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

Sublethal effects of chlorantraniliprole on immunity in Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae): Promote encapsulation by upregulating a heat shock protein 70 family gene SfHSP68.1

As an agricultural pest, the fall armyworm (FAW), Spodoptera frugiperda, poses a severe threat to agriculture in China. Chlorantraniliprole has been widely used to control this pest. In our previous studies, we discovered that LD10, LD20, and LD30 chlorantraniliprole promoted encapsulation in the 4th instar larvae of the FAW, with LD30 chlorantraniliprole having the most significant effect. To further investigate the molecular mechanism underlying the sublethal effects of chlorantraniliprole on encapsulation in the FAW, this study conducted the effects of encapsulation in 4th instar larvae of the FAW exposed to LD30 chlorantraniliprole. Then, we analyzed the transcriptome of the FAW hemolymph treated with LD30 chlorantraniliprole and identified genes related to encapsulation using RNAi. Our results showed that the encapsulation in the FAW was enhanced at 6, 12, 18, 24, and 48 h after exposure to LD30 chlorantraniliprole. Additionally, LD30 chlorantraniliprole significantly affected the expression of certain immune-related genes, with the heat shock protein 70 family gene SfHSP68.1 showing the most significant upregulation. Subsequent interference with SfHSP68.1 resulted in a significant inhibition of encapsulation in FAW. These findings suggested that LD30 chlorantraniliprole can promote encapsulation in the FAW by upregulating SfHSP68.1 expression. This study provides valuable insights into the sublethal effects of chlorantraniliprole on encapsulation in the FAW and the interaction between encapsulation and heat shock proteins (HSPs).

Exposure to the Natural Compound Climacostol Induces Cell Damage and Oxidative Stress in the Fruit Fly Drosophila melanogaster

The ciliate Climacostomum virens produces the metabolite climacostol that displays antimicrobial activity and cytotoxicity on human and rodent tumor cells. Given its potential as a backbone in pharmacological studies, we used the fruit fly Drosophila melanogaster to evaluate how the xenobiotic climacostol affects biological systems in vivo at the organismal level. Food administration with climacostol demonstrated its harmful role during larvae developmental stages but not pupation. The midgut of eclosed larvae showed apoptosis and increased generation of reactive oxygen species (ROS), thus demonstrating gastrointestinal toxicity. Climacostol did not affect enteroendocrine cell proliferation, suggesting moderate damage that does not initiate the repairing program. The fact that climacostol increased brain ROS and inhibited the proliferation of neural cells revealed a systemic (neurotoxic) role of this harmful substance. In this line, we found lower expression of relevant antioxidant enzymes in the larvae and impaired mitochondrial activity. Adult offsprings presented no major alterations in survival and mobility, as well the absence of abnormal phenotypes. However, mitochondrial activity and oviposition behavior was somewhat affected, indicating the chronic toxicity of climacostol, which continues moderately until adult stages. These results revealed for the first time the detrimental role of ingested climacostol in a non-target multicellular organism.

Effect of climate change on hematotoxicity/hepatoxicity oxidative stress, Oncorhynchus mykiss, under controlled conditions

Described as the 'main ecological factor', temperature, strongly affects the physiological stress responses of fish. In order to evaluate the effects of temperature variations on fish culture and food value chain, the present study was designed as a climate change model. Furthermore, the present study provides a theoretical basis for a better understanding of the mechanisms of the environmentally induced changes. In this direction, we examined the blood physiology and oxidative stress responses induced by temperature variation in the rainbow trout, a temperature-sensitive cold-water fish. The obtained results showed that climate changes promoted the inhibited activities' expressions and the development of potential tissue and hematological defense mechanisms against temperature-induced toxic damage. This study showed that climate change could be a subset of the studies on the stress physiology in aquaculture, which can be developed for new experimental designs and research collaborations. Furthermore, it highlights knowledge gaps to guide future research in this emerging field.

Mechanisms underlying citrinin-induced toxicity via oxidative stress and apoptosis-mediated by mitochondrial-dependent pathway in SH-SY5Y cells

Citrinin (CIT) is a mycotoxin produced as a secondary product by the genera Aspergillus, Penicillium, Monascus, and other strains. CIT has the potential for contaminating animal feed and human food such as maize, wheat, rye, barley, oats, rice, cheese, and sake. Although CIT is primarily known as a nephrotoxic mycotoxin, it also affects other organs, including the liver and bone marrow, and its mechanisms of toxicity have not been clearly elucidated. There is a further lack of studies investigating the potential for CIT-induced neurotoxicity and its mechanisms. In the current study, SH-SY5Y human neuroblastoma cell line was treated with CIT for 24 h to evaluate various toxicological endpoints, such as reactive oxygen species (ROS) production and apoptosis induction. Results indicate that CIT has an IC50 value of 250.90 μM and cell proliferation decreased significantly at 50 and 100 μM CIT concentrations. These same concentrations also caused elevated ROS production (≥34.76%), apoptosis (≥9.43-fold) and calcium ion mobilization (≥36.52%) in the cells. Results show a significant decrease in the mitochondrial membrane potential (≥86.8%). We also found that CIT significantly upregulated the expression of some genes related to oxidative stress and apoptosis, while downregulating others. These results suggest that apoptosis and oxidative stress may be involved in the mechanisms underlying CIT-induced neurotoxicity.

Potentiation of paraquat toxicity by inhibition of the antioxidant defenses and protective effect of the natural antioxidant, 4-hydroxyisopthalic acid in Drosophila melanogaster

Exposure to pesticides such as paraquat (PQ) is known to induce oxidative stress-mediated damage, which is implicated in neurodegenerative diseases. The antioxidant enzymes are part of the endogenous defense mechanisms capable of protecting against oxidative damage, and down-regulation of these enzymes results in elevated oxidative stress. In this study, we have evaluated the protective action of 4-hydroxyisophthalic acid (DHA-I), a novel bioactive molecule from the roots of D. hamiltonii, against PQ toxicity and demonstrated the protective role of endogenous antioxidant enzymes under the condition of oxidative stress using Drosophila model. The activity of the major antioxidant enzymes, superoxide dismutase 1 (SOD1) and catalase, was suppressed either by RNAi-mediated post transcriptional gene silencing or chemical inhibition. With the decreased in vivo activity of either SOD1 or catalase, Drosophila exhibited hypersensitivity to PQ toxicity, demonstrating the essential role of antioxidant enzymes in the mechanism of defense against PQ-induced oxidative stress. Dietary supplementation of DHA-I increased the resistance of Drosophila depleted in either SOD1 or catalase to PQ toxicity. Enhanced survival of flies against PQ toxicity indicates the protective role of DHA-I against oxidative stress-mediated damage under the condition of compromised antioxidant defenses.

