane, and the toxicity of chlordane, the growth and development of Drosophila, the homeostasis of glucose and lipid metabolism and insulin signaling pathway, lipid peroxidation-related indicators and Nrf2 signaling pathway were evaluated. We here found that exposure to high concentrations of chlordane decreased the survival rate of Drosophila and that exposure to low concentrations of chlordane caused disruption of glucose and lipid metabolism, increased insulin secretion and impairment of insulin signaling. Notably, it also led to massive ROS production and lipid peroxidation despite of the activation of Nrf2 signaling pathway, an important pathway for maintaining redox homeostasis. Collectively, chlordane causes lipid peroxidation and disrupts redox homeostasis, which may be a potential mechanism leading to impaired insulin signaling and the metabolism of glucose and lipid, ultimately affects Drosophila development.

The effects of cadmium on the development of Drosophila and its transgenerational inheritance effects

A new focus in toxicology research is the impact of parental exposure to environmental toxic substances on the characteristics of offspring. In the present study, newly produced eggs of Drosophila melanogaster were treated with different concentrations of cadmium (0, 1, 2, 4, 8 mg/kg) to study the effects of development. The results showed that cadmium changed the larval body length and weight, prolonged the pupation and eclosion time, and changed the relative expression levels of development-related genes (baz, β-Tub60D, tj). Furthermore, the parental Drosophila (F₀) were treated with cadmium (4.5 mg/kg) from egg stage, and when grows to adults, they mated in standard medium to produce the de-stressed offspring (F₁-F₄) to assess the transgenerational effects of developmental delay. The results showed that the delayed effects of the pupation and eclosion time could be maintained for two generations, and the inhibiting effects of juvenile hormone (JH) and ecdysone (20-hydroxyecdysone, 20E) could be maintained for two or three generations. More importantly, cadmium increased the expression of DNA methylation-related genes (dDnmt2, dMBD2/3) in the ovaries (F₀-F₂) and testicles (F₀ and F₁). In addition, cadmium accumulated in parental Drosophila (F₀) was not transmitted to offspring through reproductive pathway. These results demonstrate that the developmental toxicity caused by cadmium could be transmitted to the de-stressed offspring, and the observed transgenerational inheritance effects may be associated with epigenetic regulation, underscoring the need to consider fitness of future generations in evaluating the toxicity and environmental risks of cadmium.

Single and mixed exposure to cadmium and mercury in Drosophila melanogaster: Molecular responses and impact on post-embryonic development

Heavy metals, like many other chemical elements, are naturally present in the environment; however, the concentrations of these metals in various environmental matrices have increased through their intensive use in many human activities (such as industry, mining and agriculture). Among the heavy metals, cadmium (Cd) and mercury (Hg) induce a wide variety of defects in animals. While the effects of these heavy metals have been widely documented, a single exposure paradigm is typically used. Few studies have focused on evaluating combined exposure to these metals. However, in the environment, animals are confronted with a plethora of substances simultaneously; thus, the presence and origin of such substances must be determined to reduce the sources of contamination. Using the model of the fruit fly Drosophila melanogaster, for which many tools are readily available, we investigated how different concentrations of Cd and Hg in single and combined exposures impact post-embryonic development. In parallel, we evaluated the extended expression pattern of 38 molecular targets used as potential biomarkers of exposure through qPCR. Our results showed that both metals caused developmental delays and mortality in dose-dependent responses. Both metals were able to deregulate genes involved in hormonal control, general stress, and oxidative stress. Importantly, we confirmed synergistic interactions between Cd and Hg. Our results indicate the importance of assessing several biomarkers and their kinetics in mixtures. Drosophila represents a useful model for monitoring the toxicity of substances in polluted environments.

