Impact of a short-term diazinon exposure on the osmoregulation potentiality of Caspian roach (Rutilus rutilus) fingerlings

Population-specific responses to pollution exposure suggest local adaptation of invasive red swamp crayfish Procambarus clarkii along the Mediterranean French coastline

Anthropogenic stressors can have an impact in a broad range of physiological processes and can be a major selective force leading to rapid evolution and local population adaptation. In this study, three populations of the invasive crayfish Procambarus clarkii were investigated. They are geographically separated for at least 20 years, and live in different abiotic environments: a freshwater inland lake (Salagou lake) with no major anthropogenic influence and two other coastal wetlands regularly polluted by pesticides along the Mediterranean coast (Camargue region and Bages-Sigean lagoon). Collected adults were genetically characterized using the mitochondrial COI gene and haplotype frequencies were analyzed for genetic variability within and between populations. Results revealed a higher genetic diversity for these invasive populations than any previous report in France, with more than seven different haplotypes in a single population. The contrasting genetic diversity between the Camargue and the other two populations suggest different times and sources of introduction. To identify differences in key physiological responses between these populations, individuals from each population were maintained in controlled conditions. Data on oxygen consumption rates indicate that the Salagou and Bages-Sigean populations possess a high inter-individual variability compared to the Camargue population. The low individual variability of oxygen consumption and low genetic diversity suggest a specific local adaptation for the Camargue population. Population-specific responses were identified when individuals were exposed to a pesticide cocktail containing azoxystrobin and oxadiazon at sublethal concentrations. The Salagou population was the only one with altered hydro-osmotic balance due to pollutant exposure and a change in protease activity in the hepatopancreas. These results revealed different phenotypic responses suggesting local adaptations at the population level.

Glucocorticoid hormones in relation to environmental exposure to bisphenols and multiclass pesticides among middle aged-women: Results from hair analysis

Bisphenols and pesticides have been shown to alter circulating glucocorticoids levels in animals, but there is limited human data. Moreover, measurements from biological fluids may not be able to reflect long-term status of non-persistent pollutants and glucocorticoids due to the high variability in their levels. Using hair analysis, we examined the associations between glucocorticoid hormones and environmental exposure to multi-class organic pollutants among a healthy female population aged 25-45 years old. Concentrations of four glucocorticoids, four polychlorinated biphenyl congeners (PCBs), seven polybrominated diphenyl ether congeners (PBDEs), two bisphenols and 140 pesticides and their metabolites were measured in hair samples collected from 196 Chinese women living in urban areas. Due to the low detection frequency of some pollutants, associations were explored only on 54 pollutants, i.e. PCB 180, bisphenol A, bisphenol S and 51 pesticides and their metabolites. Using stability-based Lasso regression, there were associations of cortisol, tetrahydrocortisol, cortisone, and tetrahydrocortisone with 14, 10, 13 and 17 biomarkers of exposure to pollutants, respectively, with bisphenol S, p,p'-dichlorodiphenyldichloroethylene, diethyl phosphate, 3,5,6-trichloro-2-pyridinol, thiamethoxam, imidacloprid, fipronil, tebuconazole, trifluralin, pyraclostrobin and 1-(3,4-dichlorophenyl)-3-methylurea being associated with at least three of the four hormones. There were also associations between cortisone/cortisol molar ratio and pollutants, namely dimethyl phosphate, 3-methyl-4-nitrophenol, carbofuran, λ-cyhalothrin, permethrin, fipronil, flusilazole, prometryn and fenuron. Some of these relationships were confirmed by single-pollutant linear regression analyses. Overall, our results suggest that background level of exposure to bisphenols and currently used pesticides may interfere with the glucocorticoid homeostasis in healthy women.

Impact of Chlorpyrifos on Cytopathological Indices in Mangrove Crab, Episesarma tetragonum (Fabricius)

Chlorpyrifos is an organophosphate insecticide occurring in aquatic ecosystems. Due to exposure to xenobiotics, several harmful effects on aquatic organisms are noticed worldwide. Mangrove crabs are an ecologically important aquatic invertebrate species in food web interactions and in the mangrove ecosystem. Therefore, this study aimed to evaluate the cytotoxic effects of chlorpyrifos on the mangrove crab, Episesarma tetragonum. Crabs were exposed to 0.0294 and 0.0588 ppm of chlorpyrifos for 7 and 28 days. Cytopathologic effects on the gill, hepatopancreas, and muscle were investigated, and observations were compared with a control group. The results suggest that chlorpyrifos induces time- and concentration-dependent cytopathological alternations in the gill and exhibited epithelial lifting, oedema, necrosis, and a fusion of secondary lamellae and haemorrhage. The deceased hepatopancreas showed infiltration, a large lumen formation, and the disappearance of haemocytes, while the muscle tissue showed atrophy, necrosis, a wavy appearance, an accumulation of granular material between muscle fibres, and fragmentation in a mangrove crab. This study shows the great potential of cytopathological investigations, allows us to assess the sensitivity of various aquatic animal species to potentially dangerous compounds, and calculates safe concentrations with which to reduce pesticide use.