Oxidative Stress, HSP70/HSP90 and eNOS/iNOS Serum Levels in Professional Divers during Hyperbaric Exposition

Heat shock proteins (HSPs) have protective effects against oxidative stress and decompression sickness. Nitric oxide may reduce bubble formation during decompression and its activity is regulated by HSPs. A simulated dive can cause the HSP response. The aim of this study was to describe the effect of simulated dives on the antioxidant system, HSPs, and nitric oxide synthase response and demonste the relationship between the concentration of HSPs and the intensification of oxidative stress. A total of 20 healthy professional divers took part in training, consisting of simulated dry dives in a hyperbaric chamber and split into experiment I (30 m exposure, 400 kPa) and experiment II (60 m exposure, 700 kPa) over 24 h. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) and the concentrations of malondialdehyde (MDA), heat shock protein 70 (HSP70), heat shock protein 90 (HSP90), endothelial (eNOS) and inducible (iNOS) nitric oxide synthase were measured. Increases in the activity of SOD and MDA concentration were demonstrated. The activity of GPx depended on the dive profile. The HSP70 serum level in both experiments was significantly lower after the dives. The mean HSP90 level was significantly higher after the simulated dive at 60 m. A significant relationship between HSP concentration and SOD/GPx activity was demonstrated. eNOS concentration increased after 60 m exposure. No change in iNOS concentration was observed. In conclusions, the simulated dive significantly affected the antioxidant system, heat shock protein expression and nitric oxide synthase; however, the changes depend on the diving conditions. There is a relationship between the expression of HSPs and the intensity of oxidative stress.

Effects of Fluoride on Submandibular Glands of Mice: Changes in Oxidative Biochemistry, Proteomic Profile, and Genotoxicity

Although fluoride (F) is well-known to prevent dental caries, changes in cell processes in different tissues have been associated with its excessive exposure. Thus, this study aimed to evaluate the effects of F exposure on biochemical, proteomic, and genotoxic parameters of submandibular glands. Twenty one old rats (n = 30) were allocated into three groups: 60 days administration of drinking water containing 10 mgF/L, 50 mgF/L, or only deionized water (control). The submandibular glands were collected for oxidative biochemistry, protein expression profile, and genotoxic potential analyses. The results showed that both F concentrations increased the levels of thiobarbituric acid–reactive substances (TBARS) and reduced glutathione (GSH) and changed the proteomic profile, mainly regarding the cytoskeleton and cellular activity. Only the exposure to 50 mgF/L induced significant changes in DNA integrity. These findings reinforce the importance of continuous monitoring of F concentration in drinking water and the need for strategies to minimize F intake from other sources to obtain maximum preventive/therapeutic effects and avoid potential adverse effects.

Heat Shock Protein 70 Family in Response to Multiple Abiotic Stresses in the Silkworm

Simple Summary

Heat shock protein 70 family is widely distributed in all the organisms, which plays important roles in protein folding and preventing protein denaturation. Heat or cold stress response has been studied in some insects, but there is a lack of systematic investigation on the response of the same species to multiple stressors. Here, we performed genome-wide identification of heat shock protein 70 family in the silkworm, Bombyx mori. Using the silkworm as a model, the transcription profiles of all the genes against heat, cold, and pesticides were studied. Our findings would provide insights into the functional diversification of heat shock proteins 70 in insects.

Abstract

The 70 kDa heat shock proteins play important roles in protecting organisms against environmental stresses, which are divided into stress-inducible forms (HSP70s) and heat shock cognates (HSC70s). In this study, heat shock protein 70 family was identified in the whole genome of the silkworm. Based on the known nomenclature and phylogenetic analysis, four HSP70s and five HSC70s were classified. Relatively, heat shock cognates were more conservative and were constitutively expressed in various tissues of the silkworm larvae. Under thermal (37 °C and 42 °C) and cold (2 °C) stresses, the expressions of HSP70–1, HSP70–2, and HSP70–3 were up-regulated, and the highest induction reached 4147.3, 607.1, and 1987.3 times, respectively. Interestingly, HSC70–1, HSC70–4, and HSC70–5 also showed slight induced expressions in the fat body and/or midgut under thermal stresses. In addition, the expression of HSP70–1 was induced by dichlorvos and phoxim insecticides, while most HSC70 genes were inhibited. The results suggested that stress-inducible forms play more important roles in adaptation to various stresses than HSC70s.

Bacopaside-I Alleviates the Detrimental Effects of Acute Paraquat Intoxication in the Adult Zebrafish Brain

Paraquat (PQ), an environmental neurotoxicant, causes acute fatal poisoning upon accidental or intentional ingestion (suicidal cases) worldwide. To date, an effective remedy for PQ toxicity is not available. In this study, we have evaluated the therapeutic efficacy of Bacopaside-I (BS-I), an active compound found in the plant extract of Bacopa monnieri (Brahmi), against acute PQ intoxication using zebrafish as a model organism. Adult zebrafish were injected with a dose of either 30 mg/kg or 50 mg/kg PQ. PQ-intoxicated zebrafish showed an increased rate of mortality and oxidative imbalance in their brain. Also, the proliferation of neural cells in the adult zebrafish brain was inhibited. However, when BS-I pretreated zebrafish were intoxicated with PQ, the toxic effects of PQ were ameliorated. PQ treatment also affected the expression of particular genes concerned with the apoptosis and dopamine signaling, which was not altered by BS-I administration. Our results highlight the efficiency of BS-I as a novel therapeutic agent for PQ intoxication. It further compels us to search and evaluate the molecular mechanisms targeted by BS-I to develop a potent therapy for acute PQ intoxication.

Cr(VI)-induced DNA damage is lessened by the modulation of hsp70 via increased GSH de novo synthesis in Drosophila melanogaster

Hexavalent chromium [Cr(VI)] is a genotoxic chemical, and in the chemical-exposed organism, oxidative stress is one of the leading causative mechanisms of genotoxicity. Heat shock protein-70 (Hsp70) is reported to be modulated in environmental chemical exposed organisms. Inadequate information on the protective role of Hsp70 in chemical-induced DNA lesions prompted us to investigate this possibility in a well-studied genetically tractable in vivo model Drosophila melanogaster. In the midgut cells of Cr(VI)-exposed hsp70-knockout (KO), -knockdown (KD), and -overexpression Drosophila strains, no significant change in double-strand breaks generation was observed in comparison to similarly exposed w ¹¹¹⁸ and the respective genetic control strain after 48 h. Therefore, the role of hsp70 was investigated on oxidative DNA damage induction in the exposed organisms after 24 h. Oxidized DNA lesions (particularly oxidized purine-based lesions), 8-oxo-dG level, and oxidative stress endpoints were found to be significantly elevated in hsp70-KO and -KD strains in comparison to similarly exposed w ¹¹¹⁸ and respective genetic control strain. On the contrary, in ubiquitous hsp70-overexpression strain exposed to Cr(VI), these endpoints were significantly lowered concurrently with increased GSH level through elevated gclc, and gclm expression, Gclc level, and GCL activity. The study suggests that as a consequence of hsp70 overexpression, the augmented GSH level in cells vis-a-vis GSH de novo synthesis can counteract Cr(VI)-induced oxidized DNA lesions.