No water, no mating: Connecting dots from behaviour to pathways

Insects hold considerable ecological and agricultural importance making it vital to understand the factors impacting their reproductive output. Environmental stressors are examples of such factors which have a substantial and significant influence on insect reproductive fitness. Insects are also ectothermic and small in size which makes them even more susceptible to environmental stresses. The present study assesses the consequence of desiccation on the mating latency and copulations duration in tropical Drosophila melanogaster. We tested flies for these reproductive behavioral parameters at varying body water levels and with whole metabolome analysis in order to gain a further understanding of the physiological response to desiccation. Our results showed that the duration of desiccation is positively correlated with mating latency and mating failure, while having no influence on the copulation duration. The metabolomic analysis revealed three biological pathways highly affected by desiccation: starch and sucrose metabolism, galactose metabolism, and phenylalanine, tyrosine and tryptophan biosynthesis. These results are consistent with carbohydrate metabolism providing an energy source in desiccated flies and also suggests that the phenylalanine biosynthesis pathway plays a role in the reproductive fitness of the flies. Desiccation is a common issue with smaller insects, like Drosophila and other tropical insects, and our findings indicate that this lack of ambient water can immediately and drastically affect the insect reproductive behaviour, which becomes more crucial because of unpredictable and dynamic weather conditions.

Consequences of a short-term exposure to a sub lethal concentration of CdO nanoparticles on key life history traits in the fruit fly (Drosophila melanogaster)

Nanoparticles of cadmium oxide (CdO NPs) are among the most common industrial metal oxide nanoparticles. Early adulthood (P1) fruit flies (D. melanogaster) were exposed for 7 days to a sub lethal concentration (0.03 mg CdO NPs/mL, which was 20% of the LC₅₀), spiked into food media to test whether short episodes of CdO NPs exposures early in adult life have long-lasting effects on life history traits such as fecundity well beyond exposure times. All studied life history traits, as well as climbing behavior were adversely affected by exposure to CdO NPs. A blistered wing phenotype was also observed in the non-exposed progeny (F1) of adult flies (P1) and their fecundity was significantly decreased (-50%) compared to the fecundity of non-exposed (control) F1 flies. Expressions of antioxidant enzymes encoding genes; catalase and superoxide dismutase (SOD2) were significantly up regulated in P1 flies compared to control. Expression of metallothionein encoding genes (MTn A-D) were significantly up-regulated in both parent flies (P1) and their progeny (F1) after exposure of P1 flies to CdO NPs compared to non-exposed control flies, suggesting long-term potential effects. Taken together, these findings indicate that short-term exposure to a sub-lethal CdO NP concentration is sufficient to have long-lasting, adverse effects on fruit flies.

Exploring the multilevel effects of triclosan from development, reproduction to behavior using Drosophila melanogaster

Triclosan (TCS) is widely used as an antibacterial agent, but its residue in the environment poses a great threat. In this study, Drosophila melanogaster were treated with series concentrations of TCS and the effects on development, behavior, reproduction, and oxidative stress indicators were investigated. The results showed that high concentrations of TCS severely interfered with the metamorphosis, resulting in lower hatching rate and longer development time. The hatching rate was only 75.00% ± 4.08% in 0.80 mg/mL TCS group. TCS also showed dose-dependent damage to the fertility of flies, causing ovarian defects and decreased the number of offspring. Almost no offspring adults hatched when exposed to high concentrations of TCS (0.50 and 0.80 mg/mL), and the hatching rate was 0% in 0.80 mg/mL TCS group. Larvae crawling, adult climbing and anti-starvation ability were also affected to varying degrees and showed hormesis. TCS could damage larval intestinal cells in a dose-dependent manner, and injury was lightened with culture time prolonging to 30 h. It is noteworthy that TCS caused redox imbalance with an increase on catalase (CAT) activity and decrease on reactive oxygen species (ROS) level. Our results conclude that TCS elicits multiple impacts on Drosophila and its rational use should be strengthened.

Cellular alterations and damage to the renal tissue of marine catfish Arius arius following Cd exposure and the possible sequestrant role of Metallothionein

Cd is a non-degradable heavy metal pollutant with no known biological role. When taken up by living organisms from the environment, it causes extensive tissue damage. Here, we studied the effects of exposure to 20 mg/L^-1CdCl₂for 0, 24, 48, and 72 h on the renal tissue of marine catfish Arius arius. Cd uptake, metallothionein (MT) induction, microarchitectural alterations, DNA fragmentation, and caspase-3 activity were studied. Cd and MT levels were time-dependent and positively correlated. The diameter of the Bowman's capsule and tubules was significantly increased. Meanwhile, the density, diameter, and volume of the glomerulus as well as the density and volume of tubules decreased. Cd induced apoptosis though elevatedcaspase-3 activity. These results support the notion that exposure to sublethal Cd levels induces oxidative stress, leading to structural and functional impairment of the kidneys. Cd uptake and MT induction can serve as useful environmental biomarkers.