Modulatory role of dietary curcumin and resveratrol on growth performance, serum immunity responses, mucus enzymes activity, antioxidant capacity and serum and mucus biochemicals in the common carp, Cyprinus carpio exposed to abamectin

In this study, we investigate the potentials of dietary curcumin and resveratrol on blood biochemistry, immune responses and resistance to the toxicity of the pesticide, abamectin. 540 common carps (30.78 ± 0.17 g) were randomly distributed into 18 tanks (30 fish per tank), as six experimental groups (T1: non-supplemented and on-exposed fish, T2: 300 mg/kg curcumin, T3: 300 mg/kg resveratrol, T4: 12.5% LC₅₀ of abamectin, T5: 300 mg/kg curcumin +12.5% LC₅₀ of abamectin, T6: 300 mg/kg resveratrol + 12.5% LC₅₀ of abamectin). Use of 300 mg/kg resveratrol in the diet of non-abamectin exposed fish improved the growth performance (P < 0.05), while such effects were not observed for curcumin (P > 0.05). There were no differences in the final weight (FW), feed conversion ratio (FCR) and weight gain (WG) between control and fish of the treatments, resveratrol + abamectin and curcumin + abamectin (P < 0.05). The immune components in blood [lysozyme, complement activity, Total immunoglobulin (total Ig), protease, myeloperoxidase (MPO), nitro-blue-tetrazolium (NBT), peroxidase, albumin] and mucus [acid phosphatase (ACP), alkaline phosphatase (ALP), esterase, antiprotease)] and antioxidant enzymes [(superoxide dismutase (SOD), glutathione peroxidase (GPx)] exhibited various change patterns compared to the control group, however, these components were almost all higher in fish supplemented with curcumin and resveratrol in an abamectin-free medium than in control and other groups (P < 0.05). In most cases, the levels of immune and antioxidant components in the control did not show significant difference with the treatments, resveratrol + abamectin and curcumin + abamectin (P > 0.05). Abamectin induced oxidative stress in fish, as the malondialdehyde (MDA) levels significantly increased in the exposed fish compared to non-exposed groups (P < 0.05). It appears that neither curcumin nor resveratrol were as effective in preventing oxidative stress, because MDA levels were higher in exposed fish (abamectin, curcumin + abamectin, resveratrol + abamectin) than in control and non-exposed individuals (P < 0.05). Curcumin and resveratrol also showed protective effects on liver, since the levels of liver metabolic enzymes [aspartate transaminase (AST), ALP, lactate dehydrogenase (LDH)] were lower in the supplemented fish in a abamectin-free medium than in control (P < 0.05). Curcumin and resveratrol also mitigated the stress responses in the exposed fish, as cortisol and glucose levels showed significant decreases in the supplemented fish (P < 0.05). In conclusion, this study revealed that abamectin can depress the growth and immunity in the common carp. Although, both resveratrol and curcumin were mitigated the toxic effects of abamectin, it seems that resveratrol be more effective than curcumin.

Dietary Sargassum angustifolium (Macro-Algae, Sargassaceae) extract improved antioxidant defense system in diazionon-exposed common carp, Cyprinus carpio

The effects of different dietary levels of algae (Sargassum angustifolium) extract were investigated on the antioxidant system of common carp, Cyprinus carpio. Fish (30.2 ± 2.1 g) were fed 0 (control), 5, 10 and 15 g/kg basal diet of Sargassum angustifolium extract (SAE) for 60 days and then exposed to an environmentally relevant concentration of diazinon (2 mg/l) for 24 h. The biochemical assays were conducted in two times including at the end of feeding period and after 24 h exposure to diazinon. According to the results, malondialdehyde (MDA) levels in the liver remained unchanged (P>0.01) during feeding period, while significantly increased in response to diazinon in control and fish fed 5 and 10 g/kg diet SAE (P<0.01). The hepatic metabolic enzymes (AST: Aspartate aminotransferase, ALT: alanine aminotransferase, LDH: lactate dehydrogenase, CK: creatine kinase) showed no significant changes in all groups during feeding period, while these enzymes increased in Non-SAE supplemented fish and those fed 5 and 10 g/kg SAE after exposure to diazinon (P<0.01). Although little elevations were observed in the activity of hepatic antioxidant enzymes (CAT: catalase, SOD: superoxide dismutase, GPx: Glutathione peroxidase) in fish fed SAE, these elevations were not significant (P>0.01). After exposure to diazinon, antioxidant enzymes significantly decreased in control and fish fed 5 g/kg diet SAE, while the fish of 10 and 15 g/kg diet SAE treatments showed significant elevations (P<0.01). The antioxidant-related genes (sod, cat, gpx) significantly expressed more in response to dietary SAE compared to control (P<0.01). After exposure to diazinon, all groups showed significant elevations in antioxidant-related genes (P<0.01). In conclusion, the results of the present study revealed the antioxidant enhancing effects of SAE at dietary levels of 10 and 15 g/kg diet, which this effect may be attributed to some antioxidant components in the chemical composition of the macro-algae or to the direct effect of SAE on antioxidant defence system of the fish.

Effects of short-term exposure to the heavy metal, nickel chloride (Nicl2) on gill histology and osmoregulation components of the gray mullet, Mugil cephalus

