The possible protective role of selenium on the visual cortex of adult albino rat on exposure to potassium dichromate

The visual cortex is very important in mammals for processing of visual information. Exposure to heavy metals such as potassium dichromate poses serious health threat to human beings. The aim of this work is to study the effect of potassium dichromate on the visual cortex of adult albino rat and also to identify the possibility of selenium as protective agent against toxicity of potassium dichromate. A total number of 40 adult albino rats weighting (200-250) gm were used. They divided into four groups: control group, potassium dichromate received group, potassium dichromate and selenium received group and selenium received group. The rats received treatment for 6 weeks. After 6 weeks, they were sacrificed. The present study showed that potassium dichromate causes degeneration of granular neurons in layer IV and pyramidal neurons in layer V. Morphometric results revealed statistically significant decrease in the number of granule and pyramidal cells in potassium dichromate received group as compared with control group. Most of degenerative changes are improved by selenium.

Appraisal of the Pre-Emptive Effect of Lactoferrin Against Chromium-Induced Testicular Toxicity in Male Rats

Lactoferrin (LCF), a potent naturally occurring antioxidant, is a crucial component in preventing potassium dichromate (PDC) toxicity. The goal of the current work was to study the potential efficacy of LCF in preventing PDC(CrVI)-induced testicular toxicity and oxidative injury in rats. Six groups of male rats of Wistar stain were randomly categorized into: group 1, which served as the control; group 2 and 3 received LCF (200 and 300 mg/kg orally, respectively); group 4 received PDC (2 mg/kg i.p.); group 5 and 6 pretreated with LCF, followed by PDC as in group 4 with 90 min apart for 28 days. PDC-intoxicated rats showed a significantly altered spermogram with abnormal sperm morphology. PDC significantly upregulated serum FSH and downregulated testosterone levels. Additionally, PDC decreased the levels of testicular key antioxidant biomarkers (catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH)) with elevated lipid peroxidation marker (TBARS) and testicular chromium content. Moreover, it upregulated testicular proinflammatory cytokines, IL-1, IL-6, IL-10, and TNF-α, induced histopathological changes in testes with significant immunohistochemical expression of FasL and moderate expression of Nrf2. Pretreatment with LCF significantly mitigated PDC-induced testicular toxicity by enhancing spermogram, improving hormonal levels, restoring testicular oxidant/antioxidant balance, and decreasing testicular IL-1, IL6, IL-10, and TNFα levels, and amending both FasL and Nrf2 immunohistochemical-expression. Additionally, LCF improved testicular histopathological picture and spermatogenesis. Our results highlight the importance of LCF as a superior protective modulator of PDC-induced testicular injury.

Nephroprotective Efficacy of Selenium and Zinc Against Potassium Dichromate-Induced Renal Toxicity in Pregnant Wistar Albino Rats

Hexavalent chromium (CrVI) compounds are potent toxicants commonly used in numerous industries. Thus, potential toxic effects and health hazards are of high relevance. Selenium (Se) and zinc (Zn) are known for their antioxidant and chemoprotective properties. However, little is known about their protective effects against CrVI-induced renal damage during pregnancy. In this context, the present study aimed to investigate the protective efficacy of these two essential elements against potassium dichromate-induced nephrotoxicity in pregnant Wistar Albino rats. Female rats were divided into control and four treated groups of six each receiving subcutaneously on the 3rd day of pregnancy, K₂Cr₂O₇ (10 mg/kg, s.c. single dose) alone, or in association with Se (0.3 mg/kg, s.c. single dose), ZnCl₂ (20 mg/kg, s.c. single dose) or both of them simultaneously. The nephrotoxic effects were monitored by the evaluation of plasma renal parameters, oxidative stress biomarkers, DNA damage, and renal Cr content. The obtained results showed that K₂Cr₂O₇ disturbed renal biochemical markers, induced oxidative stress and DNA fragmentation in kidney tissues, and altered renal histoarchitecture. The co-administration of Se and/or ZnCl₂ has exhibited pronounced chelative, antioxidant, and genoprotective effects against K₂Cr₂O₇-induced renal damage and attenuated partially the histopathological alterations. These results suggest that Se and Zn can be used as efficient nephroprotective agents against K₂Cr₂O₇-induced toxicity in pregnant Wistar Albino rats.

Nephroprotective role of Echinacea purpurea against potassium dichromate-induced oxidative stress, inflammation, and apoptosis in rats

Environmental and occupational exposure to chromium compounds, especially hexavalent chromium [Cr(VI)], is widely recognized as a potential nephrotoxic in humans and animals. Its toxicity is associated with the overproduction of free radicals, which induces oxidative damage. Echinacea purpurea (L.) Moench is an herbaceous perennial plant rich in phenolic components and frequently used for its medicinal benefits. The current work evaluated the effectiveness of E. purpurea (EP) against oxidative stress and nephrotoxicity induced by potassium dichromate in male rats. Male Wistar rats were divided into four groups: control, E. purpurea (EP; 50 mg/kg; once daily for 3 weeks), hexavalent chromium (Cr(VI); 15 mg/kg; single intraperitoneal dose), and EP + Cr(VI) where rats were pretreated with EP for 3 weeks before receiving CrVI, respectively. Results revealed that rats exposed to Cr(VI) showed a significant increase in PC, TBARS, and H₂ O₂ , kidney function biomarkers (Urea, creatinine, and uric acid), lactate dehydrogenase activity (LDH), TNF-α, IL-18, nuclear factor kappa B (NFκB), and IGF-1 (Insulin-like growth factor-1) levels as well as a considerable decline in metallothionein (MT), glutathione (GSH) content, enzymatic antioxidants (SOD, CAT, GPx, GR, and GST), alkaline phosphatase (ALP) activities, and protein content. Cr(VI) induced apoptosis in kidney tissues as revealed by upregulation of Bax and caspase 3 and downregulation of Bcl-2. Furthermore, EP treatment ameliorated the Cr(VI)-induced histopathological and ultrastructure variations of kidney tissue, which was confirmed by the biochemical and molecular data. It is clear from the results of this study that EP exerts nephroprotective effects by improving the redox state, suppressing inflammatory reaction and cell apoptosis as well as ameliorating the performance of kidney tissue architecture, which is eventually reflected by the improvement of kidney function in rats.

Luteolin mitigates potassium dichromate-induced nephrotoxicity, cardiotoxicity and genotoxicity through modulation of Kim-1/Nrf2 signaling pathways

Environmental and occupational exposure to chromium compounds has become potential aetiologic agent for kidney disease with excessive generation of free radicals, apoptosis, and inflammatory. These pathophysiologic mechanisms of potassium dichromate (K₂ Cr₂ O₇ ) have been well correlated with nephrotoxicity and cardiotoxicity. The cardioprotective and nephroprotective effects of Luteolin, a known potent antioxidant were evaluated in this study with 40 healthy rats in four experimental groups: Group A (normal saline), Groups B (30 mg/kg K₂ Cr₂ O₇ ), Group C (Luteolin 100 mg/kg and K₂ Cr₂ O₇ 30 mg/kg), and Group D (Luteolin 200 mg/kg and K₂ Cr₂ O₇ 30 mg/kg), respectively. Markers of antioxidant defense system, oxidative stress, blood pressure and micronucleated polychromatic erythrocytes (MnPEs), immunohistochemistry of Kidney, injury molecule (Kim-1), nuclear factor erythroid 2-related factor 2 (Nrf2), and cardiac troponin I were determined. Administration of K₂ Cr₂ O₇ increased blood pressure parameters in systolic, diastolic and mean arterial blood pressures, markers of oxidative stress, and frequency of micronucleated polychromatic erythrocytes, together with reduction in serum nitric oxide level. Renal Kim-1 and cardiac troponin I expressions were higher, but lower expressions of renal and cardiac Nrf2 were recorded with immunohistochemical analysis. Pre-treatment with Luteolin restored blood pressure parameters, with concomitant reduction in oxidative stress indicators, augmented antioxidant mechanisms and serum Nitric oxide level, lowered the expressions of Kim-1, cardiac troponin I and up-regulated of both cardiac and renal Nrf2, reduced the frequency of micronucleated polychromatic erythrocytes. Taken together, this study therefore demonstrates the cardioprotective, nephro protective and antigenotoxic effects of Luteolin through antioxidantive and radical scavenging mechanisms.