RNAi-based screens uncover a potential new role for the orphan neuropeptide receptor Moody in Drosophila female germline stem cell maintenance

Reproduction is highly sensitive to changes in physiology and the external environment. Neuropeptides are evolutionarily conserved signaling molecules that regulate multiple physiological processes. However, the potential reproductive roles of many neuropeptide signaling pathways remain underexplored. Here, we describe the results of RNAi-based screens in Drosophila melanogaster to identify neuropeptides/neuropeptide receptors with potential roles in oogenesis. The screen read-outs were either the number of eggs laid per female per day over time or fluorescence microscopy analysis of dissected ovaries. We found that the orphan neuropeptide receptor encoded by moody (homologous to mammalian melatonin receptors) is likely required in somatic cells for normal egg production and proper germline stem cell maintenance. However, the egg laying screens had low signal-to-noise ratio and did not lead to the identification of additional candidates. Thus, although egg count assays might be useful for large-scale screens to identify oogenesis regulators that result in dramatic changes in oogenesis, more labor-intensive microscopy-based screen are better applicable for identifying new physiological regulators of oogenesis with more subtle phenotypes.

Effects of zinc acquired through the plant-aphid-ladybug food chain on the growth, development and fertility of Harmonia axyridis

Heavy metal pollution is an increasingly serious problem in agricultural ecosystems. Zinc accumulation in the food chain may harm the physiological functions of organisms, including herbivorous and predatory insects. Its effects on development and reproduction in Harmonia axyridis are largely unknown. In this study, five Zn solutions (25, 50, 100, and 150 mg/kg) plus control (0 mg/kg) were used to treat broad beans and to water the resulting seedlings. Aphids fed on these seedlings were eaten by H. axyridis ladybugs. Zn accumulation was found at all three trophic levels. Compared with the control group, ladybugs in the 25, 50, and 100 mg/kg groups had significantly reduced weight gain from the 4^th instar to adulthood. Pupae and larvae (instars 1-4) in the 150 mg/kg group had the lowest survival of any group; pupal mortality in the 100 mg/kg group was significantly higher than that in the control group. Under Zn stress, female adults had inhibited expression of Vg1, Vg2 and VgR, reducing egg production and hatchability. Zn thus negatively affected their fertility. These results provide a theoretical basis for future exploration of soil heavy metal pollution impacts in ecosystems.

Effect of terpinolene against the resistant Staphylococcus aureus strain, carrier of the efflux pump QacC and β-lactamase gene, and its toxicity in the Drosophila melanogaster model

Efflux pumps and β-lactamases are mechanisms of bacterial resistance that exist in Staphylococcus aureus, where both mechanisms are expressed simultaneously in the SA K4100 strain, with its efflux pump being characterized as QacC (Quaternary Ammonium Compounds C). The search for inhibitors of these mechanisms has grown gradually, with research on isolated compounds, including terpenes, which have innumerable biological activities, being common. This study sought to evaluate the antibacterial activity of Terpinolene against the S. aureus K4100 strain, carrying a QacC efflux pump and β-lactamase, as well as to evaluate its toxicity in the Drosophila melanogaster arthropod model. Determination of the Minimum Inhibitory Concentration (MIC) was performed by broth microdilution. Efflux pump inhibition was evaluated by the MIC reduction of Oxacillin and Ethidium Bromide (EtBr). β-Lactamase inhibition was analyzed by the MIC reduction of Ampicillin with Sulbactam. Toxicity was verified by mortality parameters and locomotor assays in D. melanogaster. The results demonstrated that Terpinolene did not present a direct antibacterial activity (MIC ≥ 1024 μg/mL). However, a reduction in MIC was observed when Terpinolene was associated with Oxacillin (161.26-71.83 μg/mL) and EtBr (45.25-32 μg/mL), possibly by a β-lactamase and efflux pump inhibition, thus evidencing a modulatory activity. Terpinolene presented D. melanogaster mortality with an EC₅₀ of 34.6 μL/L within 12 h of exposure. Additionally, Terpinolene presented damage to the locomotor system after the second hour of exposure, with the effect increasing in a concentration-dependent manner. In conclusion, new tests should be carried out to investigate the Terpinolene reinforcement of antibiotic activity and toxic activity mechanisms of action.