Heat Shock Proteins in Oxidative Stress and Ischemia/Reperfusion Injury and Benefits from Physical Exercises: A Review to the Current Knowledge

Heat shock proteins (HSPs) are molecular chaperones produced in response to oxidative stress (OS). These proteins are involved in the folding of newly synthesized proteins and refolding of damaged or misfolded proteins. Recent studies have been focused on the regulatory role of HSPs in OS and ischemia/reperfusion injury (I/R) where reactive oxygen species (ROS) play a major role. ROS perform many functions, including cell signaling. Unfortunately, they are also the cause of pathological processes leading to various diseases. Biological pathways such as p38 MAPK, HSP70 and Akt/GSK-3β/eNOS, HSP70, JAK2/STAT3 or PI3K/Akt/HSP70, and HSF1/Nrf2-Keap1 are considered in the relationship between HSP and OS. New pathophysiological mechanisms involving ROS are being discovered and described the protein network of HSP interactions. Understanding of the mechanisms involved, e.g., in I/R, is important to the development of treatment methods. HSPs are multifunctional proteins because they closely interact with the antioxidant and the nitric oxide generation systems, such as HSP70/HSP90/NOS. A deficiency or excess of antioxidants modulates the activation of HSF and subsequent HSP biosynthesis. It is well known that HSPs are involved in the regulation of several redox processes and play an important role in protein-protein interactions. The latest research focuses on determining the role of HSPs in OS, their antioxidant activity, and the possibility of using HSPs in the treatment of I/R consequences. Physical exercises are important in patients with cardiovascular diseases, as they affect the expression of HSPs and the development of OS.

Xenobiotic mediated diabetogenesis: Developmental exposure to dichlorvos or atrazine leads to type 1 or type 2 diabetes in Drosophila

The increased incidence of diabetes to the magnitude of a global epidemic is attributed to non-traditional risk factors, including exposure to environmental chemicals. However, the contribution of xenobiotic exposure during the development of an organism to the etiology of diabetes is not fully addressed. Developing stages are more susceptible to chemical insult, but knowledge on the consequence of the same to the onset of diabetes is residual. In this context, by using Drosophila melanogaster having conserved Insulin/Insulin growth factor-like signaling (IIS) as well as glucose homeostasis as a model, we evaluated the potential of developmental exposure to dichlorvos (DDVP, an organophosphorus pesticide) or atrazine (herbicide) to cause diabetes in exposed organisms. Flies exposed to DDVP during their development display insulin deficiency or type 1 diabetes (T1D) while those exposed to atrazine show insulin resistance or type 2 diabetes (T2D), suggesting that exposure to these xenobiotics during organismal development can result in diabetes and that different mechanisms underlie pesticide mediated diabetes. We show that oxidative stress-mediated c-Jun N-terminal kinase (JNK) signaling activation underlies insulin resistance in flies exposed to atrazine during their development while DDVP-mediated T1D involves activation of caspase-mediated cell death pathway. Mitigation of oxidative stress through over-expression of SOD2 in atrazine (20μg/ml) exposed flies, revealed significantly decreased oxidative stress levels and reduced phosphorylation of JNK. Moreover, glucose and Akt phosphorylation levels in SOD2 over-expression flies exposed to atrazine were comparable to those in controls, suggesting restoration in insulin sensitivity. Therefore, exposure to xenobiotics during development is a common risk factor for the development of type 1 or type 2 diabetes. Accordingly, the present study cautions against the use of such diabetogenic pesticides. Also, mitigation of oxidative stress or anti-oxidant supplementation could be a potential therapy for xenobiotic mediated type 2 diabetes.

Evaluation of DNA interaction, genotoxicity and oxidative stress induced by iron oxide nanoparticles both in vitro and in vivo: attenuation by thymoquinone

Iron oxide nanoparticles (IONPs) are known to induce cytotoxicity in various cancer cell lines through the generation of reactive oxygen species (ROS). However, the studies on its potential to induce toxicity in normal cell lines and in vivo system are limited and ambiguity still exists. Additionally, small molecules are known to interact with the DNA and cause damage to the DNA. The present study is designed to evaluate the potential interaction of IONPs with DNA along with their other toxicological effects and subsequent attenuation by thymoquinone both in vitro (primary lymphocytes) and in vivo (Wistar rats). IONPs were characterized by TEM, SEM-EDS, and XRD. The results from DNA interaction studies showed that IONPs formed a complex with DNA and also got intercalated between the base pairs of the DNA. The decrease in percent cell viability of rat’s lymphocytes was observed along with an increase in ROS generation in a dose-dependent manner (50, 100, 200, 400 and 800 μg/ml of IONPs). The genetic damage in in vivo might be due to the generation of ROS as depletion in anti-enzymatic activity was observed along with an increase in lipid peroxidation in a dose–dependent manner (25, 50, 100 mg/kg of IONPs). Interestingly, supplementation of thymoquinone in combination with IONPs has significantly (P < 0.05) attenuated the genetic and oxidative damage in a dose-dependent manner both in vitro and in vivo. It can be concluded that thymoquinone has the potential to attenuate the oxidative stress and genetic toxicity in vitro and in vivo.

Molecular basis for efficacy of Guduchi and Madhuyashti feeding on different environmental stressors in Drosophila

Stressors of different kinds adversely affect life history parameters like growth, development, and reproduction. Organisms overcome the negative impact of environmental stressors and strive to reach a tolerant state through genetic and metabolic activities. Ayurvedic formulations are reported to have life trait benefitting properties which improve capacity to withstand stress and tolerate adverse conditions. Guduchi (Tinospora cordifolia) and Madhuyashti (Glycirrhiza glabra) Ayurvedic formulations are known to have immunomodulatory, intellect promoting, and adaptogenic properties, thus favoring good health and healthy aging. Present study investigates the efficacy of Guduchi and Madhuyashti in providing tolerance to different stresses and the underlying mechanisms using the Drosophila model. Drosophila larvae/flies fed on Guduchi or Madhuyashti were better thermo-protected, which correlated with increased expression of heat shock genes even without the heat shock. Guduchi or Madhuyashti feeding also increased antimicrobial peptide expression, thus providing better tolerance to pathogenic assaults. Feeding on Guduchi- or Madhuyashti- supplemented food also enhanced starvation and desiccation tolerance. However, neither of these formulations provided beneficial effects when grown under crowded conditions or when exposed to oxidative stressors.