The gray mullet, Mugil cephalus is an inshore and bottom-feeding fish species of Oman sea. Therefore, the gray mullet may be more exposed to heavy metal contamination, as the toxic impacts of heavy metals mullet has been reported in various studies. This study was conducted to evaluate the toxic effects of the heavy metal, nickel (as NiCl₂) on osmoregulation of the gray mullet by measuring blood biochemicals, hormones, minerals and gill histology. Fish (10 fish/tank) were experimentally exposed to NiCl₂ at three environmentally relevant concentrations of 5, 10 and 15 μg/l for 96 h. Then, fish were challenged with seawater (35 mg/l) for a period of 120 min. The samples (blood and gill tissue) were collected After 96 exposure to NiCl2 and during salinity challenge (30, 60 and 120 min post challenge). The plasma levels of cortisol and glucose significantly increased in NiCl_2-exposed fish. In addition, cortisol increased in all experimental groups 30 min after salinity challenge and then returned gradually to the same levels as the control at 120 min post salinity challenge (PSC). The triiodothyronine (T3) and thyroxine (T4) levels significantly decreased in response to 10 and 15 μg/l NiCl₂. In all groups, the thyroid hormones significantly elevated at 30 min PSC. After 30 min PSC, T3 levels in all NiCl_2-exposed fish and T4 in the treatment, 10 μg/l NiCl₂ remained unchanged throughout the salinity challenge. In the treatment, 5 μg/l NiCl₂, T4 levels were recovered at 120 min PSC and reached the same levels as the control. Exposure of fish to high concentrations of NiCl₂ and salinity stress increased the lactate levels. However, lactate levels in 5 and 10 μg/l NiCl₂ groups were recovered at 120 min PSC and reached the same levels as the control. Furthermore, plasma protein increased in response to 10 and 15 μg/l NiCl₂. At 30 PSC, the protein levels decreased in control and 5 μg/l NiCl₂ group, while it remained unchanged in fish exposed to 10 and 15 μg/l NiCl₂ throughout the salinity challenge. Exposure of fish to NiCl₂ disrupted the electrolyte (Na⁺, Cl^-) balance both before and after salinity challenge, which may be due to gill lesions induced by the heavy metal and following alternations in gill permeability. However, fish in 5 μg/l NiCl₂ re-established the ionic balance in the blood at the end of salinity challenge period. The malondialdehyde (MDA) levels significantly increased in response to 10 and 15 μg/l NiCl₂. The MDA levels returned to the same levels as the control group at 120 min PSC. The results of the present study showed that nickel-induced toxicity (especially at high concentrations) can reduce the osmoregulation capabilities of mullet. However, fish are able to recover from the toxic effects over time, if contamination be eliminated.

Protective effects of dietary Lavender (Lavandula officinalis) essential oil against Malathion-induced toxicity in rainbow trout (Oncorhynchus mykiss)

The present study was aimed to evaluate the moderating properties of Lavender (Lavandula officinalis) essential oil (LEO) against immunotoxic effects of the organophosphate pesticide, malathion in rainbow trout, Oncorhynchus mykiss. For this purpose, fish were supplemented with LEO at dietary concentrations of 0.5, 1, 2 and 4 ml/kg diet LEO for 56 days. A non-LEO supplemented group was also considered as control. After 57 days feeding trial, biochemicals were assayed in the blood and kidney tissue and then fish exposed to a sub-lethal concentration of malathion [0.24 mg/l equal to 30% of LC50 (0.8 mg/L)]. After 57 days feeding trial, the serum total immunoglobulin, respiratory burst activity, lysozyme activity and complement activity significantly elevated in fish treated with 1 and 2 ml LEO/kg diet compared to non-LEO supplemented individuals (P<0.01). Such changes were not observed in non-LEO supplemented fish (P>0.01). Significant elevations were observed in the expression of the immune genes (iNOS and C3 genes) in fish treated with 0.2–2 mg LEO/kg diet compared to non-supplemented ones (P<0.01). The lysozyme and complement activity significantly decreased in fish fed 4 ml/kg diet (P<0.01). After exposure to malathion, all immune components significantly declined in control and those treated with 0.5, 1 and 4 ml LEO/kg diet (P<0.01). In contrast, the immunity components exhibited no significant changes in fish treated with 2 ml LEO/kg diet after exposure (P>0.01). The expression of iNOS and C3 genes significantly reduced in control and fish fed 0.5, 1 and 4 ml LEO/kg diet in response to malathion (P<0.05). Furthermore, the expression of these genes showed no significant changes in fish fed with 2 ml LEO/kg diet after exposure (P>0.01). The findings of the present study suggested an immunoprotective role for dietary LEO at optimized dietary concentrations of 1 and 2 ml LEO/kg diet against oxidative stress and toxicity induced by malathion. Nevertheless, LEO at high dietary concentration (4 ml/kg diet) had reducing effects on the fish immunity.

Testing for population differences in evolutionary responses to pesticide pollution in brown trout (Salmo trutta)

Pesticides are often toxic to nontarget organisms, especially to those living in rivers that drain agricultural land. The brown trout (Salmo trutta) is a keystone species in many such rivers, and natural populations have hence been chronically exposed to pesticides over multiple generations. The introduction of pesticides decades ago could have induced evolutionary responses within these populations. Such a response would be predicted to reduce the toxicity over time but also deplete any additive genetic variance for the tolerance to the pesticides. If so, populations are now expected to differ in their susceptibility and in the variance for the tolerance depending on the pesticides they have been exposed to. We sampled breeders from seven natural populations that differ in their habitats and that show significant genetic differentiation. We stripped them for their gametes and produced 118 families by in vitro fertilization. We then raised 20 embryos per family singly in experimentally controlled conditions and exposed them to one of two ecologically relevant concentrations of either the herbicide S-metolachlor or the insecticide diazinon. Both pesticides affected embryo and larval development at all concentrations. We found no statistically significant additive genetic variance for tolerance to these stressors within or between populations. Tolerance to the pesticides could also not be linked to variation in carotenoid content of the eggs. However, pesticide tolerance was linked to egg size, with smaller eggs being more tolerant to the pesticides than larger eggs. We conclude that an evolutionary response to these pesticides is currently unlikely and that (a) continuous selection in the past has either depleted genetic variance in all the populations we studied or (b) that exposure to the pesticides never induced an evolutionary response. The observed toxicity selects against large eggs that are typically spawned by larger and older females.

