Evaluation of toxic potential of captan: Induction of hsp70 and tissue damage in transgenic Drosophila melanogaster (hsp70-lacZ) Bg9

Assessing the multi-dimensional impact of lead-induced toxicity on collembola found in maize fields: From oxidative stress to genetic disruptions

The prolonged exposure of agricultural soils to heavy metals from wastewater, particularly in areas near industrial facilities, poses a significant threat to the well-being of living organisms. The World Health Organization (WHO) has established standard permissible limits for heavy metals in agricultural soils to mitigate potential health hazards. Nevertheless, some agricultural fields continue to be irrigated with wastewater containing industrial effluents. This study aimed to assess the concentration of lead in soil samples collected from agricultural fields near industrial areas. Subsequently, we determined the lethal concentration (LC50) of lead (Pb) and other heavy metals for two Collembola species, namely Folsomia candida, a standard organism for soil ecotoxicity tests, and comparing it with Proisotoma minuta. The research further examined the toxic effects of lead exposure on these two species, revealing depletion in the energy reservoirs and alterations in the tissue histology of both organisms. The study revealed that lead can induce genotoxic damage as it evidently has moderate binding affinity with the ct-DNA and hence can cause DNA fragmentation and the formation of micronuclei. Elevated lipid peroxidation (LPO) levels and protein carbonylation levels were observed, alongside a reduction in antioxidant enzymes (CAT, SOD & GPx). These findings suggest that lead disrupts the balance between oxidants and the antioxidant enzyme system, impairing defense mechanisms and consequential derogatory damage within microarthropods. The investigation elucidates a complex network of various signaling pathways compromised as a result of lead toxicity. Hence, it presents a novel perspective that underscores the pressing necessity for implementing an integrated risk assessment framework at the investigated site.

Evaluation of the toxic potential of Bisphenol-A glycidylmethacrylate (BisGMA) on the third instar larvae of transgenic Drosophila

Introduction

In the present study the cytotoxic and genotoxic effects of Bisphenol-A glycidyl methacrylate (BisGMA) was studied on the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg9.

Materials and methods

The concentration of BisGMA i.e. 0.005, 0.010, 0.015 and 0.020 M were established in diet and the larvae were allowed to feed on it for 24 h.

Results

A dose dependent significant increase in the activity of β-galactosidase was observed compared to control. A significant dose dependent tissue damage was observed in the larvae exposed to 0.010, 0.015 and 0.020 M of BisGMA compared to control. A dose dependent significant increase in the Oxidative stress markers was observed compared to control. BisGMA also exhibit significant DNA damaged in the third instar larvae of transgenic D. melanogaster (hsp70-lacZ)Bg9 at the doses of 0.010, 0.015 and 0.020 M compared to control.

Conclusion

BisGMA at 0.010, 0.015 and 0.020 M was found to be cytotoxic for the third instar larvae of transgenic D. melanogaster (hsp70-lacZ) Bg9.

Evaluation of Bis(2-ethylhexyl) phthalate toxicity on the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg9

Bis(2-ethylhexyl) phthalate, generally known as DEHP is a synthetic compound mainly used as a plasticizer to make polyvinyl chloride products flexible and soft. The present work aimed to study the toxicity of Bis(2-ethylhexyl) phthalate on the third instar larvae of transgenic Drosophila melanogaster(hsp70-lacZ) Bg9. The hsp70 gene is associated with the β-galactosidase in our present transgenic strain therefore, the more activity of β-galactosidase will indirectly correspond to hsp70 expression. The third instar larvae were allowed to feed on the diet for 24 h having 0.001, 0.005, 0.01, and 0.02 M of Bis(2-ethylhexyl) phthalate at the final concentration. After the exposure of 24hrs, the larvae were subjected to ONPG assay, X-gal staining, trypan blue exclusion test, oxidative stress markers assays, and comet assay. A dose-dependent increase in hsp70 expression, tissue damage, Glutathione-S-transferase (GST) activity, lipid peroxidation, monoamine oxidase, caspase-9 & 3, protein carbonyl content (PCC), DNA damage and decrease in the glutathione (GSH) content, delta-aminolevulinic acid dehydrogenase (ẟ-ALD-D) and acetylcholinesterase activity were observed in the larvae exposed to 0.005, 0.01, 0.02 M of Bis-(2-ethylhexyl) phthalate. The dose of 0.001 M of Bis(2-ethylhexyl) phthalate did not showed any toxic effects and hence can be considered as No Observed Adverse Effect Level (NOAEL) for Bis(2-ethylhexyl) phthalate. The study supports the use of Drosophila for the evaluation of possible toxic effects associated with synthetic compounds.