Fluazinam impairs oxidative phosphorylation and induces hyper/hypo-activity in a dose specific manner in zebrafish larvae

Fluazinam is a pyridinamine fungicide that induces oxidative stress and mitochondrial damage in cells, and it has been reported to be neurotoxic. To characterize the biological effects of fluazinam, we assessed mitochondrial bioenergetics, dopamine system expression, and behavior of early life staged zebrafish (0.01 μM-0.5 μM). Fluazinam at environmentally-relevant levels did not induce sub-lethal effects in larvae, but at the LC₅₀ (0.5 μM), fluazinam decreased basal and ATP-linked respiration significantly in embryos. As mitochondria are directly related to redox homeostasis and apoptosis, the expression of genes related to oxidative stress and apoptosis were measured. Superoxide dismutase 2 (sod2), heat stock protein 70 (hsp70), bcl2-associated X protein (bax), and caspase 9 (casp9) mRNA levels were up-regulated by 0.5 μM fluazinam. Taken together, there was evidence for mitochondrial dysfunction and oxidative damage at the highest concentration of fluazinam (0.5 μM) tested. As there are reports for fluazinam-induced neurotoxicity in dopamine synthesizing cells, transcriptional targets in the dopamine system were assessed in the zebrafish. Tyrosine hydroxylase 1 (th1) and dopamine receptor 2a (drd2a) mRNA levels were decreased by 0.5 μM fluazinam, suggesting that this fungicide may affect the dopaminergic system. To further assess the potential for fluazinam-mediated neuromodulation, the dark photokinesis response was assessed in larvae following exposure. Larvae exposed to 0.1 μM fluazinam showed hyperactivity, while larvae exposed to 0.2 and 0.3 μM showed hypo-activity. This study demonstrates that fluazinam disrupts mitochondrial bioenergetics in zebrafish, inducing an oxidative stress response, and aberrant behaviors in larvae that are dose dependent.

Characterization of Schinus lentiscifolius Marchand (Anacardiaceae) Bark Extract and Its Effects on Lymphocyte Oxidative Stress and Heat Shock Response

Schinus lentiscifolius Marchand has been used in folk medicine to treat immunoinflammatory related diseases, which are marked by OS and altered HSR. Our study aimed to evaluate OS and HSR in lymphocytes treated with S. lentiscifolius bark extracts. S. lentiscifolius barks were partitioned with solvents to obtain hexane (SL-HEX), ethyl acetate (SL-ACOET) and methanol (SL-MEOH) extracts, and the presence of bioactive compounds was evaluated by thin layer chromatography. Total phenols were measured by the Folin-Ciocalteu method and flavonoids were identified by HPLC-DAD-ESI-MS/MS. Antioxidant capacity was verified by DPPH method, cell viability by Trypan Blue method, lipid peroxidation by TBARS and HSP70 by immunoblotting. The SL-ACOET extract presented higher content of phenolic compounds and antioxidant activity in vitro. It was able to reduce lipid peroxidation levels in lymphocytes induced by H₂ O₂ and improved cell viability. The SL-ACOET extract inhibited HSR by a decrease in both intracellular content and release of 70 kDa heat shock proteins (HSP70) and also by decrease extra-to-intracellular HSP70 ratio in lymphocytes submitted to heat shock (2 h, 41 °C). S. lentiscifolius bark extract has antioxidant activity and inhibitory effect on HSR probably due to the presence of polyphenols as the flavonoids quercetin and kaempferol.

Study of the ichthyotoxic microalga Heterosigma akashiwo by transcriptional activation of sublethal marker Hsp70b in Transwell co-culture assays

Despite the advance of knowledge about the factors and potential mechanisms triggering the ichthyotoxicity in microalgae, these remain unclear or are controversial for several species (e.g. Heterosigma). Neither typical toxicity tests carried out with cell extracts nor direct exposure to harmful species were proved suitable to unravel the mechanism of harm. Ichthyotoxic species show a complex harmful effect on fish, which is mediated through various mechanisms depending on the species. In this work, we present a method to study sub-lethal effects triggered by reactive oxygen species of a population of harmful algae in vivo over a fish cell line. To that end, Transwell co-cultures in which causative and target species are separated by a 0.4 μm pore membrane were carried out. This allowed the evaluation of the effect of the released molecules by cells in a rapid and compact test. In our method, the harmful effect was sensed through the transcriptional activation of sub-lethal marker Hsp70b in the CHSE214 salmon cell line. The method was tested with the raphidophyte Heterosigma akashiwo and Dunaliella tertiolecta (as negative control). It was shown that superoxide intracellular content and its release are not linked in these species. The methodology allowed proving that reactive oxygen species produced by H. akashiwo are able to induce the transcriptional activation of sub-lethal marker Hsp70b. However, neither loss of viability nor apoptosis was observed in CHSE214 salmon cell line except when exposed to direct contact with the raphidophyte cells (or their extract). Consequently, ROS was not concluded to be the main cause of ichthyotoxicity in H. akashiwo.

Protective role of nimbolide against chemotherapeutic drug hydroxyurea induced genetic and oxidative damage in an animal model

Nimbolide is known to be an antioxidant found in neem plant. Hydroxyurea is a medication frequently used in sickle-cell disease, different cancers and HIV infection. The present study aimed to evaluate the adverse effect of HU and possible amelioration by nimbolide in Wistar rats. To test our hypothesis, we performed genotoxicity tests, biochemical assays, and histopathological studies. We observed that HU caused higher levels of genotoxicity in the treated animals. The observed genetic and oxidative damage might be due to the presence of reactive species as HU increased the level of the malondialdehyde-a biomarker of oxidative damage. Interestingly, co-treatment of animals with HU and nimbolide showed a lower level of damage. We conclude that nimbolide significantly protects the cells from the adverse effect of HU and could be considered as a potential adjuvant for the patients under HU therapy.

Paraquat affects mitochondrial bioenergetics, dopamine system expression, and locomotor activity in zebrafish (Danio rerio)

The dipyridyl herbicide paraquat induces oxidative stress in cells and is implicated in adult neurodegenerative diseases. However, less is known about paraquat toxicity in early stages of vertebrate development. To address this gap, zebrafish (Danio rerio) embryos were exposed to 1, 10 and 100 μM paraquat for 96 h. Paraquat did not induce significant mortality nor deformity in embryos and larvae, but it did accelerate time to hatch. To evaluate whether mitochondrial respiration was related to earlier hatch times, oxygen consumption rate was measured in whole embryos. Maximal respiration of embryos exposed to 100 μM paraquat for 24 h was reduced by more than 70%, suggesting that paraquat negatively impacts mitochondrial bioenergetics in early development. Based upon this evidence for mitochondrial dysfunction, transcriptional responses of oxidative stress- and apoptosis-related genes were measured. Fish exposed to 1 μM paraquat showed higher expression levels of superoxide dismutase 2, heat shock protein 70, Bcl-2-associated X protein, and B-cell CLL/lymphoma 2a compared to control fish. No differences among groups were detected in larvae exposed to 10 and 100 μM paraquat, suggesting a non-monotonic response. We also measured endpoints related to larval behavior and dopaminergic signaling as paraquat is associated with degeneration of dopamine neurons. Locomotor activity was stimulated with 100 μM paraquat and dopamine transporter and dopamine receptor 3 mRNA levels were increased in larvae exposed to 1 μM paraquat, interpreted to be a compensatory response at lower concentrations. This study improves mechanistic understanding into the toxic actions of paraquat on early developmental stages.

