Alterations in nitrogen metabolism in freshwater fishes, Channa punctatus and Clarias batrachus, exposed to a commercial-grade λ-cyhalothrin, REEVA-5

Effects of metamifop on ammonia production and metabolism of Monopterus albus

The use of herbicides is believed to have an impact on the metabolism, physiology and biochemistry of fish. In this study, we studied the effects of metamifop on the production and metabolism of Monopterus. albus living in the water. According to the semi-lethal concentration of metamifop for 96 h, four MET concentration groups (0.2-, 0.4-, 0.6- and 0.8 mg L^-1) were set up for 96 h exposure test. The ammonia discharge rate decreased, hemolymph ammonia content increased significantly, and hemolymph urea nitrogen content decreased at all time periods of metamifop exposure. In liver, the protein content decreased, the neutral protease content increased significantly (p < 0.01), amino acid content increased, and ATP content increased significantly (p < 0.01). In brain, the protein content increased, the activity of acid protease, neutral protease and alkaline protease all decreased, amino acid content decreased significantly (p < 0.01), and the content of ATP decreased. Glutamic-pyruvic transaminase (GPT) activity did not change in liver but decreased in brain. Glutamine synthetase (GS) activity decreased in liver and increased in brain. Glutaminase (GLS) activity decreased in liver and increased in brain. In conclusion, the liver and brain tissues of M. albus react differently to MET exposure. The liver mainly synthesizes energy through hydrolyzed protein, while the brain mainly synthesizes protein. Amino acids produced by protein hydrolysis cannot be converted to alanine for storage, and the degraded amino acids lead to the elevation of endogenous ammonia. MET inhibits the removal of ammonia from M. albus. Only liver tissue can detoxify the eel by converting ammonia into glutamine. Brain should have to tolerate high levels of endogenous ammonia.

Alterations in energy metabolism, total protein, uric and nucleic acids in African sharptooth catfish (Clarias gariepinus Burchell) exposed to crude oil and fractions

Water contamination by crude oil is a growing challenge and little is known about the probabilistic and non-probabilistic ecosystem and species consequences. Therefore, research aimed at understanding species survival strategy in crude oil-contaminated environments with focus on cellular metabolic alterations and dynamics is vital. This study assessed the alterations in lactate dehydrogenase (LDH), glucose (GLU), glucose-6-phosphate dehydrogenase (G-6-PDH), total protein (TP), uric and nucleic acids (UA, RNA, and DNA) in the liver, heart, kidney, blood supernatants, and muscle homogenates of African sharptooth catfish ([ASC] Clarias gariepinus) exposed to varying bonny-light crude oil concentrations to understand the underlying cause of their delayed development as well as potential health and wellbeing. Three concentrations (20, 50, and 100 mg/L) of diluted whole bonny-light crude oil (DWC), water-soluble (WSF), and water-insoluble (WIF) fractions of bonny-light crude oil were used to grow ASC for 9 weeks at room temperature. Biochemical assessments revealed significant (at p < 0.05) elevations in heart LDH (48.57 ± 4.67 to 3011.34 ± 4.67 U/L) and blood G-6-PDH activities (54.86 ± 0.00 to 128 ± 18.29 mU/mL), GLU (0.22 ± 0.01 to 0.77 ± 0.01 mg/dL), TP (5.15 ± 0.14 to 22.33 ± 0.21 g/L), UA (0.29 ± 0.05 to 10.05 ± 0.27 mg/dL), as well as liver DNA (0.38 ± 0.02 to 2.33 ± 0.09 μg/mL) and RNA (12.52 ± 0.05 to 30.44 ± 0.02 μg/mL) levels for laboratory-grown ASC in DWC, WSF, WIF, and oil-impacted Ubeji river collected ASC relative to the control. Due to greater levels of cellular metabolic alterations in oil-impacted Ubeji River collected ASC, it is evident that bonny-light contamination levels in the river is greater than 100 mg/L. In conclusion, bonny-light crude oil is toxic to ASC and induces stress response. The ecological changes caused by bonny-light crude oil contamination may ultimately affect niche functioning and the development of organs in ASC.