Protective effect of the newly synthesized and characterized charge transfer (CT) complex against arecoline induced toxicity in third-instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg9: experimental and theoretical mechanistic insights

Agents that suppress the toxic effect of arecoline (a chemical present in the Areca nut fruit) have become a need of the hour owing to its several harmful effects on human beings. Although some drug molecules have been developed for this purpose, yet, simple, easy to prepare, and economical molecules with remarkable potency are still a challenge to design. The present work thus becomes important as it involves the synthesis of a new charge transfer complex (CTC) material, which has, for the first time, been screened to investigate its effect on the toxic effects of arecoline. The newly designed material (CL), which is generated from the reaction between 2,4,6-trinitrophenol (TNP) and pyrazole (PYZ), has been crystallized by a slow evaporation method and characterized by employing spectral studies including single crystal X-ray crystallography. Spectrophotometry studies with the inclusion of the Benesi-Hildebrand equation reveal 1 : 1 stoichiometry and physical parameters of CL. Assays were used for determining the protective effect of CL against arecoline. CL was found to (dose-dependently) decrease β-galactosidase activity, damage in tissue and DNA damage caused by arecoline (80 μM) in the third-instar larvae of the transgenic Drosophila melanogaster (hsp70-lacZ)Bg⁹. The possible mechanism of this effect was explored through fluorescence and UV-vis spectroscopy. The possibility of suppression of arecoline action on the muscarinic acetylcholine receptor 1-G11 protein complex (found in the cell membrane) in the presence of CL was studied theoretically by molecular docking. Density functional theory (DFT) also theoretically supported various aspects of the designed material concerning the energy profile of the orbitals (HOMO-LUMO) as well as the energy minimized structure. Furthermore, time dependent (TD) DFT corroborated the electronic properties of the designed material.

Atrazine or bisphenol A mediated negative modulation of mismatch repair gene, mlh1 leads to defective oogenesis and reduced female fertility in Drosophila melanogaster

The study reports the effects of an herbicide (atrazine) and a plasticizer (Bisphenol A, BPA) on the transcriptional modulation of a mismatch repair gene (mlh1) and its adverse consequences on female fertility using Drosophila as a model. Through a chemical screen, we show that exposure to atrazine or BPA significantly downregulates mlh1 and the exposed flies had reduced fertility with smaller ovaries having reduced number of mature oocytes and abnormal distribution of ovarian follicles with increased apoptosis in them. These females had increased double-strand breaks as well as reduced synaptonemal complex formation in their ovaries suggesting altered meiotic crossing over. The eggs of these females were defective in their maternal transcripts as well as proteins and consequently, after fertilization, these eggs exhibited abnormal embryonic development. Interestingly, these phenotypes parallel that of mlh1 mutants. Further, exposure of females having reduced Mlh1 levels (mlh1^e00130/CyO) to atrazine or BPA caused severe defective phenotypes at a higher proportion than normal flies. Our findings reveal the critical role of mlh1 in atrazine and BPA mediated female reproductive toxicity, and opens up a possibility of toxicants affecting female fertility by modulating the MMR genes.

Effect of geraniol against arecoline induced toxicity in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg9

In the present study geraniol at the final concentration of 10, 20, 30, and 40 µM was mixed in the diet along with 80 µM of arecoline and the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg⁹ were allowed to feed on it for 24 hrs. After the exposure of 24 hrs the larvae were subjected to ONPG, X-gal, trypan blue exclusion test, oxidative stress markers and apoptotic and comet assays. The exposure of larvae to geraniol showed a dose dependent decrease in the activity of β-galactosidase, tissue damage and oxidative stress markers. A dose dependent decrease in apoptosis and DNA damage was also observed. Molecular docking studies also support the protective role of geraniol against the arecoline induced toxicity. The results suggest that geraniol is potent in reducing the toxicity induced by arecoline in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg⁹.