The role of charge in the toxicity of polymer-coated cerium oxide nanomaterials to Caenorhabditis elegans

This study examined the impact of surface functionalization and charge on ceria nanomaterial toxicity to Caenorhabditis elegans. The examined endpoints included mortality, reproduction, protein expression, and protein oxidation profiles. Caenorhabditis elegans were exposed to identical 2-5nm ceria nanomaterial cores which were coated with cationic (diethylaminoethyl dextran; DEAE), anionic (carboxymethyl dextran; CM), and non-ionic (dextran; DEX) polymers. Mortality and reproductive toxicity of DEAE-CeO₂ was approximately two orders of magnitude higher than for CM-CeO₂ or DEX-CeO₂. Two-dimensional gel electrophoresis with orbitrap mass spectrometry identification revealed changes in the expression profiles of several mitochondrial-related proteins and proteins that are expressed in the C. elegans intestine. However, each type of CeO₂ material exhibited a distinct protein expression profile. Increases in protein carbonyls and protein-bound 3-nitrotyrosine were also observed for some proteins, indicating oxidative and nitrosative damage. Taken together the results indicate that the magnitude of toxicity and toxicity pathways vary greatly due to surface functionalization of CeO₂ nanomaterials.

The effect of elevated temperatures on the life history and insecticide resistance phenotype of the major malaria vector Anopheles arabiensis (Diptera: Culicidae)

BACKGROUND

Temperature plays a crucial role in the life history of insects. Recent climate change research has highlighted the importance of elevated temperature on malaria vector distribution. This study aims to examine the role of elevated temperatures on epidemiologically important life-history traits in the major malaria vector, Anopheles arabiensis. Specifically, the differential effects of temperature on insecticide-resistant and susceptible strains were examined.

METHODS

Two laboratory strains of A. arabiensis, the insecticide-susceptible SENN and the insecticide-resistant SENN DDT strains, were used to examine the effect of elevated temperatures on larval development and adult longevity. The effects of various elevated temperatures on insecticide resistance phenotypes were also examined and the biochemical basis of the changes in insecticide resistance phenotype was assessed.

RESULTS

SENN and SENN DDT larvae developed at similar rates at elevated temperatures. SENN DDT adult survivorship did not vary between control and elevated temperatures, while the longevity of SENN adults at constantly elevated temperatures was significantly reduced. SENN DDT adults lived significantly longer than SENN at constantly elevated temperatures. Elevated rearing temperatures, as well as a short-term exposure to 37 and 39 °C as adults, augmented pyrethroid resistance in adult SENN DDT, and increased pyrethroid tolerance in SENN. Detoxification enzyme activity was not implicated in this phenotypic effect. Quercertin-induced synergism of inducible heat shock proteins negated this temperature-mediated augmentation of pyrethroid resistance.

CONCLUSION

Insecticide-resistant A. arabiensis live longer than their susceptible counterparts at elevated temperatures. Exposure to heat shock augments pyrethroid resistance in both resistant and susceptible strains. This response is potentially mediated by inducible heat shock proteins.

Transcription of four Rhopalosiphum padi (L.) heat shock protein genes and their responses to heat stress and insecticide exposure

The bird cherry-oat aphid, Rhopalosiphum padi (L.), a worldwide destructive pest, is more heat tolerant than other wheat aphids, and it has developed resistance to different insecticides. Heat shock proteins (HSPs) play an important role in coping with environmental stresses. To investigate Hsp transcriptional responses to heat and insecticide stress, four full-length Hsp genes from R. padi (RpHsp60, RpHsc70, RpHsp70-1, and RpHsp70-2) were cloned. Four RpHsps were expressed during all R. padi developmental stages, but at varying levels. The mRNA levels of RpHsps were increased under thermal stress and reached maximal induction at a lower temperature (36°C) in the alate morph than in the apterous morph (37°C or 38°C). RpHsp expressions under heat stress suggest that RpHsp70-1 and RpHsp70-2 are inducible in both apterous and alate morphs, RpHsc70 is only heat-inducible in apterous morph, and RpHsp60 exhibits poor sensitivity to heat stress. The pretreatment at 37°C significantly increase both the survival rate and the RpHsps expression level of R. padi at subsequent lethal temperature. Under exposure to two sublethal concentrations (LC₁₀ and LC₃₀) of beta-cypermethrin, both RpHsp70-1 and RpHsp70-2 expressions were induced and reached a maximum 24h after exposure. In contrast, expression of RpHsp60 was not induced by either sublethal concentration of beta-cypermethrin. Moreover, the responses of RpHsp70-1 and RpHsp70-2 to heat shock were more sensitive than those to beta-cypermethrin. These results suggest that induction of RpHsp expression is related to thermal tolerance, and that RpHsp70-1 and RpHsp70-2 are the primary genes involved in the response to both heat and pesticide stress.

Dichlorvos exposure results in large scale disruption of energy metabolism in the liver of the zebrafish, Danio rerio

Background

Exposure to dichlorvos (DDVP), an organophosphorus pesticide, is known to result in neurotoxicity as well as other metabolic perturbations. However, the molecular causes of DDVP toxicity are poorly understood, especially in cells other than neurons and muscle cells. To obtain a better understanding of the process of non-neuronal DDVP toxicity, we exposed zebrafish to different concentrations of DDVP, and investigated the resulting changes in liver histology and gene transcription.

Results

Functional enrichment analysis of genes affected by DDVP exposure identified a number of processes involved in energy utilization and stress response in the liver. The abundance of transcripts for proteins involved in glucose metabolism was profoundly affected, suggesting that carbon flux might be diverted toward the pentose phosphate pathway to compensate for an elevated demand for energy and reducing equivalents for detoxification. Strikingly, many transcripts for molecules involved in β-oxidation and fatty acid synthesis were down-regulated. We found increases in message levels for molecules involved in reactive oxygen species responses as well as ubiquitination, proteasomal degradation, and autophagy.

To ensure that the effects of DDVP on energy metabolism were not simply a consequence of poor feeding because of neuromuscular impairment, we fasted fish for 29 or 50 h and analyzed liver gene expression in them. The patterns of gene expression for energy metabolism in fasted and DDVP-exposed fish were markedly different.

Conclusion

We observed coordinated changes in the expression of a large number of genes involved in energy metabolism and responses to oxidative stress. These results argue that an appreciable part of the effect of DDVP is on energy metabolism and is regulated at the message level. Although we observed some evidence of neuromuscular impairment in exposed fish that may have resulted in reduced feeding, the alterations in gene expression in exposed fish cannot readily be explained by nutrient deprivation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1941-2) contains supplementary material, which is available to authorized users.

