Apoptosis of tiger shrimp (Penaeus monodon) haemocytes induced by Escherichia coli lipopolysaccharide

This study was aimed at investigating the toxicity mechanism of lipopolysaccharide (LPS) on Penaeus monodon haemocytes at a cellular level. Reactive oxygen species (ROS) production, nitric oxide (NO) production, non-specific esterase activity, cytoplasmic free-Ca^2 + (CF-Ca^2 +) concentration, DNA damaged cell ratio and apoptotic cell ratio of in vitro LPS-treated haemocytes were measured by flow cytometry. Two concentrations of Escherichia coli LPS (5 and 10 μg mL^? 1) were used. Results showed that ROS production, NO production and CF-Ca^2 + concentration were significantly induced in the LPS-treated haemocytes. Ratio of DNA damaged cell and apoptotic cell increased caused by LPS, while esterase activity increased at the initial 60 min and dropped later. The initial increase in esterase activity suggested that LPS activated the release of esterase, and the later decrease might result from apoptosis. These results indicated that LPS would induce oxidative stress on shrimp haemocytes, and cause Ca^2 + release, DNA damage and subsequently cell apoptosis. This process of ROS/RNS-induced Ca^2 +-mediated apoptosis might be one of the toxicity mechanisms of LPS on shrimp haemocytes.     

An immune responsive multidomain galectin from bay scallop Argopectens irradians

Galectins are a family of β-galactoside-binding lectins which play crucial roles in innate immunity of vertebrates and invertebrates. In the present study, the cDNA of a galectin with multiple carbohydrate-recognition domains (CRDs) was cloned from bay scallop Argopectens irradians (designated AiGal1) by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) techniques. The full-length cDNA of AiGal1 was of 2235 nucleotides, encoding a polypeptide of 549 amino acids. SMART program analysis revealed that AiGal1 contained four galectin CRDs, and all the CRDs contained the two consensus motifs essential for ligand-binding. Quantitative real-time PCR was employed to investigate the tissue distribution of AiGal1 mRNA and temporal expression in haemocytes of scallops challenged with Vibrio anguillarum, Micrococcus luteus and Pichia pastoris. The AiGal1 mRNA could be detected in all tested tissues with the highest expression level in hepatopancreas. After challenged by V. anguillarum and M. luteus, the expression level of AiGal1 mRNA was both up-regulated and reached the maximum level at 9 h (1.52 fold, P < 0.05) and 18 h (2.89 fold, P < 0.01) post challenge, respectively. However, there was no significant difference in the mRNA expression of AiGal1 in haemocytes after P. pastoris challenge (P > 0.05). These results collectively indicated that AiGal1 was a new member of the galectin family and involved in the immune responses against bacterial infection.     

Plasma paraoxonase-1, oxidized low-density lipoprotein and lipid peroxidation levels in gout patients

Gout patients have a high incidence of atherosclerotic coronary heart disease. Low serum paraoxonase (PON) activity is considered a risk factor for atherosclerosis. The relationships among paraoxonase-1 (PON1) activity, oxidative stress parameters, and atherosclerosis in gout is not known. Therefore, we determined the plasma levels of malondialdehyde (MDA), oxidized low-density lipoprotein (Ox-LDL), and activities of PON1/superoxide dismutase (SOD) activities in 49 gout patients (mean age 44.2 ± 7.0 years) and 42 healthy, age-matched controls (mean age 45.0 ± 9.3 years). PON1 was measured spectrophotometrically, MDA by thiobarbituric acid method, SOD by Griess reaction, and Ox-LDL by sandwich ELISA. Lipid and other biochemical parameters were determined by routine laboratory methods. In gout patients, PON1/SOD activities and MDA/Ox-LDL levels were 131.3 ± 25.3/75.3 ± 28.9 kU l⁻¹ and 6.12 ± 1.67 nmol ml⁻¹/690.1 ± 180.2 μg l⁻¹, respectively. In controls, these were 172.5 ± 27.8/94.0 ± 26.3 kU l⁻¹ and 4.10 ± 1.25 nmol ml⁻¹/452.3 ± 152.1 μg l⁻¹, respectively. Thus, in gout patients, there was a significant decrease in PON1 (P < 0.01) and SOD (P < 0.05) activities, and an increase in MDA (P < 0.01) and Ox-LDL (P < 0.01) levels compared with controls. PON1 activity correlated positively with SOD (P < 0.05), and negatively with MDA (P < 0.01) and Ox-LDL (P < 0.01). These results suggest that gout patients were in a state of oxidative stress and the protective effects of HDL against atherosclerosis maybe dependent on PON1 activity. These findings may explain in part the reported increase in cardiovascular mortality in gout patients.     