Single and combined toxicity of amino-functionalized polystyrene nanoparticles with potassium dichromate and copper sulfate on brine shrimp Artemia franciscana larvae

The increasing use and disposal of plastics has become a persistent problem in the marine environment, calling for studies that refer to realistic scenarios to understand their effects on biota. Particularly, the understanding about the effects of co-exposure with nanoplastic particles and metals on aquatic organisms is still limited. The present work aimed to investigate the acute toxicity of amino-functionalized polystyrene nanoparticles (PS-NH₂; 50 nm) as proxy for nanoplastics on brine shrimp Artemia franciscana larvae under different culture conditions and at different stages of development, as well as the combined effect with two reference toxicants - potassium dichromate (K₂Cr₂O₇) and copper sulfate (CuSO₄). Nauplii (instar II or III larval stages) were exposed to different concentrations of PS-NH₂ (0.005 to 5 μg mL^-1) for up to 48 h, with or without agitation in order to mimic a more realistic environmental scenario. Larval mobility and PS-NH₂ accumulation were monitored under microscopy. PS-NH₂ alone showed toxicity only at the highest concentration tested (5 μg mL^-1) regardless the incubation method used (61.2 + 3.1% and 65.0 + 4.5% with and without agitation, respectively). Moreover, instar III stage was the most sensitive to PS-NH₂ exposure (38.2% immobility in 24 h of exposure; 5 μg mL^-1). Evidence of PS-NH₂ retention in the gastrointestinal tract in a concentration- and time-dependent manner was also obtained. Mixtures of PS-NH₂ (0.005 and 5 μg mL^-1) with different concentrations of K₂Cr₂O₇ increased the immobilization rate of the larvae after 48 h of exposure, when compared to the K₂Cr₂O₇ alone. Similar results were observed for CuSO₄ in the co-exposure conditions at different concentrations. However, exposing nauplii to a mixture of PS-NH₂ (0.005 μg mL^-1) and CuSO₄ decreased immobilization rate, in comparison to the group exposed to CuSO₄ alone. The present work highlights the potential risk posed by nanoplastics to zooplanktonic species through their interaction with other toxicants.

Rosmarinus officinalis essential oil modulates renal toxicity and oxidative stress induced by potassium dichromate in rats

BACKGROUND

Chromium hexavalent (CrVI) is known as a toxic contaminant that induced oxidative stress and nephrotoxicity in humans and animals. Rosmarinus officinalis is a perennial herb rich in biologically active constituents that have powerful antioxidant properties. So, the current work evaluated the effectiveness of Rosmarinus officinalis essential oil (REO) against alterations induced by potassium dichromate in the kidney of male rats.

METHODS

GC-MS analysis, in vitro total phenol contents, and DPPH scavenging activity of REO were estimated. Thirty-five Wistar male rats were categorized into 5 groups. The first group was the control, the second one was orally administered rosemary essential oil (REO; 0.5 mL/kg BW), the third group was injected intraperitoneally with hexavalent chromium (CrVI; 2 mg/kg BW) for 14 days, the fourth group used as the protective group (REO was administrated 30 min before i.p. injection of CrVI) and the fifth group applied as the therapeutic group (rats injected with CrVI 30 min followed by oral administration of REO), respectively.

RESULTS

Twenty-nine components were detected with high total phenolic contents and high DPPH scavenging activity. Results revealed that CrVI- intoxicated rats showed a valuable increase in oxidative stress profile (TBARS and H₂O₂) and a notable decline in glutathione (GSH), total protein content, and enzymatic antioxidants (SOD, CAT, GPx, and GST). Furthermore, serum kidney functions biomarkers (urea, creatinine, and uric acid) were increased significantly. Also, the administration of CrVI showed histological and immunohistochemical (PCNA-ir) changes in rat kidney tissue. Otherwise, administration of REO pre or post-treatment with CrVI significantly restored most of the biochemical parameters in addition to improvement in kidney tissue architecture. Moreover, individual intake with REO exhibited an amendment in oxidative stress markers.

CONCLUSION

Conclusively, REO had a potential antioxidant capacity in ameliorating K₂Cr₂O₇-induced nephrotoxicity, especially in the protection group.

Protective effects of selenium and zinc against potassium dichromate-induced thyroid disruption, oxidative stress, and DNA damage in pregnant Wistar rats

Hexavalent chromium (CrVI) is an environmental pollutant and an endocrine-disrupting metal. Se and Zn are essential trace elements, known to play a crucial role in thyroid homeostasis. However, there is a lack of data reporting thyrotoxicity during gestation. In this study, we investigated the protective effects of selenium and zinc against potassium dichromate-induced thyrotoxicity in pregnant Wistar rats. Thirty pregnant Wistar rats were divided into control and four treated groups receiving subcutaneously (s.c) on the 3rd day of pregnancy, K2Cr2O7 (10 mg/kg, s.c) alone, or in association with Se (0.3 mg/kg, s.c), ZnCl2 (20 mg/kg, s.c), or both of them simultaneously. The hormonal profile, oxidative stress biomarkers, DNA damage, and histological modifications were evaluated. Our main findings showed that K2Cr2O7 promoted hypothyroidism, oxidative stress, genotoxicity, and histological alterations in the thyroid gland. The co-treatment with Se or ZnCl2 has mitigated K2Cr2O7-induced thyrotoxicity in pregnant Wistar rats by exhibiting antioxidant and genoprotective effects. However, the combined co-treatment of both of them was less thyroprotective, and therefore, further investigations on the synergetic interaction of Se and Zn against CrVI toxicity using different doses and exposure routes are required.

Prenatal exposure to hexavalent chromium disrupts testicular steroidogenic pathway in peripubertal F1 rats

We have reported sub-fertility in F1 progeny rats with gestational exposure to hexavalent chromium [Cr(VI)], which had disrupted Sertoli cell (SC) structure and function, and decreased testosterone (T). However, the underlying mechanism for reduced T remains to be understood. We tested the hypothesis "transient prenatal exposure to Cr(VI) affects testicular steroidogenesis by altering hormone receptors and steroidogenic enzyme proteins in Leydig cells (LCs)." Pregnant Wistar rats were given drinking water containing 50, 100, and 200 mg/L potassium dichromate during gestational days 9-14, encompassing fetal differentiation window of the testis from the bipotential gonad. F1 male rats were euthanized on postnatal day 60 (peripubertal rats with adult-type LCs alone). Results showed that prenatal exposure to Cr(VI): (i) increased accumulation of Cr(III) in the testis of F1 rats; (ii) increased serum levels of luteinizing and follicle stimulating hormones (LH and FSH), and 17β estradiol, and decreased prolactin and T; (iii) decreased steroidogenic acute regulatory protein, cytochrome P450 11A1, cytochrome P450 17A1, 3β- and 17β-hydroxysteroid dehydrogenases, cytochrome P450 aromatase and 5α reductase proteins, (iv) decreased specific activities of 3β and 17β hydroxysteroid dehydrogenases; (v) decreased receptors of LH, androgen and estrogen in LCs; (vi) decreased 5α reductase and receptor proteins of FSH, androgen, and estrogen in SCs. The current study concludes that prenatal exposure to Cr(VI) disrupts testicular steroidogenesis in F1 progeny by repressing hormone receptors and key proteins of the steroidogenic pathway in LCs and SCs.

Hexavalent chromium induces renal apoptosis and autophagy via disordering the balance of mitochondrial dynamics in rats

The use of hexavalent chromium (Cr(VI)) in many industrial processes has resulted in serious environmental pollution problems. Cr(VI) causes organ toxicity in animals after ingestion or inhalation. However, the exact mechanism by which Cr(VI) produces kidney damage remains elusive. Herein, we investigated whether Cr(VI)-induced kidney damage is related to the disorder of mitochondrial dynamics. In this study, 28 male rats were divided into four groups and intraperitoneally injected with 0, 2, 4, and 6 mg/kg body weight potassium dichromate for 5 weeks. Experiment included analysis of renal histopathology and ultrastructure, determination of biochemical indicators, and measurement of related protein content. The results showed that Cr(VI) induced kidney injury through promotion of oxidative stress, apoptosis, and disorder of mitochondrial dynamics in a dose-dependent manner. The protein levels of the silent information regulator two ortholog 1 (Sirt1), peroxisome proliferation-activated receptor-g coactivator-1a (PGC-1a), and autophagy-related proteins were significantly decreased after Cr(VI) exposure. These findings suggest that Cr(VI) leads to the disorder of mitochondrial dynamics by inhibiting the Sirt1/PGC-1a pathway, which leads to renal apoptosis and autophagy in rats.

Modulatory effect of Turnera diffusa against testicular toxicity induced by fenitrothion and/or hexavalent chromium in rats

Oxidative stress and increased production of reactive oxygen species have been implicated in pesticides and heavy metals toxicity. The objective of this study was to investigate the efficacy of Turnera diffusa Willd (damiana) on counteracting fenitrothion (FNT) and/or potassium dichromate (CrVI)-induced testicular toxicity and oxidative injury in rats. FNT and/or CrVI intoxicated animals revealed a significant increase in thiobarbituric acid reactive substances and hydrogen peroxide levels. While, reduced glutathione and protein content, as well as antioxidant enzymes, phosphatases, and aminotransferases activities, were significantly decreased. In addition, significant changes in testosterone and follicle-stimulating hormone levels were detected. Furthermore, histological and immunohistochemical alterations were observed in rat testes and this supported the observed biochemical changes. On the other hand, rats treated with damiana alone decreased lipid peroxidation and increased most of the examined parameters. Moreover, damiana pretreatment to FNT and/or CrVI-intoxicated rats showed significant improvement in lipid peroxidation, enzyme activities, and hormones as compared with their respective treated groups. Conclusively, rats treated with both FNT and/or CrVI showed pronounced hazardous effect especially in their combination group in addition, Turnera diffusa had a potential protective role against FNT and/or CrVI induced testicular toxicity.