The effect of diazinon on blood glucose homeostasis: a systematic and meta-analysis study

Though evidence exists on the association between diazinon (DZN), an organophosphate pesticide, with hyperglycemia, contrasting reports also exist. Herein, we performed a systematic and meta-analysis study to address this issue. A systematic search was conducted in PubMed, Ovid Medline, Google Scholar, Scopus, and Web of Science up to April 5, 2020, searching for animal studies (rodents and fish) that assessed the impact of DZN on blood glucose concentration. The risk of bias was assessed by the SYRCLE's RoB scale. Once each article's quality was assessed, a random-effects meta-regression was used to pool the data into a meta-analysis. Heterogeneity between the studies was evaluated with the I square and Q test. Random-effect meta-analysis of 19 studies (I2 = 90.5%, p < 0.001) indicated low heterogeneity between the studies. DZN significantly increased blood glucose levels in the exposed versus control groups (95% CI: 2.46-4.94; Z = 5.86; p < 0.001). Subgroup analysis indicated that the effect of high-dose (3.40 (95% CI: 2.03-4.76)) DZN on changes in blood glucose was more pronounced than in the low dose (4.83 (95% CI: 1.56-8.11)). It was also ascertained that the blood glucose level was significantly higher in females (3.55 (95% CI: 2.21-4.89)) versus males (4.87 (95% CI: 0.20-9.55)) exposed to DZN. No publication bias was observed. Sensitivity analysis showed the robustness of the (standardized mean differences: 3.26-4.03). Our findings establish an association between DZN exposure and hyperglycemia in rodents and fish, which is both dose- and gender-dependent.

The effect of the insecticide diazinon on the osmoregulation and the avoidance response of the white leg shrimp (Penaeus vannamei) is salinity dependent

Diazinon is one of the insecticides that represent a high risk for Costa Rican estuarine environments due to its widespread use in pineapple plantations. In estuaries, organisms are frequently submitted to stress caused by natural factors (e.g., continuous changes in salinity levels) and, additionally, to stress due to contamination. Therefore, the driving question of this study was: will organisms be more susceptible to suffer the deleterious effects caused by diazinon because of the stress resulting from the salinity changes? The estuarine shrimp Penaeus vannamei was used as the model organism and two responses were measured: osmoregulation (the physiological effect after a forced and continuous 24 h-exposure) and avoidance [the behavioural effect after a short (3 h) non-forced, multi-compartmented exposure]. Juveniles were exposed to diazinon (0.1, 1, 10 and 100 μg/L) at three different salinities (10, 20 and 30). Disruption in the capacity to regulate the haemolymph osmotic pressure was observed at a salinity of 30 in individuals exposed to diazinon and methanol (used as vehicle). At that salinity, the ability of shrimps to detect and avoid the highest diazinon concentrations was impaired. P. vannamei juveniles inhabit environments with a high variation in salinity, but with an optimum osmotic point close to a salinity of 20; therefore, the higher the salinity, the greater the vulnerability of shrimps to the effects of diazinon. From an ecological point of view, this combined effect of salinity and contamination might also limit the spatial distribution of the organisms.

The effects of diazinon on the cell types and gene expression of the olfactory epithelium and whole-body hormone concentrations in the Persian sturgeon (Acipenser persicus)

The olfactory function and imprinting of odorant information of the native stream play a critical role during the homing migration in fish. Pesticides may impair olfactory imprinting by altering olfaction and hormone functions. The present study aimed to determine how diazinon impacts olfactory epithelium morphology and cell composition, as well as hormone concentrations in Persian sturgeon (Acipenser persicus) during their lifetime in freshwater and, also during diazinon-free saltwater acclimation. Fingerlings were exposed to 0, 150, 300, and 450 μg·L^-1 of diazinon in freshwater for 7 days and then were transferred to diazinon-free saltwater by gradually increasing salinity up to 12 ppt. After diazinon exposure, the number of olfactory receptor cells (ORCs) and goblet cells (GCs) decreased and increased, respectively, and the expression of G-protein αolf (GPαolf) and calmodulin-dependent kinase II delta (CAMKIId) was down-regulated and up-regulated, respectively. Transferring the fish to diazinon-free saltwater (8 and 12 ppt) raised the number of ORCs, supporting cells (SCs), GCs, and GPαolf expression, and down-regulated CAMKIId without any significant differences among treatments. Exposure to diazinon increased whole-body cortisol at the high concentration, while decreased whole-body thyroxin (T4) and triiodothyronine (T3) in a dose-dependent manner. Although whole-body T4 and T3 increased in all the treatments after saltwater acclimation (8 and 12 ppt), the level of these hormones was lower in fish that had been exposed to diazinon than in the control. These results showed that diazinon can disrupt olfactory epithelium morphology and cell composition as well as hormone concentrations, which in turn may affect the olfactory imprinting in Persian sturgeon fingerlings.

Biochemical responses of a freshwater fish Cirrhinus mrigala exposed to tris(2-chloroethyl) phosphate (TCEP)

Freshwater fish Cirrhinus mrigala were exposed to tris(2-chloroethyl) phosphate (TCEP) with three different concentrations (0.04, 0.2, and 1 mg/L) for a period of 21 days. During the study period, thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) levels were significantly (p < 0.05) inhibited. The superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and lipid peroxidation (LPO) levels were increased significantly (p < 0.05) in gills, liver, and kidney tissues, whereas glutathione (GSH) and glutathione peroxidase (GPx) (except liver tissue) activities were inhibited when compared to the control group. Likewise, exposure to TCEP significantly (p < 0.05) altered the biochemical (glucose and protein) and electrolyte (sodium, potassium, and chloride) levels of fish. Light microscopic studies exhibited series of histopathological anomalies in the gills, liver, and kidney tissues. The present study reveals that TCEP at tested concentrations causes adverse effects on fish and the studied biomarkers could be used for monitoring the ecotoxicity of organophosphate esters (OPEs).

