J. Wang

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.

Effects of dietary oxidized oil on laying performance, lipid metabolism, and apolipoprotein gene expression in laying hens.

We studied the effects of dietary oxidized oils on serum lipid metabolic indices, estradiol level, and the gene expression of apolipoprotein B-100 and apolipoprotein VLDL-II in laying hens. Hy-Line Grey hens (280 ± 10 d old; average egg production, 90.0 ± 2.5%) were allotted to 1 of 4 dietary treatments, which were supplemented with 0 (control group), 1% (low oxidized group), 2% (moderately oxidized group), or 4% (highly oxidized group) thermally oxidized soybean oil. Each treatment contained 6 replicates, with 12 birds each. The feeding trial lasted for 30 d. Laying performance data were recorded weekly. Other indices were measured on d 0, 2, 6, 14, and 30 of the feeding trial. Hens in the moderately and highly oxidized groups had significantly lowered feed conversion ratios (P < 0.05). Those in the highly oxidized group also had decreased concentrations of serum very low density lipoprotein cholesterol on d 30 (P < 0.05) compared with the very low density lipoprotein cholesterol of hens in the moderately oxidized group. Hens in the moderately oxidized group had significantly increased expression of apolipoprotein B-100 (P < 0.05) from d 6 to 30. Consequently, hepatic triglyceride increased in this group on d 30 (P < 0.05). Serum triglyceride decreased in the moderately oxidized group on d 30 (P < 0.05), which may have been caused by the activation of peroxisome proliferator-activating receptor α. Serum estradiol levels were not significantly affected by oxidized oils at any time of measurement, but were significantly different between d 0 and 30 within the moderately oxidized group. This fact indicated that the effect of oxidized oils on apolipoprotein B-100 might partially be a cumulative result of the increasing secretion of estradiol. The results suggested that oxidized oil may affect the performance of laying hens through the regulation of apolipoproteins and estradiol.

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 dietary pyrroloquinoline quinone disodium on growth, carcass characteristics, redox status, and mitochondria metabolism in broilers

The potential benefits of supplementing pyrroloquinoline quinone disodium (PQQ·Na2) in the diet of broiler chicks were explored. We first examined the effect of different levels of dietary PQQ·Na2 on growth performance, carcass characteristics, and plasma biochemical parameters (trial 1). A total of 490 1-day-old male Arbor Acres (AA) broiler chicks were randomly divided into 5 dietary groups supplemented with 0, 0.05, 0.1, 0.2, or 0.4 mg PQQ·Na2/kg feed. As the 0.2 mg/kg PQQ·Na2 supplement gave the best performance, we then investigated whether this level of PQQ·Na2 influenced the redox status of plasma samples and mitochondrial-related metabolism (trial 2). A total of 120 1-day-old male AA chicks were randomly divided into 2 groups supplemented with 0 or 0.2 mg PQQ·Na2/kg diet. In trial 1, birds fed a diet containing 0.2 mg PQQ·Na2/kg showed lower feed conversion ratio compared with those fed the control diet in the overall study (d 1 to 42, P=0.039). Breast muscle yield (d 42) increased quadratically in response to dietary PQQ·Na2 supplementation (P=0.021). Analysis of plasma biochemical parameters revealed that feeding broiler chicks with ≤0.4 mg/kg PQQ·Na2 did not cause adverse health effects. In trial 2, birds fed 0.2 mg/kg PQQ·Na2 again showed improved feed efficiency than the control birds in the grower and overall phases (P=0.038 and 0.016, respectively). In addition, dietary PQQ·Na2 supplementation resulted in a higher anti-oxidative capacity (P=0.001), lower redox potential (P=0.008), and higher hepatic citrate synthase activity (P=0.002). In contrast, no difference in hepatic mitochondrial DNA copy number was observed between the 2 experimental groups (P>0.1). These results indicate that PQQ·Na2 is a potentially effective feed additive for improving feed efficiency, stimulating breast muscle development, and maintaining redox status in broiler chicks. Enhancement of mitochondria efficiency, rather than modulating mitochondria numbers, may underlie the growth-promoting effect of PQQ·Na2.

