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

Heat Shock Proteins as Potential Indicators of Induced Stress in Nematodes

Heat shock proteins (HSPs) in all animals studied to date constitute potential indicators of stress, under various environmental conditions. The goal of this chapter is to show, for the first time, the suitability of the approach based on evaluation of the expression levels of heat shock proteins, as good indicators of stress induced in nematodes by the cultivation of resistant plant varieties or by other potential stressors.

Household prallethrin-based insecticide toxicity on different C. elegans life stage: A possible sign of Huntington Disease

Household insecticide is largely used for insect and ectoparasite control, in city centers as well as in the countryside. The pyrethroids are the most used class of insecticide, these compounds in low doses have low toxicity for mammalians, in comparison to other compounds, with insecticide effects. The contact of these compounds in sublethal doses begins in early life and many cases, in intrauterine life. Considerable diseases still with undefined etiology, such as neurodegenerative conditions, and Huntington's Disease (HD) is one of them. HD is related to overexpression of Polyglutamine (PolyQ40), its aggregation, and non-solubilization, which leads to neural, behavioral, and cognitive damage. In our study, we evaluate the effect of two sublethal doses of a prallethrin-based insecticide (P-BI), in three different Caenorhabditis elegans life stages transgenerational, neonatal, and lifespan. We evaluated the Body bends and pharyngeal pumping rate, and social feeding as behavioral biomarkers. As well as acetylcholinesterase activity (AChE), PolyQ40 aggregation, antioxidant enzymes, and heat shock protein (HSP) expression. We observe that the toxic effect of P-BI is more pronounced on transgenerational and lifespan exposure. Both sublethal doses of P-BI decreased the AChE activity and retard the HSP expression as well as increased the PolyQ40 aggregates indicating a clear biomarker for possible effect in the progression of the HD, by the environmental contamination.

Protective effect of Catharanthus roseus plant extracts against endosulfan and its isomers induced impacts on non-targeted insect model, Drosophila melanogaster and live brain cell imaging

Endosulfan has been recognized as a highly controversial pesticide due to its acute toxicity, potential bioaccumulation, persistency, and long-range atmospheric transport. Several plant extracts act as antioxidant agents against wide-range of pesticide toxicity hazards through the free radicals scavenging properties. Plants' secondary metabolites are considered as efficient protective agents against various cellular toxic injuries. Understanding these properties of botanicals, several researchers currently focused on the detoxification and ameliorative potency of plant extracts against highly toxic chemicals. In our studies, we focused on the endosulfan total and its isomers (alpha and beta) induced changes on Drosophila melanogaster and their ameliorative effects by co-administrated with methanolic and aqueous extracts of Catharanthus roseus whole plant. We selected the 1/5th EC₅₀ concentration of alpha-endosulfan, beta-endosulfan, and endosulfan (total) and co-administrated with 1/50th EC₅₀ concentration of aqueous and methanolic extracts and evaluated their ameliorative effects, in terms of verifying the life stage activities, protein profiling and also by using live brain cells imaging. We finally concluded that, the methanolic and aqueous extracts inhibit the toxic impacts caused by endosulfan and its isomers and also increasing the survival rate of the test organism.

Toxicological effects of trichlorfon on hematological and biochemical parameters in Cyprinus carpio L. following thermal stress

Trichlorfon is a moderately toxic organophosphate pesticide that is widely used in aquaculture. This study investigated the effects of trichlorfon on hematological parameters, biochemical factors, and stress reaction in Cyprinus carpio L. The fish were exposed to acute concentrations of trichlorfon (0, 0.5, 1.0, 2.0, and 4.0 mg L^-1) at 25 °C and 15 °C for 1 and 2 weeks, after which several parameters were evaluated to assess the effects of the pesticide. Significant decreases were observed in red blood cell (RBC) Count, hemoglobin (Hb) level, hematocrit (Ht), and plasma protein levels after each exposure period. In contrast, notable increases in mean corpuscular volume (MCV), mean cell hemoglobin (MCH), calcium, and glucose levels were observed in the trichlorfon-treated groups. Additionally, there were significant increases in the plasma levels of glutamate-oxaloacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT), and alkaline phosphatase (ALP) following the exposure to trichlorfon. Furthermore, the results showed a relationship between toxic stress and increment in HSP70 and cytochrome P450 1A (CYP1A) expression over time. Ht, MCV, MCH, and the value of other biochemical parameters were quite lower at 15 °C than their corresponding values were at 25 °C, which indicated the decreased physical activity at 15 °C. The results of the present work indicate that acute exposure to trichlorfon and thermal stimulus could damage erythropoietic tissue. Additionally, hepatocytes function and physiological mechanisms could be impaired. Ht, glucose, GOT, GPT, HSP70, and CYP1A levels might be useful biomarkers of trichlorfon toxicity in contaminated aquatic ecosystems.

