Effects of Atrazine and Chlorpyrifos on Autophagy-Related Genes in the Brain of Common Carp: Health-Risk Assessments.

This study assessed the impacts of atrazine (ATR), chlorpyrifos (CPF), and a combined ATR/CPF exposure on the brain of common carp (Cyprinus carpio L.). The carp were sampled after a 40-days exposure to CPF and ATR, individually or in combination, followed by a 40-days recovery period to measure autophagy and antioxidant activity. The results indicate that the anti-superoxide anion and anti-hydroxy radical activities decreased upon exposure to ATR, CPF, and the ATR/CPF combination but increased after a subsequent 40-days recovery period. Quantitative real-time PCR and Western blot analyses revealed that the mRNA and protein levels of LC3B and dynein in common carp decreased significantly after exposure to ATR and CPF alone or in combination. Moreover, the mRNA and protein levels of beclin1 gene decreased significantly only in the 116 and 11.3 µg/L treatment groups. However, the mRNA and protein levels of all tested genes increased significantly after a 40-days recovery. Transmission electron microscope demonstrated the occurrence of autolysosomes in the recovery groups but not in the exposure groups. These results suggest that exposure to ATR, CPF, or their combination promotes oxidative stress and autophagic responses in the brain of common carp.

Effect of cold stress on expression of AMPKalpha-PPARalpha pathway and inflammation genes.

Animals are exposed to various environmental stresses every day, including the stress associated with living in cold temperatures. The aim of this study was to investigate the possible mechanisms of interaction between lipid metabolism and inflammation induced by cold stress in the livers of chickens. Fifteen-day-old male chicks were randomly allocated into 12 groups (10 chickens per group). After exposure of the chickens to the cold stress, cholesterol fractionation was used to examine high-density lipoprotein (HDL) and low-density lipoprotein (LDL) concentrations. Aminotransferase activities were examined with the use of the aspartate transaminase (AST) and alanine transaminase (ALT) assay. The AMP-activated protein kinase alpha-proliferator-activated receptor alpha (AMPKalpha-PPARalpha) pathway genes (AMPKalpha1, AMPKalpha2, PPARalpha, carnitine palmitoyltransferaseI [CPTI], acetyl-CoA carboxylase [ACC]) and inflammatory cytokines (prostaglandin E synthase [PGEs], inducible nitric oxide synthase [iNOS], heme oxygenase-1 [HO-1], nuclear factor kappa-light-chain-enhancer of activated B cells [NF-kappaB], cyclooxygenase-2 [COX-2], and TNF-alpha-like factor [LITAF]) were also measured. The results showed that during the response to cold stress, serum LDL and HDL cholesterol concentrations increased. Histopathologic analyses provided evidence that liver tissues were seriously injured in the chickens exposed to the cold stress. Serum aminotransferase activities were also increased in the group of animals exposed to the cold stress. Additionally, the expressions of AMPKalpha-PPARalpha pathway genes and inflammatory cytokine genes were significantly increased in the animals exposed to cold temperatures. These results suggested that increased inflammation was a feature associated with a lipid-metabolism disorder in the livers of chickens exposed to cold stress.

Possible correlation of selenoprotein W with inflammation factors in chicken skeletal muscles.

The aim of the present study was to investigate the possible correlation of selenoprotein W (SelW) with inflammatory injury induced by dietary selenium (Se) deficiency in chicken. One-day-old male chickens were fed either a commercial diet or a Se-deficient diet for 55 days. Then, the expression levels of SelW messenger RNA (mRNA) and inflammation-related genes (NF-κB, TNF-α, iNOS, COX-2, and PTGES) in chicken skeletal muscles (wing muscle, pectoral muscle, and thigh muscle) were determined at 15, 25, 35, 45, and 55 days old, respectively. In addition, the correlation between SelW mRNA expression and inflammation-related genes were assessed. The results showed that dietary Se deficiency reduced the mRNA expression of SelW in chicken wing, pectorals, and thigh muscles. In contrast, Se deficiency increased the mRNA expression levels of inflammation-related genes in chicken skeletal muscle tissues at different time points. The Pearson's correlation coefficients showed that the mRNA expression levels of inflammation-related genes were significantly negative related to SelW (p < 0.05). These data showed that Se deficiency induced the inflammatory response in chicken skeletal muscle. As one important selenoprotein gene in skeletal muscles, SelW may play a role in the regulation of inflammation reaction in Se-deficiency myopathy.

