丁酸梭菌介导mTOR信号通路调控猪肠上皮细胞炎症反应的分子机制

本试验旨在研究丁酸梭菌（CB）介导雷帕霉素靶蛋白（mTOR）信号通路调控产肠毒素大肠杆菌K88（ETEC K88）感染猪肠上皮细胞（IPEC-J2）炎症反应的分子机制。按试验步骤处理细胞,利用1×103 cfu/mL 的ETEC K88感染IPEC-J2以及400 nmol/L的mTOR抑制剂处理IPEC-J2,到达作用时间后,分别收集细胞及培养上清,然后按照猪肿瘤坏死因子（TNF-α）和猪白细胞介素-8（IL-8）检测试剂盒说明书进行细胞因子检测,以及使用荧光定量PCR（qPCR）法进行ZO-1、occludin和mTOR表达量的检测。结果表明：与ETEC组相比,抑制剂+ETEC组、CB+ETEC组和抑制剂+CB+ETEC组ZO-1和occludin的表达量均显著升高,或有升高趋势,ZO-1的表达量分别升高了86.59%、31.48%和133.98%,occludin的表达量分别升高了69.34%、18.63%和87.52%,而mTOR的表达量分别降低了40.81%、11.62%和52.43%。与CB+ETEC组相比,抑制剂+CB+ETEC组在mTOR活性被抑制后ZO-1和occludin的表达量极显著升高了77.97%和58.07%,而mTOR的表达量极显著降低了46.18%,CB与抑制剂协同逆转ETEC造成的紧密连接蛋白表达下降。综上所述,ETEC K88能够激活mTOR信号通路,而CB通过介导mTOR信号通路能够降低ETEC K88感染IPEC-J2引起的炎症反应,并提高紧密连接蛋白的表达量,从而减轻细胞损伤。 [关键词] 猪肠上皮细胞|丁酸梭菌|产肠毒素大肠杆菌K88|mTOR信号通路|肠道健康     

Effect of pharmacological concentrations of zinc oxide with or without the inclusion of an antibacterial agent on nursery pig performance

A study involving nine research stations from the NCR-42 Swine Nutrition Committee used a total of 1,978 crossbred pigs to evaluate the effects of dietary ZnO concentrations with or without an antibacterial agent on postweaning pig performance. In Exp. 1, seven stations (IA, MI, MN, MO, NE, ND, and OH) evaluated the efficacy of ZnO when fed to nursery pigs at 0, 500, 1,000, 2,000, or 3,000 mg Zn/kg for a 28-d postweaning period. A randomized complete block experiment was conducted in 24 replicates using a total of 1,060 pigs. Pigs were bled at the 28-d period and plasma was analyzed for Zn and Cu. Because two stations weaned pigs at < 15 d (six replicates) and five stations at > 20 d (18 replicates) of age, the two sets of data were analyzed separately. The early-weaned pig group had greater (P < 0.05) gains, feed intakes, and gain:feed ratios for the 28-d postweaning period as dietary ZnO concentration increased. Later-weaned pigs also had increased (P < 0.01) gains and feed intakes as the dietary ZnO concentration increased. Responses for both weanling pig groups seemed to reach a plateau at 2,000 mg Zn/kg. Plasma Zn concentrations quadratically increased (P < 0.01) and plasma Cu concentrations quadratically decreased (P < 0.01) when ZnO concentrations were > 1,000 mg Zn/kg. Experiment 2 was conducted at seven stations (KY, MI, MO, NE, ND, OH, and OK) and evaluated the efficacy of an antibacterial agent (carbadox) in combination with added ZnO. The experiment was a 2 x 3 factorial arrangement in a randomized complete block design conducted in a total of 20 replicates. Carbadox was added at 0 or 55 mg/kg diet, and ZnO was added at 0, 1,500, or 3,000 mg Zn/ kg. A total of 918 pigs were weaned at an average 19.7 d of age. For the 28-d postweaning period, gains (P < 0.01), feed intakes (P < 0.05), and gain:feed ratios (P < 0.05) increased when dietary ZnO concentrations increased and when carbadox was added. These responses occurred in an additive manner. The results of these studies suggest that supplemental ZnO at 1,500 to 2,000 mg Zn/kg Zn improved postweaning pig performance, and its combination with an antibacterial agent resulted in additional performance improvements.     

Effect of dietary selenium source, level, and pig hair color on various selenium indices