Heat Shock Protein 70 Prevents Hyperoxia-Induced Disruption of Lung Endothelial Barrier via Caspase-Dependent and AIF-Dependent Pathways

Exposure of pulmonary artery endothelial cells (PAECs) to hyperoxia results in a compromise in endothelial monolayer integrity, an increase in caspase-3 activity, and nuclear translocation of apoptosis-inducing factor (AIF), a marker of caspase-independent apoptosis. In an endeavor to identify proteins involved in hyperoxic endothelial injury, we found that the protein expression of heat-shock protein 70 (Hsp70) was increased in hyperoxic PAECs. The hyperoxia-induced Hsp70 protein expression is from hspA1B gene. Neither inhibition nor overexpression of Hsp70 affected the first phase barrier disruption of endothelial monolayer. Nevertheless, inhibition of Hsp70 by using the Hsp70 inhibitor KNK437 or knock down Hsp70 using siRNA exaggerated and overexpression of Hsp70 prevented the second phase disruption of lung endothelial integrity. Moreover, inhibition of Hsp70 exacerbated and overexpression of Hsp70 prevented hyperoxia-induced apoptosis, caspase-3 activation, and increase in nuclear AIF protein level in PAECs. Furthermore, we found that Hsp70 interacted with AIF in the cytosol in hyperoxic PAECs. Inhibition of Hsp70/AIF association by KNK437 correlated with increased nuclear AIF level and apoptosis in KNK437-treated PAECs. Finally, the ROS scavenger NAC prevented the hyperoxia-induced increase in Hsp70 expression and reduced the interaction of Hsp70 with AIF in hyperoxic PAECs. Together, these data indicate that increased expression of Hsp70 plays a protective role against hyperoxia-induced lung endothelial barrier disruption through caspase-dependent and AIF-dependent apoptotic pathways. Association of Hsp70 with AIF prevents AIF nuclear translocation, contributing to the protective effect of Hsp70 on hyperoxia-induced endothelial apoptosis. The hyperoxia-induced increase in Hsp70 expression and Hsp70/AIF interaction is contributed to ROS formation.

Efficacy of methuselah gene mutation toward tolerance of dichlorvos exposure in Drosophila melanogaster

Adverse reports on the exposure of organisms to dichlorvos (DDVP; an organophosphate insecticide) necessitate studies of organismal resistance/tolerance by way of pharmacological or genetic means. In the context of genetic modulation, a mutation in methuselah (mth; encodes a class II G-protein-coupled receptor (GPCR)) is reported to extend (~35%) the life span of Drosophila melanogaster and enhance their resistance to oxidative stress induced by paraquat exposure (short term, high level). A lack of studies on organismal tolerance of DDVP by genetic modulation prompted us to examine the protective efficacy of mth mutation in exposed Drosophila. Flies were exposed to 1.5 and 15.0 ng/ml DDVP for 12-48 h to examine oxidative stress endpoints and chemical resistance. After prolonged exposure of flies to DDVP, antioxidant enzyme activities, oxidative stress, glutathione content, and locomotor performance were assayed at various days (0, 10, 20, 30, 40, 50) of age. Flies with the mth mutation (mth(1)) showed improved chemical resistance and rescued redox impairment after acute DDVP exposure. Exposed mth(1) flies exhibited improved life span along with enhanced antioxidant enzyme activities and rescued oxidative perturbations and locomotor insufficiency up to middle age (~20 days) over similarly exposed w(1118) flies. However, at late (≥30 days) age, these benefits were undermined. Further, similarly exposed mth-knockdown flies showed effects similar to those observed in mth(1) flies. This study provides evidence of tolerance in organisms carrying a mth mutation against prolonged DDVP exposure and further warrants examination of similar class II GPCR signaling facets toward better organismal health.

Induction of hsp70, hsp90, and catalase activity in planarian Dugesia japonica exposed to cadmium

The hsp70 and hsp90 expression patterns and catalase (CAT) activity in the freshwater planaria Dugesia japonica exposed to cadmium (Cd) under laboratory conditions were investigated. Planaria were exposed to a range of Cd concentrations (0–150 μg Cd/L) for 24 h. The expression levels of hsp70 and hsp90 were determined by relative quantitative real-time polymerase chain reaction. Within the overall dose range in the experiment, the expression level of hsp70 and the activity of CAT in D. japonica were altered significantly. Hsp70 was induced in D. japonica upon Cd exposure concentrations as low as 9.375 μg Cd/L. No significant effect on the expression level of hsp90 was observed. Our findings demonstrated that stress gene hsp70, but not hsp90, was responsive to Cd contamination in D. japonica. CAT activity was significantly induced at concentrations of 18.75, 37.5, and 75 μg Cd/L after 24-h exposure. We recommend that the use of hsp70 as a biomarker should be complemented by evidence of changes in other parameters, such as CAT activity, in D. japonica.

Molecular cloning and sequence analysis of heat shock proteins 70 (HSP70) and 90 (HSP90) and their expression analysis when exposed to benzo(a)pyrene in the clam Ruditapes philippinarum

HSP70 and HSP90 are the most important heat shock proteins (HSPs), which play the key roles in the cell as molecular chaperones and may involve in metabolic detoxification. The present research has obtained full-length cDNAs of genes HSP70 and HSP90 from the clam Ruditapes philippinarum and studied the transcriptional responses of the two genes when exposed to benzo(a)pyrene (BaP). The full-length RpHSP70 cDNA was 2336bp containing a 5' untranslated region (UTR) of 51bp, a 3' UTR of 335bp and an open reading frame (ORF) of 1950bp encoding 650 amino acid residues. The full-length RpHSP90 cDNA was 2839bp containing a 107-bp 5' UTR, a 554-bp 3' UTR and a 2178-bp ORF encoding 726 amino acid residues. The deduced amino acid sequences of RpHSP70 and RpHSP90 shared the highest identity with the sequences of Paphia undulata, and the phylogenetic trees showed that the evolutions of RpHSP70 and RpHSP90 were almost in accord with the evolution of species. The RpHSP70 and RpHSP90 mRNA expressions were detected in all tested tissues in the adult clams (digestive gland, gill, adductor muscle and mantle) and the highest mRNA expression level was observed in the digestive gland compared to other tissues. Quantitative real-time RT-PCR analysis revealed that mRNA expression levels of the clam RpHSP70, RpHSP90 and other xenobiotic metabolizing enzymes (XMEs) (AhR, DD, GST, GPx) in the digestive gland of R. philippinarum were induced by benzo(a)pyrene (BaP) and the absolute expression levels of these genes showed a temporal and dose-dependent response. The results suggested that RpHSP70 and RpHSP90 were involved in the metabolic detoxification of BaP in the clam R. philippinarum.