Selenium deficiency inhibits the conversion of thyroidal thyroxine (T4) to triiodothyronine (T3) in chicken thyroids.

Selenium (Se) influences the metabolism of thyroid hormones in mammals. However, the role of Se deficiency in the regulation of thyroid hormones in chickens is not well known. In the present study, we examined the levels of thyroidal triiodothyronine (T3), thyroidal thyroxine (T4), free triiodothyronine, free thyroxine (FT4), and thyroid-stimulating hormone in the serum and the mRNA expression levels of 25 selenoproteins in chicken thyroids. Then, principal component analysis (PCA) was performed to analyze the relationships between the selenoproteins. The results indicated that Se deficiency influenced the conversion of T4 to T3 and induced the accumulation of T4 and FT4. In addition, the mRNA expression levels of the selenoproteins were generally decreased by Se deficiency. The PCA showed that eight selenoproteins (deiodinase 1 (Dio1), Dio2, Dio3, thioredoxin reductase 2 (Txnrd2), selenoprotein i (Seli), selenoprotein u (Selu), glutathione peroxidase 1 (Gpx1), and Gpx2) have similar trends, which indicated that they may play similar roles in the metabolism of thyroid hormones. The results showed that Se deficiency inhibited the conversion of T4 to T3 and decreased the levels of the crucial metabolic enzymes of the thyroid hormones, Dio1, Dio2, and Dio3, in chickens. In addition, the decreased selenoproteins (Dio1, Dio2, Dio3, Txnrd2, Seli, Selu, Gpx1, and Gpx2) induced by Se deficiency may indirectly limit the conversion of T4 to T3 in chicken thyroids. The information presented in this study is helpful to understand the role of Se in the thyroid function of chickens.

Effect of selenium on selenoprotein expression in the adipose tissue of chickens.

This study describes the effects of selenium (Se) deficiency on the messenger ribonucleic acid (mRNA) expression of 25 selenoproteins (Sels) (including glutathione peroxidases (GPx1-GPx4), thioredoxin reductases (TrxR1-TrxR3), iodothyronine deiodinases (ID1-ID3), selenophosphate synthetase 2 (SPS2), 15-kDa Sel (Sel15), SelH, SelI, SelK, SelM, Sepn1, SelO, Sepx, Selpb, SelS, SelT, SelW, Sepp1, and SelU in the adipose tissues (subcutaneous adipose, visceral adipose, and articular adipose) of chickens. One hundred and fifty 1-day-old chickens were randomly assigned to two groups of 75 each and were fed a low-Se diet (0.032 mg/kg Se) or a control diet (0.282 mg/kg Se). The expression levels of 25 Sel mRNAs were determined on days 35, 45, and 55 from three parts (subcutaneous adipose, visceral adipose, and articular adipose) of the chicken adipose tissues. The results showed that the expression levels of the 25 Sel mRNAs were significantly lower (P < 0.05) in the low-selenium group than in the control group. In addition, the Sel mRNA expression levels in the three adipose tissues were observed to decrease in a time-dependent manner with increasing feeding time.

Protective roles of selenium on nitric oxide-mediated apoptosis of immune organs induced by cadmium in chickens.