Probiotic mitigates the toxic effects of potassium dichromate in a preclinical study: a randomized controlled trial

BACKGROUND

The present study aimed to evaluate the nutritional, physiological and biochemical effects of dietary supplementation of an association of probiotic bacteria in rats intoxicated with chromium (VI). Ninety-six male rats, recently weaned, were randomly divided into eight groups (n = 12): Control, DK12, DK24 and DK36 (0, 0.12, 0.24 and 0.36 g kg^-1 of K₂ Cr₂ O₇ incorporated in the basal feed, respectively) and groups Prob, DK12 + Prob, DK24 + Prob and DK36 + Prob received a progressive dose of 0, 0.12, 0.24 and 0.36 g kg^-1 of K₂ Cr₂ O₇ incorporated in the basal feed and supplemented with 0.02 g kg^-1 of an association of probiotic bacteria (Lactobacillus acidophilus, Enterococcus faecium, Bifidobacterium thermophilum and Bifidobacterium longum).

RESULTS

After 90 days, we observed significant (P < 0.05) and dose-dependent alterations from incorporation of increasing doses of chromium (VI) related to nutritional, physiological and biochemical parameters. These changes were attenuated (P < 0.05) with probiotic supplementation.

CONCLUSION

Supplementation with probiotics in the diet beneficially modified the nutritional and physiological parameters, as well as hepatic, renal, glycemic and lipid profiles, of animals intoxicated with increasing doses of K₂ Cr₂ O₇ . © 2018 Society of Chemical Industry.

Mutagenic and histopathological effects of hexavalent chromium in tadpoles of Lithobates catesbeianus (Shaw, 1802) (Anura, Ranidae)

The potential mutagenic and histopathological effects of the hexavalent chromium were investigated in Lithobates catesbeianus tadpoles. These larvae (GS 25-31) were exposed to three nominal concentrations of potassium dichromate (4, 12, and 36 mg L^-1) and 5 mg L^-1 of Cyclophosphamide as a positive control (PC), for 24 h. A negative control (NC) was also added to the experiment. Our results showed that, in general, the micronuclei (MN) were less frequent than the erythrocyte nuclear abnormalities (ENA); there was a significant difference in the frequency of MN between the NC and all treated groups (p < 0.05) in a concentration-dependent curve, in addition the PC did not differ from the chromium treatments. Also, only PC and the group treated with potassium dichromate at 36 mg L^-1 showed significantly higher frequencies of ENA than NC (p < 0.05). Chromium treatments promoted cell retention in the Sub-G1 phase and a decrease of cells in the S and G2/M phases indicating inhibition of the cell cycle. All treatments with chromium led to liver and kidney histopathological lesions, especially with 36 mg L^-1 (greater number of lesions). In conclusion, hexavalent chromium was mutagenic to L. catesbeianus tadpoles and its toxic effects also resulted in anti-mitotic activity, besides inducing histopathological alterations in liver and kidney. Amphibians have been proven to be useful bioindicators, and we suggest that tadpoles of different species can be used to represent the environmental impacts in aquatic ecosystems.

An Evaluation of Boar Spermatozoa as a Biosensor for the Detection of Sublethal and Lethal Toxicity

A novel, objective, and rapid computed motility inhibition (CMI) assay was developed to identify and assess sublethal injury in toxin-exposed boar spermatozoa and compared with a subjective visual motility inhibition (VMI) assay. The CMI values were calculated from digital micrographic videos using a custom MATLAB^® script by contrasting the motility index values of each experiment with those of the background and control experiments. Following a comparison of the CMI and VMI assays results, it was determined that their agreement depended on the shape of the dose-response curve. Toxins that exhibited a steep slope were indicative of good agreement between the assays. Those depicted by a gentle decline in the slope of the dose-response curve, the CMI assay were shown to be two times more sensitive than the VMI assay. The CMI assay was highly sensitive to the inhibition of mitochondrial function and glucose transport activity by sublethal doses of toxins and to disruption of cellular cation homeostasis by carrier ionophoric toxins, when compared to the cytotoxicity and lethal toxicity assays (i.e., that evaluated the inhibition of cell proliferation in somatic cell lines (FL, PK-15, and MNA cells)) and disruption to spermatozoa membrane integrity. The CMI assay recognized subtle sublethal toxicity changes in metabolism, manifested as a decrease in boar spermatozoa motility. Thus, it was feasible to effectively compare the objectively-measured numerical values for motility inhibition using the CMI assay against those reflecting lethal damage in the spermatozoa cells and somatic cell lines using a cytotoxicity assay.

Ameliorative effects of nano-elemental selenium against hexavalent chromium-induced apoptosis in broiler liver

The current study examined the ameliorative effects of nano-elemental selenium (Nano-Se) against chromium-VI (K₂Cr₂O₇)-induced apoptosis in chickens. The expression of apoptosis-related genes was evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. A total of 60, one-day-old broiler chickens allotted to six equal groups, i.e., control group (standard diet), Cr(VI)-exposed group (K₂Cr₂O₇ via drinking water), Nano-Se group (Nano-Se at 0.5 mg/kg via diet), protection group (K₂Cr₂O₇ + Nano-Se), cure group (K₂Cr₂O₇ for initial 2 weeks and then Nano-Se), and prevention group (opposite to the cure group) and were detected by the activities of pro-apoptosis (Bax, Caspase-3) and anti-apoptosis (Bcl-2) genes expression at day 35 of the experiment. Intense apoptosis was observed in liver tissues of chickens exposed to K₂Cr₂O₇. The Nano-Se supplementation caused a significant decrease (P < 0.01) in the mRNA expression levels of Bax and Caspase-3 genes, while significantly elevated (P < 0.05) mRNA expression level of Bcl-2 gene was observed in Nano-Se experimental groups as compare to control and Cr(VI)-exposed group. The results quantified by the RT-qPCR were further confirmed by the western blot analysis. Altogether, these results suggest anti-apoptotic effects of Nano-Se in the chicken liver, which is interesting for further study. The present findings suggested that Nano-Se has protective effects against K₂Cr₂O₇-induced apoptosis in broilers liver and can serve a key role as a protective agent against apoptosis.

Ascorbic acid protects male rat brain from oral potassium dichromate-induced oxdative DNA damage and apoptotic changes: the expression patterns of caspase-3, P 53, Bax, and Bcl-2 genes

Our study designed to study the potential of potassium dichromate (K₂Cr₂O₇) oral exposure to induce damage in male rat brain and to compare the possible protective role of vitamin C (VC) either pre and/or concurrent supply against (K₂Cr₂O₇) induced changes. Thirty male rats were divided into five groups. First control group received distilled water (C), second received 120 mg/kg b.wt (VC), third received 25 mg/kg b.wt K₂Cr₂O₇ (Cr), fourth group received VC together with K₂Cr₂O₇ by the same former doses (VC + Cr), and the fifth group received the same oral doses of VC 2 weeks prior to and along with K₂Cr₂O₇ for 6 weeks (VC + Cr pro/co treated). The obtained results revealed that K₂Cr₂O₇ induced a significant decrease in cholinergic activity, glutathione reductase GR activity, reduced glutathione content GSH and ATP levels. Furthermore, K₂Cr₂O₇ induced a significant increase in oxidative DNA damage indicated by 8-hydroxy 2'-deoxyguanosine (8OH2'dG) and formation of apoptotic DNA ladders, significant increase in malondialdehyde (MDA), protein carbonyl, and lactate dehydrogenase enzyme. Increased mRNA expression of pro-apoptotic genes, including caspase-3, p53, and Bax, unlike Bcl-2 expression, was decreased. K₂Cr₂O₇ increased caspase-3 and decreased Bcl-2 immuno-labeling. VC supply noticeably ameliorates K₂Cr₂O₇-induced changes which were more significantly in VC pro and concurrent supplement rather than VC concurrent supply only. Finally, it is concluded that K₂Cr₂O₇ oral administration induced oxidative apoptotic changes in rat brain and confirms the usefulness of VC pre and concurrent supply for the amelioration of K₂Cr₂O₇-induced events more significantly than VC concurrent supply only.

Transgenerational Effects of Toxicants: An Extension of the Daphnia 21-day Chronic Assay?

