Gang Tian

Protective effects of dietary arginine supplementation against oxidative stress in weaned piglets

Oxidative stress is detrimental to animals. Previous studies have indicated that arginine (Arg) may function as a potential substance against oxidative stress. The present study was conducted to explore the potential mechanisms behind the Arg-induced protective effects against oxidative stress in piglets. A total of thirty-six piglets were randomly allocated to six groups with six replicates per group. Piglets were subjected to three dietary treatments (namely two groups per treatment) in week 1 and fed with a basal diet (ArgL) or the basal diet supplemented with 0.8% (ArgM) or 1.6% (ArgH) L-Arg, respectively. On day 8, piglets were injected intraperitoneally either with diquat (10 mg/kg body weight) or sterile saline. The whole trial lasted 11 d. Results showed that dietary Arg supplementation did not affect growth performance in week 1. Oxidative stress significantly decreased the growth performance of piglets (P < 0.05). However, ArgH attenuated the negative effects of oxidative stress on feed intake and significantly increased the total antioxidant capacity in the liver under oxidative stress (P < 0.05). Both ArgM and ArgH enhanced the activities of plasma glutathione peroxidases and superoxide dismutases and decreased the IL-6 and TNF-a mRNA level in the liver under oxidative stress (P < 0.05). The present study not only shows that Arg can function as a potential nutrient to alleviate oxidative stress responses through the enhancement of antioxidant capacity, and inhibition of the expression of inflammatory cytokines, but the results also suggest that alleviation of oxidative stress responses using dietary nutrient components deserves further attention in the future.

Nutrition and health relevant regulation of intestinal sulfur amino acid metabolism

Sulfur amino acids (SAA), particularly methionine and cysteine, are critical for the gut to maintain its functions including the digestion, absorption and metabolism of nutrients, the immune surveillance of the intestinal epithelial layer and regulation of the mucosal response to foreign antigens. However, the metabolism of SAA in the gut, specifically the transmethylation of methionine, will result in a net release of homocysteine, which is shown to be associated with cardiovascular disease and stroke. Furthermore, the extensive catabolism of dietary methionine by the intestine or by luminal microbes may result in a decrease in nutritional efficiency. Therefore, the regulation of SAA metabolism in the gut is not only nutritionally relevant, but also relevant to the overall health and well-being. The superiority of dl-2-hydroxy-4-methylthiobutyrate to dl-methionine in decreasing homocysteine production, alleviating stress responses, and reducing the first-pass intestinal metabolism of dietary methionine may provide a promising implication for nutritional strategies to manipulate SAA metabolism and thus to improve the nutrition and health status of animals and perhaps humans.

Cost-effective lignocellulolytic enzyme production by Trichoderma reesei on a cane molasses medium

BackgroundCane molasses, an important residue of the sugar industry, have the potential as a cost-effective carbon source that could serve as nutrients for industrial enzyme-producing microorganisms, especially filamentous fungi. However, the enzyme mixtures produced in such a complex medium are poorly characterized. In this study, the secretome of Trichoderma reesei grown on a cane molasses medium (CMM) as well as on a lactose-based conventional medium (LCM) were compared and analyzed by using proteomics.ResultsIn this study we show that both the CMM and LCM can serve as excellent growth media for T. reesei. The enzyme expression patterns in the two media were similar and a considerable number of the identified proteins on two-dimensional gel electrophoresis (2-DE) gels were those involved in biomass degradation. The most abundant cellulolytic enzymes identified in both media were cellobiohydrolases (Cel7A/Cel6A) and endoglucanases (Cel7A/Cel5A) and were found to be more abundant in CMM. We also found that both media can serve as an inducer of xylanolytic enzymes. The main xylanases (XYNI/XYNIV) and xyloglucanase (Cel74A) were found at higher concentrations in the CMM than LCM.ConclusionsWe analyzed the prevalent proteins secreted by T. reesei in the CMM and LCM. Here, we show that hydrolytic enzymes are cost-effective and can be produced on cane molasses as a carbon source which can be used to digest lignocellulolytic biomass.

