Response of selenium-dependent glutathione peroxidase in the freshwater bivalve Anodonta woodiana exposed to 2,4-dichlorophenol,2,4,6-trichlorophenol and pentachlorophenol

Antioxidant Defence in Labeo rohita to Biotic and Abiotic Stress: Insight from mRNA Expression, Molecular Characterization and Recombinant Protein-Based ELISA of Catalase, Glutathione Peroxidase, CuZn Superoxide Dismutase, and Glutathione S-Transferase

Fish possess numerous enzymatic antioxidant systems as part of their innate immunity. These systems have been poorly studied in Labeo rohita (rohu). The present study characterized and investigated the role of antioxidant genes in the defence mechanisms against two types of stressors, including infection and ammonia stress. Four key genes associated with antioxidant activity-catalase, glutathione peroxidase, glutathione S-transferase, and CuZn superoxide dismutase were successfully cloned and sequenced. These genes were found to be expressed in different tissues and developmental stages of rohu. The expression levels of these antioxidant genes in the liver and anterior kidney tissues of rohu juveniles were modulated in response to bacterial infection (Aeromonas hydrophila), parasite infection (Argulus siamensis), poly I:C stimulation and ammonia stress. Additionally, the recombinant proteins derived from these genes exhibited significant antioxidant and antibacterial activities. These proteins also demonstrated a protective effect against A. hydrophila infection in rohu and had an immunomodulatory role. Furthermore, indirect ELISA assay systems were developed to measure these protein levels in healthy as well as A. hydrophila and ammonia-induced rohu serum. Overall, this study characterized and emphasised the importance of the antioxidant mechanism in rohu's defence against oxidative damage and microbial diseases.

Transcriptomic analysis reveals the genes involved in tetrodotoxin (TTX) accumulation, translocation, and detoxification in the pufferfish Takifugu rubripes

Tetrodotoxin (TTX) is a potent marine neurotoxin that exists in a variety of aquatic and terrestrial organisms. Pufferfish in different habitats show great variation in their TTX contents. Exploring the genes involved in TTX metabolism could contribute to our understanding of the molecular mechanisms underlying TTX accumulation, translocation, and detoxification in pufferfish. In this study, transcriptomic analysis was used to identify the functional genes related to TTX metabolism in the blood, liver, and muscle of the toxic and non-toxic tiger puffer (Takifugu rubripes). A total of 6101 differentially expressed genes (DEGs) were obtained after transcriptomic analysis; of these, 2401 were identified in the blood, 2262 in the liver, and 1438 in the muscle. After enrichment analysis, fourteen genes encoding glutathione S-transferases (GSTs), glutathione peroxidase (GPx), thioredoxins (TXNs), superoxide dismutase (SOD), ATP-binding cassettes (ABCs), apolipoproteins (APOs), inhibitors of apoptosis protein (IAP), and solute carrier (SLC), which are mainly antioxidant enzymes, membrane transporters, or anti-apoptotic factors, were revealed in the blood. Thirty-six genes encoding SLCs, ABCs, long-chain-fatty-acid-CoA ligases (ACSLs), interleukin 6 cytokine family signal transducer (IL6ST), endoplasmic reticulum (ER), and heat shock protein family A (Hsp70) were involved in transmembrane transporter activity and innate immune response. Notably, a large number of slc genes were found to play critical and diverse roles in TTX accumulation and translocation in the liver of T. rubripes. Nine genes from the slc, hsp70, complement C5 (c5), acsl, er, and serpin peptidase inhibitor (serpin) gene families were found to participate in the regulation of protein processing and anti-apoptosis. These results reflect the diverse functions of genes closely related to TTX accumulation, translocation, and detoxification in T. rubripes.

