Shiwen Xu

Effects of atrazine and chlorpyrifos on activity and transcription of glutathione S-transferase in common carp (Cyprinus carpio L.).

Glutathione S-transferase isoenzymes (GSTs) play a critical role in detoxification pathways. Here we report the tissue distribution of four antioxidant GSTs gene in common carp, and their expression profiles. We also investigated the GSTs activity in different tissues after exposure to the agricultural chemicals atrazine (ATR), chlorpyrifos (CPF), and their mixture. Relative changes in the mRNA abundance of the GST isoforms were examined by real time PCR in liver, brain, kidney and gill of common carp. After exposure and recovery, we observed a statistically significant decrease in the GSTs activity in animals exposed to high concentrations of ATR (428 μg/L), CPF (116 μg/L), and their mixture (113 μg/L). At basal levels of tissue expression, four GSTs transcript were detected in liver, brain, kidney, and gill. High expression levels were found in all examined tissues. Transcription of some GST isoforms, GST kappa (GSTK), GST theta (GSTT) and GST rho (GSTR), decreased after exposure to CPF and ATR for the entire experimental period in both the kidney and gill. However, increased transcription of GST mu (GSTM) was observed in the kidney or gill 20 d after exposure to ATR or CPF, respectively. Transcription of both GSTT and GSTR was inhibited for the entire experimental period in the brain, kidney and gill of animals exposed to the ATR/CPF mixture, but transcription of GSTM was induced in the liver after 40 d of exposure. In summary, changes in the GSTs activity and their transcription varied within each organ and among organs of common carp after exposure to ATR, CPF, and their mixture.

Effects of atrazine and chlorpyrifos on the mRNA levels of IL-1 and IFN-γ2b in immune organs of common carp.

Atrazine (ATR) and chlorpyrifos (CPF) are widely used in agriculture has resulted in a series of toxicological and environmental problems. The aim of this study was to investigate the effects of ATR, CPF and their mixture on the mRNA levels of interleukin-1β (IL-1β), interleukin receptor I (IL-1RI) and interferon gamma (IFN-γ2b) in both spleen and head kidney of Common carp. In this study, juvenile common carp were exposed to ATR (at concentrations of 4.28, 42.8 and 428 μg/L), CPF (at concentrations of 1.16, 11.6 and 116 μg/L), and their mixture (at concentrations of 1.16, 11.6 and 116 μg/L). The mRNA levels of IL-1β, IL-1R1 and IFN-γ2b in spleen and head kidney were detected by using RT-PCR. Our results indicated that IL-1β, IL-1R1 expression significantly increased after exposure in high concentration ATR, CPF and their mixture, but IFN-γ2b mRNA shown different expression trends. Our results suggested that ATR, CPF and their mixture probably induced damages on spleen and head kidney may be association with increasing IL-1β, IL-1R1 mRNA synthesis. After 20-day recovery test, IL-1β, IL-1R1 and IFN-γ2b mRNA expression remain at high level in majority of the treated groups, we concluded that the restoration of tissue and immune system damage probably needs longer time.

Effects of cold stress on nitric oxide in duodenum of chicks

Animals may suffer from a variety of environmental stressors every day, among which is cold stress, which commonly exists in cold regions. The aim of this study was to investigate changes in antioxidative function and inducible nitric oxide synthase-nitric oxide (iNOS-NO) system activity in the duodenum of chicks as a reaction to cold stress. A total of 84 male chicks (15 d old) were randomly allocated to 12 groups (7 chickens/group). There were 1 control group and 5 treatment groups for acute cold stress and 3 control groups and 3 treatment groups for chronic cold stress. Antioxidative function was examined by superoxide dismutase (SOD), and oxidative damage was examined by malondialdehyde (MDA) detection. The iNOS-NO system activity was identified by NO content and NOS activity assay, and the transcription of iNOS mRNA was tested by fluorescence quantitative PCR. The results showed that under acute cold stress MDA level increased, the activity of NO in the duodenum fluctuated, and the activity of SOD and iNOS in the duodenum first increased and then decreased, whereas the expression of iNOS mRNA decreased. Under chronic cold stress the activity of SOD, NO, and NOS first decreased and then increased, whereas the MDA level and the expression of iNOS mRNA increased. The results indicated that both acute and chronic cold stress could cause duodenum oxidative stress and change in iNOS, which was related to the intestinal damage process.