Polydatin attenuates cadmium-induced oxidative stress via stimulating SOD activity and regulating mitochondrial function in Musca domestica larvae

Cadmium (Cd) is a widespread environment contaminant due to the development of electroplating and metallurgical industry. Cd can be enriched by organisms via food chain, causing the enlarged environmental problems and posing threats to the health of humans. Polydatin (PD), a natural stilbenoid compound derived from Polygonum cuspidatum, shows pronouncedly curative effect on oxidative damage. In this work, the protective effects of PD on oxidative damage induced by Cd in Musca domestica (housefly) larvae were evaluated. The larvae were exposed to Cd and/or PD, subsequently, the oxidative stress status, mitochondria activity, oxidative phosphorylation efficiency, and survival rate were assessed. Cd exposure generated significant increases of malondialdehyde (MDA), reactive oxygen species (ROS) and 8-hydroxy-2-deoxyguanosine (8-oxoG) in the housefly larvae, causing mitochondrial dysfunction and survival rate decline. Interestingly, pretreatment with PD exhibited obviously mitochondrial protective effects in the Cd-exposed larvae, as evidenced by reduced MDA, ROS and 8-oxoG levels, and increased activities of superoxide dismutase (SOD), mitochondrial electron transfer chain, and mitochondrial membrane potential, as well as respiratory control ratio. These results suggested that PD could attenuate Cd-induced damage via maintaining redox balance, stimulating SOD activity, and regulating mitochondria activity in housefly larvae. As a natural polyphenolic chemical, PD can act as a potential candidate compounds to relieve Cd injury.

Evaluation of the Antibacterial Activity and Efflux Pump Reversal of Thymol and Carvacrol against Staphylococcus aureus and Their Toxicity in Drosophila melanogaster

The antibacterial activity and efflux pump reversal of thymol and carvacrol were investigated against the Staphylococcus aureus IS-58 strain in this study, as well as their toxicity against Drosophila melanogaster. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method, while efflux pump inhibition was assessed by reduction of the antibiotic and ethidium bromide (EtBr) MICs. D. melanogaster toxicity was tested using the fumigation method. Both thymol and carvacrol presented antibacterial activities with MICs of 72 and 256 µg/mL, respectively. The association between thymol and tetracycline demonstrated synergism, while the association between carvacrol and tetracycline presented antagonism. The compound and EtBr combinations did not differ from controls. Thymol and carvacrol toxicity against D. melanogaster were evidenced with EC50 values of 17.96 and 16.97 µg/mL, respectively, with 48 h of exposure. In conclusion, the compounds presented promising antibacterial activity against the tested strain, although no efficacy was observed in terms of efflux pump inhibition.

Multigenerational effects of cadmium on the lifespan and fertility of Drosophila melanogaster

Although the damage and tolerance mechanisms of Cd stress are known, the data on genetic risk are limited. The aim of this study was to assess the chronic toxicity of Cd, genetic responses, and multigenerational effects in five generations of Drosophila melanogaster. For each generation, lifespan and fertility were statistically analysed and the expression of apoptosis- (p53 and caspase-3) and epigenesis-related (dDnmt2 and dMBD2/3) genes was examined. Lifespan and fertility significantly declined under Cd stress and these effects were maintained for two generations and one generation, respectively, when Cd stress was removed. The expression of p53 and caspase-3 was significantly up-regulated after exposure, suggesting that apoptosis contributes to the resistance mechanism. Their altered expression was retained for two generations. Furthermore, high expression of dDnmt2 and dMBD2/3 accompanied Cd exposure, which was passed on to three generations, suggesting that genetic modifications in apoptosis-related genes are carried to the offspring through epigenetic regulation.