Mild pentachlorophenol-mediated uncoupling of mitochondria depletes ATP but does not cause an oxidized redox state or dopaminergic neurodegeneration in Caenorhabditis elegans

Aims

Mitochondrial dysfunction is implicated in several diseases, including neurological disorders such as Parkinson's disease. However, there is uncertainty about which of the many mechanisms by which mitochondrial function can be disrupted may lead to neurodegeneration. Pentachlorophenol (PCP) is an organic pollutant reported to cause mitochondrial dysfunction including oxidative stress and mitochondrial uncoupling. We investigated the effects of PCP exposure in Caenorhabditis elegans, including effects on mitochondria and dopaminergic neurons. We hypothesized that mild mitochondrial uncoupling by PCP would impair bioenergetics while decreasing oxidative stress, and therefore would not cause dopaminergic neurodegeneration.

Results

A 48-hour developmental exposure to PCP causing mild growth delay (∼10 % decrease in growth during 48 h, covering all larval stages) reduced whole-organism ATP content > 50 %, and spare respiratory capacity ∼ 30 %. Proton leak was also markedly increased. These findings suggest a main toxic mechanism of mitochondrial uncoupling rather than oxidative stress, which was further supported by a concomitant shift toward a more reduced cellular redox state measured at the whole organism level. However, exposure to PCP did not cause dopaminergic neurodegeneration, nor did it sensitize animals to a neurotoxic challenge with 6-hydroxydopamine. Whole-organism uptake and PCP metabolism measurements revealed low overall uptake of PCP in our experimental conditions (50 μM PCP in the liquid exposure medium resulted in organismal concentrations of < 0.25 μM), and no measurable production of the oxidative metabolites tetra-1,4-benzoquinone and tetrachloro-p-hydroquinone.

Innovation

This study provides new insights into the mechanistic interplay between mitochondrial uncoupling, oxidative stress, and neurodegeneration in C. elegans. These findings support the premise of mild uncoupling-mediated neuroprotection, but are inconsistent with proposed broad "mitochondrial dysfunction"-mediated neurodegeneration models, and highlight the utility of the C. elegans model for studying mitochondrial and neurotoxicity.

Conclusions

Developmental exposure to pentachlorophenol causes gross toxicological effects (growth delay and arrest) at high levels. At a lower level of exposure, still causing mild growth delay, we observed mitochondrial dysfunction including uncoupling and decreased ATP levels. However, this was associated with a more-reduced cellular redox tone and did not exacerbate dopaminergic neurotoxicity of 6-hydroxydopamine, instead trending toward protection. These findings may be informative of efforts to define nuanced mitochondrial dysfunction-related adverse outcome pathways that will differ depending on the form of initial mitochondrial toxicity.

In vivo toxicity evaluations of halophenolic disinfection byproducts in drinking water: A multi-omics analysis of toxic mechanisms

Halophenolic disinfection byproducts (DBPs) in drinking water have attracted considerable concerns in recent years due to their wide occurrence and high toxicity. The liver has been demonstrated as a major target organ for several halophenolic DBPs. However, little is known about the underlying mechanisms of liver damage caused by halophenolic DBPs. In this study, 2,4,6-trichlorophenol (TCP), 2,4,6-tribromophenol (TBP) and 2,4,6-triiodiophenol (TIP) were selected as representative halophenolic DBPs and exposed to C57BL/6 mice at an environmentally-relevant concentration (0.5 μg/L) and two toxicological concentrations (10 and 200 μg/L) for 12 weeks. Then, a combination of histopathologic and biochemical examination, liver transcriptome, serum metabolome, and gut microbiome was adopted. It was found that trihalophenol exposure significantly elevated the serum levels of alkaline phosphatase and albumin. Liver inflammation was observed at toxicological concentrations in the histopathological examination. Transcriptome results showed that the three trihalophenols could impact immune-related pathways at 0.5 μg/L, which further contributed to the disturbance of pathways in infectious diseases and cancers. Notably, TBP and TIP had higher immunosuppressive effects than TCP, which might lead to uncontrolled infection and cancer. In terms of serum metabolic profiles, energy metabolism pathway of citrate cycle and amino acid metabolism pathways of valine, leucine, and isoleucine were also significantly affected. Integration of the metabolomic and transcriptomic data suggested that a 12-week trihalophenol exposure could prominently disturb the glutathione metabolism pathway, indicating the impaired antioxidation and detoxification abilities in liver. Moreover, the disorder of the intestinal flora could interfere with immune regulation and host metabolism. This study reveals the toxic effects of halophenolic DBPs on mammalian liver and provides novel insights into the underlying mechanisms of hepatotoxicity.