Effects of nutritional level on pork quality and gene expression of μ-calpain and calpastatin in muscle of finishing pigs

The study was designed to investigate the effects of nutritional level (control diet (CD), 14.19% crude protein, 13.81MJ of DE/kg; low nutritional level diet (LND), 11.08% crude protein, 12.55MJ of DE/kg) on pork quality and gene expression of mu-calpain and calpastatin in muscle of finishing pigs. The LND treatment increased drip loss (P<0.05), had a trend to increase intramuscular fat (IMF) content (P=0.09), decreased Warner-Bratzler shear force (WBSF) of pork (P<0.05), improved mRNA level of mu-calpain (P<0.05) in skeletal muscle, but had no effect on gene expression of calpastatin, compared with the CD treatment. These data suggest that a moderately reduced energy and protein diet increased pork tenderness and intramuscular fat. The increase in tenderness by LND treatment may be partly due to increased gene expression of mu-calpain in muscle.

Inhibition of adipogenic differentiation by myostatin is alleviated by arginine supplementation in porcine-muscle-derived mesenchymal stem cells

Porcine mesenchymal stem cells in postnatal muscle have been demonstrated to differentiate into adipocytes. This increases adipocyte number and lipid accumulation, and is thought to be the origin of intramuscular fat. In this study, the effects of myostatin and arginine on adipogenic differentiation in mesenchymal stem cells derived from porcine muscle (pMDSCs) were investigated in vitro. Intracellular triglyceride levels were reduced by exogenous myostatin and increased by arginine supplementation or myostatin antibody (P<0.01). The inhibition of lipid accumulation by myostatin in pMDSCs was alleviated by arginine supplementation (P<0.01). Expression patterns of adipogenic transcription factors showed that exogenous myostatin suppressed PPARγ2 and aP2 expression (P<0.01), while supplemental arginine or myostatin antibody promoted ADD1 expression (P<0.01). Furthermore, compared with the addition of either myostatin protein or antibody alone, ADD1 and PPARδ expression were promoted by the combination of arginine and myostatin (P<0.01), and arginine combined with myostatin antibody promoted the expression of ADD1, PPARδ, C/EBPα, PPARγ2 and LPL in pMDSCs (P<0.05). These results suggest that myostatin inhibits adipogenesis in pMDSCs, and that this can be alleviated by arginine supplementation, at least in part, through promoting ADD1 and PPARδ expression.

Mammary inflammation around parturition appeared to be attenuated by consumption of fish oil rich in n-3 polyunsaturated fatty acids

BackgroundMastitis endangers the health of domestic animals and humans, and may cause problems concerning food safety. It is documented that n-3 polyunsaturated fatty acids (PUFA) play significant roles in attenuating saturated fatty acids (SFA)-induced inflammation. This study was therefore conducted to determine whether mammary inflammation could be affected by consumption of diets rich in n-3 PUFA.MethodsForty-eight rats after mating began to receive diets supplemented with 5% fish oil (FO) or 7% soybean oil (SO). Blood and mammary tissue samples (n = 6) at day 0 and 14 of gestation and day 3 postpartum were collected 9 hours after intramammary infusion of saline or lipopolysaccharide (LPS) to determine free fatty acids (FFA) concentration and FA composition in plasma and inflammation mediators in mammary tissues.ResultsAt day 14 of gestation and day 3 postpartum, the FO-fed rats had lower plasma concentrations of C18:2n6, C20:4n6, total n-6 PUFA and SFA, and higher plasma concentrations of C20:5n3 and total n-3 PUFA than the SO-fed rats. Plasma C22:6n3 concentration was also higher in the FO-fed than in the SO-fed rats at day 3 postpartum. Compared with the SO-fed rats, the FO-fed rats had lower mammary mRNA abundance of xanthine oxidoreductase (XOR) and protein level of tumor necrosis factor (TNF)-α, but had higher mammary mRNA abundances of interleukin (IL)-10 and peroxisome proliferator-activated receptor (PPAR)-γ at day 14 of gestation. Following LPS infusion at day 3 postpartum, the SO-fed rats had increased plasma concentrations of FFA, C18:1n9, C18:3n3, C18:2n6 and total n-6 PUFA, higher mammary mRNA abundances of IL-1β, TNF-α and XOR but lower mammary mRNA abundance of IL-10 than the FO-fed rats.ConclusionsMammary inflammation around parturition appeared to be attenuated by consumption of a diet rich in n-3 PUFA, which was associated with up-regulated expression of IL-10 and PPAR-γ.