Plasma follicle stimulating hormone,ovulation rate and fertility in Merino ewes treated with bovine follicular fluid

Charcoal-treated bovine follicular fluid (bFF) given as four 5-ml subcutaneous injections to 13 Merino-Border Leicester ewes around the time of natural luteolysis suppressed (P<0.01) plasma levels of follicle stimulating hormone (FSH) [from 1.08 ± 0.05 to 0.41 ± 0.03, mean ± s.e.m. of log_e (ng+ 1) /mlplasma]. This was followed (P < 0.01) by hypersecretion or a rebound of FSH (to 1.46 ± 0.11) lasting 32 h in 10 of the treated ewes, and then by a further fall (to 0.73 ± 0.03, P < 0.05) before the surge (1.21 ± 0.07, P < 0.05) associated with the preovulatory surge of luteinizing hormone (LH).Plasma FSH at 56–72 h before the LH surge (i.e., at the time of the FSH rebound) was correlated with the subsequent ovulation rate (n=13, r= + 0.73, P < 0.01). Fewer ewes treated with four injections of 2 or 5 ml of bFF than control ewes (injected with bovine plasma) became pregnant (28 of 41 vs. 38 of 41, χ² = 4.05, P < 0.05), although plasma progesterone was similar at Day 11 in treated and control ewes. It is concluded that plasma FSH during such a rebound influences the subsequent ovulation rate in sheep.     

Effect of dietary β-glucan on growth performance,fecal microbial shedding and immunological responses after lipopolysaccharide challenge in weaned pigs

Two experiments (Exp.) were conducted to evaluate the effects of β-glucan inclusion in the diet on growth performance and immune function after lipopolysaccharide (LPS) challenge. In Exp. 1, a total of 40 weaned pigs (progeny of Landrace×Yorkshire sows by Duroc) with an initial body weight (BW) of 7.89 ± 0.84 kg (21 ± 2 d) of age) were used in a 28-day (d) experiment to determine the effects of dietary β-glucan on growth performance. Pigs were allotted randomly to two treatments consisting of addition of 0 or 0.1 g β-glucan/kg diet with four replicate pens per treatment and five pigs per pen. Growth performance was not affected by β-glucan supplementation throughout the experiment. However, dietary β-glucan reduced (P<0.05) the number of fecal Escherichia coli. In Exp. 2, a total of 20 weaned barrows (6.22 ± 0.25 kg of BW and 21 ± 2 d of age) individually raised in metabolic cages were used to evaluate immunological responses following LPS challenge. Pigs were fed 0 or 0.1 g β-glucan/kg diet for 42 d. At the end of the trial, half of the pigs (n = 5) from each treatment were injected intraperitoneal with E. coli LPS at a concentration of 100 μg/kg BW and the other half were injected with sterile saline solution. Treatments were arranged as a 2×2 factorial, with the main effect of LPS challenge (saline vs. LPS) and β-glucan supplementation (0 g/kg vs. 0.1 g/kg). After LPS injection, blood was taken at 0, 2, 4, 6, 8 and 12 hours (h) for the blood cell counts and blood inflammatory response. Dietary β-glucan increased (P<0.05) leukocytes counts at 4, 6 and 8 h, and blood lymphocyte concentrations at 2, 4 and 6 h and LPS challenge increased (P<0.05) counts of leukocytes at 2, 4, 6 and 8 h and blood lymphocyte at 2 and 4 h post-challenge. The rectal temperature was increased (P<0.05) at 2, 4, 6 and 8 h after LPS challenge. Dietary β-glucan reduced (P<0.05) and LPS challenge increased (P<0.05) blood plasma tumor necrosis factor-α (TNF-α) concentration at 2 and 4 h post-challenge. Dietary β-glucan increased (P<0.05) the concentration of the cluster of differentiation antigens 4 cells (CD4⁺) at 2, 4 and 6 h, and of 8 (CD8⁺) at 4 and 6 h post-challenge, respectively. The LPS challenge increased (P<0.05) CD4⁺ and CD8⁺ cell concentrations at 2, 4 and 6 h post-challenge. The CD4⁺:CD8⁺ ratio was reduced (P<0.05) by LPS challenge but was increased (P<0.05) by dietary β-glucan at 2, 4, 6 and 8 h post-challenge. In conclusion, dietary β-glucan decreased E. coli numbers but did not affect growth performance in weaned pigs and may offer benefits on immune function in weaned pigs challenged with LPS.     