Basis for using thioredoxin as an electron donor by Schizosaccharomyces pombe Gpx1 and Tpx1

Glutathione (GSH) peroxidases (GPxs or GSHPx) and thioredoxin (Trx) peroxidases (TPxs) are two classes of peroxidases that catalyze the reduction of peroxides. GPxs and TPxs generally use GSH or Trx, respectively, to recycle the oxidized cysteine (Cys) residue in the protein. However, it is unclear why unlike human GPxs, the Schizosaccharomyces pombe Gpx1 (spGpx1) prefers Trx over GSH for recycling of the active-site peroxidatic Cys residue. Here, we compared spGpx1 and S. pombe Tpx1 (spTpx1) protein sequences with those of their respective homologs in Saccharomyces cerevisiae and humans. Our analysis revealed that like spTpx1, spGpx1 contains a pair of conserved Cys residues (Cys36 and Cys82). These two conserved Cys residues are named peroxidatic and resolving Cys residues, respectively, and are found only in GPxs and TPxs that prefer Trx as an electron donor. Our analysis suggested that Cys36 and Cys82 in spGpx1 are most likely to form a disulfide bond upon oxidation of Cys36. Molecular modelling predicted that a conformational change might be required for the formation of this disulfide bond. Evolutionary analysis suggested that fungal GPxs and TPxs are related by divergent evolution from a common ancestor. Our analyses support a prediction that while spGpx1 and spTpx1 are phylogenetically and functionally different, they evolved from a common ancestor and use a similar mechanism for recycling of the active-site peroxidatic Cys residue.

spGpx1 contains two conserved Cys residues (Cys36 and Cys82), which may form a disulfide bond upon oxidation and the reduction of this disulfide bond is most likely to be mediated by Trx in vivo.

Fungal GPxs and TPxs evolved from a common ancestor.

2,4-dichlorophenol exposure induces lipid accumulation and reactive oxygen species formation in zebrafish embryos

2,4-dichlorophenol (2,4-DCP) is commonly found in the aquatic environment that can be formed by the conversion of triclosan, which is a high production volume endocrine disturbing chemical. The study aims to understand the potential developmental toxicity of 2,4-DCP by using the in vivo zebrafish. We exposed the 2,4-DCP to the zebrafish embryos and collected the samples at several selected developmental stages (70-85% epiboly/10-12 somite/prim-5) for the whole mount in situ hybridization. The staining is used to investigate the ventral patterning, presumptive neural formation, and brain development. Results suggested that the 2,4-DCP exposure (up to 2.5 mg/L) did not affect the tested developmental processes in the survived embryos. Further experiments on lipid accumulation and oxidative stress were carried out at 5 days post fertilization larvae. Results showed the accumulation of oil droplets and induction of reactive oxygen species (ROS) in the larvae after the highest dosage exposure (2.5 mg/L). The real-time qPCR results suggested that the alternation of lipid metabolism was due to the reduced mRNA expressions of proliferator-activated receptor alpha (ppar-α) and acetyl-CoA carboxylase (acc); while the suppressed glutathione peroxidase (gpx) mRNA expression was responsible for the induction of the ROS. To conclude, the study provided scientific merits of understanding 2,4-DCP toxicity, and suggested the possible underlying mechanism of the defects.