Little is known about the influence of subchronic cadmium exposure on apoptosis in the immune organs of birds and the protective effects on apoptosis by selenium against cadmium. The aim of this study was to investigate the effect of subchronic cadmium exposure on nitric oxide and apoptosis in the immune organs of chicken and the protective roles of selenium against cadmium-induced apoptosis. Two hundred ten 30-day-old chickens were randomly assigned to three groups and were fed a basal diet, cadmium+selenium (as 150 mg of CdCl2 per kg of diet+10 mg of Na2SeO3 per kg of diet ) or cadmium (as 150 mg of CdCl2 per kg of diet) in basic diets for 15, 30, 45, and 60 days. Then, the production of nitric oxide, messenger RNA (mRNA level), and the activity of inducible nitric oxide synthase, ultrastructural changes, TUNEL assay, and flow cytometric analysis of apoptosis and Bcl-2 and p53 mRNA levels in the immune organs were examined. The results showed that cadmium exposure caused ultrastructural damage and increased production of nitric oxide, mRNA level, and activity of inducible nitric oxide synthase, the degree, and the number of apoptotic cells in a time-dependent manner. Cadmium exposure decreased Bcl-2 mRNA level and increased p53 mRNA level in a time-dependent manner. Selenium supplementation during dietary cadmium reduced the production of nitric oxide, the mRNA level, and activity of inducible nitric oxide synthase, ultrastructural damage, and apoptosis in the immune organs of chicken. It indicated that cadmium induced nitric oxide-mediated apoptosis of immune organs, and selenium played protective effects against cadmium-induced apoptosis in the immune organs of chickens.

Global DNA hypomethylation: a potential mechanism in King pigeon nerve tissue damage induced by avermectin.

As an effective insecticidal and nematicidal agent, avermectin (AVM) has been widely used in agricultural production and stock farming areas. Subsequently, the residues of AVM or its active metabolites in animal manure pose a toxic threat to non-target organisms in the environment. As the most characteristic epigenetic phenomena, DNA methylation status is a useful biological signal for the toxicity assessment of environmental chemical toxicants. In this study, analyses of the overall level of genomic DNA methylation were performed, and the expression levels of DNA methyltransferases (DNMTs), as well as demethylase methyl-CpG-binding domain protein 2 (MBD2), in pigeon brain tissues after subchronic exposure (with a AVM concentration of 20 mg/kg, 40 mg/kg and 60 mg/kg, respectively) to AVM for 30, 60 and 90 days were investigated. Global DNA hypomethylation and down-regulation of DNMT mRNA expression occurred in a dose-time-dependent manner in pigeon brains. The expression level of MBD2, which functions as a demethylase, was significantly enhanced in a dose-dependent but not time-dependent manner. In addition, the elevated expression level of MBD2 had a more robust effect on genomic DNA hypomethylation compared to changes in DNMT expression. Taken together, these results suggested that subchronic dose exposures of AVM could affect the global DNA methylation status, and this mechanism is closely related to changes in the expression levels of DNMTs and MBD2.

The effects of avermectin on amino acid neurotransmitters and their receptors in the pigeon brain.

The objective of this study was to examine the effects of avermectin (AVM) on amino acid neurotransmitters and their receptors in the pigeon brain. Four groups two-month-old American king pigeons (n=20/group) were fed either a commercial diet or an AVM-supplemented diet (20mg/kg·diet, 40 mg/kg·diet, or 60 mg/kg·diet) for 30, 60, or 90 days. The contents of aspartic acid (ASP), glutamate (GLU), glycine (GLY), and γ-aminobutyric acid (GABA) in the brain tissues were determined using ultraviolet high-performance liquid chromatography (HPLC). The expression levels of the GLU and GABA receptor genes were analyzed using real-time quantitative polymerase chain reaction (qPCR). The results indicate that AVM exposure significantly enhances the contents of GABA, GLY, GLU, and ASP in the cerebrum, cerebellum, and optic lobe. In addition, AVM exposure increases the mRNA expression levels of γ-aminobutyric acid type A receptor (GABAAR), γ-aminobutyric acid type B receptor (GABABR), N-methyl-d-aspartate 1 receptor (NR1), N-methyl-d-aspartate 2A receptor (NR2A), and N-methyl-d-aspartate 2B receptor (NR2B) in a dose- and time-dependent manner. Moreover, we found that the most damaged organ was the cerebrum, followed by the cerebellum, and then the optic lobe. These results show that the AVM-induced neurotoxicity may be associated with its effects on amino acid neurotransmitters and their receptors. The information presented in this study will help supplement the available data for future AVM toxicity studies.