Acetylcholinesterase (AChE) and heat shock proteins (Hsp70) of gypsy moth (Lymantria dispar L.) larvae in response to long-term fluoranthene exposure

Polycyclic aromatic hydrocarbons (PAHs) may affect biochemical and physiological processes in living organisms, thus impairing fitness related traits and influencing their populations. This imposes the need for providing early-warning signals of pollution. Our study aimed to examine changes in the activity of acetylcholinesterase (AChE) and the concentration of heat shock proteins (Hsp70) in homogenates of brain tissues of fifth instar gypsy moth (Lymantria dispar L.) larvae, exposed to the ubiquitous PAH, fluoranthene, supplemented to the rearing diet. Significantly increased activity of AChE in larvae fed on the diets with high fluoranthene concentrations suggests the necessity for elucidation of the role of AChE in these insects when exposed to PAH pollution. Significant induction of Hsp70 in gypsy moth larvae reared on the diets containing low fluoranthene concentrations, indicate that changes in the level of Hsp70 might be useful as an indicator of pollution in this widespread forest species.

Evaluation of the toxic potential of calcium carbide in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9)

In the present study the toxic potential of calcium carbide (CaC2) was studied on the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9). The third instar larvae were exposed to 2, 4, 8, 16 and 32×10(-3)g/ml of CaC2 in diet for 24h. The results reveal that the dose 2×10(-3)g/ml was not toxic but the remaining doses showed a dose dependent significant increase in the hsp70 expression, β-galactosidase activity, tissue damage, oxidative stress markers (lipid peroxidation and protein carbonyl content), glutathione-S-transferase activity, expression of Caspase 3 and 9, apoptotic index and DNA damage (midgut cells). A significant reduction as compared to control group in total protein, glutathione content and acetylcholinesterase activity was also observed. The Inductively Coupled Plasma Atomic Emission Spectroscopy analysis (ICPAES) reveals the presence of copper, iron, sodium, aluminium, manganese, calcium, nickel and mercury. The toxic effects of CaC2 in the present study may be attributed to the impurities present in it.

sHsp22.6, an intronless small heat shock protein gene, is involved in stress defence and development in Apis cerana cerana

Small heat shock proteins (sHSPs) play an important role in protecting against stress-induced cell damage and fundamental physiological processes. In this study, we identified an intronless sHsp gene from Apis cerana cerana (AccsHsp22.6). The open reading frame of AccsHsp22.6 was 585 bp and encoded a 194 amino acid protein. Furthermore, a 2064 bp 5'-flanking region was isolated, and potential transcription factor binding sites associated with development and stress response were identified. Quantitative PCR and western blot analyses demonstrated that AccsHsp22.6 was detected at higher levels in the midgut than in other tissues tested, and it is highly expressed during the shift to different development stages. Moreover, AccsHsp22.6 was significantly up-regulated by abiotic and biotic stresses, such as 4 °C, 16 °C, 42 °C, cyhalothrin, pyridaben, H2O2, UV, CdCl2, 20-hydroxyecdysone and Ascosphaera apis treatments. However, AccsHsp22.6 was slightly repressed by other stresses, including 25 °C, phoxim, paraquat and HgCl2 treatments. The recombinant AccsHSP22.6 also exhibited significant temperature tolerance, antioxidation and molecular chaperone activity. In addition, we found that knockdown of AccsHsp22.6 by RNA interference remarkably reduced temperature tolerance in A. cerana cerana. Taken together, these results suggest that AccsHsp22.6 plays an essential role in the development stages and defence against cellular stress.