Effects of atrazine and chlorpyrifos on acetylcholinesterase and Carboxylesterase in brain and muscle of common carp

The aim of this study was to investigate the effects of chlorpyrifos (CPF), atrazine (ATR) and the mixture of them on acetylcholinesterase (AChE) and carboxylesterase (CbE) in brain and muscle of common carp, respectively. 220 carps were averagely divided into 11 groups according to the different treatments and concentration, including the exposure and recovery experiments. The activities of AChE and CbE of the brain and muscle were determined at the end of the exposure and the recovery. The results showed that in the control group, the specific enzymatic activities in the brain were higher than that in the muscle. The activities of AChE and CbE in the exposure groups were significantly lower than that in the control group except for the CbE activity in the ATR low-dose group. There was a negative dose-response relationship between the activities of AChE and CbE and the pesticides concentration. The activities of AChE and CbE in the recovery groups were significantly higher than that in the exposure group except for the CbE activity in the ATR low-dose group, AChE activity in the high-dose group of the mixture of ATR and CPF, and AChE activity of the brain in the CPF high-dose group. The results suggested that: (1) brain AChE may be considered as a very sensitive and early biomarker of exposure to CPF, ATR, or the mixture of ATR and CPF, (2) brain CbE may be used as a secondary biomarker for evaluating the exposure to CPF, ATR, or the mixture of ATR and CPF and (3) the change of the AChE and CbE activities caused by the mixture of ATR and CPF was more sensitive than that caused by the ATR or CPF alone.

Effects of subchronic cadmium poisoning on DNA methylation in hens.

Cadmium is a persistent pollutant that poses a threat to most biological organisms including birds. Although toxicity of cadmium is mainly linked to cancer, the mechanism of its carcinogenic activity remains poorly understood. Since DNA methylation is linked to cancer, we have examined the effect of cadmium on DNA methylation and DNMTs mRNA expression in hen liver and kidney. Sixty 50-day-old hyline-white hens were randomly allocated into 3 equal groups; a control group fed a basal diet, a low-dose group fed the basal diet spiked with 140mg/kg CdCl(2), and a high-dose group fed the basal diet spiked with 210mg/kg CdCl(2). After 60 days, liver and kidney samples were analysed for cadmium by FAAS, DNA methylation level by HPLC and DNMTs mRNA levels by semi-quantitative RT-PCR. The DNA methylation levels and the expressions of DNMT1 and DNMT3a mRNA in liver and kidney were significantly elevated by the cadmium treatment but there was no change in the expression of DNMT3b mRNA in the two tissues. The fact that cadmium increases DNA methylation and the expressions of DNMT1 and DNMT3a mRNA in liver and kidney suggests DNA methylation may be involved in the carcinogenic action of cadmium.

Alterations in mRNA expression of acetylcholinesterase in brain and muscle of common carp exposed to atrazine and chlorpyrifos.

The uses of pesticides and herbicides have become an integral part of modern agricultural systems. The intensive use of pesticides chlorpyrifos (CPF) and herbicides atrazine (ATR) has resulted in serious environmental problems. Herein, we have developed real-time quantitative polymerase chain reaction assays for common carp (Cyprinus carpio L.) mRNA. The levels of AChE mRNA were evaluated in brain and muscle collected from common carp by treatment of ATR, CPF, and their mixture. The decreased transcription of AChE was detected in both tissues at different doses of the toxicants in the end of exposure tests, and the changes were improved in the end of recovery tests in varying degrees. It is suggested that transcription inhibition of AChE might be significant in long-playing single or associated exposure of ATR and CPF in common carp. Alteration in transcription of AChE caused by ATR, CPF, and their mixture could reveal the toxic mechanisms related to cholinergic signaling.