Antioxidative role of selenoprotein W in oxidant-induced chicken splenic lymphocyte death.

To verify the antioxidative role of SelW in oxidant-induced chicken splenic lymphocyte, in this report, the influence of selenite supplementation and SelW gene silence on H2O2-mediated cell viability and cell apoptosis in cultured splenic lymphocyte derived from spleen of chicken were examined. The cultured cells were treated with sodium selenite and H2O2, or knocked down SelW with small interfering RNAs (siRNAs). The lymphocytes were examined for cell viability, cell apoptosis and mRNA expression levels of SelW and apoptosis-related genes (Bcl-2, Bax, Bak-1, caspase-3 and p53). The results show that the mRNA expression of SelW were effectively increased after treatment with sodium selenite, and H2O2-induced cell apoptosis was significantly decreased and cell viability was significantly increased. 20 µM H2O2 was found to induce cell apoptosis and decrease cell viability, which was alleviated obviously when cells were pretreated with sodium selenite before exposure to 20 µM H2O2. Meanwhile, H2O2 induced a significantly up-regulation of the Bax/Bcl-2 ratio, Bax, Bak-1, caspase-3 and p53 and down-regulation of Bcl-2 (P < 0.05). When lymphocytes were pretreated with Se before treated with H2O2, the Bax/Bcl-2 ratio and mRNA expression of those genes were significantly decreased, and Bcl-2 was increased (P < 0.05). SelW siRNA-transfected cells were more sensitive to the oxidative stress induced by treatment of H2O2 than control cells. Silencing of the lymphocyte SelW gene decreased their cell viability, and increased their apoptosis rate and susceptibility to H2O2. Silencing of SelW significantly up-regulated the Bax/Bcl-2 ratio, Bax, Bak-1, caspase-3 and p53 and down-regulated Bcl-2 (P < 0.05). The present study demonstrates that SelW plays an important role in protection of splenic lymphocyte of birds from oxidative stress.

Protective effects of selenium on cadmium-induced brain damage in chickens.

Selenium (Se) is an important dietary micronutrient with antioxidative roles. Cadmium (Cd), a ubiquitous environmental pollutant, is known to cause brain lesion in rats and humans. However, little is reported about the deleterious effects of subchronic Cd exposure on the brain of poultry and the protective roles on the brain by Se against Cd. The aim of this study was to investigate the protective effects of Se on Cd-induced brain damage in chickens. One hundred twenty 100-day-old chickens were randomly assigned to four groups and were fed a basal diet, or Se (as 10 mg Na2SeO3/kg dry weight of feed), Cd (as 150 mg CdCl2/kg dry weight of feed), or Cd + Se in their basic diets for 60 days. Then, concentrations of Cd and Se, production of nitric oxide (NO), messenger RNA (mRNA) level and activity of inducible NO synthase (iNOS), level of oxidative stress, and histological and ultrastructural changes of the cerebrum and cerebellum were examined. The results showed that Cd exposure significantly increased Cd accumulation, NO production, iNOS activities, iNOS mRNA level, and MDA content in the cerebrum and cerebellum. Cd treatment obviously decreased Se content and antioxidase activities and caused histopathological changes in the cerebrum and cerebellum. Se supplementation during dietary Cd obviously reduced Cd accumulation, NO production, mRNA level and activity of iNOS, oxidative stress, and histopathological damage in the cerebrum and cerebellum of chickens. It indicated that Se ameliorates Cd-induced brain damage in chickens by regulating iNOS-NO system changes, and oxidative stress induced by Cd and Se can serve as a potential therapeutic for Cd-induced brain lesion of chickens.

Cold stress induces antioxidants and Hsps in chicken immune organs.