Comparing dioxin-like polychlorinated biphenyls in most consumed fish species of the Caspian Sea

Among polychlorinated biphenyls (PCBs), dioxin-like PCBs (DL-PCBs) are of the most concern for human health. In this study, the levels of 12 DL-PCBs congeners were measured in 125 fish samples of the Caspian Sea, Iran. Five fish species (Oncorhynchus mykiss, Vimba vimba, Cyprinus carpio, Rutilus frisii kutum and Chelon saliens) were collected from 5 coastal cities of the Caspian Sea (25 samples per each city). Duncan's multi-scope test was used to compare the mean of DL-PCBs in different fish species and different cities. Probabilistic risk of exposure to DL-PCBs and sensitivity analysis were assessed using Monte Carlo simulation approach. The average (standard deviation) of DL-PCBs in fish samples ranged from 232 (16) to 1156 (14) pg/g lipids. The total maximum concentration was detected in Cyprinus carpio from Bandar Anzali, the minimum in Vimba vimba from Chalos. In all samples, non-carcinogenic risk of exposure to DL-PCBs was in safe level (Hazard Quotient < 1). In contrast, the lifetime cancer risk estimated for Bandar Anzali, Bandar Torkaman, and Rasht exceeded the threshold value of 1 × 10^-6 suggested by United States Environmental Protection Agency. Sensitivity analysis indicated that the concentration of DL-PCBs and exposure frequency were the most effective parameters in increasing carcinogenic risk.

Pesticides With Potential Thyroid Hormone-Disrupting Effects: A Review of Recent Data

Plant Protection Products, more commonly referred to as pesticides and biocides, are used to control a wide range of yield-reducing pests including insects, fungi, nematodes, and weeds. Concern has been raised that some pesticides may act as endocrine disrupting chemicals (EDCs) with the potential to interfere with the hormone systems of non-target invertebrates and vertebrates, including humans. EDCs act at low doses and particularly vulnerable periods of exposure include pre- and perinatal development. Of critical concern is the number of pesticides with the potential to interfere with the developing nervous system and brain, notably with thyroid hormone signaling. Across vertebrates, thyroid hormone orchestrates metamorphosis, brain development, and metabolism. Pesticide action on thyroid homeostasis can involve interference with TH production and its control, displacement from distributor proteins and liver metabolism. Here we focused on thyroid endpoints for each of the different classes of pesticides reviewing epidemiological and experimental studies carried out both in in vivo and in vitro. We conclude first, that many pesticides were placed on the market with insufficient testing, other than acute or chronic toxicity, and second, that thyroid-specific endpoints for neurodevelopmental effects and mixture assessment are largely absent from regulatory directives.

Impact of chlorpyrifos on behavior and histopathological indices in different tissues of freshwater fish Channa punctatus (Bloch)

The present systematic experiment was conducted to estimate the impact of behavioral and pathological indices on freshwater fish Channa punctatus exposed to sub-lethal concentration (5 ppm) of an organophosphorus insecticide chlorpyrifos (CPF). Fish were segregated into four experimental groups (G1, control; G2, 10 days; G3, 20 days; and G4, 30 days exposure), each group comprises 15 fish in triplicate. The behavioral and histological changes were assessed in each group. Severe behavioral changes were observed in the 30 days, moderate changes in the 20 days, and mild changes in the 10 days exposure groups respectively when compared with the control group. The pathologic lesions such as inter lamellae space, necrotic lamellae, fused lamellae, and lifting of lamellae epithelium in gills; vacuolation, blood conjunctions, and necrotic hepatocytes in the liver; and lamina propria, fusion of villi, and flattened villi in the intestine were observed. These structural alterations of the gills, liver, and intestine could affect respiration, osmotic and ionic regulation; absorption, storage and secretion; digestion; and absorption of nutrients respectively, which in turn could adversely affect the growth and survival of freshwater fish Channa punctatus. This study serves as a biomonitoring tool for the effects of organophosphorus insecticide CPF on the aquatic biota.

Comparative Analysis of the aquaporin Gene Family in 12 Fish Species

Simple Summary

Aquaporins (Aqps) are a group of membrane proteins. In this study, 166 Aqp genes were identified in 12 fish species. Gene organization, motif distribution, recombination, and selection pressure were performed to investigate their evolutionary characteristics. In addition, expression profiles of Aqps were also examined under pathogens infection and organophosphorus pesticide stress. This study will provide a useful reference for further functional study.

Abstract

Aquaporins (Aqps) are a class of water channel proteins that play key roles in many physiological functions and cellular processes. Here, we analyzed 166 putative Aqp genes in 12 fish species and divided them into four groups. Gene organization and motif distribution analyses suggested potentially conserved functions in each group. Several recombination events were identified in some members, which accelerate their divergence in evolution. Furthermore, a few positive selection sites were identified, and mutations at these sites could alter the stability of Aqp proteins. In addition, expression profiles of some Aqp genes under pathogen infection and organophosphorus pesticide stress were also investigated. The result implied that several Aqp genes may affect different immune responses and osmoregulation. This study provides a comparative analysis of the fish Aqp gene family to facilitate further functional analyses.