Cadmium-induced developmental alteration and upregulation of serine-type endopeptidase transcripts in wild freshwater populations of Chironomus plumosus

Cadmium, a toxic heavy metal, is a persistent environmental contaminant with irreversible toxicity to aquatic organisms. Chironomus plumosus, a natural species, is the largest sediment-burrowing aquatic midge in freshwater environments. In this study, we evaluated developmental defects in C. plumosus resulting from Cd exposure. In C. plumosus larvae, Cd exposure induced decreased survival and growth rates, reduction of emergence rate and sex ratio, and delayed emergence, as well as elevating the incidence of split tooth deformities. To identify potential biomarker genes to assess environmental pollutants such as Cd, we identified differentially expressed genes (DEGs) in C. plumosus exposed to various Cd concentrations. Among fourteen characterized DEGs, serine-type endopeptidase (SP) and heat shock protein 70 (HSP70) genes exhibited significant upregulation in C. plumosus larvae after Cd exposure. Therefore, we evaluated SP and HSP70 responses in natural C. plumosus populations collected from three sites of a Korean river and analyzed their correlations with eighteen environmental quality characteristics using principal component analysis. The highest expression of SP and HSP70 transcripts was observed in C. plumosus populations from Yeosu in Korea, which has high concentrations of polluting heavy metals. SP transcript expression was positively correlated with concentrations of Cd, Pb, Al, Fe, NO2, and NO3. These results suggested that environmental pollutants such as Cd can impair proteolytic activity in the digestive system of C. plumosus and may ultimately induce developmental alterations. We therefore suggest SP as a potential biomarker to assess the effects of environmental pollutants in aquatic ecosystems.

Bioaccumulation of Cadmium Affects Development, Mating Behavior, and Fecundity in the Asian Corn Borer, Ostrinia furnacalis

Heavy metal pollution is becoming an increasingly serious problem in agricultural ecosystems. Heavy metals such as cadmium (Cd) accumulate in the food chain and may lead to detrimental effects on the physiological functions of living organisms, including herbivorous insects. One such example is the Asian Corn Borer, Ostrinia furnacalis (Lepidoptera: Pyralidae). However, how Cd can affect the development and reproduction of O. furnacalis is largely unknown. In this study, we exposed larvae of O. furnacalis to a diet containing Cd and investigated the effects of Cd on the development, mating behavior, and fecundity of the insect. We showed that Cd accumulates in the larvae and inhibits development by extending larval and pupal duration and decreasing the survival rate. The excretion of Cd through multiple routes during the larval and pupal stages resulted in low levels of residual Cd in the adult insects, which were not fed with Cd. However, the mating behavior and fecundity of these insects were significantly affected, compared to control insects. This suggests that the bioaccumulation of heavy metals such as Cd has long lasting and detrimental effects on O. furnacalis over the entire life cycle, affecting fecundity, even when specimens are only exposed at an early life stage.

Toxicological effects of ciprofloxacin exposure to Drosophila melanogaster

The abuse of ciprofloxacin (CIP) may cause serious side effects and the mechanisms underlying these effects remain unclear. Here, we determinate the 48 h, 72 h and 96 h LC₅₀ values of CIP to Drosophila melanogaster and demonstrate a series of adverse effects after D. melanogaster was exposed to CIP at a sublethal concentration (3.2 mg mL^-1). Treated individuals showed shorter lifespan, delayed development and many of the treated larvae failed to pupate or hatch. Smaller body size was observed at every life stage when exposed to CIP and the size of pupae, the weight of third-instar larvae exhibited a perfectly dose-response relationship that the larger concentration exposed to, the smaller body size or lighter weight is. Moreover, reduction in fat body cell viability, elevated oxidative stress markers (SOD and CAT) and down-regulation of diap1, ex, two target genes of Yorkie (Yki), was observed in response to CIP exposure. Most importantly, we found two types of black spot in Drosophila and the proportion of larvae with a black spot was positively related to the treatment dose, which is new in the field. This study provides a scientific basis for the potential harm caused by abuse of quinolones with the goal of urging cautious use of antibiotics.