Mechanism of Increased Tyrosine (Tyr<Superscript>99</Superscript>) Phosphorylation of Calmodulin During Hypoxia in the Cerebral Cortex of Newborn Piglets: The Role of nNOS-Derived Nitric Oxide

The present study aims to investigate the mechanism of calmodulin modification during hypoxia and tests the hypothesis that hypoxia-induced increase in Tyr⁹⁹ phosphorylation of calmodulin in the cerebral cortex of newborn piglets is mediated by NO derived from nNOS. Fifteen piglets were divided into normoxic (Nx, n = 5), hypoxic (Hx, F_iO₂ of 0.07 for 1 h, n = 5) and hypoxic-pretreated with nNOSi (Hx-nNOSi, n = 5) groups. nNOS inhibitor I (selectivity >2,500 vs. eNOS and >500 vs. iNOS) was administered (0.4 mg/kg, I.V.) 30 min prior to hypoxia. Cortical membranes were isolated and tyrosine phosphorylation (Tyr⁹⁹ and total) of calmodulin determined by Western blot using anti-phospho-(pTyr⁹⁹)-calmodulin and anti-pTyr antibodies. Protein bands were detected by enhanced chemiluminescence, analyzed by densitometry and expressed as absorbance. The pTyr⁹⁹ calmodulin (ODxmm²) was 78.55 ± 10.76 in Nx, 165.05 ± 12.26 in Hx (P < 0.05 vs. Nx) and 96.97 ± 13.18 in Hx-nNOSi (P < 0.05 vs. Hx, P = NS vs. Nx). Expression of total tyrosine phosphorylated calmodulin was 69.24 ± 13.69 in Nx, 156.17 ± 16.34 in Hx (P < 0.05 vs. Nx) and 74.18 ± 3.9 in Hx-nNOSi (P < 0.05 vs. Hx, P = NS vs. Nx). The data show that administration of nNOS inhibitor prevented the hypoxia-induced increased Tyr⁹⁹ phosphorylation of calmodulin. Total tyrosine phosphorylation of calmodulin was similar to Tyr⁹⁹ phosphorylation. We conclude that the mechanism of hypoxia-induced modification (Tyr⁹⁹ phosphorylation) of calmodulin is mediated by NO derived from nNOS. We speculate that Tyr⁹⁹ phosphorylated calmodulin, as compared to non-phosphorylated, binds with a higher affinity at the calmodulin binding site of nNOS leading to increased activation of nNOS and increased generation of NO.     