The aim of this study was to investigate the effects of cold stress on oxidative indexes, immune function, and the expression levels of heat shock protein (Hsp90, Hsp70, Hsp60, Hsp40, and Hsp27) in immune organs of chickens. Two hundred forty 15-day-old male chickens were randomly divided into 12 groups and kept under the temperature of (12 ± 1) °C for acute and chronic cold stress. There were one control group and five treatment groups for acute cold stress and three control groups and three treatment groups for chronic cold stress. The results showed that cold stress influence the activities of antioxidant enzymes in the immune organs. The activities of SOD and GSH-Px were first increased then decreased, and activity of total antioxidation capacity (T-AOC) was significantly decreased (P < 0.05) at the acute cold stress in chicks; however, T-AOC activities were significantly increased (P < 0.05) at the chronic cold stress in these tissues. Cold stress induced higher level of malondialdehyde (MDA) in chicken immune organs. In addition, the cytokine contents were increased in cold stress groups. As one protective factor, the expression levels of Hsps were increased significantly (P < 0.05) in both cold stress groups. These results suggested that cold stress induced the oxidative stress in the three tissues and influenced immune function of chicks. Higher expression of Hsps (Hsp90, Hsp70, Hsp60, Hsp40, and Hsp27) may play a role in protecting immune organs against cold stress.

The role of heat shock proteins in inflammatory injury induced by cold stress in chicken hearts.

The aim of this study was to investigate the effects of cold stress on the expression levels of heat shock proteins (Hsps90, 70, 60, 40, and 27) and inflammatory factors (iNOS, COX-2, NF-κB, TNF-α, and PTGEs) and oxidative indexes in hearts of chickens. Two hundred forty 15-day-old male chickens were randomly divided into 12 groups and kept at the temperature of 12 ± 1 °C for acute and chronic cold stress. There were one control group and five treatment groups for acute cold stress, three control groups, and three treatment groups for chronic cold stress. After cold stress, malondialdehyde level increased in chicken heart; the activity of superoxide dismutase and glutathione peroxidase in the heart first increased and then decreased. The inflammatory factors mRNA levels were increased in cold stress groups relative to control groups. The histopathological analysis showed that heart tissues were seriously injured in the cold stress group. Additionally, the mRNA levels of Hsps (70, 60, 40, and 27) increased significantly (P < 0.05) in the cold stress groups relative to the corresponding control group. Meanwhile, the mRNA level and protein expression of Hsp90 decreased significantly (P < 0.05) in the stress group, and showed a gradually decreasing tendency. These results suggested that the levels of inflammatory factors and Hsps expression levels in heart tissues can be influenced by cold stress. Hsps commonly played an important role in the protection of the heart after cold stress.

Effects of atrazine and chlorpyrifos on the production of nitric oxide and expression of inducible nitric oxide synthase in the brain of common carp (Cyprinus carpio L.).

The study aimed to investigate the effects of atrazine (ATR), chlorpyrifos (CPF), and the mixture of them on nitric oxide (NO) and inducible nitric oxide synthase (iNOS) in the brain of common carp. The triazine herbicide ATR and the organophosphorus insecticide CPF are frequently and extensively applied in agriculture all over the world. 220 Carps were averagely divided into eleven groups according to the different treatments and concentration, including the exposure and recovery experiments. In the present study, we investigated production of NO, iNOS activity and iNOS mRNA and protein expression in the brain of the common carp after a 40d exposure to ATR, CPF, alone or in combination, and a 40d recovery treatment. The results showed that the activity of iNOS and production of NO were significantly higher in all groups of fish exposed to high doses ATR, CPF and their mixture compared to control fish. After a 40d recovery treatment, iNOS activity and production of NO were lower than in the corresponding exposure groups in all the recovery groups. The mRNA and protein levels of iNOS were significantly higher in the high-dose group of ATR and CPF compared to control group, but were significantly lower in the group of the mixture of ATR and CPF compared to control group. Results indicated that NO and iNOS were involved in oxidative stress and brain tissue damage induced by ATR, CPF, and their mixture. Thus, the information presented in this study is helpful to understand the mechanism of ATR-, CPF- and ATR/CPF-mixture-induced neurotoxicity in fish.

Gene expression of endoplasmic reticulum resident selenoproteins correlates with apoptosis in various muscles of se-deficient chicks.