Evaluation of the toxic potential of arecoline toward the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg9

Arecoline is the key component of areca nut and has been suggested as a carcinogenic agent. In the present study, the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg9 were allowed to feed on a diet having 5, 10, 20, 40 and 80 μM arecoline for 24 h. After the completion of 24 h, the larvae were subjected to ONPG assay, X-gal staining, trypan blue exclusion test, oxidative stress markers, and apoptotic and comet assays. A dose-dependent increase in the β-galactosidase activity, tissue damage, glutathione-S-transferase (GST) activity, lipid peroxidation assay, monoamine oxidase (MAO), caspase-9 and 3, protein carbonyl content (PCC), apoptotic index, and DNA damage and decrease in glutathione (GSH) content, delta aminolevulinic acid dehydrogenase (δ-ALA-D), and acetylcholinesterase (AChE) activity were observed in the larvae exposed to 20, 40 and 80 μM arecoline. The results suggest that arecoline is toxic at 20, 40, and 80 μM toward the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg9 . Arecoline did not show any toxic effects at 5 and 10 μM.

The mitochondrial uncoupler 2,4-dinitrophenol attenuates sodium nitroprusside-induced toxicity in Drosophila melanogaster: potential involvement of free radicals

The toxicity of sodium nitroprusside (SNP) (an inducer of oxidative/nitrosative stress) and the attenuation of SNP effects by 2,4-dinitrophenol (DNP) (that induces mild uncoupling of respiration) were evaluated in the Drosophila melanogaster model system. Fly larvae were raised on food supplemented with 1.0 mM SNP, 0.5 or 1.25 mM DNP, or with mixtures 1.0 mM SNP plus 0.5 or 1.25 mM DNP. Food supplementation with SNP decreased larval viability and pupation height whereas supplementation with DNP substantially reversed these changes. Biochemical analyses of oxidative stress markers and activities of antioxidant and associated enzymes were carried out on 2-day-old flies emerged from control larvae and larvae fed on food supplemented with SNP, DNP, or SNP/DNP mixtures. Larval exposure to SNP lowered activities of aconitase, while the presence of DNP reduced the negative impact of SNP by raising aconitase activity back to near control levels. Larval treatment with SNP also elevated the contents of carbonyl protein, uric acid and low molecular mass thiols and produced higher activities of superoxide dismutase, glutathione S-transferase, glucose-6-phosphate dehydrogenase and thioredoxin reductase in adult flies. However, the presence of DNP in the food mixtures prevented SNP-induced changes in thioredoxin reductase and glucose-6-phosphate dehydrogenase activities, as well as uric acid and low-molecular-mass thiol content. The potential mechanisms by which DNP exerts protective effects against SNP toxicity are discussed.

2,4-dinitrophenol partially alleviates ferrocyanide-induced toxicity in Drosophila melanogaster

The toxicity of potassium ferrocyanide (PFC) and protective effects of 2,4-dinitrophenol (DNP) under PFC treatment were tested on the Drosophila melanogaster model system. Fly larvae were raised on food supplemented with PFC at concentrations of 1.0 mM and mixtures with DNP in concentrations of 0.50 and 1.25 mM, either alone or in combination with 1.0 mM PFC. Food supplementation with PFC decreased larvae viability or pupation height, whereas when larvae were fed by PFC and DNP combination the decrease was less pronounced. Larval exposure to PFC and mixtures of DNP and PFC lowered activities of aconitase. Larval treatment with PFC resulted in higher carbonyl protein, uric acid, and low molecular mass thiols content and higher activity of thioredoxin reductase in adult flies, while DNP in mixtures with PFC relieved these effects. Furthermore, treatment with PFC/DNP mixtures resulted in higher activities of superoxide dismutase and glutathione-S-transferase. It is proposed that PFC toxicity is mainly related to the cyanide and iron ions, released during its decomposition. The potential mechanisms of protective DNP effects against PFC toxicity are discussed.