Light colour influences the behaviour and stress physiology of captive tench (<Emphasis Type="Italic">Tinca tinca</Emphasis>)

Groups of juvenile tench (7.02 ± 0.28 g) were reared under four different light regimes; blue light, red light (80 Wm⁻² 12L:12D photoperiod) white light (912 ± 210 lux, 80 Wm⁻², 12L:12D photoperiod) and no light (0 lux) (0L:24D). Visibility of fish out of shelters was used as an indicator of activity and was monitored by video recording. Blood plasma cortisol concentrations were also measured. Fish under blue or white light were significantly less active during the photophase than those under red or no light (P < 0.01). Red light produced similar activity patterns to fish receiving 24 h darkness. Plasma cortisol concentrations were also significantly influenced (P < 0.05) with the fish under white light having the highest plasma cortisol concentration (317 ± 62 ng cm⁻³) compared to fish in the dark treatment (106 ± 36 ng cm⁻³). Thus, the provision of coloured light filters increases activity in juvenile tench and may reduce their intrinsic stress level.     

Dye degradation,antimicrobial and larvicidal activity of silver nanoparticles biosynthesized from Cleistanthus collinus

The present study aimed in green synthesis and characterization of silver nanoparticles (AgNPs) using the leaves of Cleistanthus collinus. The NPs showed various absorption peaks between 3402 cm⁻¹ and 1063 cm⁻¹. FTIR spectrum revealed the presence of OH group, alkene, aromatic hydrocarbon, aliphatic fluro compound and aliphatic chloro compounds. Scanning electron microscopic analysis revealed the particle size ranged from 30 to 50 nm. The biosynthesized NPs have potent activity against Shigella dysentriae, Staphylococcus aureus and Bacillus subtilis and the zone of inhibition was 21 ± 1, 20 ± 2, 16 ± 2 mm, respectively. Toxicity of the synthesized NPs was tested on green gram (Vigna radiata) seed at various concentrations (20–100%) and germination was induced by NPs treated seeds. Shoot length and root length was higher in NPs treated plant than control plant (p < 0.01). Elevated level of catalase (CAT) and superoxide dismutase (SOD) and about 13% CAT and 7% SOD activity registered than control. Superoxide dismutase activity of root and shoot varied based on the dosage of AgNPs (p < 0.01). Also, the NPs (1%) showed significant larvicidal activity on Aedes aegypti and 100% mortality was achieved after 24 h treatment. The green synthesized NPs reduced methylene blue and 4-nitrophenol significantly (p < 0.01). The colouration of methylene blue and 4-nitrophenol were considerably reduced after 60 min showed the potential of dye degrading ability.     

Hypoxia-induced Activation of Epidermal Growth Factor Receptor (EGFR) Kinase in the Cerebral Cortex of Newborn Piglets: The Role of Nitric Oxide

The present study aims to investigate the mechanism of EGFR kinase activation during hypoxia and tests the hypothesis that hypoxia-induced increased activation of EGFR kinase in the cerebral cortical membrane fraction of newborn piglets is mediated by nitric oxide (NO) derived from neuronal nitric oxide synthase (nNOS). Fifteen newborn piglets were divided into normoxic (Nx, n = 5), hypoxic (Hx, n = 5) and hypoxic-treated with nNOS inhibitor (Hx-nNOSi, n = 5). Hypoxia was induced by an FiO2 of 0.07 for 60 min. nNOS inhibitor I (selectivity >2,500 vs. endothelial NOS, eNOS, and >500 vs. inducible NOS, iNOS) was administered (0.4 mg/kg, i. v.) 30 min prior to hypoxia. EGFR kinase tyrosine phosphorylation at Tyr1173, an index of activation of EGFR kinase, was determined by Western blot analysis using an anti-phospho (pTyr¹¹⁷³)-EGFR kinase antibody. Protein bands were analyzed by imaging densitometry and expressed as absorbance (OD × mm²). EGFR kinase activity was determined radiochemically using immunopurified enzyme. EGFR kinase activity was expressed as pmols/mg protein/hr. Density of phosphor (pTyr¹¹⁷³)-EGFR kinase (OD × mm²) was 60.2 ± 9.8 in Nx, 177.0 ± 26.9 in Hx (P < 0.05 vs. Nx) and 79.9 ± 15.7 in Hx-nNOSi (P < 0.05 vs. Hx, P = NS vs. Nx). Activity of EGFR kinase (pmoles/mg protein/hr) was 4,603 ± 155 in Nx, 8,493 ± 427 in Hx (P < 0.05 vs. Nx) and 4,516 ± 104 in Hx-nNOSi (P < 0.05 vs. Hx, P = NS vs. Nx). Pretreatment with nNOS inhibitor prevented the hypoxia-induced increased phosphorylation and increased activity of EGFR kinase. We conclude that the mechanism of hypoxia-induced increased activation of EGFR kinase is mediated by nNOS-derived NO.     