Effects of 2,4-dichlorophenol exposure on zebrafish: Implications for the sex hormone synthesis

2,4-Dichlorophenol (2,4-DCP), an estrogenic endocrine disruptor, is widely spread in aquatic environments and may interfere with normal physiological functions in fish. However, the influence of this chemical on the synthesis of sex hormones is not well understood. In the present study, zebrafish (Danio rerio) were exposed to 2,4-DCP (80 and 160 μg/L) with or without fadrozole (an aromatase inhibitor which inhibits the synthesis of estradiol) from 20 to 40 days post fertilization. Then, the sex ratio, the content of vitellogenin (VTG) and sex hormones (androstenedione (ASD), estrone (E1), 17β-estradiol (E2), estriol (E3), testosterone (T) and 11-ketotestosterone (11-KT)) were studied. Furthermore, the expression of genes involved in synthesis of sex hormones (cyp19a1a, cyp19a1b, 17β-hsd, 11β-hsd and cyp11b) along with the DNA methylation in cyp19a1a and cyp19a1b promoters was analyzed. The results showed that 2,4-DCP exposure led to female-biased ratio, increased the content of ASD, E2 and VTG, as well as the ratio of E2/11-KT, while decreased the levels of androgens (T and 11-KT). The sex hormonal change can be explained by the significant up-regulation of cyp19a1a, cyp19a1b, 17β-hsd and 11β-hsd genes. In addition, hypomethylation of cyp19a1a promoter was involved in this process. Notably, fadrozole can partly attenuate 2,4-DCP-induced feminization, and recover the levels of ASD, E2 and 11-KT. Thus, these results demonstrate that 2,4-DCP induces feminization in fish by disrupting the synthesis of sex hormones.

Tissue-Biased and Species-Specific Regulation of Glutathione Peroxidase (GPx) Genes in Scallops Exposed to Toxic Dinoflagellates

Marine bivalves could accumulate paralytic shellfish toxins (PSTs) produced by toxic microalgae, which might induce oxidative stress. Glutathione peroxidases (GPxs) are key enzymes functioning in the antioxidant defense, whereas our understanding of their roles in PST challenge in bivalves is limited. Herein, through genome-wide screening, we identified nine (CfGPx) and eight (PyGPx) GPx genes in Zhikong scallop (Chlamys farreri) and Yesso scallop (Patinopecten yessoensis), respectively, and revealed the expansion of GPx3 sub-family in both species. RNA-Seq analysis revealed high expression of scallop GPx3s after D stage larva during early development, and in adult hepatopancreas. However, in scallops exposed to PST-producing dinoflagellates, no GPx was significantly induced in the hepatopancreas. In scallop kidneys where PSTs were transformed to higher toxic analogs, most CfGPxs were up-regulated, with CfGPx3s being acutely and chronically induced by Alexandrium minutum and A. catenella exposure, respectively, but only one PyGPx from GPx3 subfamily was up-regulated by A. catenella exposure. Our results suggest the function of scallop GPxs in protecting kidneys against the oxidative stresses by PST accumulation or transformation. The tissue-, species-, and toxin-dependent expression pattern of scallop GPxs also implied their functional diversity in response to toxin exposure.

Risk assessment of cardiotoxicity to zebrafish (Danio rerio) by environmental exposure to triclosan and its derivatives

Triclosan (TCS) and its two derivatives (2,4-dichlorophenol and 2,4,6-trichlorophenol) are priority pollutants that coexist in aquatic environments. Joint exposure of TCS, 2,4-dichlorophenol and 2,4,6-trichlorophenol, hereafter referred to as TCS-DT, contributes severe toxicity to aquatic organisms. There is currently a paucity of data regarding TCS-DT molecular toxicity, especially on cardiac diseases. We used zebrafish (Danio rerio) as a model organism, and evaluated the molecular-level cardiotoxicity induced by TCS-DT from embryonic to adult stages. TCS-DT exposure prominently led to phenotypic malformations, such as pericardial cysts, cardiac bleeding, increased SV-BA distance, decreased heart rate and reduced ejection fraction, as well as abnormal swimming behavior. Analyses of the GO and KEGG pathways revealed enrichment pathways related to cardiac development and screened for significantly down-regulated adrenaline signaling in cardiomyocytes. The cardiac marker genes (amhc, cmlc2, vmhc, and nkx2.5) were obtained through protein-protein interaction (PPI) networks, and expressed as down-regulation by WISH. After chronic exposure to TCS-DT from 30 to 90-dpf, both body mass and heart indexes prominently increased, showing myocardial hypertrophy, abnormal heart rate and histopathological injury. Heart tissue damage included disordered and ruptured myocardial fibers, broken and dissolved myofilaments, nuclear pyknosis, mitochondrial injury and inflammatory cell infiltration. Further, abnormal changes in a series of cardiac functions-related biomarkers, including superoxide dismutase, triglyceride, lactate dehydrogenase and creatinine kinase MB, provided evidence for cardiac pathological responses. These results highlight the molecular mechanisms involving TCS-DT induced cardiac toxicity, and provide theoretical data to guide prevention and treatment of pollutant-induced cardiac diseases.