Comparative toxicity of silver nanoparticle and ionic silver in juvenile common carp (Cyprinus carpio): Accumulation, physiology and histopathology

Many studies have investigated the potential negative effects of silver on aquatic organisms, but most focused on short-term exposure in few species. Moreover, there are many uncertainties about differences in potential toxicity mechanisms and adverse effects of silver nanoparticles (AgNPs) and ionic form of silver (AgNO₃). We investigated chronic effects of AgNPs and AgNO₃ on the juvenile common carp (Cyprinus carpio). AgNPs and AgNO₃ accumulated in the liver, gill and intestine, respectively and highest was related to AgNPs. Our results indicated, silver uptake was accompanied with histological alteration in the target organs such that different tissue lesions were observed in exposed groups. Superoxide dismutase (SOD), catalase (CAT) and lactate dehydrogenase (LDH) activity and also hsp70, ghrelin and IGF-1 genes expression were induced in both forms. After 7 days, highest hsp70 gene expression was observed in AgNO₃ treatment and highest ghrelin and IGF-1 gene expression was observed in AgNPs treatment. The results revealed that adverse effects of AgNPs on different aspects of the health of juvenile common carp, may not be solely a result of particle dissolution. In addition, the main toxic mechanism of AgNPs was probably related to the accumulation of silver followed by the molecular and oxidative stress response.

Effects of ZnO nanoparticles in the Caspian roach (Rutilus rutilus caspicus)

Most studies investigating the toxicity of zinc oxide nanoparticles (ZnO NPs) focused on the effect of size, whereas exposure concentration and duration remained poorly understood. In this study, the effect of acute and sub-acute exposures of ZnO NPs on Zn compartmentalization and biomarkers' expression were investigated in Rutilus rutilus caspicus (Caspian roach) considering various exposure scenarios: i) the assessment of the concentration-response curves and median lethal concentration (LC₅₀); ii) the assessment of the effects of organisms exposed at LC₅₀ value and one tenth of LC₅₀ value of ZnO NPs suspensions for 4 d and 28 d, respectively; iii) the assessment of 14 d depuration period. The same concentrations of ZnSO₄ were investigated. The highest Zn accumulation was detected in gill after sub-acute exposure (4.8 mg/L; 28 d) followed by liver, kidney and muscle. In gill, liver and muscle, Zn from Zn NPs accumulated higher concentrations. Depuration (14 d) decreased Zn content in each organ, but no complete removal occurred except for muscle. Biomarkers' activity was significantly over expressed after treatments, but depuration brought back their values to background levels and most effects were related to acute concentrations (48 mg/L; 4 d) and in presence of ZnSO₄. Histopathological analyses showed that the exposure to ZnO NPs increased lesions in gill, liver and kidney, with a direct proportionality between alterations and Zn accumulated in the target organs. After depuration, lesions regressed for both ZnO NPs and ZnSO₄, but not in a complete way. These data could contribute to increase the knowledge about ZnO NPs risk assessment in aquatic vertebrates, suggesting that the size of ZnO NPs can influence biomarker and histopathological effects.

Biomarker and histopathological responses of Lates calcarifer on exposure to sub lethal concentrations of chlorpyrifos

Bioassay tests on fingerlings (3.0 ± 0.5cm) of euryhyaline fish Lates calcarifer were conducted using customized continuous flow through system and derived 96h acute toxicity value for chlorpyrifos (CPF). Based on the measured concentration of CPF mean median lethal concentration (LC₅₀) of 1.07µg/l with lower and upper 95% confidence limits (0.95 and 1.19µg/l). No observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values were found to be 0.4, 0.09 and 0.07µg/l respectively. Key biomarker enzyme activities such as esterase, superoxide dismutase and malate dehydrogenase were measured in whole body tissues of the fish fingerlings on exposure to sublethal toxicity of CPF resulting in inhibition of enzyme activities. Native gel electrophoresis revealed single isoform of SOD and MDH enzyme activities exhibiting time and concentration dependent inhibition. Interestingly, three isoforms of esterase activity were witnessed, two isoforms didn't show changes and one isoform was completely inhibited. The observed changes indicated continuous production of reactive oxygen species (ROS) in cells, affecting the integrity and function of cell membrane. Decreased MDH activity indicates reduction of ATP production in the mitochondria leading to susceptibility of fish fingerlings due to the imposed CPF toxicity. Histopathological changes are evident as physiological signatures of chemical interactions in the cell and are prominently used for the evaluation of toxic effects. Gills and eye tissues were selected considering the possible effects on respiratory surfaces and vision impairment. Their tissue sections were observed for changes in primary & secondary lamellae, and retina of the eye respectively. Prominent pathological lesions of gills and retina of the eye include degeneration of cells, fusion, lifting of epithelium and increased cellular space, detachment of pigment epithelium, fusion of photoreceptor cells, respectively on exposure to 30 days of sub lethal concentrations. CPF was found to be highly toxic, affecting the vital functions of respiration, vision and cellular activities leading to susceptibility of fish fingerlings.

Modification of saltwater stress response in Cyprinus carpio (Linnaeus, 1758) pre-exposed to pesticide indoxacarb

To evaluate the effects of indoxacarb on saltwater stress response in Cyprinus carpio, the fish were pre-exposed to indoxacarb (0, 0.75, 1.5 and 3mg/L denoted as CP, 0.75IT, 1.5IT and 3IT, respectively) for 21 days and then released to saltwater. A negative control (CN) group was included (the fish were held in indoxacarb-free water for the entire experiment). The fish were sampled immediately (0h) and 24, 48 and 72h after the salinity exposure for the analysis of plasma cortisol, glucose and sodium, chloride, potassium and calcium levels. All fish pre-exposed to 3mg/L indoxacarb, died after the first day of salinity challenge. CP showed typical cortisol response after the salinity challenge, but, cortisol response of the fish pre-exposed to indoxacarb (0.75IT and 1.5IT) was blocked. Plasma glucose increased significantly in all groups compared to the CN; however, this elevation had no consistent trend in 0.75IT and 1.5IT which indicated interference in glucose response due to indoxacarb exposure. Plasma sodium increased (compared to CN) in all groups after the salinity challenge. However, elevation in plasma chloride and potassium was significantly different among the groups and the indoxacarb-treated fish showed slightly sooner ionic disturbance. The results clearly indicate that indoxacarb impairs stress response of C. carpio and the fish may not be able to respond normally to additional stressors, which threatens their survival.