Effect of L-ascorbic Acid on the hsp70 Expression and Tissue Damage in the Third Instar Larvae of Transgenic Drosophila melanogaster (hsp70-lacZ) Bg(9)

All living organisms respond to various physical or chemical stressors by the induction of heat shock protein (HSP). The present study was performed on transgenic Drosophila melanogaster (hsp70-lacZ) Bg⁹ in which the transformation vector is inserted with a P-element, the line contains wild-type hsp70 sequence up to the lacZ fusion point. The effect of L-ascorbic acid on the hsp70 expression and tissue damage was studied at the doses of 1, 2, 4, and 8 × 10^–4 g/ml in the third instar larvae of transgenic D. melanogaster (hsp70-lacZ) Bg⁹. The larvae were exposed to different doses of L-ascorbic acid for 24 and 48 hours. A dose-dependent significant increase in the hsp70 expression was observed at 2, 4, and 8 × 10^–4 g/ml of L-ascorbic acid for both 24 and 48 hours. The tissue damage was observed only in the 48 hours of exposure and mostly only in the salivary glands of the third instar larvae of transgenic D. melanogaster (hsp70-lacZ) Bg⁹. The present study also validates and supports the use of transgenic D. melanogaster (hsp70-lacZ) Bg⁹ for the toxicological evaluations.

Sodium nitroprusside toxicity in Drosophila melanogaster: delayed pupation, reduced adult emergence, and induced oxidative/nitrosative stress in eclosed flies

The toxicity of sodium nitroprusside (SNP) was tested on the Drosophila melanogaster model system. Fly larvae were raised on food supplemented with SNP at concentrations of 0.01-1.5 mM. Food supplementation with SNP caused a developmental delay in flies and reduced adult eclosion. Biochemical analyses such as levels of oxidative stress markers and activities of antioxidant and associated enzymes were carried out on 2-day-old flies emerged from control and SNP-fed larvae. Larval exposure to SNP resulted in lower activities of aconitase and catalase in adult flies relative to the control cohort. However, larval treatment with SNP led to higher carbonyl protein content and higher activities of superoxide dismutase, glucose-6-phosphate dehydrogenase, thioredoxin reductase, and glutathione-S-transferase in flies. Among the parameters tested, aconitase activity and developmental end points may be useful early indicators of toxicity caused by SNP. The study also suggests that the toxicity of SNP may arise not just from its direct effects, but also from its decomposition products such as nitric oxide and iron ions.

Effect of Thiovit® Jet on the structure of thoracic microtrichia/trichomes in Drosophila melanogaster

Widely used fungicides and pesticides are known to have profound effect on several nontarget organisms, which is a cause of concern. The present study aims to demonstrate the effect of a fungicide, Thiovit® Jet on the structure of epidermal microtrichia (trichome) of the dorsal thorax in Drosophila melanogaster. External morphology and structural variations of thoracic appendages have been extensively studied using scanning electron microscope from flies treated with different concentrations of Thiovit Jet (20, 30, 40 or 200 μg/ml). Similar to the effect of other fungicides like captan and captafol which are reported to produce somatic mutations in the same organism, the present study successfully demonstrates variation in the trichome/microtrichia structure of the dorsal thorax of D. melanogaster. Structural variations were observed to be associated with different concentrations of Thiovit Jet (30, 40 and 200 μg/ml), but the maximum notable change was found with 40 μg/ml treatment. The gross abnormality in the trichome structure may be due to mutation in proteins associated with normal cuticular deposition.

Effect of the steroid K-canrenoate on hsp70 expression and tissue damage in transgenic Drosophila melanogaster (hsp70-lacZ) Bg9

In the present study the effect of 0.1, 0.2, 0.4, 0.8, and 1.0 µL/mL of the steroid K-canrenoate was evaluated in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg(9) for 6, 24, and 48 hours of duration. The treatment of 0.1, 0.2, and 0.4 µL/mL of K-canrenoate did not induce the activity of hsp70 significantly compared to the control. The treatments of 0.8 and 1.0 µL/mL of K-canrenoate not only caused tissue damage but also induced a significant increase in the expression of hsp70 for the different durations of exposure. The results of the present study suggest that the K-canrenoate at 0.8 and 1.0 µL/mL is cytotoxic and caused tissue damage in the third instar larvae of transgenic D. melanogaster (hsp70-lacZ) Bg(9).