Molecular characterization of AwSox2 from bivalve Anodonta woodiana: Elucidating its player in the immune response

Sox2 is an embryonal stem cell Ag essential for early embryonic development, tissue homeostasis and immune regulation. In the current study, one complete Sox2 cDNA sequence was cloned from freshwater bivalve Anodonta woodiana and named AwSox2. Histological changes of testis derived from Bisphenol A (BPA) treatment were analyzed by hematoxylin and eosin staining. Expressions of AwSox2 derived from BPA, LPS and polyinosinic:polycytidylic (Poly I:C) challenge were measured by quantitative real-time PCR. The full-length cDNA of AwSox2 contained an open reading frame of 927 nucleotides bearing the typical structural features of Sox2 family. Obvious degeneration, irregular arrangement of spermatids, and clotted dead and intertwined spermatids were observed in BPA-treated groups. Administration of BPA could result in a dose-dependent up-regulation of AwSox2 expression in the male gonadal tissue of A. woodiana. In addition, expression of AwSox2 was significantly induced by LPS and Poly I:C treatment in the hepatopancreas, gill and hemocytes, compared with that of control group. These results indicated that up-regulations of AwSOx2 are closely related to apoptosis of spermatogonial stem cells derived from BPA treatment as well as enhancement of immune defense against LPS and Poly I:C challenge in A. woodiana.

Urinary levels of environmental phenols and parabens and antioxidant enzyme activity in the blood of women

BACKGROUND

The balance between oxidative stress and antioxidant enzymes is one biological mechanism by which environmental and lifestyle exposures affect health outcomes. Yet, no studies have examined the relationship between environmental phenolic compounds and parabens or their mixtures in relation to antioxidant enzyme activity in women of reproductive age.

METHODS

Sixteen environmental phenols and parabens were measured in urine 2-5 times across two months of follow-up in 143 women aged 18-44 years. Four antioxidant enzymes, erythrocyte and plasma glutathione peroxidase (eGPx, pGPx), glutathione reductase (GSHR), superoxide dismutase (SOD) were measured in plasma. Linear mixed models were adjusted for age, body mass index, race, and creatinine and were weighted with inverse probability of exposure weights. Multi-chemical exposures were estimated using hierarchical principal component analysis (PCA).

RESULTS

In line with our hypothesis that environmental phenols and parabens would be associated with decreased antioxidant enzymes, butyl, benzyl, ethyl, and propyl parabens were associated with lower levels of eGPx. Methyl paraben, 2,4-dichlorophenol and 2,5-dichlorophenol were associated with reduced SOD. 2,4,6-trichlorophenol was associated with increased levels of pGPx and GSHR. Several parabens were associated with modest decreases in eGPx and SOD, biomarkers of antioxidant defense. Increases in pGPx and GSHR were noted in relation to butyl and ethyl parabens. Co-exposures to parabens were associated with decreased eGPx (β = -1.08, 95% CI: -1.74, -0.43) in principal components mixed models, while co-exposure to benzophenones-3 and -1 were associated with increased eGPx (β = 0.92, 95% CI: 0.20, 1.64).

CONCLUSION

These findings indicate that nonpersistent chemicals altered antioxidant enzyme activity. Further human studies are necessary to delineate the relationship between environmental phenol and paraben exposures with erythrocyte and plasma activities of antioxidant enzymes.