The assessment of transgenerational effects should be incorporated in standard chronic toxicity protocols for the sake of a realistic extrapolation of contaminant effects to the population level. We propose a simple add-on to the standard 21-day chronic Daphnia magna assay, allowing the assessment of the reproductive performance of the offspring (F₁ generation) born from the first clutch of the parental (F₀) generation. The extended generational assay was performed simultaneously with the standard reproduction assay. With this design, we evaluated the lethal, reproductive, and transgenerational effects of four widespread and extensively used substances: a biocide/anti-fouling (copper sulphate), an industrial oxidizing agent (potassium dichromate), a pharmaceutical (paracetamol), and a quaternary ammonium compound (benzalkonium chloride). Benzalkonium chloride was the most toxic in terms of lethality, whereas paracetamol, copper sulphate, and potassium dichromate caused deleterious effects in the reproductive performance of exposed D. magna. Adverse effects in the fitness of the daughter (F₁) generation were observed in the case of maternal exposure to paracetamol and copper sulphate, although they were not very pronounced. These findings highlight the usefulness of our approach and reinforce the view-shared by other authors-of the need for a generalised formal assessment of the transgenerational effects of pollutants.

Copper oxide nanoparticles and copper sulphate act as antigenotoxic agents in drosophila melanogaster

The biological reactivity of metal and metal oxide nanomaterials is attributed to their redox properties, which would explain their pro- or anti-cancer properties depending on exposure circumstances. In this sense, copper oxide nanoparticles (CuONP) have been proposed as a potential anti-tumoral agent. The aim of this study was to assess if CuONP can exert antigenotoxic effects using Drosophila melanogaster as an in vivo model. Genotoxicity was induced by two well-known genotoxic compounds, namely potassium dichromate (PD) and ethyl methanesulfonate (EMS). The wing-spot assay and the comet assay were used as biomarkers of genotoxic effects. In addition, changes in the expression of Ogg1 and Sod genes were determined. The effects of CuONP cotreatment were compared with those induced by copper sulfate (CS), an agent releasing copper ions. Using the wing-spot assay, CuONP and CS were not able to reduce the genotoxic effects of EMS exposure, but had the ability to decrease the effects induced by PD, reducing the frequency of mutant twin-spots that arise from mitotic recombination. In addition, CuONP and CS were able to reduce the DNA damage induced by PD as determined by the comet assay. In general, similar qualitative antigenotoxic effects were obtained with both copper compounds. The antigenotoxic effects of environmentally relevant and non-toxic doses of CuONP and CS may be explained by their ability to partially restore the expression levels of the repair gene Ogg1 and the antioxidant gene Cu,ZnSod, both of which are inhibited by PD treatment. Environ. Mol. Mutagen. 58:46-55, 2017. © 2016 Wiley Periodicals, Inc.

Gallic acid attenuates chromium-induced thyroid dysfunction by modulating antioxidant status and inflammatory cytokines

Hexavalent chromium-mediated oxidative stress causes severe organ damage. The present study was designed to investigate the possible thyroprotective effect and underlying mechanisms of gallic acid using rat model of potassium dichromate-induced thyroid dysfunction. Forty adult male albino rats were divided into 4 groups: control, gallic acid (20mg GA/kg b. wt), potassium dichromate (2mg PD/kg b. wt) and the fourth group was co-treated with PD and GA. PD-injection resulted in decreased serum free triiodothyonine (FT3), free thyroxine (FT4) with concomitant significant increase in thyroid stimulating hormone (TSH) levels. Superoxide dismutase (SOD), glutathione-S-transferase (GST) activities and their respective mRNA expression and reduced glutathione (GSH) content were significantly decreased. Thyroid nitrosative stress marker (NO level and iNOS mRNA and protein expression) and pro-inflammatory cytokines (serum TNF-α, IL-6 and thyroid TNF-α, IL-6 and COX-2 gene and protein expression levels) were disturbed. Histopathological changes revealed distended, collapsed and degenerated follicles with vacuolated cytoplasm. GA co-treatment attenuated pro-inflammatory cytokines, the thyroid expression of iNOS, TNF-α, IL-6 and COX-2, decreased the elevated lipid peroxidation biomarkers and NO level and up- regulated SOD and GST mRNA expression levels. In conclusion, GA has shown strong modulatory potential against PD-induced inflammation and oxidative stress in albino rats.

Elevated tissue Cr levels, increased plasma oxidative markers, and global hypomethylation of blood DNA in male Sprague-Dawley rats exposed to potassium dichromate in drinking water

Hexavalent chromium [Cr (VI)] is prevalent in ground water in some areas, but evidence on the toxic effects of Cr (VI) via ingestion through drinking water remains insufficient. The aims of our study were to investigate the toxic effects of Cr (VI) through oral water ingestion on oxidative stress and DNA methylation. Thirty-two Sprague-Dawley rats were randomly divided into four groups, and exposed to porassium dichromate (K2 Cr2 O7 ; 0, 30, 100, and 300 mg/L) in drinking water for 4 weeks. Mean body weight gain, mean water consumption, clinical chemistry determinations, and oxidative stress levels in plasma were measured. Global DNA methylation changes and DNA methylation status at the promoter of p16 gene were also detected. After 4 weeks, mild anemic effects and increased plasma malondialdehyde (MDA) levels occurred in rats exposed to 100 mg/L or 300 mg/L of Cr (VI). Plasma glutathione peroxidase (GSH-Px) activity decreased in all exposed groups. Global DNA methylation levels were reduced in 100 mg/L and 300 mg/L exposure groups. However, DNA methylation status at the promoter of P16 gene remained unchanged in all K2 Cr2 O7- treated groups. The correlation analysis indicated that increased MDA levels were closely correlated to global DNA hypomethylation. Our results indicated that oral ingestion of Cr (VI) through drinking water caused not only oxidative stress in plasma, but also global DNA hypomethylation in blood cells from male rats, and a good correlation was found between increased MDA levels and reduced global DNA methylation. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1080-1090, 2016.

Renoprotective Effect of Lactoferrin against Chromium-Induced Acute Kidney Injury in Rats: Involvement of IL-18 and IGF-1 Inhibition

Hexavalent chromium (CrVI) is a heavy metal widely used in more than 50 industries. Nephrotoxicity is a major adverse effect of chromium poisoning. The present study investigated the potential renoprotective effect of lactoferrin (Lf) against potassium dichromate (PDC)-induced acute kidney injury (AKI) in rats. Beside, because previous studies suggest that interlukin-18 (IL-18) and insulin-like growth factor-1 (IGF-1) play important roles in promoting kidney damage, the present work aimed to evaluate the involvement of these two cytokines in PDC model of AKI and in the potential renoprotective effect of lactoferrin. Adult male albino Wistar rats were pretreated with Lf (200mg/kg/day, p.o.) or (300mg/kg/day, p.o.); the doses that are usually used in the experiment studies, for 14 days followed by a single dose of PDC (15mg/kg, s.c.). PDC caused significant increase in serum urea, creatinine, and total protein levels. This was accompanied with decreased renal glutathione content, and increased renal malondialdehyde, IL-18, IL-4, nuclear factor kappa B (NFκB), IGF-1, and the phosphorylated form of forkhead box protein O1 (FoxO1) levels. Moreover, normal expression IFN-γ mRNA and enhanced expression of TNF-α mRNA was demonstrated in renal tissues. Histopathological investigations provoked deleterious changes in the renal tissues. Tubular epithelial hyperplasia and apoptosis were demonstrated immunohistochemically by positive proliferating cell nuclear antigen (PCNA), Bax, and Caspase-3 expression, respectively. Pretreatment of rats with Lf in both doses significantly corrected all previously mentioned PDC-induced changes with no significant difference between both doses. In conclusion, the findings of the present study demonstrated the involvement of oxidative stress, inflammatory reactions, tubular hyperplasia and apoptosis in PDC-induced AKI. It suggested a role of IL-18 through stimulation of IL-4-induced inflammatory pathway, and IGF-1 through triggering FoxO1-induced cell proliferation. Moreover, the study revealed that Lf protected the kidney against Cr-induced AKI in rats and significantly showed antioxidant, anti-inflammatory, and anti-proliferative properties with down-regulation of IL-18 and IGF-1.