Effect of methyl methanesulfonate on hsp70 expression and tissue damage in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg

Methyl methanesulfonate (MMS) is an anti-carcinogenic drug and its toxicity has been reported in various experimental models. The hsp70s are a family of ubiquitously expressed heat shock proteins. In the recent years, hsp70 has been considered to be one of the candidate genes for predicting cytotoxicity against environmental chemicals. Nowadays emphasis is given to the use of alternatives to mammals in testing, research and education. The European Centre for the Validation of Alternative Methods (EVCAM) has recommended the use of Drosophila as an alternative model for scientific studies. Almost all living organisms possess proteins with a similar structure to that of hsp70s. In the present study, the toxicity of MMS was evaluated by quantifying hsp70 expression and tissue damage in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg(9), at different doses and hours of exposure. We studied the effect of 0.25, 0.50, 0.75 and 1.0 µl/ml of MMS at 2, 4, 24 and 48 hours of exposure on hsp70 expression by using the soluble O-nitrophenyl-β-D-galactopyranoside (ONPG) assay and on establishing the tissue damage by the Trypan blue exclusion assay in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg(9). A dose-dependent increase in the expression of hsp70 was observed at 0.25, 0.50, and 0.75 µl/ml of MMS compared to the control. At the highest dose, i.e. 1.0 µl/ml of MMS, the activity of hsp70 was decreased due to tissue damage.

Environmental chemical mediated male reproductive toxicity: Drosophila melanogaster as an alternate animal model

Industrialization and indiscriminate use of agrochemicals have increased the human health risk. Recent epidemiological studies raised a concern for male reproduction given their observations of reduced sperm counts and altered semen quality. Interestingly, environmental factors that include various metals, pesticides and their metabolites have been causally linked to such adversities by their presence in the semen at levels that correlate to infertility. The epidemiological observations were further supported by studies in animal models involving various chemicals. Therefore, in this review, we focused on male reproductive toxicity and the adverse effects of different environmental chemicals on male reproduction. However, it is beyond the scope of this review to provide a detailed appraisal of all of the environmental chemicals that have been associated with reproductive toxicity in animals. Here, we provided the evidence for reproductive adversities of some commonly encountered chemicals (pesticides/metals) in the environment. In view of the recent thrust for an alternate to animal models in research, we subsequently discussed the contributions of Drosophila melanogaster as an alternate animal model for quick screening of toxicants for their reproductive toxicity potential. Finally, we emphasized the genetic and molecular tools offered by Drosophila for understanding the mechanisms underlying the male reproductive toxicity.

Diphenyl diselenide [(PhSe)2] inhibits Drosophila melanogaster delta-aminolevulinate dehydratase (delta-ALA-D) gene transcription and enzyme activity

The main objective of the present study was to compare the inhibitory effect of diphenyl diselenide (PhSe)(2) and Pb(2+) on mice and fruit fly delta-Aminolevulinate dehydratase (delta-ALA-D). Optimum pH was quite different for mice (pH 6.5) and flies (pH 8.5). At pH 8.5, the inhibitory potency of (PhSe)(2) was higher for the fruit flies (IC(50) 8.2 micromol/l) than for mice (IC(50) 19.5 micromol/l). Pb(2+) inhibited mice delta-ALA-D at pH 6.5 (IC(50) 6.2 micromol/l) and 8.5 (IC(50) 5.6 micromol/l) with higher potency than the fly enzyme (IC(50) 43.7 micromol/l). delta-ALA-D transcription was reduced by 15% in flies exposed to 0.3 mmol/kg (PhSe)(2), which is similar to the reduction observed in activity measured in the presence of dithiothreitol. The three-dimensional prediction by SWISS-PROT mouse and fly delta-ALA-D revealed differences in the number of hydrogen bonds and turns for the 2 enzymes. Sulfhydryl groups (-SH) that could be oxidized by (PhSe)(2) are conserved in the two sources of enzyme. Distinct responsiveness to pH, (PhSe)(2) and Pb(2+) of these enzymes may be related to subtle differences in tertiary or quaternary structure of mouse and fly delta-ALA-D. Furthermore, mechanism underlying enzyme inhibition after in vivo exposure seems to be different for Drosophila melanogaster and rodent enzymes.