NMR-based metabolomic study on the toxicological effects of pesticide, diazinon on adaptation to sea water by endangered Persian sturgeon, Acipenser persicus fingerlings

NMR-based metabolomics was applied to explore metabolic impacts of diazinon on sea water adaptation of Persian sturgeon fingerlings, Acipenser persicus. Fingerlings were exposed to sub-lethal concentrations of diazinon in freshwater (FW) for 96 h (short-term trial) and 12 days (long-term trial) and then exposed in brackish water (BW) (12 mg L^-1 salinity) for 24 h. After 96 h and 12 days exposure in FW, identified metabolites (amino acids, osmolytes, energy metabolites) showed different change-patterns compared to control group (P < 0.05) as follow: (A) short-term trial: higher plasma levels of glucose, lactate (in all diazinon-exposed fish), acetate and acetoacetate (in 0.9 mg L^-1diazinon treatment); lower levels of creatine (in all diazinon-exposed fish), trimethylamine-N-oxide, choline, taurine, betaine, N,N-dimethylglycine and almost all amino acids in fish exposed to high concentrations of diazinon (0.54 and 0.9 mg L^-1 diazinon). (B) Long-term trial: higher plasma levels of lipid oxidation metabolites and almost all amino acids in fish exposed to 0.54 and 0.9 mg L^-1 diazinon; lower levels of creatine, trimethylamine-N-oxide, N,N-dimethylglycine, betaine, choline (in all diazinon-exposed fish), glucose (in 0.54 and 0.9 mg L^-1diazinon treatments) and taurine (in 0.9 mg L^-1 diazinon treatment). When fish were exposed in BW for 24 h, the plasma levels of osmolytes decreased significantly in almost all experimental groups of short-term and long-term trial (P < 0.05). In short-term trial, the plasma levels of glucose in all groups and lactate in 0.18 and 0.54 mg L^-1 diazinon treatments increased after salinity challenge (P < 0.05). However, a significant decrease was observed in lactate levels in 0.9 mg L^-1 diazinon treatment (P < 0.05). Also, the plasma levels of amino acids decreased mostly in fish of control group than exposed fish (P < 0.05). The plasma glycerol concentration showed a significant decrease only in fish of 0.54 mg L^-1 diazinon treatment (P < 0.05). In long term trial, the energetic metabolites (acetate, acetoacetate, glycerol) showed significant increases mostly in fish exposed to high concentrations of diazinon (P < 0.05). Phosphocreatine was detected only in groups exposed to 0.54 and 0.9 mg L^-1 diazinon. Some amino acids decreased in control and diazinon-exposed groups while glycine (in control and 0.18 mg L^-1 diazinon treatment), glutamine and alanine (in 0.9 mg L^-1 diazinon treatment) elevated significantly after 24 h acclimation in BW (P < 0.05). Our results may help to understand the effects of pesticides on fish osmoregulation from a metabolic approach.

Effects of nanoparticles in species of aquaculture interest

Recently, it was observed that there is an increasing application of nanoparticles (NPs) in aquaculture. Manufacturers are trying to use nano-based tools to remove the barriers about waterborne food, growth, reproduction, and culturing of species, their health, and water treatment in order to increase aquaculture production rates, being the safe-by-design approach still unapplied. We reviewed the applications of NPs in aquaculture evidencing that the way NPs are applied can be very different: some are direclty added to feed, other to water media or in aquaculture facilities. Traditional toxicity data cannot be easily used to infer on aquaculture mainly considering short-term exposure scenarios, underestimating the potential exposure of aquacultured species. The main outputs are (i) biological models are not recurrent, and in the case, testing protocols are frequently different; (ii) most data derived from toxicity studies are not specifically designed on aquaculture needs, thus contact time, exposure concentrations, and other ancillary conditions do not meet the required standard for aquaculture; (iii) short-term exposure periods are investigated mainly on species of indirect aquaculture interest, while shrimp and fish as final consumers in aquaculture plants are underinvestigated (scarce or unknown data on trophic chain transfer of NPs): little information is available about the amount of NPs accumulated within marketed organisms; (iv) how NPs present in the packaging of aquacultured products can affect their quality remained substantially unexplored. NPs in aquaculture are a challenging topic that must be developed in the near future to assure human health and environmental safety. Graphical abstract ᅟ.