Cr (VI) induced oxidative stress and toxicity in cultured cerebellar granule neurons at different stages of development and protective effect of Rosmarinic acid

Chromium (Cr) is a widespread metal ion in the workplace, industrial effluent, and water. The toxicity of chromium (VI) on various organs including the liver, kidneys, and lung were studied, but little is known about neurotoxicity. In this study, neurotoxic effects of Cr (VI) have been investigated by cultured cerebellar granule neurons (CGNs). Immature and mature neurons were exposed to different concentrations of potassium dichromate for 24 h and cytotoxicity was measured by MTT assay. In addition, immature neurons were exposed for 5 days as regards cytotoxic effect in development stages. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and the protective effect of Rosmarinic acid on mature and immature neurons exposed to potassium dichromate, were measured. Furthermore, lipid peroxidation, glutathione peroxidase (GPx), and acetylcholinesterase activity in mature neurons were assessed following exposure to potassium dichromate. The results indicate that toxicity of Cr (VI) dependent on maturation steps. Cr (VI) was less toxic for immature neurons. Also, Cr (VI) induced MMP reduction and ROS production in both immature and mature neurons. In Cr (VI) treated neurons, increased lipid peroxidation and GPx activity but not acetylcholinesterase activity was observed. Interestingly, Rosmarinic acid, as a natural antioxidant, could protect mature but not immature neurons against Cr (VI) induced toxicity. Our findings revealed vulnerability of mature neurons to Cr (VI) induced toxicity and oxidative stress.

Is UV radiation changing the toxicity of compounds to zebrafish embryos?

At ecosystems level, environmental parameters such as temperature, pH, dissolved oxygen concentration and intensity of UV radiation (UVR) have an important role on the efficiency of organisms' physiological and behavioral performances and consequently on the capacity of response to contaminants. Insignificant alterations of these parameters may compromise this response. In addition, these parameters can additionally alter chemical compounds by inducing their degradation, producing thereafter other metabolites. Understanding the combined effects of chemicals and environmental parameters is absolutely necessary for an adequate prediction of risk in aquatic environments. According to this scenario, this work aims at studying the combined toxicity of UVR and three xenobiotics: the biocide triclosan (TCS), the metal chromium (as potassium dichromate, PD) and the fungicide prochloraz (PCZ). To achieve this goal zebrafish (Danio rerio) embryos (3h post fertilization (hpf)) were exposed to several concentrations of each chemical combined with different UV intensities; mortality and eggs were recorded every 24h for the all test duration (96 h). Results showed different response patterns depending on the toxicant, stress levels and duration of exposure. The combination of UVR and TCS indicated a dose ratio deviation where synergism was observed when UVR was the dominant stressor (day 2). The combination of UVR and PD presented a dose level dependency at day 3 indicating antagonism at low stress levels, changing with time where at day 4, a dose ratio deviation showed statistically that synergism occurred at higher PD concentrations. Finally, UVR combined with PCZ indicated a dose ratio at day 3 and dose level deviation at day 4 of exposure, suggesting a synergistic response when PCZ is the dominant stressor in the combination. The obtained results in this study highlighted the importance of taking into account the possible interaction of stressors and time of exposure to better predict environmental risk.

Mutagenic Effects of Potassium Dichromate as Evaluated by Means of Animal and Plant Bioindicators

BACKGROUND

Chromium typically occurs in two oxidation states in the natural environment, Cr(3+) [Cr(III)] and Cr(6+) [Cr(VI)]. Out of the two chromium species, Cr(VI) is the most mobile, labile and toxic. Hexavalent chromium [Cr(VI)] compounds are classified by the International Agency for Research on Cancer (IARC) as carcinogenic agents to humans. The main source of release of chromium in aquatic ecosystems is related to the industrial application of this metal in metallurgies, tanneries, and in the manufacturing of paints and dyes. The ecotoxicology of Cr(VI) is linked to its environmental persistence and the ability to induce adverse effects in biological systems. In the present study, we evaluated mutagenic effects of Cr(VI) in animal and plant bioindicators.

MATERIALS AND METHODS

We evaluated primary DNA damage and frequencies of micronuclei (MN) and morphological nuclear abnormalities (NA) in erythrocytes in peripheral blood of the fish Oreochromis niloticus exposed to potassium dichromate at 12 mg l(-1). The genotoxicity and cytotoxicity of Cr(VI) in the onion (Allium cepa) test were also assessed.

RESULTS

The comet assay showed a significant increase of tailed nucleoids in the erythrocytes of fish treated with K2Cr2O7; MN frequency was also increased in the treatments; cytotoxicity of a low concentration of potassium dichromate, however, was not confirmed.

CONCLUSION

The combination of both systems - animal and plant - is adequate and advantageous for mutagenicity evaluation. The findings indicate that at the concentration tested, the chromium compound is a clastogenic as well as an aneugenic.

Oxidative Stress Markers and Histological Analysis in Diverse Organs from Rats Treated with a Hepatotoxic Dose of Cr(VI): Effect of Curcumin

Hexavalent chromium [Cr(VI)] compounds are extremely toxic and carcinogenic. Despite the vast quantity of reports about Cr(VI) toxicity, the information regarding its effects when it is intraperitoneally (i.p.) administered is still limited. In contrast, it has been shown that curcumin prevents hepatotoxicity induced by a single intraperitoneal injection of 15 mg/kg body weight (b.w.) of potassium dichromate (K2Cr2O7). This study aims to evaluate oxidative stress markers, the activity of antioxidant enzymes, and the potential histological injury in brain, heart, lung, kidney, spleen, pancreas, stomach, and intestine from rats treated with a hepatotoxic dose of K2Cr2O7 (15 mg/kg b.w.), and the effect of curcumin pretreatment. Rats were divided into four groups: control, curcumin, K2Cr2O7, and curcumin+K2Cr2O7. At the end of the treatment, plasma and ascites fluid were collected and target organs were dissected out for biochemical and histological analysis. K2Cr2O7 induced hepatotoxicity but failed to induce in all the other studied organs either oxidative or histological injury, since levels of malondialdehyde (MDA), glutathione (GSH), and the activity of superoxide dismutase (SOD), catalase (CAT), and related GSH enzymes were unchanged. As expected, curcumin was safe. Lack of K2Cr2O7-induced toxicity in those target organs could be due to the following: (1) route of administration, (2) absorption through the portal circulation, (3) lower dose than needed, (4) short time of exposure, or (5) repeated doses are required to produce damage. Thus, the intraperitoneal injection of 15 mg/kg of K2Cr2O7, that is able to induce hepatotoxicity, was unable to induce histological and oxidative damage in other target organs.

[Changes in lung injury and oxidative stress of Sprague-Dawley rats after single intratracheal instillation of potassium dichromate]

OBJECTIVE

To investigate the changes in lung injury and oxidative stress of sprague-Dawleyy (SD) rats at different times after single intratracheal instillation of potassium dichromate.

METHODS

A total of 50 healthy male SD rats were randomly divided into control group and potassium dichromate group. The potassium dichromate group and the control group received 3 ml/kg intratracheal instillation of K2Cr2O7 (1.5 mg/kg) and normal saline, respectively. Rats in these two groups were sacrificed in batches at 1, 3, 7, 14, and 28 days after exposure. The changes in the following indices were observed and analyzed: body weight, lung coefficient, alkaline phosphatase (AKP) in bronchoalveolar lavage fluid, glutathione peroxidase (GSH-Px) in lung homogenate, and reduced glutathione (GSH) in serum.

RESULTS

The rats in the potassium dichromate group had significantly decreased body weight on day 1 and day 3 after exposure than the control group (P<0.05). Lung coefficient increased significantly on day 7 (P<0.05) and kept increasing until the end of the experiment. The potassium dichromate group had a significantly higher activity of AKP than the control group on day 1 and day 7 after exposure (P<0.05). However, the potassium dichromate group had a significantly lower activity of GSH-Px than the control group on day 1 and day 3 after exposure (P<0.05). And the potassium dichromate group had a lower activity of reduced GSH than the control group on day 3 and day 7 after exposure.

CONCLUSION

Single intratracheal instillation of 1.5 mg/kg potassium dichromate could result in lung inflammatory injury. of SD rats, and the injury is more severe on day 7 after exposure. Body injury is related to antioxidant activity, and the antioxidant.activity cannot recover completely on day 28 after exposure.

Developmental toxicity, acute toxicity and mutagenicity testing in freshwater snails Biomphalaria glabrata (Mollusca: Gastropoda) exposed to chromium and water samples

A protocol combining acute toxicity, developmental toxicity and mutagenicity analysis in freshwater snail Biomphalaria glabrata for application in ecotoxicological studies is described. For acute toxicity testing, LC50 and EC50 values were determined; dominant lethal mutations induction was the endpoint for mutagenicity analysis. Reference toxicant potassium dichromate (K2Cr2O7) was used to characterize B. glabrata sensitivity for toxicity and cyclophosphamide to mutagenicity testing purposes. Compared to other relevant freshwater species, B. glabrata showed high sensitivity: the lowest EC50 value was obtained with embryos at veliger stage (5.76mg/L). To assess the model applicability for environmental studies, influent and effluent water samples from a wastewater treatment plant were evaluated. Gastropod sensitivity was assessed in comparison to the standardized bioassay with Daphnia similis exposed to the same water samples. Sampling sites identified as toxic to daphnids were also detected by snails, showing a qualitatively similar sensitivity suggesting that B. glabrata is a suitable test species for freshwater monitoring. Holding procedures and protocols implemented for toxicity and developmental bioassays showed to be in compliance with international standards for intra-laboratory precision. Thereby, we are proposing this system for application in ecotoxicological studies.