2,4-Dichlorophenol induces feminization of zebrafish (Danio rerio) via DNA methylation

2,4-Dichlorophenol (2,4-DCP) is a ubiquitous contaminant of aquatic environments with an estrogenic effect on fish. However, the molecular mechanism underlying this effect remains elusive. To this end, the present study aimed to explore the effect of 2,4-DCP on sex differentiation and its relevant mechanism in zebrafish (Danio rerio). The results showed that a female-biased sex ratio was induced after exposing larval zebrafish to 2,4-DCP (0-160 μg/L) from 20 to 50 days post fertilization (dpf). The feminization of zebrafish was accompanied by decreased expression of male-related genes (sox9a, amh and dmrt1) under 2,4-DCP from 20 to 50 dpf. However, the expression of female-related genes (cyp19a1a, foxl2 and esr1) was also suppressed. Nevertheless, it is noteworthy that the methylation level of sox9a promoter was significantly increased, which may result in the significantly decreased expression of sox9a and ultimately the feminization effect of 2,4-DCP on zebrafish. In addition, 5-aza-2'-deoxycytidine (5-AZA), a methyltransferase inhibitor, significantly reduced the methylation level, increased the expression of sox9a, and partly impaired the feminization effect caused by 2,4-DCP, which further confirmed the importance of DNA methylation of sox9a in 2,4-DCP-induced feminization. These findings provide novel insights into the epigenetic mechanisms of DCP-induced estrogenic effect in fish.

Potential Role of Selenium Against Hepatotoxicity Induced by 2,4-Dichlorophenoxyacetic Acid in Albino Wistar Rats

The present study aims to investigate the hepatoprotective effects of selenium on toxicity induced by 'Désormone Lourd' based on 2,4-dichlorophenoxyacetic acid in Wistar rats. Male Wistar rats were divided into four groups and were treated orally. The (C) group was used as a control, while the test groups were treated with Se (0.2 mg/kg b.w.), 2,4-D (5 mg/kg b.w.) or both (2,4-D + Se) for 4 weeks. Our results showed that chronic treatment with 2,4-D resulted in hepatotoxicity, as revealed by an increase in liver function markers Aminotransferases (ALT, AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and total bilirubin (TB), along with reduced total protein content and albumin. An overall pro-oxidant effect was associated with a decrease in the reduced glutathione (GSH) content and the enzymatic activity of glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx), and an increase in malondialdehyde (MDA) and protein carbonyl levels (PCO). Microscopic observation of liver in 2,4-D-treated rats reveals lesions, which results in perivascular inflammatory infiltration around the vessel, sinusoidal dilatation and vacuolization of hepatocytes. However, selenium supplementation in 2,4-D-treated rats elicited a reduction in the toxic effects of the pesticide by improving the studied parameters, which was confirmed by the histological study of the liver. Selenium appears to have a promising prophylactic effect through its effective anti-radical action against the hepatotoxic effects of 2,4-D.

Does salinity modulates the response of Mytilus galloprovincialis exposed to triclosan and diclofenac?

In the present study Mytilus galloprovincialis mussels were exposed for 28 days to three salinities: 30 (control), 25 and 35. Simultaneously, organisms at each salinity were exposed to either the antimicrobial agent Triclosan (TCS) or the pharmaceutical drug Diclofenac (DIC) at 1 μg/L. Salinity alone and exposure to PPCPs changed mussel's metabolic capacity and oxidative status, but no additive or synergetic effects resulting from the combined exposures were observed. Overall, the metabolic capacity of mussels was decreased when exposed to TCS and DIC under control salinity, which was less pronounced at salinities out of the control level. TCS had a notorious effect over glutathione peroxidase activity while DIC exposure enhanced catalase response. Such defence mechanisms were able to prevent cellular damage but still a clear reduction in GSH/GSSG ratio after PPCPs exposures indicates oxidative stress which could compromise bivalve's performance to further stressing events.