Chronic effects of a binary insecticide Acer 35 EC on Nile tilapia Oreochromis niloticus through a multi-biomarker approach

Acer 35 EC is a widely used insecticide (a binary mixture of lambda-cyhalothrin and acetamiprid) in pest control in many West African countries, particularly in the cotton culture in north Benin. The aim of this study was to investigate the chronic effects of Acer 35 EC on Nile tilapia Oreochromis niloticus juveniles using a multi-biomarker approach under laboratory conditions. For this purpose, fish were exposed to sublethal concentrations of Acer 35 EC (0, 1 and 10% of LC₅₀- 96 h value). After 28 and 56 days of exposure, several biomarkers were measured in males and females including enzymatic activities related to detoxification and oxidative stress, neurotoxicity and immune responses, sex steroid hormones (testosterone, 17β-estradiol and 11-keto-testosterone) and histological alterations of liver, kidney and gonads. An Integrated Biomarker Response (IBR) was then calculated. The results showed a reduction of cholinesterase activity in muscles, and intercellular superoxide anion production in both sexes. Female steroidogenesis and gametogenesis were affected, especially testosterone levels and oocyte growth. More alterations were observed in liver after exposure to Acer 35 EC. In both sexes, IBR values were higher after 56 days than after 28 days of exposure. In conclusion, based on a large set of biomarkers and IBR values, the chronic exposure to low doses of insecticide Acer 35 EC seems to impair different physiological functions in Nile tilapia juveniles on a time-dependent manner, with a stronger impact on females than on males.

The Antioxidant Role of a Taurine-Enriched Diet in Combating the Immunotoxic and Inflammatory Effects of Pyrethroids and/or Carbamates in Oreochromis niloticus

Simple Summary

Insecticidal pollution of surface waters is known to hurt the growth, survival, and breeding of aquatic animals. Different types of insecticides are known to be toxic to different aquatic organisms, particularly to fish species. In different types of wastewater, the fishes get exposed to different mixtures of insecticides. The current study hypothesized that co-exposure to lambda-cyhalothrin (LCT) and methomyl (MTM) insecticides might be more harmful due to duplicated effects than exposure to either one of them at a time. Oreochromis niloticus was the target fish in this study. The combative roles of taurine (TUR) against LCT and MTM exposures were evaluated. In the present work, exposure of O. niloticus to LCT and/or MTM exhibited adverse effects on immunological parameters, including leukocyte count, complement 3 concentration, antioxidant enzyme concentrations, and mRNA expression for cytokines (TNF-α and IL-1β) and chemokines (CC and CXC). This study also elucidated the more severe toxic effect of LCT than exposure to MTM in O. niloticus fish. The immune response and growth performance of O. niloticus showed marked improvements when provided a 1% TUR-enriched supplement.

Abstract

Indiscriminate use of insecticides is a major concern due to its ubiquitous occurrence and potential toxicity to aquatic animals. This study investigated the adverse effects of lambda-cyhalothrin (LCT; C₂₃H₁₉ClF₃NO₃) and methomyl (MTM; C₅H₁₀N₂O₂S) on immune system modulations and growth performance of juvenile fishes. The supportive role of a taurine (TUR; C₂H₇NO₃S)-supplemented diet was also evaluated. Juvenile O. niloticus fishes were exposed to LCT (0.079 µg/L), MTM (20.39 µg/L), or both in water and were fed on a basal diet only or taurine-supplemented basal diet. Exposure to LCT and MTM retarded growth and increased mortality rate. LCT and MTM reduced antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase) and innate and humoral immunity but upregulated interleukin and chemokine expressions. Moreover, exposure to LCT and MTM elevated 8-OHdG levels and increased the mortality of Oreochromis niloticus after the experimental bacterial challenge. The TUR-enriched diet enhanced antioxidant enzymes and acted as a growth promoter and anti-inflammatory agent. TUR can modify innate and adaptive immune responses. Furthermore, TUR supplementation is a beneficial additive candidate for mitigating LCT and MTM toxicities mixed with O. niloticus aquafeed.

Response of juvenile Lophiosilurus alexandri to osmotic and thermic shock

The objective of the present study was to evaluate the physiological responses of juvenile Lophiosilurus alexandri submitted to osmotic and thermic shock. Thirty juveniles were used for each test, of which 10 were not subjected to stress and remained in normal conditions (fresh water at 28.0 °C). The others were submitted to stress shock (saline water of 10.0 g of salt/L or water cooled to 18.0 °C). Blood samples were taken at 0 h (no exposure to the stress factor) and 1 h and 24 h after the tests. At 24 h, the survivorship was 100% in both tests. In both the osmotic and thermic shock tests, cortisol and glucose levels were higher at 1 h but then decreased after 24 h. Lactate dehydrogenase showed differences in the temperature test, but there was no difference between 1 and 24 h after exposure to osmotic shock (P > 0.05). The difference was recorded in blood gas variables (pH, PvCO₂, PvO₂, hemoglobin, sO₂, BE, tCO₂, HCO₃^-, and stHCO₃^-) and electrolytes (Na⁺, Ca⁺⁺, nCa⁺⁺, and K⁺) in both experiments. With regard to hematology and blood biochemistry, exposure to thermal shock did not affect (P > 0.05) ALP, total plasma protein, hematocrit, and ALT and AST at 1 h and 24 h. ALP and total protein in the blood of fish submitted to the osmotic shock were lowest (P < 0.05) at 24 h. Leukocyte and erythrocyte counts exhibited differences after osmotic shock, in contrast to erythrocyte counts of the temperature test, which did not change in 24 h (P > 0.05). Juveniles of L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose), while the others (hematological, biochemical, and gasometric) varied in compensation for normal physiological reestablishment.