A new manganese superoxide dismutase identified from Beauveria bassiana enhances virulence and stress tolerance when overexpressed in the fungal pathogen

A superoxide dismutase (SOD) was characterized from Beauveria bassiana, a fungal entomopathogen widely applied to insect control. This 209-aa enzyme (BbSod2) showed no more than 71% sequence identity to other fungal Mn-SODs, sharing all conserved residues with the Mn-SOD family and lacking a mitochondrial signal. The SOD activity of purified BbSod2 was significantly elevated by Mn²⁺, suppressed by Cu²⁺ and Zn²⁺ but inhibited by Fe³⁺. Overexpressing the enzyme in a BbSod2-absent B. bassiana strain enhanced its SOD activity (107.2 ± 6.1 U mg⁻¹ protein) by 4–10-fold in different transformants analyzed. The best BbSod2-transformed strain with the SOD activity of 1,157.9 ± 74.7 U mg⁻¹ was 93% and 61% more tolerant to superoxide-generating menadione in both colony growth (EC₅₀ = 2.41 ± 0.03 versus 1.25 ± 0.01 mM) and conidial germination (EC₅₀ = 0.89 ± 0.06 versus 0.55 ± 0.07 mM), and 23% more tolerant to UV-B irradiation (LD₅₀ = 0.49 ± 0.02 versus 0.39 ± 0.01 J cm⁻²). Its virulence to Spodoptera litura larvae was enhanced by 26% [LT₅₀ = 4.5 (4.2–4.8) versus 5.7 (5.2–6.4) days]. Our study highlights for the first time that the Mn²⁺-cofactored, cytosolic BbSod2 contributes significantly to the virulence and stress tolerance of B. bassiana and reveals possible means to improving field persistence and efficacy of a fungal formulation by manipulating the antioxidant enzymes of a candidate strain.     

Short-term inhibition of prolactin secretion by naloxone treatment in the pregnant gilt

The involvement of endogenous opioids in modulation of prolactin (PRL) secretion during pregnancy in the pig was studied. Twenty-four crossbred pregnant gilts (150 ± 10 kg) were cannulated via the cephalic vein 24–48 h before treatment with 1 mg kg⁻¹ body weight of naloxone (NAL) or 3 ml of saline (CONT) i.v. at Day 40 (NAL, n = 6; CONT, n = 6) or Day 70 (NAL, n = 6; CONT, n = 6) of pregnancy. Blood plasma was collected at 15 min intervals from 1 h before to 3 h after treatment with NAL or saline. At Day 40 of pregnancy, administration of NAL caused a decrease in mean plasma PRL concentrations at 60 min, 120 min and 180 min post-treatment (NAL, 19.1 ± 1.3 ng ml⁻¹, P < 0.05; 15.8 ± 0.6 ng ml⁻¹, P < 0.001; 14.6 ± 0.7 ng ml⁻¹, P < 0.001, respectively) when compared with the CONT group (22.9 ± 0.7 ng ml⁻¹, 21.6 ± 0.6 ng ml⁻¹ and 22.4 ± 0.5 ng ml⁻¹, respectively). Mean plasma estradiol concentration was higher (P < 0.01) in the NAL group during the second and third hour post-treatment than in the CONT group. At Day 70 of pregnancy, infusion of NAL also decreased (P < 0.001) plasma PRL concentrations at 60 min, 120 min and 180 min after treatment (20.1 ± 1.6 ng ml⁻¹, 16.2 ± 1.5 ng ml⁻¹ and 14.8 ± 0.4 ng ml⁻¹, respectively) compared with the CONT group (33.4 ± 1.7 ng ml⁻¹, 34.1 ± 1.3 ng ml⁻¹ and 29.1 ± 0.9 ng ml⁻¹, respectively). Estradiol concentrations were not different (P > 0.05) between groups in this stage of gestation. Mean concentrations of progesterone were similar during the pre- and post-treatment periods in both stages of pregnancy.These data would suggest a possible role of the opioids in modulation of PRL secretion at these stages of pregnancy in the pig.     