Response of a novel selenium-dependent glutathione peroxidase from thick shell mussel Mytilus coruscus exposed to lipopolysaccharide, copper and benzo[α]pyrene

Glutathione peroxidase (GPx) plays an important antioxidant role in cellular defense against environmental stress. In the present study, a novel selenium-dependent glutathione peroxidase termed McSeGPx firstly identified in thick shell mussel Mytilus coruscus. McSeGPx consists of 197 amino acid residues, characterized with one selenocysteine residue encoded by an opal stop codon TGA, one selenocysteine insertion sequence (SECIS) in the 3' untranslated region (UTR), two active site motifs and one signature sequence motif. McSeGPx transcripts were constitutively expressed in all examined tissues, and were significantly induced in gills and digestive glands with the stimulations of lipopolysaccharide (LPS), copper (Cu) and benzo[α]pyrene (B[α]P). Additionally, rough increases in McSeGPx activity were detected in both tissues under the challenge of LPS, Cu and B[α]P. Collectively, these results suggested that McSeGPx affiliate to selenocysteine dependent GPx (SeGPx) family and might play an important role in mediating the environmental stressors and antioxidant response in M. coruscus.

Kolaviron attenuated arsenic acid induced-cardiorenal dysfunction via regulation of ROS, C-reactive proteins (CRP), cardiac troponin I (CTnI) and BCL2

Arsenic acid is one of the abundant environmental pollutants present in soil, water and the air. Undoubtedly, it has found its way to the food chain in which humans and animals are the final targets thereby causing arrays of disease conditions including cardiovascular and renal dysfunction. Hence, the use of phytochemicals present in medicinal plants has gained global acceptance as chemotherapeutic agents that can prevent, ameliorate, reverse or treat diseases. From our study, arsenic acid intoxication led to significant increase in heart rate (HR), QRS, together with prolonged QT and QTc interval. However, Kolaviron (KV) at the dosage of 100 and 200 mg/kg body weight reversed the aforementioned electrocardiographic (ECG) changes. KV pre-treatment also ameliorated cardiorenal dysfunction via significant reduction in cardiac and renal markers of oxidative stress such as malondialdehyde, hydrogen peroxide generation, myeloperoxidase activity and nitric oxide contents. Immunohistochemistry revealed expressions of renal C-reactive proteins (CRP) and expressions of anti-apoptotic protein BCL2 in KV treated rats. Furthermore, cardiac troponin I (CTnI) expressions were lower in KV treated rats. Taken together, KV mitigated arsenic-acid induced cardiovascular dysfunction via up-regulation of antioxidant defense system and down-regulation of inflammatory and apoptotic signaling pathways.

Response a chronic effects of PBDE-47: Up-regulations of HSP60 and HSP70 expression in freshwater bivalve Anodonta woodiana

Heat shock proteins (HSPs) play an important role in adaption of environmental stress by protein folding, membrane translocation, degradation of misfolded proteins and other regulatory processes. Our previous study showed oxidative stress generated from polybrominated diphenyl ether-47 (PBDE-47) could cause an acute toxicity on freshwater bivalve Anodonta Woodiana, but the effect of chronic toxicity need to be elucidated. In order to further investigate the chronic effect of PBDE-47, clams A. Woodiana were randomly divided into the PBDE-47 treated group administrated with PBDE-47 at a concentration 3.36 μg/L and control group treated with a similar volume dimethyl sulfoxide. Two complete HSP sequences were isolated from A. Woodianaa and respectively named AwHSP60 and AwHSP70. They were widely distributed in foot, gill, hepatopancreas, adductor muscle, heart, hemocytes and mantle. Administration of PBDE-47 could result in a significant up-regulation of AwHSP60 and AwHSP70 expressions in the hepatopancreas, gill and hemocytes. In the hepatopancreas, compared with that of control group, mRNA level of AwHSP60 increased more than 89.9% (P < 0.05) from day 1-15, AwHSP70 increased more 2.79 times (P < 0.01). In the gill, during experiment observed, expression of AwHSP60 increased more 2.09 times (P < 0.01) in contrasted with that of control group. Significant up-regulation of AwHSP70 expression showed a reversed U shape. In the hemocytes, AwHSP60 and AwHSP70 expressions of PBDE-47 treated group respectively increased more 2.09 times (P < 0.05) and 1.81 times (P < 0.05) compared with that of control group. These results indicated that up-regulations of AwHSP60 and AwHSP70 expression are contribute to enhancing adaption of bivalve A. Woodiana exposed to PBDE-47 treatment.