Dietary selenium (Se) deficiency causes muscular dystrophy in various species, but the molecular mechanism remains unclear. Our objectives were to investigate: 1) if dietary Se deficiency induced different amounts of oxidative stress, lipid peroxidation, and cell apoptosis in 3 skeletal muscles; and 2) if the distribution and expression of 4 endoplasmic reticulum (ER) resident selenoprotein genes (Sepn1, Selk, Sels, and Selt) were related to oxidative damages in these muscles. Two groups of day-old layer chicks (n = 60/group) were fed a corn-soy basal diet (33 µg Se/kg; produced in the Se-deficient area of Heilongjiang, China) or the diet supplemented with Se (as sodium selenite) at 0.15 mg/kg for 55 d. Dietary Se deficiency resulted in accelerated (P < 0.05) cell apoptosis that was associated with decreased glutathione peroxidase activity and elevated lipid peroxidation in these muscles. All these responses were stronger in the pectoral muscle than in the thigh and wing muscles (P < 0.05). Relative distribution of the 4 ER resident selenoprotein gene mRNA amounts and their responses to dietary Se deficiency were consistent with the resultant oxidative stress and cell apoptosis in the 3 muscles. Expression of Sepn1, Sels, and Selt in these muscles was correlated with (r > 0.72; P < 0.05) that of Sepsecs encoding a key enzyme for biosynthesis of selenocysteine (selenocysteinyl-tRNA synthase). In conclusion, the pectoral muscle demonstrated unique expression patterns of the ER resident selenoprotein genes and GPx activity, along with elevated susceptibility to oxidative cell death, compared with the other skeletal muscles. These features might help explain why it is a primary target of Se deficiency diseases in chicks.

Effects of cold stress on mRNA expression of immunoglobulin and cytokine in the small intestine of broilers.

To investigate the effects of cold stress on mRNA expression of immunoglobulin and cytokine in small intestine of broilers, eighty-four 15-day-old male chickens were randomly divided into 12 groups. There were 1 control (25°C) and 5 acute stress groups (under the temperature of 12 ± 1°C) for 1, 3, 6, 12 and 24h, 3 control (25°C) and 3 chronic cold stress groups (under the temperature of 12 ± 1°C) for 5, 10, and 20d. The mRNA expression levels of IL-2, IL-4, IL-7, IL-10, IL-17, IFN-γ, IgA, IgM, IgG, plgR, and TGF-ß4 in duodenum, jejunum and ileum were detected by real-time PCR. The results showed that expression levels of IgM, IgA, IgG, plgR and IL-7 had an increased tendency in acute and chronic cold stress, especially plgR that was markedly increased in the duodenum than jejunum and ileum in the acute cold stress. In addition, the mRNA expression levels of IL-2, IFN-γ, IL-4, IL-17 and TGF-ß4 had a first increased then decreased tendency in acute and chronic cold stress groups, however, expression levels of IL-4 were higher in the stress groups than control groups. The histopathological detect showed that issues in cold stress group was seriously injured. These results demonstrated that cold stress could cause the change of immune function in chicken intestinal.

Selenoprotein W serves as an antioxidant in chicken myoblasts.

BACKGROUND: Selenoprotein W (SelW) was thought to play an antioxidant role in mammals. Because chicken SelW has no cysteine (Cys) at the residue 37 (Cys37) that is required for the presumed antioxidant function in mammals, this study was conducted to determine whether chicken SelW possessed the same function. METHODS: Small interfering RNAs (siRNAs) technology was applied to suppress the SelW expression in chicken embryonic myoblasts. Thereafter, these myoblasts were treated with different concentrations of H2O2 and assayed for cell viability, apoptosis rate, reactive oxygen species (ROS) status, and expression levels of apoptosis-related genes and proteins (Bax, Bcl-2, and caspase-3). RESULTS: Silencing of the myoblast SelW gene decreased their cell viability, and increased their apoptosis rate and susceptibility to H2O2. While the knockout down of SelW up-regulated Bax and caspase-3 and down-regulated Bcl-2, the induced oxidative injuries were alleviated by treatment with a ROS scavenger, N-acetyl-l-cysteine (NAC). CONCLUSION: Chicken SelW protected embryonic myoblasts against cell apoptosis mediated by endogenous and exogenous H2O2. GENERAL SIGNIFICANCE: Chicken SelW possesses antioxidant function similar to the mammalian homologues despite the lack of Cys37 in the peptide.