Effects of diazinon on adaptation to sea-water by the endangered Persian sturgeon, Acipenser persicus, fingerlings

To replenish the depleting populations of sturgeon fishes especially Persian sturgeon, Acipenser persicus in the Caspian Sea, millions of Persian sturgeon fingerlings are farmed through artificial propagation and released into the Iranian river estuaries annually. Fish osmoregulation is a vital physiological process that can be affected during the release. Many Iranian river estuaries are under the influence of pesticides originating from farming activities that may affect osmoregulation. In this study, Persian sturgeon fingerlings were exposed to sublethal concentrations (0, 0.18, 0.54, 0.9mgL(-)(1)) of diazinon for 96h (short-term trial) and 12 days (long-term trial) in fresh water (FW) and then fish were exposed in brackish water (BW) for 24h. After 96h and 12 days of exposure in FW, the lower levels of plasma triidothyronine (T3), thyroxine (T4), Na(+), Cl(-), K(+), gill Na(+)/K(+)- ATPase activity and number of chloride cells were observed in exposed fish (0.54 and 0.9mgL(-)(1) diazinon) compared to control group and 0.18mgL(-)(1) diazinon treatment. Also, higher levels of plasma cortisol (except 0.18mgL(-)(1) diazinon treatment in long-term trial) were observed in diazinon exposed fish compared to control group. However, gill Na(+)/K(+)-ATPase activity and the number of chloride cells were higher in fingerlings exposed to diazinon compared than control. When fish were exposed in BW for 24h, the following changes occurred: (a) in short-term trial: increases in cortisol and Cl(-) levels (0.54mgL(-)(1) diazinon ), Na(+) (0.9mgL(-)(1) diazinon ) and gill Na(+)/K(+)-ATPase activity (0.18mgL(-)(1) diazinon ). In control group, cortisol, T4, Na(+), gill Na(+)/K(+)-ATPase activity and the number of chloride cells increased significantly. (b) In long-term trial: increases in K(+) levels in fish exposed to 0.9mgL(-)(1) diazinon, Na+ in all diazinon concentrations and decreases in chloride cells number in fish exposed to 0.18mgL(-)(1) diazinon. In control group, significant increases were observed in cortisol, T3, Na(+) and chloride cells number. Finally, gill showed many histopathological damages during exposure in FW and BW. Our results suggest that the contamination of river estuaries with diazinon may alter the osmoregulation ability of released Persian sturgeon fingerlings, which could lead to a failure in their restocking program in the Caspian Sea.

The response of thyroid hormones, biochemical and enzymological biomarkers to pyrene exposure in common carp (Cyprinus carpio)

Polycyclic Aromatic Hydrocarbons (PAHs) are discharged into aquatic environments through anthropogenic activities mainly industrial and municipal effluents. There is little information on the adverse effects of pyrene, a member of the PAH family which is classified as a priority pollutant by the USEPA, on fish biochemical and physiological endpoints, particularly thyroid hormones. The present study investigated the effects of subacute semi-static pyrene exposure on biochemical, enzymological and ionoregulatory responses as well as thyroid hormones in common carp (Cyprinus carpio). The fish (140±10g, 1(+) year) were exposed to 10, 50 and 100µg/l nominal concentrations of pyrene for 35 days. The results revealed that pyrene at these concentrations significantly altered plasma levels of glucose, cholesterol, triglyceride, total protein, albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). Moreover, plasma thyroid hormones (T3 and T4) were significantly decreased in fish exposed to pyrene. In contrast, plasma electrolytes (sodium, potassium and calcium) levels remained statistically unchanged after exposure to the various pyrene concentrations. In conclusion, the studied biomarkers may be used as monitoring tools to evaluate pyrene toxicity. Pyrene induced diverse effects on the physiological endpoints of common carp, thus this chemical should be considered in toxicity studies concerning PAHs. Furthermore, this study confirmed that there was an interaction between pyrene and the thyroid system in fish. Therefore, the thyroid system may be used to assess the impact of pyrene on fish.

Exposure of Persian sturgeon (Acipenser persicus) to cadmium results in biochemical, histological and transcriptional alterations

Sturgeon is one of the endangered families of fish in the Caspian Sea region, where there is up to 80% of their global caching. Unfortunately, in recent years, increase of pollutants has been resulted in their total population reduction. Due to their benthic nature, sturgeons are at great risk of exposing to contaminants such as cadmium. Despite their endangered status in the Caspian Sea, there are only a few studies on characterizing the relative sensitivity of sturgeons to cadmium. Adverse effects associated with pollution on angiogenesis are mediated by hypoxia inducing factor-1 (HIF-1) and vascular endothelial growth factor (VEGF). In this investigation, gene expression of two distinct HIFs-1, HIF-1α and HIF-2α, and VEGF was investigated at the mRNA transcript levels after exposure of Persian sturgeon (Acipenser persicus) to cadmium. VEGF, HIF-1α and HIF-2α expressions in treated Persian sturgeon were greater than controls. Significant increases (P<0.05) were also observed in cortisol and glucose levels compared to the control group especially in the fish exposed to higher cadmium concentration (800 μg/L). Plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactic acid dehydrogenase (LDH) levels were increased in the cadmium-exposed fish, although the observed increases were not significant between the control and 200 μg/L cadmium treatment at some sampling time points. Gill tissues also showed histopathological changes in the cadmium treatments. Overall, results indicated that cadmium resulted in some alterations in biochemical parameters, mRNA transcript level expression of two important angiogenesis related genes as well as histological alterations in Persian sturgeon.

Biochemical and histological changes in fish, spotted scat (Scatophagus argus) exposed to diazinon

Pesticide accumulates in aquatic ecosystems and exerts toxic effects on aquatic animals. In this study, stress parameters and tissue histopathology under acute diazinon exposure were investigated in fish, scat (Scatophagus argus). Spotted scat was exposed to different diazinon concentrations (0, 10, 20, 30 μg L(-1)) for 24, 48, 72, 96 h. Cortisol and glucose levels showed a significant increase after exposure to different diazinon concentration with increase in exposure time. The electrolytes (K(+), Cl(-), Ca(2+), Na(+)) and glucose were differentially affected during the exposure to diazinon. Gill and kidney tissues showed many histopathological changes in diazinon-exposed fish. These results suggest that the release of spotted scat (S. argus) into the diazinon-contaminated regions may alter their physiology and jeopardize their survival.