Toxic potential of municipal solid waste leachates in transgenic Drosophila melanogaster (hsp70-lacZ): hsp70 as a marker of cellular damage

Municipal solid wastes (MSWs) are one of the major sources of environmental pollution. Leachates from these wastes might contaminate the water sources and affect quality of environment. The study was carried out to determine the possible toxic effects of leachates from MSW in transgenic Drosophila melanogaster (hsp70-lacZ). Third instar larvae exposed to 1.0-3.0% of these leachates at different time intervals were examined for hsp70 expression, oxidative stress enzyme activities, proteotoxicity, tissue damage along with effect on emergence and reproduction. Maximum hsp70 expression was observed in the larvae exposed to highly acidic leachates. Overwhelming of hsp70 expression in the exposed larvae caused a concomitant decline in total protein content and a significant elevation in oxidative stress enzymes and lipid peroxidation (LPO) product. The leachates caused a significant delay in emergence of flies and affected the reproductive performance of the flies at the tested concentrations. The present study highlights the toxic potential of MSW leachates and the advantage of Drosophila as a model to evaluate the impact of leachates at organismal and cellular levels, also advocating Hsp70 as the first tier indicator of toxicity.

Synthetic pyrethroid cypermethrin induced cellular damage in reproductive tissues of Drosophila melanogaster: Hsp70 as a marker of cellular damage

We tested a working hypothesis of whether the synthetic pyrethroid cypermethrin, used worldwide for insecticidal purpose, causes adverse effects on reproduction in Drosophila melanogaster. Freshly eclosed first instar larvae of a transgenic strain of Drosophila melanogaster, Bg9, transgenic for hsp70 (hsp70-lacZ), were transferred to different dietary concentrations of the test chemical (0.002, 0.02, 0.2, 0.5, and 50.0 ppm). Larval mortality was observed at the higher dosed groups (0.2, 0.5, and 50.0 ppm). Following pair mating of virgin flies emerging from the treatment groups, a significant (p<0.05) effect on reproduction was observed in the lowest two dietary concentrations of the test chemical as compared to control. The test chemical exhibited a hazardous effect on the reproductive organs of the exposed organism as evident by Hsp70 expression and tissue damage. The impact of damage was comparatively more prominent in male flies than in females. Hsp70 expression was restricted only within the testis lobes of male, while ovary in the female fly did not exhibit any Hsp70 expression. Interestingly, the accessory glands of male flies in these treatment groups reflected intense tissue damage as evident by Trypan Blue staining. This was further corroborated by ultrastructural changes like higher vacuolization and disorganized filamentous bodies in the accessory glands of these groups. The present study indicates a profound effect on reproduction by cypermethrin and suggests the protective role of hsp70.

Hazardous effect of organophosphate compound, dichlorvos in transgenic Drosophila melanogaster (hsp70-lacZ): Induction of hsp70, anti-oxidant enzymes and inhibition of acetylcholinesterase

We tested a working hypothesis that stress genes and anti-oxidant enzyme machinery are induced by the organophosphate compound dichlorvos in a non-target organism. Third instar larvae of Drosophila melanogaster transgenic for hsp70 were exposed to 0.1 to 100.0 ppb dichlorvos and 5.0 mM CuSO(4) (an inducer of oxidative stress and stress genes) and hsp70, and activities of acetylcholinesterase (AchE), superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPO) product were measured. The study was further extended to examine tissue damage, if any, under such conditions. A concentration- and time-dependent increase in hsp70 and anti-oxidant enzymes was observed in the exposed organism as compared to control. A comparison of stress gene expression with SOD, CAT activities and LPO product under similar experimental conditions revealed that induction of hsp70 precedes the anti-oxidant enzyme activities in the exposed organism. Further, concomitant with a significant inhibition of AChE activity, significant induction of hsp70 was observed following chemical exposure. Mild tissue damage was observed in the larvae exposed to 10.0 ppb dichlorvos for 48 h when hsp70 expression reaches plateau. Dichlorvos at 0.1 ppb dietary concentration did not evoke significant hsp70 expression, anti-oxidant enzymes and LPO and AchE inhibition in the exposed organism, and thereby, was found to be non-hazardous to D. melanogaster. Conversely, 1.0 ppb of the test chemical stimulated a significant induction of hsp70 and anti-oxidant enzymes and significant inhibition of AchE; hence this concentration of test chemical was hazardous to the organism. The present study suggests that (a) both stress genes and anti-oxidant enzymes are stimulated as indices of cellular defense against xenobiotic hazard in D. melanogaster with hsp70 being proposed as first-tier bio-indicator of cellular hazard, (b) 0.1 ppb of the test chemical may be regarded as No Observed Adverse Effect Level (NOAEL), and 1.0 ppb dichlorvos as Low Observed Adverse Effect Level (LOAEL).