Synergistic effects of toxic elements on heat shock proteins

Heat shock proteins show remarkable variations in their expression levels under a variety of toxic conditions. A research span expanded over five decades has revealed their molecular characterization, gene regulation, expression patterns, vast similarity in diverse groups, and broad range of functional capabilities. Their functions include protection and tolerance against cytotoxic conditions through their molecular chaperoning activity, maintaining cytoskeleton stability, and assisting in cell signaling. However, their role as biomarkers for monitoring the environmental risk assessment is controversial due to a number of conflicting, validating, and nonvalidating reports. The current knowledge regarding the interpretation of HSPs expression levels has been discussed in the present review. The candidature of heat shock proteins as biomarkers of toxicity is thus far unreliable due to synergistic effects of toxicants and other environmental factors. The adoption of heat shock proteins as "suit of biomarkers in a set of organisms" requires further investigation.

Induction of oxidative stress and related transcriptional effects of sodium fluoride in female zebrafish liver

The effects of sodium fluoride (NaF) exposure on the induction of oxidative stress and alteration of gene expressions were studied in the liver of female zebrafish (Danio rerio). Zebrafish, exposed to 15 ppm NaF for 30 and 90 days, exhibited liver histopathology including hyperplassia, cytoplasmic degeneration and nuclear fragmentation. Antioxidant enzyme (GST, CAT, SOD) activities in the liver altered significantly; the mRNA levels for the genes encoding antioxidant proteins, such as Gst, Cat, Cu/ZnSod, MnSod as well as Gpx were significantly upregulated at 30 days NaF-treatment along with the stress marker gene Hsp70 and phase I detoxyfying gene Cyp1A1. Moreover, the transcriptional pattern of Ucp2, related to mitochondrial reactive oxygen species (ROS) production, upregulated significantly at 90 days NaF-treatment. ROS generation was evidensed by fluoroscence microscopy. The results of this study will help to understand the mechanism of oxidative stress induced by NaF in fish.

Evaluation of the toxic potential of graphene copper nanocomposite (GCNC) in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9.)

Graphene, a two-dimensional carbon sheet with single-atom thickness, have attracted the scientific world for its potential applications in various field including the biomedical areas. In the present study the graphene copper nanocomposite (GCNC) was synthesized, characterized and evaluated for its toxic potential on third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9) . The synthesized GCNC was analyzed by X-ray diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), atomic force microscopy (AFM), and fourier transform infrared spectroscopy (FTIR). The GCNC in 0.1% DMSO was sonicated for 10 min and the final concentration of 0.033, 0.099, 0.199 and 3.996 µg/µl of diet were established. The third instar larvae were allowed to feed on it separately for 24 and 48 hrs. The hsp70 expression was measured by O-nitrophenyl-β-D-galactopyranoside assay, tissue damage by trypan blue exclusion test and β-galactosidase activity was monitored by in situ histochemical β-galactosidase staining. Oxidative stress was monitored by performing lipid peroxidation assay and total protein estimation. Ethidium bromide/acridine orange staining was performed on midgut cells for apoptotic index and the comet assay was performed for the DNA damage. The results of the present study showed that the exposure of 0.199 and 3.996 µg/µl of GCNC were toxic for 24 hr of exposure and for 48 hr of exposure: 0.099, 0.199 and 3.996 µg/µl of GCNC was toxic. The dose of 0.033 µg/µl of GCNC showed no toxic effects on its exposure to the third instar larvae for 24 hr as well as 48 hrs. This dose can be considered as No Observed Adverse Effect Level (NOAEL).

Syntheses and antitumor activities of N'1,N'3-dialkyl-N'1,N'3-di-(alkylcarbonothioyl) malonohydrazide: the discovery of elesclomol

A series of N'(1),N'(3)-dialkyl-N'(1),N'(3)-di(alkylcarbonothioyl) malonohydrazides have been designed and synthesized as anticancer agents by targeting oxidative stress and Hsp70 induction. Structure-activity relationship (SAR) studies lead to the discovery of STA-4783 (elesclomol), a novel small molecule that has been evaluated in a number of clinical trials as an anticancer agent in combination with Taxol.

Effects of malachite green on the mRNA expression of detoxification-related genes in Nile tilapia (Oreochromis niloticus) and other major Chinese freshwater fishes

The use of malachite green (MG) in fish farming is prohibited in China due to its potentially toxicological and carcinogenic nature, but it is still illegally used in some places. The aim of this study was to investigate the time and concentration-dependent responses of xenobiotic metabolizing and detoxification-related genes in diverse fishes exposed to MG both in vivo and in vitro. Experimental fish were administered to two exposure groups of malachite green (MG) (0.10 and 0.50 mg L⁻¹) for 8 h. The hepatocytes isolated from Nile tilapia were incubated with MG (0.5, 1.0, and 2.0 mg L⁻¹) for 8 and 24 h, respectively. In vivo, exposure to 0.10 and 0.50 mg L⁻¹ MG for 8 h caused significant changes of the detoxification-related genes on the mRNA expression levels. Low-concentration (0.10 mg L⁻¹) level of MG induced significant increase on the mRNA expression level of GSTR gene in Nile tilapia and other fishes. The mRNA expression of grass carp UCP2 was significantly induced when exposed to 0.5 mg L⁻¹ MG. However, the mRNA expression levels of GSTA, CYP1A, and GPX were inhibited significantly by 0.5 mg L⁻¹ MG in Nile tilapia, grass carp, and Taiwan snakehead. In vitro, the significant increase of mRNA expression of these genes was detected after exposure to 0.5 mg L⁻¹ MG (UCP2), and 1.0 mg L⁻¹ MG (CYP1A1, GSTA, GSTR, and UCP2). The induction of hepatic CYP1A1, GSTA, GSTR, and UCP2 in response to MG suggested a potential role of fish CYP1A1, GSTA, GSTR, and UCP2 in MG metabolism.

Biomarkers in marine mussels, Mytilus galloprovincialis, exposed to environmentally relevant levels of the pesticides, chlorpyrifos and penoxsulam

The present study examines the influence of environmentally relevant concentrations of two pesticides, chlorpyrifos and penoxsulam on mussel physiological status. For this reason, lysosomal membrane stability (LMS), reactive oxygen species (ROS), DNA damage, protein carbonylation (PCC) and antioxidant capacity (TAC) in hemaolymph and hemocytes of the mussels was measured. Mussels were exposed to a range of concentrations of the pesticides chlorpyrifos and penoxsulam and the response of animals to the destabilization of lysosomal membrane in hemocytes (LMS) was studied. Subsequently, the half maximal effective concentration (EC50) for both pesticides was calculated. The animals were subsequently exposed for 0, 1, 3, 5, 7, 15 and 30 days to 10 times less concentration than EC50 of each pesticide (0.05 μg/l) and changes in LMS, ROS, DNA damage, protein carbonylation and antioxidant capacity of mussels was evaluated. Our results showed a significant change in the response of mussels for all parameters tested after 30 days exposure, in relation to the controls. The pesticides at the environmental concentrations used induced changes to the animal physiology through causing oxidative stress and lysosomal abnormalities and their usage in the agriculture demands great care. In addition, the results show that ROS, DNA damage, protein carbonylation and antioxidant capacity could constitute, after further investigation, reliable biomarkers for the evaluation of pollution or other environmental stressors.