Avermectin induced liver injury in pigeon: Mechanisms of apoptosis and oxidative stress

Extensive use of avermectin (AVM) can result in environment pollution, and it is important to evaluate the potential impact this antibiotic has on ecological systems. Few published literatures have discussed the liver injury mechanisms induced by AVM on birds. In this study, pigeons were exposed to feed containing AVM (0, 20, 40 and 60 mg/kg diet) for 30, 60, 90 days respectively. The results showed that AVM increased the number of apoptosis and the expression level of caspase-3, 8, fas mRNA in the liver of pigeons. Ultrastructural alterations, including mitochondrial damage and chromatin aggregation, become severe with increase exposure dose. Exposure to AVM induced significant changes in antioxidant enzyme {superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px)} activities and malondialdehyde (MDA) content, augmented protein carbonyl (PCO) content and DNA-protein crosslink (DPC) coefficient, in a concentration-dependent manner in the liver of pigeons. Our results show that AVM has toxic effect in pigeon liver, and the mechanism of injury caused by AVM is closely related to apoptosis and oxidative stress.

Effects of cold stress on the messenger ribonucleic acid levels of peroxisome proliferator-activated receptor-γ in spleen, thymus, and bursa of Fabricius of chickens

This study was to investigate the expression trait of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) gene and the effect of cold stress on the mRNA levels of PPAR-gamma in spleen, thymus, and bursa of Fabricius of chickens. Eighty-four 1-d-old male chickens were randomly allocated to 12 groups (7 chickens per group). There was 1 control group and 5 treatment groups for acute cold stress and 3 control groups and 3 treatment groups for chronic cold stress. Chickens were maintained in our animal facility, kept under a 16L:8D cycle and temperature (30 +/- 2 degrees C), and given free access to standard chow and water. The cold stress was initiated when the birds were 15 d of age, with the duration of the acute cold stress being 1, 3, 6, 12, and 24 h, and the chronic cold stress was 5, 10, and 20 d, respectively. Cold stress temperature was 12 +/- 1 degrees C. Spleen, thymus, and bursa of Fabricius were collected for the assessment of the mRNA levels by real-time PCR after stress termination. The results showed that the PPAR-gamma gene is expressed in spleen, thymus, and bursa of Fabricius, and its expression level is different in different tissues and at different ages. Acute cold stress significantly decreased (P < 0.05) the mRNA levels of the PPAR-gamma gene of spleen and thymus in all treatment groups and significantly increased (P < 0.05) the mRNA levels of the PPAR-gamma gene of bursa of Fabricius in all treatment groups. Compared with the corresponding control groups, chronic cold stress resulted in a significant increase (P < 0.05) of the mRNA levels of the PPAR-gamma gene in spleen and a significant decrease (P < 0.05) of the mRNA levels of the PPAR-gamma gene in thymus and bursa of Fabricius. The results indicate that the PPAR-gamma gene is expressed in all 3 immune organs and has different expression traits. The magnitude and direction of change in PPAR-gamma gene expression differs with the type of cold stress applied and also varies by tissue.

Effects of zearalenone on calcium homeostasis of splenic lymphocytes of chickens in vitro

Zearalenone (ZEA) is an estrogenic mycotoxin. It is produced by several Fusarium species and can contaminate food and feed. To investigate the role of calcium homeostasis in ZEA-induced toxicity of poultry and elucidate its cytotoxic mechanism, splenic lymphocytes isolated from chickens were exposed to ZEA (0-25 μg/mL) for 48 h. The intracellular calcium concentration ([Ca2+]i), pH, calmodulin (CaM) mRNA levels, and Na+/K+-ATPase activities and Ca2+-ATPase activities were detected by the fluorescent dyes Fluo-3/AM and BCECF/AM, quantitative real-time PCR, and chromatometry. Supernatant CaM concentrations were simultaneously detected by ELISA. As the ZEA exposure concentration increased, the [Ca2+]i and CaM mRNA levels gradually increased, while intracellular pH, CaM concentrations of supernatants, and intracellular Na+,K+-ATPase and Ca2+-ATPase activities gradually decreased in a dose-dependent manner. There were significant differences (P<0.05 or P<0.01) between the treatment groups and the control group. These results indicate that ZEA cytotoxicity arises by causing an imbalance in calcium homeostasis and intracellular acidification in lymphocytes.