Effects of temperature - heavy metal interactions, antioxidant enzyme activity and gene expression in wheat (Triticum aestivum L.) seedlings

In this study, the effect of heat and chromium (Cr) heavy metal interactions on wheat seedlings (Triticum aestivum L. cv. Ç-1252 and Gun91) was investigated by measuring total chlorophyll and carotenoid levels, catalase (CAT) and ascorbate peroxidase (APX) antioxidant enzyme activities, and MYB73, ERF1 and TaSRG gene expression. Examination of pigment levels demonstrated a decrease in total chlorophyll in both species of wheat under combined heat and heavy metal stress, while the carotenoid levels showed a slight increase. APX activity increased in both species in response to heavy metal stress, but the increase in APX activity in the Gun91 seedlings was higher than that in the Ç-1252 seedlings. CAT activity increased in Gun91 seedlings but decreased in Ç-1252 seedlings. These results showed that Gun91 seedling had higher resistance to Cr and Cr + heat stresses than the Ç-1252 seedling. The quantitative molecular analyses implied that the higher resistance was related to the overexpression of TaMYB73, TaERF1 and TaSRG transcription factors. The increase in the expression levels of these transcription factors was profound under combined Cr and heat stress. This study suggests that TaMYB73, TaERF1 and TaSRG transcription factors regulate Cr and heat stress responsive genes in wheat.

Toxicity testing with the benthic diatom Navicula libonensis (Schoeman 1970): procedure optimisation and assessment of the species sensitivity to reference chemicals

Periphytic communities are good indicators of river quality due to their general sensitivity to several pollutants. The primary objective of this study was to develop and optimize an ecotoxicological testing methodology using the freshwater benthic diatom Navicula libonensis. This species was selected due to its ubiquity and suitability for use under laboratory conditions. In the most suitable test medium (Chu10) the diatom demonstrated comparable sensitivity to potassium dichromate and 3,5-dichlorophenol using growth rate as the reference parameter, with median effect concentrations (ErC50) in the same order of magnitude (0.119 and 0.799 mg L(-1)) respectively. Yield-based estimates did not confirm this pattern and potassium dichromate was one order of magnitude more toxic than 3,5-dichlorophenol. The sensitivity of N. libonensis to the reference chemicals was higher than that published in the literature for several standard planktonic microalgae. This advantage, as well as the ability to grow the species in the laboratory, supports further efforts towards the standardisation of a toxicity testing protocol. In addition, the functional role of benthic diatoms in lotic ecosystems justifies their inclusion in risk assessment test batteries to better cover an environmental compartment that has so far been neglected.

Acute spill-mimicking exposure effect of hexavalent chromium on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch)

Acute exposure to hexavalent chromium (as 10, 20, and 40 mg/L potassium dichromate for 96 h) adversely affected the pituitary-ovarian axis of a teleost Channa punctatus. The toxic impact of metal exposure on fish ovary was revealed in the form of increased percentage of atretic follicles, significantly in 20 mg/L and 40 mg/L exposure groups. The follicular atresia mostly occurred in vitellogenic (stage II and stage III) oocytes. Reduction of serum level of 17β-estradiol was also significant in 20 mg/L and 40 mg/L exposure groups. The increase of LH-immunointensity of pituitary gonadotrophs (LHβ-immunoreactive cells) and their hypertrophy was evident, significantly in fish of 40 mg/L exposed group. Thus, the present acute metal spill-mimicking laboratory study clearly demonstrated that short-term exposures to high doses of hexavalent chromium may disrupt reproduction of the fish and affect their population.

Acute toxicity by water containing hexavalent or trivalent chromium in native Brazilian fish, Piaractus mesopotamicus: anatomopathological alterations and mortality

This study evaluated the toxicity of hexavalent and trivalent compounds of chromium to the pacu, Piaractus mesopotamicus, in acute exposures of 96 h through mortality and histopathological responses. Hexavalent potassium dichromate was more toxic than trivalent compounds of chromium chloride, chromium oxide and chromium carbochelate. Sufficient mortalities occurred only with potassium dichromate to yield an LC50 value at 124.2 mg L(-1). Hexavalent chromium caused reversible and irreversible lesions, which may affect organ functionality. Histopathological evaluation showed that trivalent chromium caused lesions of lower severity. Pacu subjected to different concentrations of chromium carbochelate showed no histopathological changes in the kidneys, liver, skin and gills, being similar to those of the control fish. Among the three sources of Cr(3+), only chromium chloride at 200 mg L(-1) resulted in mortality, which reached 100 % within the first 18 h. These findings confirm that trivalent chromium, when administered within recommended levels, may be used safely in aquaculture.

[Comparative analysis of ionizing radiation and xenobiotics influence on spermatogenic epithelium and dominant lethal mutations output in laboratory animals]

The study covered state of spermatogenic epithelium and dominant lethal mutations output in mice of BALB/c and CBA lines, subjected to total gamma-irradiation and in Wistar rats after intraperitoneal injection of potassium bichromate (K2Cr2,O7) in small and sublethal doses. The BALB/c line mice under low irradiation dose (0.25 Gy) demonstrated stimulation effect on spermatogenic epithelium, but in the CBA line mice no such effect was seen. Both mice lines under irradiation of 0.25 Gy and 1.0 Gy demonstrated increase in pathologic sperm counts and in percentage ofpreimplantation embryonal death. In rats, injection of potassium bichromate in doses of 0.028 mg/kg and 2.8 mg/kg increased number of micronuclear spermatids, larger pathologic sperm counts and percentage of postimplantation deaths. Thus, lower general embryonal deaths under radiation exposure is due to preimplantation embryonal deaths, under exposure to 6-valent chromium--is due to postimplantation losses.

A single-parameter logistic equation for fitting concentration-response curves from standard acute ecotoxicity assays

A set of 69 concentration-response curves from 5 acute ecotoxicity assays was fitted with a 2-parameter logistic equation. High correlation between values of regression parameters suggested similar slopes of the curves. This enabled derivation of the empirical single-parameter logistic equation with the sole median effective concentration (EC50) parameter. Such an equation might be useful in the evaluation of lower-quality (preliminary) experimental data and for the reduction of the number of test organisms and of testing costs.

Transcriptomic analysis provides insights on hexavalent chromium induced DNA double strand breaks and their possible repair in midgut cells of Drosophila melanogaster larvae

Hexavalent chromium [Cr(VI)] is a well known mutagen and carcinogen. Since genomic instability due to generation of double strand breaks (DSBs) is causally linked to carcinogenesis, we tested a hypothesis that Cr(VI) causes in vivo generation of DSBs and elicits DNA damage response. We fed repair proficient Drosophila melanogaster (Oregon R(+)) larvae Cr(VI) (20.0μg/ml) mixed food for 24 and 48h and observed a significant (p<0.05) induction of DSBs in their midgut cells after 48h using neutral Comet assay. Global gene expression profiling in Cr(VI)-exposed Oregon R(+) larvae unveiled mis-regulation of DSBs responsive repair genes both after 24 and 48h. In vivo generation of DSBs in exposed Drosophila was confirmed by an increased pH2Av immunostaining along with the activation of cell cycle regulation genes. Analysis of mis-regulated genes grouped under DSB response by GOEAST indicated the participation of non-homologous end joining (NHEJ) DSB repair pathway. We selected two strains, one mutant (ligIV) and another ku80-RNAi (knockdown of ku80), whose functions are essentially linked to NHEJ-DSB repair pathway. As a proof of principle, we compared the DSBs generation in larvae of these two strains with that of repair proficient Oregon R(+). Along with this, DSBs generation in spn-A and okr [essential genes in homologous recombination repair (HR) pathway] mutants was also tested for the possible involvement of HR-DSB repair. A significantly increased DSBs generation in the exposed ku80-RNAi and ligIV (mutant) larvae because of impaired repair, concomitant with an insignificant DSBs generation in okr and spn-A mutant larvae indicates an active participation of NHEJ repair pathway. The study, first of its kind to our knowledge, while providing evidences for in vivo generation of DSBs in Cr(VI) exposed Drosophila larvae, assumes significance for its relevance to higher organisms due to causal link between DSB generation and Cr(VI)-induced carcinogenesis.