Exposure-dependent variation in cryolite induced lethality in the non-target insect, Drosophila melanogaster

The starting point of toxicity testing of any chemical in an organism is the determination of its Lethal Concentration 50 (LC₅₀). In the present study, LC₅₀ of a fluorinated insecticide cryolite is determined in a non-target insect model, Drosophila melanogaster. Interestingly, the result shows that acute LC₅₀ of cryolite was much greater in comparison to the chronic one in case of Drosophila larvae. Larvae which were exposed to 65,000 to 70,000 µg/ml cryolite through food showed 50% mortality after 18 hours of acute exposure, whereas only 150 to 160 µg/ml cryolite was sufficient to cause 50% mortality in case of chronic exposure. Thus cryolite in a small amount when applied once cannot produce noticeable changes in Drosophila, whereas the same amount when used continuously can be fatal. The non-feeding pupal stage was also seen to be affected by chemical treatment. This suggests that the test chemical affects the developmental fate and results in failure of adult emergence. Absence of chemical-induced mortality in adults assumes that the toxicity of cryolite might be restricted to the preimaginal stages of the organism. Reduction in body size of larvae after ingestion of cryolite (with food) in acute treatment schedule is another interesting finding of this study. Some individuals consuming cryolite containing food cannot survive whereas the few survivors manifest a significant growth retardation which might be due to a tendency of refusal in feeding. Hence the present findings provide a scope of assessment of risk of other similar non-target groups.

Monitoring the developmental impact of copper and silver nanoparticle exposure in Drosophila and their microbiomes

There is concern that waste waters containing manufactured metal nanoparticles (NPs) originating from consumer goods, will find their way into streams and larger water bodies. Aquatic invertebrates could be vulnerable to such pollution, and here we have used fruit flies, Drosophila melanogaster, as a model invertebrate, to test for the effect of NPs on fitness. Both copper NP and microparticle (MP)-containing medium slowed development, reduced adult longevity and decreased sperm competition. In contrast, ingestion of silver resulted in a significant reduction in developmental success only if the metal particles were nanosized. Ag NP-treatments resulted in reduced developmental success as assessed by larval and pupal survival as well as larval climbing ability, but there was no impact of silver on adult longevity and little effect on reproductive success. However, Cu NPs generally appeared to be no more toxic to this invertebrate model than the bulk counterpart. The impact of silver ingestion in larvae was further investigated by 454 pyrosequencing of the 16S rRNA genes of the midgut flora. There was a striking reduction in the diversity of the gut microbiota of Ag NP-treated larvae with a rise in the predominance of Lactobacillus brevis and a decrease in Acetobacter compared to control or Ag MP-treatment groups. Importantly, these experiments show that perturbation of the microbial assemblage within a metazoan model may contribute to Ag NP-mediated toxicity. These observations have implications for impact assessments of nanoparticles as emerging contaminants.

Study of the changes in life cycle parameters of Drosophila melanogaster exposed to fluorinated insecticide, cryolite

The study explored variations in the life cycle parameters in Drosophila melanogaster as a function of treatment with fluorinated insecticide, cryolite. Some of the life cycle parameters considered in this study were larval duration, pupal duration, and percentage of adult fly emergence in D. melanogaster of Oregon R strain. Freshly hatched first instar larvae were transferred to different dietary concentrations of the test chemical (5, 10, 15, 20, 40, 60, 80, 100, 150, and 200 ppm). Larval duration, pupal duration, and the emergence of flies of both treated and control groups were recorded. Results obtained show a significant ( p < 0.001–0.05) change in the mentioned parameters in the treated flies when compared with the controls. Interestingly, the percentage emergence of flies shows a decreasing trend along with increase in treatment concentration and almost no detectable emergence is observed in 200 ppm treatment category until the 20th day of experiment. Thus, the study indicates insecticide-induced variation in duration of different life stages and thereby suggests an effect of the fluorinated insecticide on the biology of a nontarget organism like Drosophila.

Organochlorine pesticide, endosulfan induced cellular and organismal response in Drosophila melanogaster

The effect of endosulfan (0.02-2.0μgmL(-1)) to Drosophila melanogaster (Oregon R(+)) at the cellular and organismal levels was examined. Third instar larvae of D. melanogaster and the strains transgenic for hsp70, hsp83 and hsp26 were exposed to endosulfan through food for 12-48h to examine the heat shock proteins (hsps), reactive oxygen species (ROS) generation, anti-oxidant stress markers and xenobiotic metabolism enzymes. We observed a concentration- and time-dependent significant induction of only small hsps (hsp23>hsp22) in the exposed organism in concurrence with a significant induction of ROS generation, oxidative stress and xenobiotic metabolism markers. Sub-organismal response was to be propagated towards organismal response, i.e., delay in the emergence of flies and decreased locomotor behaviour. Organisms with diminished locomotion also exhibited significantly lowered acetylcholinesterase activity. A significant positive correlation observed among ROS generation and different cellular endpoints (small hsps, oxidative stress markers, cytochrome P450 activities) in the exposed organism indicate a modulatory role of ROS in endosulfan-mediated cellular toxicity. The study thus suggests that the adverse effects of endosulfan in exposed Drosophila are manifested both at cellular and organismal levels and recommends Drosophila as an alternative animal model for screening the risk caused by environmental chemicals.