Effect of the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment

It has been demonstrated that precooling with ice slurry ingestion enhances endurance exercise capacity in the heat. However, no studies have yet evaluated the optimal timing of ice slurry ingestion for precooling. This study aimed to investigate the effects of varying the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment. Ten active male participants completed 3 experimental cycling trials to exhaustion at 55% peak power output (PPO) after 15 min of warm-up at 30% PPO at 30 °C and 80% relative humidity. Three experimental conditions were set: no ice slurry ingestion (CON), pre-warm-up ice slurry ingestion (−1 °C; 7.5 g kg⁻¹) (PRE), and post-warm-up ice slurry ingestion (POST). Rectal and mean skin temperatures at the beginning of exercise in the POST condition (37.1±0.2 °C, 33.8±0.9 °C, respectively) were lower than those in the CON (37.5±0.3 °C; P<0.001, 34.8±0.8 °C; P<0.01, respectively) and PRE (37.4±0.2 °C; P<0.01, 34.6±0.7 °C; P<0.01, respectively) conditions. These reductions increased heat storage capacity and resulted in improved exercise capacity in the POST condition (60.2±8.7 min) compared to that in the CON (52.0±11.9 min; effect size [ES]=0.78) and PRE (56.9±10.4 min; ES=0.34) conditions. Ice slurry ingestion after warm-up effectively reduced both rectal and skin temperatures and increased cycling time to exhaustion in a warm environment. Timing ice slurry ingestion to occur after warm-up may be effective for precooling in a warm environment.     

Reproductive performance of heifers induced to oestrous asynchrony by suprabasal plasma progesterone levels

Suprabasal progesterone concentrations around oestrus have induced disturbances in oestrous behaviour and ovulation. To determine whether fertility in such an altered oestrus can be maintained at normal levels with additional inseminations (AI) until ovulation, fertility was compared in heifers (n = 11) inseminated in normal oestrous cycles and thereafter in cycles in which the animals were treated with progesterone in order to create suprabasal concentrations after luteolysis. The treatment consisted of silicone implants containing 10.6 mg kg⁻¹ of progesterone inserted subcutaneously on Day 8 of the oestrous cycle (day of ovulation designated Day 0) and removed on Day 25. Both in control oestrous cycles and oestrous cycles under progesterone treatment, growth of the ovulatory follicle and ovulation were determined by frequent ultrasound scanning. Blood was collected frequently for further analysis of progesterone, oestradiol-17β and luteinising hormone (LH). Insemination was performed 12 h after onset of standing oestrus. if ovulation did not occur 24 h after AI, heifers were inseminated again until ovulation. Pregnancy was diagnosed by ultrasound 25 days after ovulation.In control oestrous cycles, plasma progesterone decreased to 0.3 ± 0.3 nmol 1⁻¹. Duration of oestrus was 22.9 ± 2.0 h, the interval from onset of oestrus to ovulation was 32.4 ± 2.3 h and the interval from LH peak to ovulation was 28.6 ± 1.4 h. The interovulatory interval was 20.7 ± 0.6 days. In oestrous cycles in treated heifers, progesterone decreased to 1.0 ± 0.3 nmol l⁻¹ (P > 0.10) and the interovulatory interval was prolonged to 23.5 ± 1.0 days (P < 0.05). Standing oestrus lasted 47.2 ± 12.0 h (P = 0.09, n = 7). The interval from the onset of oestrus to ovulation was 59.4 ± 13.0 h (P = 0.08) and the interval from LH peak to ovulation 25.8 ± 1.3 h (P > 0.10). The prolonged oestrus was associated with increased (P < 0.05) growth of the ovulatory follicle and higher (P < 0.05) release of oestradiol-17β. Conception rates were 90% and 46% (P < 0.05), and the numbers of AI per heifer were 1.1 ± 0.1 and 3.4 ± 0.6 (P < 0.01) for control oestrous cycles and after treatment, respectively.The induction of suprabasal concentrations of progesterone caused asynchronies similar to those observed in cases of repeat breeding. The repeated AI did not maintain fertility at normal levels. It is suggested that the extended growth of the ovulatory follicle may cause impaired oocyte maturation or it may alter the maternal milieu owing to the prolonged release of oestradiol.     