Trimethylamine deposition in the egg yolk from laying hens with different FMO3 genotypes

The A/T polymorphism at position nt 1,034 of the chicken FMO3 cDNA sequence is associated with elevated levels of trimethylamine (TMA) in the egg yolk, which is responsible for the fishy egg flavor. This study was aimed to investigate yolk TMA deposition in eggs from different FMO3 genotype (AA, AT, TT) laying hens fed a high level of choline, and the relationship between egg yolk TMA contents and yolk acceptability. A total of 132 genotyped laying hens, 38 wk of age, were assigned to 1 of the 4 dietary treatments: 1) a control group of AA hens fed 370 mg of choline/kg of diet (practical choline level, provided by 500 mg of choline chloride/kg of diet); 2) AA hens were fed 2,960 mg of choline/kg of diet (higher dietary choline level, provided by 4,000 mg of choline chloride/kg of diet); 3) AT hens were fed 2,960 mg of choline/kg of diet; and 4) TT hens were fed 2,960 mg of choline/kg of diet. All layers were fed a 370 mg of choline/kg added diet for a period of 1-wk adaptation followed by a 6-wk trial period. A remarkable increase in yolk TMA concentration of TT hens (P < 0.001) caused by dietary choline addition at 2,960 mg/kg was observed. The relationship between TMA concentration in the egg yolk (μg/g, y) and deposition time (1~42 d, x) for TT hens is y = 0.0005x(3) - 0.0419x(2) + 1.0924x + 0.4323 (R(2) = 0.9259). The fish-flavor scores of egg yolks rose steadily (R(2) = 0.9324) as the TMA concentration increased, and there was also a corresponding decrease in the acceptance score (R(2) = 0.8276). The eggs were acceptable when the yolk TMA concentrations were less than 4.516 μg/g of yolk.

Effect of dietary choline supplementation under different flavin-containing monooxygenase 3 genotypes on trimethylamine metabolism in laying hens

To evaluate the effect of flavin-containing monooxygenase 3 (FMO3) genotype and dietary choline supplementation on trimethylamine (TMA) metabolism in HyLine Brown laying hens, a 3 × 2 two-factorial arrangement was employed with FMO3 genotypes (AA, AT, and TT) and dietary choline supplemental levels (370 and 2,960 mg/kg of diet) as main effects. At 46 wk of age, 108 hens of AT genotype and 108 hens of TT genotype were randomly allotted to one of the 2 dietary treatments, and each dietary treatment consisted of 6 replicates with 9 birds each. A total of 24 hens with AA genotype was allotted to one of the 2 dietary treatments that consisted of 6 replicates with 2 hens. Hens were fed the diet with 370 mg/kg of choline supplementation for 1 wk of adaptation followed by a 6-wk trial period. Yolk TMA concentration was increased by dietary supplemental choline at 2,960 mg/kg (P < 0.05), and TT hens showed a higher TMA content in egg yolks than that in AA and AT hens (P < 0.05). Dietary supplementation of choline at 2,960 mg/kg increased the TMA concentration of cecal chyme (P < 0.05) and serum (P < 0.05). Hepatic FMO3 mRNA levels in hens were reduced by higher choline added to the diet (P < 0.05). The TMA and methimazole oxidation rate in AA hens was higher than those in AT and TT hens (P < 0.05). A higher choline diet decreased hepatic FMO3 activity by 33.99% (P < 0.05) and 61.39% (P < 0.05) toward TMA and methimazole, respectively. These results suggest that lower hepatic FMO3 activity caused by the mutation may be responsible for the genotype difference in the TMA metabolism. Exposure to a high dosage of dietary choline increased TMA synthesis in the cecum, suppressed activity of FMO3 in liver, and consequently aggravated the burden of TMA metabolism, especially in TT hens.