Isolation and characterization of two glutathione S-transferases from freshwater bivalve Anodonta woodiana: Chronic effects of pentachlorophenol on gene expression profiles

Glutathione S-transferases (GST) play a prominent role in protecting cells against oxidative stress. Our previous study showed that the reactive oxygen species (ROS) generated from pentachlorophenol (PCP) could cause an acute impact on freshwater bivalve Anodonta Woodiana, but its chronic toxicity remain unclear. In order to investigate the chronic effect of PCP, clams A. Woodiana were randomly grouped into PCP treated group in which animals were administrated with 13.9 μg/L concentrations of PCP, and control group those with similar volume dimethyl sulfoxide. In addition, two complete GST sequences were isolated from A. Woodianaa and respectively named AwGST1 and AwGST2. The full-length cDNA of AwGST1 was consisted of a 5' untranslated region (UTR) of 132 bp, a 3' UTR of 80 bp and an open reading frame (ORF) of 609 bp encoding a polypeptide of 203 amino acids. The full-length cDNA of AwGST2 contained a 5' UTR of 57 bp, a 3' UTR of 291 bp and an ORF of 678 bp encoding a polypeptide of 226 amino acids. The constitutive expression levels of AwGST1 and AwGST2 were examined in different tissues including foot, mantle, adductor muscle, heart, hepatopancreas, hemocytes and gill. Administration of PCP could result in a significant increase of AwGST1 and AwGST2 expression in the hepatopancreas, gill and hemocytes. In the hepatopancreas, AwGST1 mRNA levels of PCP treated group increased more than 28.73% at day 1, then 70.37% (P < 0.05) at day 3, reach to 6.64 times (P < 0.01) at day 15 in contrasted with that of control group. AwGST2 increased more 18.18%, 82.88% (P < 0.05) and 2.43 times (P < 0.01) at day 1, 3 and 15, respectively. In the gill, AwGST1 expression showed a significant up-regulation in the PCP treated group during experiment observed compared with that of control group, mRNA level of AwGST2 increased more than 1.44 times (P < 0.05). In addition, expressions of AwGST1 and AwGST2 were significantly induced after PCP treatment in the hemocytes. These results indicated that up-regulations of AwGST1 and AwGST2 expression in bivalve A. woodiana are contribute to against oxidative stress derived from PCP treatment during experiment observed.

Toxic effects in juvenile sea cucumber Apostichopus japonicas (Selenka) exposure to benzo[a]pyrene

To understand the physiological response of sea cucumber, Apostichopus japonicas, were exposed to different concentration of benzo[a]pyrene (B[a]P), and the growth, survival, antioxidant enzyme (SOD and T-AOC) activities were tested. Meanwhile, the quantitative real-time PCR technology was utilized to quantize the expression of immune related genes (i.e. innate immune genes, HSP genes and anti-oxidative genes). In our result, the SOD activity and T-AOC activity were induced at lower level of B[a]P (0.03 μg/L), however, a reduction of SOD activity and T-AOC activity were observed at relatively high B[a]P concentration (3 and 9 μg/L) for A. japonicas. Furthermore, the distinct expression patterns of selected immune-related genes were detected among different concentrations, and a general trend of down-regulation was observed at higher concentration. Especially, lysozyme almost showed the highest down-regulation at all concentrations, followed by NOS. Collectively, the growth, survival and expression signatures of immune related genes reflected an overall suppression of innate immunity in sea cucumber following exposure. Future functional studies should be carried out to characterize the detailed roles of immune genes and their related responses under B[a]P toxicity. Additionally, better understanding of the molecular indicators governing the healthy status under environmental toxicity would facilitate a healthy and sustainable culture program.