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.

Cypermethrin elicited responses in heat shock protein and feeding in Caenorhabditis elegans

Heat shock proteins (Hsp) are a family of stress proteins, which are elicited in response to a variety of stressors in organisms. The objective of this study was to explore the potential of cypermethrin, a synthetic pyrethroid insecticide, on induction of small heat shock proteins (Hsp16) and feeding response in transgenic Caenorhabditis elegans PC72 (Hsp16-LacZ). A concentration-dependent inhibition in feeding was evident in worms exposed to cypermethrin (31%, 46% and 56% at 5, 10, 15 mM, respectively) beyond 4h while marked induction of heat shock protein-16 expression was evident after 12h exposure (as evident from quantitative analysis). Maximum expression of Hsp16 was observed throughout the body of the worms 24h after exposure similar to that evident in the worms exposed to heat shock at 30 degrees C. These data suggest that cypermethrin possesses the potential to induce Hsp16 as well as inhibit feeding in C. elegans at non-lethal concentrations. C. elegans (PC72) thus could serve as a convenient model to study the early toxic effects of xenobiotics.

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.

Induction of hsp70, alterations in oxidative stress markers and apoptosis against dichlorvos exposure in transgenic Drosophila melanogaster: Modulation by reactive oxygen species

We examined a hypothesis that reactive oxygen species (ROS) generated by organophosphate compound dichlorvos modulates Hsp70 expression and anti-oxidant defense enzymes and acts as a signaling molecule for apoptosis in the exposed organism. Dichlorvos (0.015-15.0 ppb) without or with inhibitors of Hsp70, superoxide dismutase (SOD) and catalase (CAT) were fed to the third instar larvae of Drosophila melanogaster transgenic for hsp70 (hsp70-lacZ) Bg(9) to examine Hsp70 expression, oxidative stress and apoptotic markers. A concentration- and time-dependent significant increase in ROS generation accompanied by a significant upregulation of Hsp70 preceded changes in antioxidant defense enzyme activities and contents of glutathione, malondialdehyde and protein carbonyl in the treated organisms. An inhibitory effect on SOD and CAT activities significantly upregulated ROS generation and Hsp70 expression in the exposed organism while inhibition of Hsp70 significantly affected oxidative stress markers induced by the test chemical. A comparison made among ROS generation, Hsp70 expression and apoptotic markers showed that ROS generation is positively correlated with Hsp70 expression and apoptotic cell death end points indicating involvement of ROS in the overall adversity caused by the test chemical to the organism. The study suggests that (a) Hsp70 and anti-oxidant enzymes work together for cellular defense against xenobiotic hazard in D. melanogaster and (b) free radicals may modulate Hsp70 expression and apoptosis in the exposed organism.

Adverse effect of organophosphate compounds, dichlorvos and chlorpyrifos in the reproductive tissues of transgenic Drosophila melanogaster: 70kDa heat shock protein as a marker of cellular damage

The study highlights the adverse effects of organophosphate compounds dichlorvos and chlorpyrifos on reproduction in Drosophila. Freshly eclosed first instar larvae of Drosophila melanogaster transgenic for hsp70 (hsp70-lacZ) Bg(9) were fed on 0.015-150.0ppb dichlorvos and chlorpyrifos mixed food. Virgin flies eclosing from the normal and contaminated food were pair-mated to examine the effect of the test chemicals on reproduction of the exposed organisms. Expression of hsp70, sex peptide (SP or Acp70A), accessory gland protein (Acp36DE) and tissue damage was examined in reproductive organs of adult fly. Exposed organisms exhibited a dose-dependent significantly reduced reproductive outcome and males were found to be more sensitive than females. Hsp70 expression was restricted only within the testis lobes of male fly while it was not induced in the ovary of the female. In concurrence with absence of hsp70 expression in the accessory glands of male fly, tissue damage was evident in them. Acp70A and Acp36DE expression were found to be significantly downregulated at the higher concentrations of the test chemicals. The study suggests that (i) dichlorvos is more deleterious to fly reproduction compared to chlorpyrifos with an adverse effect on Acp70A and Acp36DE expression required to facilitate normal reproduction; (ii) hsp70 may be used as a marker of cellular damage against dichlorvos and chlorpyrifos in Drosophila.