Use of the microalgae Thalassiosira weissflogii to assess water toxicity in the Suape industrial-port complex of Pernambuco, Brazil

Microalgae are among the organisms that are most frequently recommended to assess water toxicity levels. They provide qualitative and quantitative population changes and have become important in environmental monitoring. The aim of the present study was to assess the sensitivity of the microalgae Thalassiosira weissflogii to water toxicity in the Suape industrial-port complex, and to potassium dichromate in the months of July, September and November of 2010 and January and September of 2011, as well as to compare the microalgae results to those obtained in tests with the sea urchin Lytechinus variegatus. The chronic toxicity tests with both species followed standardized methods. Once the exposure period was completed, the population increase of the algae was assessed using cell density and growth rate data and the percentage of L. variegatus pluteus larvae revealing normal and aberrant development was determined. The algal growth and percentage of pluteus results demonstrated that toxicity in the studied area varied according to the month. The present study confirmed that the best timeframe to conclude tests with the microalgae T. weissflogii was 72 h. The microalgae cell density results after 72 h were sufficient to assess the toxicity of surface water samples and were more sensible than the growth rates. The microalgae T. weissflogii was a sensitive test-organism for seawater toxicity.

EPR detection of paramagnetic chromium in liver of fish (Anguilla anguilla) treated with dichromate(VI) and associated oxidative stress responses-contribution to elucidation of toxicity mechanisms

The impact of chromium (Cr) on fish health has been the subject of numerous investigations, establishing a wide spectrum of toxicity, attributed particularly to the hexavalent form [Cr(VI)]. However, reports on the simultaneous assessment of Cr toxicity in fish and its toxico-kinetics, namely involving metal speciation, are scarce. Therefore, keeping in view the understanding of the mechanisms of Cr(VI) toxicity, this work intended to detect the formation of paramagnetic Cr species in liver of Anguilla anguilla following short-term dichromate(VI) intraperitoneal treatment (up to 180 min), assessing simultaneously the pro-oxidant properties. The formation of Cr(V) and Cr(III) was examined by electron paramagnetic resonance (EPR), as an innovative approach in the context of fish toxicology, and related with the levels of total Cr. Cr(V) was successfully detected and quantified by EPR spectrometry, showing a transient occurrence, mostly between 15 and 90 min post-injection, with a peak at 30 min. The limitations of EPR methodology towards the detection and quantification of Cr(III) were confirmed. Although Cr(VI) exposure induced the antioxidant system in the eel's liver, the oxidative deterioration of lipids was not prevented. Overall, the results suggested that Cr(V), as a short-lived species, did not appear to be directly and primarily responsible for the cellular damaging effects observed, since stress responses persisted up to the end of exposure regardless Cr(V) drastic decay. Though further research is needed, ROS mediated pathways (suggested by superoxide dismutase and catalase activity induction) and formation of Cr(III) complexes emerged as the most plausible mechanisms involved in Cr(VI) toxicity.

Protective effect of ginger against toxicity induced by chromate in rats

The evaluation of the effect of ginger on the modulation of toxic effects induced by chromate is the objective of our study. 50 male rats Albinos Wistar were divided to five groups as follow: group I (T) is served as control, received a mineral water by gavage (per os); group II (G) received an experimental diet with 2% of ginger; group III (Cr) received an oral dose of potassium dichromate (15 mg/kg) and normal diet; group IV (CrG): received an oral dose of potassium dichromate (15 mg/kg) and an experimental diet containing 2% ginger; and group V (Cr(+)G) received an oral dose of potassium dichromate (25 mg/kg) and an experimental diet with 2% of ginger. The results of this study indicate that the chromate provoked a haematoxic effect (anemia), nephrotoxic, hepatotoxic, and also a perturbation in lipids profile. In addition, chromate has a pro-oxidant effect, which was indicated by decrease of reduced glutathione (GSH) levels in different tissues. However, the administration of ginger revealed a reduction of the intensity of oxidative stress induced by the chromate resulting in the decrease of the majority of the previous parameters concentrations. In conclusion we demonstrated that ginger has potent antioxidants activity, revealed by the amelioration of chromate's toxic effects. We can say that ginger has a protective effect towards damages induced by the chromate.

Toxic effects of chromium (VI) by maternal ingestion on liver function of female rats and their suckling pups

Potassium dichromate (K(2)Cr(2)O(7)) is an environmental contaminant widely recognized as a carcinogen, mutagen, and teratogen toward humans and animals. This study investigated the effects of K(2)Cr(2)O(7) on the hepatic function of pregnant and lactating rats and their suckling pups. Experiments were carried out on female Wistar rats given 700 ppm of K(2)Cr(2)O(7) in their drinking water from the 14th day of pregnancy until day 14 after delivery. Hepatotoxicity was objectified by the significant increase in liver malondialdehyde content and a significant accumulation of chromium in this soft tissue. Moreover, exposure to K(2)Cr(2)O(7) induced a decrease of glutathione, nonprotein thiols, and vitamin C in the liver of mothers and their suckling pups. Alteration of the antioxidant system in the treated group was confirmed by the significant decline of antioxidant enzyme activities such as catalase, glutathione peroxidase, while liver superoxide dismutase activity increased in mothers and decreased in their offspring. It was found that K(2)Cr(2)O(7) induced liver damages as evidenced by the elevation of plasma aminotransferases, lactate dehydrogenase activities, and bilirubin levels. Impairment of the hepatic function corresponded histologically. Our investigation revealed hemorrhage, leukocytes infiltration cells, and necrosis, which were more pronounced in the hepatocytes of mothers than in those of their suckling pups.

Ecotoxicological risks associated with tannery effluent wastewater

The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K(2)Cr(2)O(7)) and chromium sulfate Cr(2)(SO(4))(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K(2)Cr(2)O(7)) and trivalent chromium Cr(2)(SO(4))(3) were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3). All the dilutions of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K(2)Cr(2)O(7) caused significantly more damage (P<0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K(2)Cr(2)O(7) treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K(2)Cr(2)O(7)) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural industry that can obliterate ecosystem surrounding the tanneries.

[Effect of chromium on the trace element homeostasis of biosubstrates in laboratory animals]

The authors studied the levels of chromium in potable water, snow, soil, and the hair of inhabitants in 3 territorial economic zones of the Orenburg region, water and snow prooxidant loads, and the impact of excessive potassium bichromate intake on the imbalance of some elements in the blood and spleen of laboratory animals. There was dissimilar distribution between the media in relation to the area, as well as a pronounced imbalance of trace elements in the biosubstrates of experimental animals.

Effect of sublethal hexavalent chromium exposure on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch)

Exposure to sublethal hexavalent chromium (as 2 and 4 mg L⁻¹ potassium dichromate for 1 and 2 months) during late preparatory to mid prespawning phase of annual reproductive cycle severely affected the pituitary-ovarian axis of a teleost Channa punctatus. Gonadosomatic index (GSI), ovarian histopathology, immunocytochemistry of the pituitary gonadotrophs (LHβ-immunoreactive cells), and serum 17β-estradiol level revealed distinct dose and duration-dependent effects. Gonadosomatic index was declined. Diameter of ovary as well as ovarian follicles was reduced along with a distinct variation in the percentage of follicles. The greater percentage of previtellogenic follicles (stage I) and decline in vitellogenic ones (stage II and stage III) compared to control indicated the arrest of follicular development. The percentage of atretic follicles was also increased indicating toxic impact of metal on ovary. Decreased serum level of ovarian steroid 17β-estradiol further indicated the same. Chromium interference of the pituitary was demonstrated as atrophy and less immunointensity of LH-immunoreactive gonadotrophs. Thus, the hexavalent chromium impaired the pituitary-ovarian axis affecting at the sites of both pituitary and ovary.

[The study of corrective role of plant--based drugs with antioxidant action in experimental intoxication with potassium dichromate]

The disturbance of the structure and function of pulmonary surfactant system (pSS) is an essential component of almost all pulmonary diseases. Chromium compounds have a damaging effect on the PSS, which contributes to the formation of nonspecific pulmonary diseases and a burden of chrome disease. The results showed that the oil of licorice (Glycyrrhiza glabra L) protects PSS in chronic chrome intoxication.

Effect of garlic (Allium sativum) on hematology and erythrocyte antioxidant defense system of albino rats exposed to heavy metals (nickel II & chromium VI)

Heavy metals are stable environmental contaminants, causing various alterations in target tissues. Garlic has some beneficial effect in preventing heavy metal induced various alteration. The objective was to investigate the possible protective role of fresh aqueous homogenate of garlic on hematology, erythrocyte antioxidant defense system in male albino rats treated with NiSO4 and K2Cr2O7. Rats were divided into six groups. Group I was untreated control. Group II was given aqueous homogenate of garlic (orally). Group III was administered with nickel sulfate (i.p). Group IV was given NiSO4 and garlic simultaneously. Group V was administered with K2Cr2O7 (i.p). Group VI were treated simultaneously with K2Cr2O7 and garlic. RBC, WBC, platelet count, PCV%, hemoglobin concentration decreased significantly and clotting time increased significantly after nickel treatment. After chromium treatment all the values decreased except clotting time. Increased malondialdehyde and glutathione level after nickel and chromium treatment was observed. Also erythrocyte superoxide dismutase, glutathione peroxidase and catalase activities significantly increased after nickel and chromium treatment. Simultaneous garlic supplementation exhibited protective role to combat nickel toxicity, whereas no such beneficial effects were observed for chromium (VI). Garlic may partially prevent nickel and chromium induced alteration but such ameliorated effects as an antioxidant is only restricted on nickel induced alteration.