The first experiment evaluated the effects of feeding various levels of Se, two Se sources, and hair color on selenosis responses in growing-finishing pigs. The study conducted in two replicates was a 2 x 6 x 2 factorial arrangement in a split-plot design. Sodium selenite and Se-enriched yeast added at 0.3, 1, 3, 5, 7, and 10 ppm Se served as the main plot and pig hair color as the subplot. A total of 96 crossbred pigs were allotted and fed their treatment diets for a 12-wk period. White and dark (red or black) hair samples were collected from the dorsal-midline at the 4-, 8-, and 12-wk periods from one pig of each hair color from each treatment pen. Lower pig weights (P < 0.10) and daily gains (P < 0.05) occurred as dietary Se level increased when pigs were fed either Se source. Selenosis responses were somewhat more severe, when the inorganic Se source was fed. Alopecia and hoof separation were encountered after the 8-wk period when pigs were fed inorganic rather than organic Se. Plasma Se increased as dietary level increased (P < 0.01), when organic Se was provided (P < 0.01), and was higher (P < 0.05) when pigs were white-haired. A time x hair color x dietary Se level interaction (P < 0.05) occurred, in which hair Se concentration was higher in dark- than in white-colored pigs and increased as dietary Se level increased as the experiment progressed. The correlation coefficient between dietary Se level and hair Se concentration averaged 0.90 (P < 0.01). Cysteine was the amino acid in the highest concentration in hair, but this and other amino acids were not affected by Se level, Se source, or hair color. A second experiment was a 3 x 6 factorial arrangement in a split-plot design with three 9-mo-old gilts from each of the Yorkshire, Duroc, and Hampshire breeds to determine whether hair Se concentration differed by body location and breed. Hair samples were collected from the shoulder, back, rump, front-leg, belly, and hind-leg areas. Hair Se concentration was higher in red- and white-haired pigs and lower in black-haired gilts (P < 0.01). Higher hair Se concentrations (P < 0.05) occurred from the lower than from the upper body areas. Our results suggest that selenosis occurs at dietary levels > 5 ppm and that white-haired pigs exhibit alopecia sooner than dark-haired pigs. No difference in hair Se concentration occurred when diets were < 1 ppm Se, but as dietary Se level increased dark-haired pigs retained more Se in their hair than white-haired pigs.     

母猪的微量元素营养

母猪在不同的繁殖周期中,对微量元素需要量的变化很大。微量元素是胚胎生长、乳汁分泌以及生长和维持所需要的。母猪在妊娠后期和泌乳期对微量元素的需要量最高,其微量元素来自日粮和组织转换,以满足营养需要。下面就硒、铁、铜、锌、锰、碘、钴的营养作用,分别作一介绍。一、硒(Se)Se 和 V_E 可防止细胞膜(V_E)或细胞基质(Se)氧化,但在日粮中,两种元素不能完全互相替代。Se 的防氧化作用是通过     

Comparing the detection of exposure to Ehrlichia ruminantium infection on a heartwater-endemic farm by the pCS20 polymerase chain reaction assay and an indirect MAP1-B enzyme linked immunosorbent assay

Detection of heartwater is not always easy especially because all the serological assays so far available either have poor sensitivity or specificity. The indirect MAP-1B ELISA has been reported to be the most specific test for heartwater, although it does also detect antibodies to some closely related ehrlichial agents. This study was undertaken to compare two methods for the detection of heartwater infection caused by the ehrlichial agent Ehrlichia (Cowdria) ruminantium. Fifteen cattle on a heartwater-endemic farm infested with high numbers of Amblyomma hebraeum ticks, and hence exposure to E. ruminantium infection were monitored over an 8-week period by pCS20 PCR and an indirect MAP-1B ELISA. Infection was detected by pCS20 PCR in most animals with the highest number of positives (60%) in week 6 of the study. Similarly, exposure to E. ruminantium was detected by indirect MAP-1B ELISA in some animals, with the highest number of seropositives (27%) at weeks 2-6 of the study. The data demonstrated a fluctuating rickettsaemia in cattle in a heartwater-endemic area. Comparison of the two tests indicated that the pCS20 PCR assay was more reliable because it detected more infections than the indirect MAP-1B ELISA and would therefore be the method of choice for detection of E. ruminantium infection.     

Further assessment of the dietary lysine requirement of finishing gilts

A cooperative research study involving 635 gilts was conducted at eight research stations to further estimate the lysine requirement of finishing gilts. Dietary crude protein levels of the five dietary treatments ranged from 16.0 to 24.4% with calculated lysine levels of .80, .95, 1.10, 1.25, or 1.40%. Each station contributed a minimum of two replicate pens of pigs per treatment. Average initial and final weights were 53.6 and 116.4 kg, respectively. At the end of the experimental period, pigs were killed and hot carcass weight, 10th-rib fat depth, and longissimus muscle area were measured. Carcass fat-free lean percentage and fat-free lean gain were estimated from these data. Daily lysine intakes averaged 21.8, 25.9, 30.5, 34.3, and 37.8 g/d for the five treatment groups, respectively. Increasing the dietary lysine from .80 to .95% numerically increased weight gain and gain:feed, but these increases were not maintained at higher levels of dietary lysine. Overall, rate and efficiency of gain decreased (cubic, P < .01) with increasing dietary lysine. Carcasses were leaner at the two higher levels of dietary lysine as evidenced by reduced 10th rib backfat (linear, P < .01), increased longissimus area (quadratic, P < .04), and increased percentage of estimated fat-free lean (linear, P < .01). Carcass fat-free lean gain was not influenced by dietary lysine except for a small numerical improvement (P < .11) at the .95% level of dietary lysine that paralleled the improvement in body weight gain. The results indicate that the dietary lysine requirement of finishing gilts with a mean carcass fat-free lean growth rate of 306 g/d from 54 to 116 kg body weight is probably no higher than .80% of the diet to achieve maximum rate and efficiency of body weight gain and carcass lean growth rate. The results also indicate that higher dietary lysine levels may increase carcass leanness in finishing gilts, possibly due to reduced intake of NE. Whether this response is due to the effects of lysine alone, protein (i.e., other amino acids), or soybean meal is unknown.     