Induction of Heat Shock Proteins and Antioxidant Enzymes in 2,3,7,8-TCDD-Induced Hepatotoxicity in Rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is an environmental toxicant with a polyhalogenated aromatic hydrocarbon structure and is one of the most toxic man-made chemicals. Exposure to 2,3,7,8-TCDD induces reproductive toxicity, immunotoxicity, and hepatotoxicity. In this study, we evaluated how 2,3,7,8-TCDD-induced hepatotoxicity affect the expression of heat shock proteins and antioxidant enzymes using the real-time polymerase chain reaction (PCR) in rat. 2,3,7,8-TCDD increased heat shock protein (Hsp27, α-B-crystallin, Mortalin, Hsp105, and Hsp90s) and antioxidant enzymes (SOD-3, GST and catalase) expression after a 1 day exposure in livers of rats, whereas heat shock protein (α-B-crystallin, Hsp90, and GRP78) and antioxidant enzymes (SOD-1, SOD-3, catalase, GST, and GPXs) expression decreased on day 2 and then slowly recovered back to control levels on day 8. These results suggest that heat shock proteins and antioxidant enzymes were induced as protective mechanisms against 2,3,7,8-TCDD induced hepatotoxicity, and that prolonged exposure depressed their levels, which recovered to control levels due to reduced 2,3,7,8-TCDD induced hepatotoxicity.

Cellular internalization and stress response of ingested amorphous silica nanoparticles in the midgut of Drosophila melanogaster

BACKGROUND

Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (<30nm) in the midgut of Drosophila melanogaster (Oregon R(+)) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles.

METHODS

Third instar larvae of D. melanogaster were exposed orally to 1-100μg/mL of aSNPs for 12-36h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints.

RESULTS

A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration.

CONCLUSION

aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death.

GENERAL SIGNIFICANCE

Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health.

DNA methylation alterations in response to pesticide exposure in vitro

Although pesticides are subject to extensive carcinogenicity testing before regulatory approval, pesticide exposure has repeatedly been associated with various cancers. This suggests that pesticides may cause cancer via nonmutagenicity mechanisms. The present study provides evidence to support the hypothesis that pesticide-induced cancer may be mediated in part by epigenetic mechanisms. We examined whether exposure to seven commonly used pesticides (i.e., fonofos, parathion, terbufos, chlorpyrifos, diazinon, malathion, and phorate) induces DNA methylation alterations in vitro. We conducted genome-wide DNA methylation analyses on DNA samples obtained from the human hematopoietic K562 cell line exposed to ethanol (control) and several organophosphate pesticides (OPs) using the Illumina Infinium HumanMethylation27 BeadChip. Bayesian-adjusted t-tests were used to identify differentially methylated gene promoter CpG sites. In this report, we present our results on three pesticides (fonofos, parathion, and terbufos) that clustered together based on principle component analysis and hierarchical clustering. These three pesticides induced similar methylation changes in the promoter regions of 712 genes, while also exhibiting their own OP-specific methylation alterations. Functional analysis of methylation changes specific to each OP, or common to all three OPs, revealed that differential methylation was associated with numerous genes that are involved in carcinogenesis-related processes. Our results provide experimental evidence that pesticides may modify gene promoter DNA methylation levels, suggesting that epigenetic mechanisms may contribute to pesticide-induced carcinogenesis. Further studies in other cell types and human samples are required, as well as determining the impact of these methylation changes on gene expression.

Effects of organic contaminants in reactive oxygen species, protein carbonylation and DNA damage on digestive gland and haemolymph of land snails

The present study focused on early responses of land snails Eobania vermiculata to organic environmental contaminants, by investigating the use of a newly-established method for the measurement of protein carbonylation as a new biomarker of terrestrial pollution, as well as by measuring the ROS production and the DNA damage. Land snails were exposed to different concentrations of chlorpyrifos, parathion-methyl or PAHs in vivo or in vitro in the laboratory. The susceptibility of exposed snails was increased in relation to oxidative stress induced by contaminants tested. A statistically significant increase in ROS production, protein carbonylation and DNA damage was revealed in the snails treated with pollutants, compared to the untreated ones. The results indicated the effectiveness of measuring ROS production and DNA damage and reinforce the application of the present ELISA method in organic terrestrial pollution biomonitoring studies.

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.

Chlorpyrifos induces apoptosis and DNA damage in Drosophila through generation of reactive oxygen species

The present study investigated the apoptosis and DNA damage inducing potential of chlorpyrifos (CP) in Drosophila melanogaster. Third instar larvae of Drosophila were treated with different concentrations of CP (0.015-15.0 microg/L) for 2-48 h. Reactive oxygen species (ROS) generation, oxidative stress markers, DNA damage and apoptotic cell death end points were measured in them. A significant increase in DNA damage was concomitant with apoptotic mode of cell death in 15.0 microg/L CP-treated organisms for 24 and 48 h. Depolarization in mitochondrial membrane potential and increased casapase-3 and caspase-9 activities in these organisms indicated both as potential targets of CP. A significant positive correlation was observed among ROS generation, apoptosis and DNA damage. The study suggests that (i) ROS may be involved in inducing apoptosis and DNA damage in the CP-exposed larvae of Drosophila and (ii) D. melanogaster may be used as an alternative in vivo animal model for xenobiotics hazard assessment.

Polyglutamine gene function and dysfunction in the ageing brain

The coordinated regulation of gene expression and protein interactions determines how mammalian nervous systems develop and retain function and plasticity over extended periods of time such as a human life span. By studying mutations that occur in a group of genes associated with chronic neurodegeneration, the polyglutamine (polyQ) disorders, it has emerged that CAG/glutamine stretches play important roles in transcriptional regulation and protein-protein interactions. However, it is still unclear what the many structural and functional roles of CAG and other low-complexity sequences in eukaryotic genomes are, despite being the most commonly shared peptide fragments in such proteomes. In this review we examine the function of genes responsible for at least 10 polyglutamine disorders in relation to the nervous system and how expansion mutations lead to neuronal dysfunction, by particularly focusing on Huntington's disease (HD). We argue that the molecular and cellular pathways that turn out to be dysfunctional during such diseases, as a consequence of a CAG expansion, are also involved in the ageing of the central nervous system. These are pathways that control protein degradation systems (including molecular chaperones), axonal transport, redox-homeostasis and bioenergetics. CAG expansion mutations confer novel properties on proteins that lead to a slow-progressing neuronal pathology and cell death similar to that found in other age-related conditions such as Alzheimer's and Parkinson's diseases.