Preventive effects of supplemental dietary zinc on heat-induced damage in the epididymis of boars

Hyperthermia in boars reduces growth performance and sperm production. Zinc is an essential trace element in animal nutrition. Here we investigate the effects of dietary zinc on epididymal structure and function in Bama miniature pigs treated with heat exposure and investigate approaches to improve the reproductive performance in summer. Male Bama miniature pigs (n=18; aged 6 months; bodyweight=10.79±0.06 kg) were randomly allocated to 3 groups: control group (Control), heat treatment group (HT), and the diet-supplemented and heat treatment group (H+Zn). The Control and HT groups were fed with basal diet and the H+Zn group were fed with basal diet plus 1500 mg/kg zinc daily. After being fed with these 2 different diets for 30 days, pigs in the HT and H+Zn groups were exposed to 5 h of 40 °C heat treatment for 8 days. Rectal temperature and jugular venous blood were collected 3 h after onset of heat exposure on days 1, 4 and 8. Pigs were sacrificed after the termination of heat exposure. Heat treatment increased serum testosterone concentration on day 1 and 4 (P<0.01). In addition, the HT group displayed an increase in the clear cell count and a decrease in epithelium thickness in the caput epithelium (P<0.01, P<0.05), and dietary zinc protected the boars from these impairments (P<0.01, P=0.29). Evaluation of oxidative states showed that heat exposure increased the levels of malondialdehyde (MDA) and glutathione (GSH) in the epididymis (P<0.01, P<0.05), while dietary zinc reduced this elevation (P<0.01, P<0.01). Heat exposure enhanced the glucocorticoid receptor (GR) expression in the nuclei of principal and basal cells (P<0.01, P<0.01) while dietary zinc attenuated the GR immunoreactivity intensity (P<0.01, P<0.01). These results demonstrate that dietary zinc protects the epididymis from high temperature-induced impairment, alleviates oxidative stress, restores the integrity of the caput epithelium and decreases the stress response.     

Immune responses,ROS generation and the haemocyte damage of scallop Chlamys farreri exposed to Aroclor 1254

The toxic effects of Aroclor 1254 (0.05, 0.5, 5 and 50 μg l^?1) on scallop (Chlamys farreri) immune system in vivo were studied. The results showed that Aroclor 1254 had significant toxic effect on the parameters tested in this paper (P < 0.05). The total number of haemocytes, the proportion of granulocytes, phagocytosis in all groups as well as the lysosomal membrane stability (LMS) in 5, 50 μg l^?1 and bacteriolytic activity 0.5, 5, 50 μg l^?1 treatments decreased significantly, while the proportion of hyalinocytes and the production of O₂^- in all treatments remarkably increased during the sampling time and tended to be stable gradually after 6–15 d. The bacteriolytic activity in 0.05 μg l^?1 treatments, LMS in 0.05, 0.5 μg l^?1 groups and the DNA damage (comet ratios and arbitrary values) in all treatments increased at the beginning of exposure and reached their peaks on day 1, day 1, day 6 and day 3, following that they all decreased gradually and became stable after 9–15 d. When the indices reached stability, except for DNA damage was higher than controls, the others were all significantly lower than those of controls (P < 0.05). Thus, Aroclor 1254 has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms. Also it supports the speculation that the PCBs pollution is one of the important reasons of the mass mortality of the C. farreri.