Effect of organic and inorganic selenium sources and levels on sow colostrum and milk selenium content

A study was conducted to evaluate the short-term effects of feeding two dietary Se sources at various Se levels on the transfer of Se to the dam's milk and nursing pig. Six dietary treatments were arranged in a 2 x 2 factorial arrangement with two additional treatments in a randomized complete block designed experiment. Inorganic (sodium selenite) or organic (Se-enriched yeast) Se sources were added to the diet at .15 or .30 ppm Se. A non-Se-fortified corn-soybean meal basal diet served as a negative control, and a sixth group was fed .15 ppm Se from both inorganic and organic Se sources. A total of 43 sows were fed their treatment diets at 2.2 kg/d from 6 d prepartum to parturition and at full feed through a 14-d lactation period. Ten sows were initially bled at 6 d prepartum, and three sows and three pigs from their litters were bled at 7 and 14 d postpartum. Serum was analyzed for its Se concentration and glutathione peroxidase (GSH-Px) activity. Colostrum was collected within 12 h postpartum and milk at 7 and 14 d of lactation. When the basal diet was fed, sow serum GSH-Px activity declined from 6 d prepartum and remained low throughout lactation. When dietary Se levels increased, sow serum Se concentration and serum GSH-Px activity increased (P < .05) at both 7 and 14 d postpartum. The short-term feeding of either Se source at .15 or .30 ppm Se did not affect colostrum Se content when inorganic Se was fed, but it was increased when organic Se was provided. This resulted in a significant Se source x Se level interaction (P < .01). Milk Se at 7 and 14 d postpartum was 2.5 to 3 times higher when the organic Se source was provided and resulted in a significant Se source x Se level interaction (P < .05). When the combination of inorganic and organic Se was fed at .15 ppm Se, colostrum and milk Se contents were similar to those of sows fed .15 ppm Se from the organic Se source. Pig serum GSH-Px activity was not affected at 7 and 14 d of age by dietary Se level or Se source fed to the sow, but serum Se increased (P < .05) as dietary Se level increased, particularly when sows had been fed organic Se. The results demonstrated that organic Se increased milk Se content more than did inorganic Se and increased the nursing pig's serum Se. These results indicate that inorganic Se was more biologically available for sow serum GSH-Px activity, but organic Se was more effectively incorporated into milk.     

Effect of dietary selenium and vitamin E on spermatogenic development in boars

An experiment involving a total of 61 crossbred boars evaluated the effects of dietary Se and vitamin E on spermatogenic development at various stages of sexual development and the prostaglandin F2alpha (PGF2alpha) content in the seminal vesicle and prostate glands at 18 mo of age. The experiment from 5.4 to 9 mo of age was conducted as a 2 x 2 factorial in a randomized complete block design. Dietary Se at 0 or .5 ppm was the first factor and vitamin E at 0 or 220 IU/kg diet was the second. From 9 to 18 mo of age, a group of sexually active and inactive boars was a third factor. Treatment diets were fed from weaning (28 d of age) to the end of the experiment. Three boars per treatment group at 5.4 (105 kg BW), 6.2 (130 kg BW), and 9.0 (150 kg BW) mo of age were killed and the testes collected. From 9 to 18 mo of age, three boars from each dietary treatment group were used for semen collection, and another set of three to four boars from each treatment group remained sexually inactive. At 18 mo, both sets of boars were killed and their testes, prostates, and seminal vesicles were collected. The testis at each age was evaluated for sperm reserve numbers and germ and Sertoli cell populations. At 5.4 or 6.2 mo of age, testicular sperm reserves were not affected by dietary Se (P > .15), at 9.0 mo of age there was a trend for a higher (P < .10) number of sperm reserves, and by 18 mo of age the Se-fed boars had higher (P < .01) numbers of sperm reserves. Vitamin E had no effect (P > .15) on testicular sperm reserves at any age period. Boars fed dietary Se had a greater number of Sertoli cells (P < .01) and round spermatids (P < .01) at 6.2 mo of age, but by 18 mo of age the boars fed Se had more Sertoli cells (P < .05), more secondary spermatocytes (P < .01), and more round spermatids (P < .05). Vitamin E did not affect Sertoli or germ cell populations at the various ages. Boars at 18 mo of age had lower PGF2alpha concentrations in the prostate (P < .05) and seminal vesicles (P < .01) when vitamin E was fed, whereas Se had no effect. Sexually active boars had lower PGF2alpha concentrations in the seminal vesicles (P < .01) than sexually inactive boars, but there was no effect (P > .15) of sexual activity on the number of Sertoli cells, primary or secondary spermatocytes, or round spermatids. Our results indicate that Se has a role in establishing the number of boar spermatozoal reserves and Sertoli cells, whereas supplemental vitamin E did not affect these criteria.