Comparative toxic potential of market formulation of two organophosphate pesticides in transgenic Drosophila melanogaster (hsp70-lacZ)

This study investigated the working hypothesis that two widely used organophosphate pesticides; Nuvan and Dimecron, exert toxic effects in Drosophila. Transgenic D. melanogaster (hsp70-lacZ) was used as a model for assaying stress gene expression and AchE activity as an endpoint for toxicity and also to evaluate whether stress gene expression is sufficient to protect against toxic insult of the chemicals and to prevent tissue damage. The study was extended to investigate the effect of the pesticides on the life cycle and reproduction of the organism. The study showed that Nuvan affected emergence of the exposed flies more drastically than Dimecron and the effect was lethal at the highest tested concentration (0.075 ppm). While Nuvan at 0.0075 and 0.015 ppm concentrations affected reproduction of the flies significantly, the effect of Dimecron was significant only at 0.015 and 0.075 ppm. Nuvan-exposed third-instar larvae exhibited a 1.2-fold to 1.5-fold greater hsp70 expression compared to Dimecron at concentrations ranging from 0.0075 to 0.075 ppm following 12 and 18 h exposure. While maximum expression of hsp70 was observed in Nuvan-exposed third-instar larval tissues following 18 h exposure at 0.075 ppm, Dimecron at the same dietary concentration induced a maximum expression of hsp70 following 24 h exposure. Further, concomitant with a significant induction of hsp70, significant inhibition of AchE was observed following chemical exposure and temperature shock. Concurrent with a significant decline in hsp70 expression in Nuvan-exposed larvae after 48 h at 0.075 ppm, tissue damage was evident. Dimecron-exposed larvae exhibited a plateau in hsp70 induction even after 48 h exposure and moderate tissue damage was observed in these larvae. The present study suggests that Nuvan is more cytotoxic than Dimecron in transgenic Drosophila melanogaster.

Argemone oil induced cellular damage in the reproductive tissues of transgenic Drosophila melanogaster: protective role of 70 kDa heat shock protein

We explored the reproductive toxicity of argemone oil and its principal alkaloid fraction in transgenic Drosophila melanogaster (hsp70-lacZ) Bg(9). The toxicity of argemone oil has been attributed to two of its physiologically active benzophenanthridine alkaloids, sanguinarine and dihydrosanguinarine. Freshly eclosed first instar larvae of transgenic Drosophila melanogaster were transferred to different concentrations of argemone oil and its alkaloid fraction contaminated food. Virgin flies that eclosed from the contaminated food were pair-mated to look into the effect on reproduction. The study was further extended by investigating hsp70 expression and tissue damage in larval gonads, genital discs, and reproductive organs of adult fly. Our results showed that argemone oil was more cytotoxic than its principal alkaloid fraction. Moreover, it was the male fly that was more affected compared to its opposite number. The accessory glands of male reproductive system of the fly, which did not express hsp70, exhibited severe damage as evidenced by Trypan blue staining. This prompted us to explore the ultrastructural morphology of the gland, which showed acute signs of necrosis in both the cell types as evident by necrotic nuclei, higher vacuolization, and disorganized endoplasmic reticulum, decrease in the number of Golgi vesicles and disorganized, loosely packed filamentous structures in the lumen of the accessory gland, at the higher concentrations of the adulterant. The study showed the reproductive toxicity of argemone oil and its alkaloid fraction in transgenic Drosophila melanogaster and further confirmed the cytoprotective role of hsp70.

Heat shock response:hsp70 in environmental monitoring

Heat shock proteins (Hsps) are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Among the different families of Hsps, the 70 kDa family (hsp70) is the most highly conserved and has been most extensively studied. Apart from their primary role in cellular defense under stress condition, a number of studies in recent years have shown the immense potential of hsp70 in pollution monitoring using even transgenic approach both in vivo and in vitro. This article reviews the recent developments in the widespread application of hsp70 in environmental risk assessment.