Intermediary metabolic response and gene transcription modulation on the Sub-Antarctic notothenioid Eleginops maclovinus (Valenciennes, 1930) injected with two strains of Piscirickettsia salmonis

Pathogen interactions with cultured fish populations are well studied, but their effects on native fishes have not been characterized. In Chile, the disease caused by bacterial species Piscirickettsia salmonis represents one of the main issues and is considered to be one of the important pathogens in the field of aquaculture. They have been found to infect native fish. Therefore, it is necessary to understand the impact of P. salmonis on native species of local commercial value, as well as the potential impact associated with the emergence of antibiotic-resistant strains of P. salmonis. Due to this purpose, the native fish Eleginops maclovinus was used in our study. Fish were randomly distributed in tanks and intraperitoneally inoculated with two strains of P. salmonis. No mortality was recorded during the experiment. Cortisol, glucose and total α-amino acid levels increased in fish injected with AUSTRAL-005 strain compared to sham-injected and LF-89-inoculated fish. Moreover, results showed an increase in the activity of carbohydrates and lipids metabolism in liver; and an increase in the carbohydrates, lipids and total α-amino acid metabolism in muscle after injection with AUSTRAL-005. Our results suggest that P. salmonis modulates the physiology of E. maclovinus and the physiological impact increase in the presence of the antibiotic-resistant strain AUSTRAL-005.

1H-NMR-based metabolomic study on toxicity of methomyl and methidathion in fish

A ¹H-nuclear magnetic resonance (NMR) spectroscopy with multivariate analysis was applied to detect the toxicity of antiacetylcholinesterase insecticides, methomyl (methyl (1E)-N-(methylcarbamoyloxy)ethanimidothioate) and methidathion (3-(dimethoxyphosphinothioyl sulfanylmethyl)-5-methoxy-1,3,4-thiadiazol-2-one), using zebrafish (Danio rerio) and Chinese bleak (Aphyocypris chinensis). Generally, methomyl and methidathion have been believed not to highly accumulate in fish tissues. However, these pesticides showed their toxicity by altering patterns of whole-body metabolites in neurotransmitter balance, energy metabolism, oxidative stress, and muscle maintenance in low concentrations. We used Pearson correlation analysis to contextualize the metabolic markers in pesticide treated groups. We observed that the positive correlations of choline with acetate and betaine in untreated control were shifted to null correlations showing acetylcholinesterase specific toxicity. This research demonstrated the applicability and potential of NMR metabolomics in detecting toxic effects of insecticide with a modicum of concentrations in aquatic environment.

The role of vitamin C as antioxidant in protection of biochemical and haematological stress induced by chlorpyrifos in freshwater fish Clarias batrachus

The study was conducted to explore the modulatory effects of chlorpyrifos and protective role of vitamin C in tissues of Clarias batrachus. Treatments include E1 group (basal diet plus 1.65mgL(-1) CPF) and E2 group (basal diet+200mgkg body weight vitamin C and 1.65mgL(-1) CPF) along with a control group of fishes (fed on basal diet only). After 1, 7, 15, and 30d of treatment, fish tissues (brain, blood and liver) were used for the estimation of growth, biochemical and haematological parameters. The results of E1 group indicated significantly lower weight gain and survival rate. Brain AChE activity was inhibited. The RBC, Hb, respiratory burst activity, total protein and HSI were also reduced whereas WBC count, plasma glucose and haematocrit were elevated. In contrast, liver glycogen content, lactate dehydrogenase, alkaline and acid phosphatase activities were inhibited and malate dehydrogenase, aspartate, alanine amino transferase were enhanced. The E2 group of fish exhibited significant improvement in growth, survival, haematological indices, brain AChE, liver glycogen and oxidative enzyme activity. The findings support that dietary vitamin C supplementation might be helpful in abrogation of chlorpyrifos toxicity and improves growth, survival, biochemical and haematological conditions in fishes.

Biomarkers of type II synthetic pyrethroid pesticides in freshwater fish

Type II synthetic pyrethroids contain an alpha-cyano group which renders them more neurotoxic than their noncyano type I counterparts. A wide array of biomarkers have been employed to delineate the toxic responses of freshwater fish to various type II synthetic pyrethroids. These include hematological, enzymatic, cytological, genetic, omic and other types of biomarkers. This review puts together the applications of different biomarkers in freshwater fish species in response to the toxicity of the major type II pyrethroid pesticides and assesses their present status, while speculating on the possible future directions.