Microcrustaceans escape behavior as an early bioindicator of copper, chromium and endosulfan toxicity

The purpose of this work was to experimentally analyze the impact of copper, chromium and a commercial pesticide with endosulfan on the escape behavior of two copepods (Notodiaptomus conifer, Argyrodiaptomus falcifer) and three cladocerans (Daphnia magna, Pseudosida variabilis and Ceriodaphnia dubia). The experimental assays were carried out using a novel hydraulic devise designed to mimic three-speed predator capture behavior. Two concentrations, one "high" and one "low", were employed and the exposure time was 15 (±5) minutes. With two exceptions, the species exposed to heavy metals manifested higher ability to escape than controls. Both concentrations of the pesticide reduced the escape ability of cladocerans but copepods responded, in general, in a similar manner as for heavy metals. The immediate apparent advantage of low and early toxic effects is discussed and the high sensitivity of the escape behavior suggests that it could be a complementary endpoint to be used in future ecotoxicological tests.

Exposure to sublethal chromium and endosulfan alter the diel vertical migration (DVM) in freshwater zooplankton crustaceans

Among zooplankton behaviors, diel migrations constitute one of the most effective predator avoidance strategy and confer metabolic and demographic advantages. We aim to examine whether sublethal concentrations of two widespread pollutants (a pesticide with endosulfan and chromium as potassium dichromate) alter the depth selection, vertical migration and grouping of five freshwater species: Argyrodiaptomus falcifer, Notodiaptomus conifer, Pseudosida variabilis, Ceriodaphnia dubia and Daphnia magna. In a series of experimental assays, performed with 150 cm length transparent tubes, we analyzed the ascents and descents movements through periods of 24 h. Among controls, the copepods showed a tendency to remain closest to the surface, however, N. conifer registered a downward movement of 18.14 cm between 06:00 and 12:00. The cladoceran P. variabilis occupied the deeper position (85 cm), C. dubia showed a tendency to hike to the surface at 06:00 (57.7 cm) descending to lower levels at 18:00. D. magna showed a constant movement of ascent between 00:00 and 18:00, making an average travel of 29.4 cm. When subjected to pollutants, these behaviors were altered. It is hypothesized that a reduction in swimming activity and disorientation would be the main cause of such alterations. The high sensitivity of this endpoint sugests it to be adecuate as a complement in future standard toxicity tests.

Anti-Candida activity and brine shrimp toxicity assay of Ganoderma boninense

OBJECTIVES

Ganoderma (G.) boninense is a white rot fungus, which can be found in the palm oil tree. Several studies have shown that G. boninense has antimicrobial and antagonistic properties. However, there is limited information reported on antifungal properties especially on Candida (C) albicans. Hence, this study was conducted to determine the anti-Candida activity of G. boninense against C albicans.

MATERIALS AND METHODS

Crude methanolic extracts of G. boninense was obtained by maceration method with 70% methanol. Anti-Candida test was carried out using disc diffusion assay, broth dilution method, time killing profile and brine shrimp toxicity assay.

RESULTS AND CONCLUSIONS

Anti-Candida activity indicated that the mean zone of inhibition was 12.5 +/- 0.6 mm. The MIC value for C. albicans found to be 3.125 mg/ml. The result from time-killing profile showed that the growth of C albicans was inhibited hence decreases its exponential phase. For brine shrimp toxicity assay, the LC50 value was 3.59 mg/ml which proved that the extract of G. boninense is not toxic.

Linking genotoxic responses in Gammarus fossarum germ cells with reproduction impairment, using the Comet assay

Germ cells perform a unique and critical biological function: they pass down DNA that will be used for the development of the next generation. Thus there is an increasing need to understand how the adult exposure to genotoxicants could show negative impact on the offspring of aquatic organisms. Hence this work addresses the question of the consequences of germ cell DNA damage resulting from parental exposure on reproduction quality in the freshwater crustacean Gammarus fossarum, a high ecologically relevant species. Initially, the sensitivity response of mature oocytes and spermatozoa to two model genotoxicants, MMS and K(2)Cr(2)O(7) was compared by implementing the Comet assay after the exposure of these gammarids in the laboratory and after the exposure of caged organisms in the field. Spermatozoa appeared significantly more susceptible than the oocytes to genotoxicants whatever were the exposure conditions. Secondly, a significant correlation between the level of damage to the sperm DNA of exposed parents and the abnormality rate in embryos that had developed in non-contaminated water were demonstrated. Interestingly, this relationship bridges the biomarker response measured in germ cells at molecular level and its consequences at individual level for the subsequent generation. Moreover, reproduction defects were observed for a level of DNA damage exceeding a minimal threshold, which could have significant consequences for the population dynamics of this high ecologically relevant species.

Proposal of an in vivo comet assay using haemocytes of Drosophila melanogaster

This study presents the first application of an in vivo alkaline comet assay using haemocytes of Drosophila melanogaster larvae. These cells, which play a role similar to that of mammalian blood, can be easily obtained and represent an overall exposure of the treated larvae. To validate the assay, we evaluated the response of these cells to three well-known mutagenic agents: ethyl methanesulfonate (EMS), potassium dichromate (PD), and gamma radiation (γ-irradiation). Third-instar Drosophila larvae were exposed to different concentrations of EMS (1, 2, and 4 mM) and PD (0.5, 1, and 2.5 mM) and to different doses of γ-irradiation (2, 4, and 8 Gγ). Subsequently, haemolymph was extracted from the larvae, and haemocytes were isolated by centrifugation and used in the comet assay. Haemocytes exhibited a significant dose-related increase in DNA damage, indicating that these cells are clearly sensitive to the treatments. These results suggest that the proposed in vivo comet test, using larvae haemocytes of D. melanogaster, may be a useful in vivo assay for genotoxicity assessment.

Acute toxicity tests with the tropical cladoceran Pseudosida ramosa: The importance of using native species as test organisms

Cladocerans have long been used for toxicological assessments of a diverse range of substances. The use of cladocerans in toxicity tests has many advantages, such as their short life cycle, parthenogenetic reproduction (clones), and high sensitivity to toxicants, as well as the easy laboratory maintenance of cultures. The most commonly used cladoceran in ecotoxicological studies of aquatic environments is undoubtedly Daphnia magna. Standard methods using cladocerans as test organisms have been documented and adopted by major international organizations and regulatory agencies of many countries. However, today there is a growing need for improving test organisms and protocols to better reflect local species sensitivity or site-specific conditions. The present study aimed to assess the tropical species Pseudosida ramosa as a potential test organism for ecotoxicological purposes, by carrying out standard acute tests with six reference compounds. Based on the results obtained in the present study and in comparison with other cladocerans, it was found that P. ramosa was more sensitive than Daphnia magna, had a sensitivity similar to that of Daphnia similis, and was less sensitive compared to Ceriodaphnia dubia and C. silvestrii (Neotropical species), except for the salts, sodium chloride and potassium chloride. Also, when P. ramosa was compared with test organisms of other taxonomic groups, we observed that it was more sensitive than most of the others, from simple coelenterates to complex fish. Considering these results and the wide distribution of the cladoceran P. ramosa in tropical and subtropical regions, we suggest that this species can be adopted as a test organism, being a good substitute for the exotic daphnid D. magna, for monitoring of toxicants in freshwaters.

Validation test with embryonic and larval stages of Chordodes nobilii (Gordiida, Nematomorpha): sensitivity to three reference toxicants

Chordodes nobilii is a parasite whose pre- and postparasitic stages are found in different types of freshwater bodies. Due to the peculiarities of its life cycle, it acts as a link between freshwater bodies and terrestrial ecosystems. There is little toxicological information on the group Gordiida. It is only known that embryos and larvae of C. nobilii are sensitive to glyphosate and malathion at relevant concentrations in the environment. On this basis, the aims of this study were to characterize the sensitivity of the pre-parasitic stages of C. nobilii to three reference toxicants: sodium dodecyl sulfate (SDS), cadmium chloride and potassium dichromate (Cr(6+)), and to validate a previous experimental protocol for ecotoxicological risk assessment. The protocol involved acute exposure of early embryonic stages and larvae to the three toxicants for 96 h and 48 h, respectively. Embryo development was inhibited only by Cr(6+) which presented a IC(50) of 0.71 mg Cr(6+)L(-1). The development of the eggs exposed to SDS and those exposed to cadmium chloride showed no differences as compared to that of controls. However, the infective capacity of larvae derived from the eggs exposed to the three toxicants was lower than that of controls. Larval survival was affected even at the lowest concentration of the three toxicants assayed. In relation to other freshwater organisms, C. nobilii can be characterized as an organism medium to highly sensitive to the toxicants tested.