The oxidative damage and disbalance of calcium homeostasis in brain of chicken induced by selenium deficiency.

Dietary selenium (Se) deficiency can influence the function of the brain. Our objective was to investigate the effects of Se deficiency on oxidative damage and calcium (Ca) homeostasis in brain of chicken. In the present study, 1-day-old chickens were fed either a commercial diet (as control group) with 0.15 mg/kg Se or a Se-deficient diet (as L group) with 0.033 mg/kg Se for 75 days. Then, brain injury biomarkers were examined, including histological analysis, ultrastructure assay, and apoptosis assay. We also examined the effect of Se deficiency on the Se-containing antioxidative enzyme glutathione peroxidase (GSH-Px), the level of glutathione (GSH), and the Ca homeostasis in brain of chicken. The results showed that the levels of Se and GSH and activity of GSH-Px are seriously reduced by 33.8-96 % (P < 0.001), 24.51-27.84 % (P < 0.001), and 20.70-64.24 % (P < 0.01), respectively. In the present study, we also perform histological analysis and ultrastructure assay and find that Se deficiency caused disorganized histological structure, damage to the mitochondria, fusion of nuclear membrane and nucleus shrinkage, higher apoptosis rate (P < 0.001), and increase of Ca homeostasis (P < 0.05 or P < 0.01 or P < 0.001) in the brain of chicken. In conclusion, the results demonstrated that Se deficiency induced oxidative damage and disbalance of Ca homeostasis in the brain of chicken. Similar to mammals, chickens brain is also extremely susceptible to oxidative damage and selenium deficiency.

Possible correlation between selenoprotein W and myogenic regulatory factors in chicken embryonic myoblasts.

The biological function of selenium (Se) is mainly elicited through Se-containing proteins. Selenoprotein W (SelW), one member of the selenoprotein family, is essential for the normal function of the skeletal muscle system. To investigate the possible relationship of Se in the process of differentiation in chicken myoblasts and the expression of SelW, the cultured chicken embryonic myoblasts were incubated with sodium selenite at different concentrations for 72 h, and then the mRNA levels of SelW and myogenic regulatory factors (MRFs) in myoblasts were determined at 12, 24, 48, and 72 h, respectively. Furthermore, the correlation between SelW mRNA expression and MRF mRNA expression was assessed. The results showed that the sodium selenite medium enhanced the mRNA expression of SelW, Myf-5, MRF4, and myogenin in chicken myoblasts. The mRNA expression levels of MRFs were significantly correlated with those of SelW at 24, 48, and 72 h. These data demonstrate that Se is involved in the differentiation of chicken embryonic myoblasts, and SelW showed correlation with MRFs.

The disruption of mitochondrial metabolism and ion homeostasis in chicken hearts exposed to manganese.

Exposure to high levels of manganese (Mn) can result in cardiotoxicity in animals. However, little is known about the effect of excess Mn on poultry hearts. The aim of this study was to investigate the effect of dietary Mn on chicken cardiac injuries and the possible mechanisms of this process. In the present study, 400 fifty-day-old Hy-line brown cocks were randomly divided into four groups, and were fed either a commercial diet (containing 100mg/kg Mn) or a Mn-supplemented diet containing 600mg/kg, 900mg/kg, or 1800mg/kg Mn for 30, 60 or 90 days, respectively. Next, we examined several biomarkers of cardiac injury, including biochemical blood serum analyses, electrocardiogram assays, histological analyses, ultra-structural assays and apoptosis assays. To investigate the possible mechanisms of Mn-induced cardiotoxicity, we examined the effect of MnCl(2) on mitochondrial function and metal ion homeostasis. We found that subchronic MnCl(2) exposure induced damage in chicken hearts. Further investigations indicated that possible mechanisms for Mn-induced chicken cardiac injury included the disruption of mitochondrial metabolism and the alteration of ion homeostasis.