Vitamin D3 supplementation alleviates rotavirus infection in pigs and IPEC-J2 cells via regulating the autophagy signaling pathway

Vitamin D had an anti-infection effect and benefited to the intestinal health. Autophagy signaling pathway was regulated by vitamin D3 to inhibit the infection of human immunodeficiency virus type-1. Rotavirus (RV) was a major cause of the severe diarrheal disease in young children and young animals. Although evidence suggested that vitamin D3 attenuates the negative effects of RV infection via the retinoic acid-inducible gene I signaling pathway, little is known of its antiviral effect whether through the regulation of autophagy. The present study was performed to investigate whether vitamin D3 alleviates RV infection in pig and porcine small intestinal epithelial cell line (IPEC-J2) models via regulating the autophagy signaling pathway. RV administration increased the Beclin 1 mRNA abundance in porcine jejunum and ileum. 5000 IU/kg dietary vitamin D3 supplementation greatly up-regulated LC3-II/LC3-I ratios and PR-39 mRNA expression under the condition of RV challenged. The viability of IPEC-J2 was significantly inhibited by RV infection. Incubation with 25-hydroxyvitamin D3 significantly decreased the concentrations of RV antigen and non-structural protein 4 (NSP4), and up-regulated the mRNA expression of Beclin 1 and PR-39 in the RV-infected IPEC-J2 cells. And then, based on the 25-hydroxyvitamin D3 treatment and RV infection, LC3-II mRNA expression in cells was inhibited by an autophagy inhibitor 3-methyladenine (3-MA). Bafilomycin A1 (Baf A1, a class of inhibitors of membrane ATPases, inhibits maturation of autophagic vacuoles) treatment numerically enhanced the LC3-II mRNA abundance, but had no effect on NSP4 concentration. Furthermore, 25-hydroxyvitamin D3 decreased the p62 mRNA expression and increased porcine cathelicidins (PMAP23, PG1-5 and PR-39) mRNA expression in the RV-infected cells. Taken together, these results indicated that vitamin D3 attenuates RV infection through regulating autophagic maturation and porcine cathelicidin genes expression.

Effects of dietary threonine supplementation on immune challenge induced by swine Pseudorabies live vaccine in weaned pigs

The present study was conducted to determine whether dietary threonine supplementation can improve immunity of weaned pigs challenged by swine Pseudorabies live vaccine (SPLV). Thirty crossbred piglets weaned at 21 days of age were randomly assigned to three groups receiving diets containing true ileal digestible threonine (TIDT) at 0.74, 0.89 and 1.11% for 14 days. On day 8, all pigs were injected intramuscularly with SPLV or sterile 0.9% NaCl solution. SPLV injection enhanced serum IgA, IgM, IgG, IFN-γ, IL-1β, TNF-α and IL-10 concentrations (p < 0.05) and stimulated the relative mRNA abundance of Toll-like receptors (TLR3, TLR7 or TLR9) in different tissues (p < 0.05). Under no challenge, increasing dietary TIDT levels enhanced serum IgG (p < 0.05), IgM (p = 0.07) and IFN-γ (p < 0.05) concentration, tended to decrease serum IL-1β, TNF-α and IL-10 concentration, and regulated relative mRNA abundance of TLR3, TLR7 or TLR9 in different tissues (p < 0.05). However, there was a synergistic role for increasing the serum IL-10 concentration between dietary TIDT levels and SPLV injection (p < 0.05). Under SPLV challenge, increasing dietary TIDT levels attenuated the increase of the serum IFN-γ concentration, and the increase of the relative mRNA abundance of TLR3, TLR7 and TLR9 in the different tissues (p < 0.05). These results suggest that an appropriate dietary threonine supplementation could improve the immune status of weaned pigs injected with SPLV by down-regulating the expression of TLR3, TLR7 and TLR9 in tissues, and thus regulating T-helper cytokine secretion.

Arginine metabolism and its protective effects on intestinal health and functions in weaned piglets under oxidative stress induced by diquat.

The intestine plays key roles in maintaining body arginine (Arg) homoeostasis. Meanwhile, the intestine is very susceptible to reactive oxygen species. In light of this, the study aimed to explore the effects of Arg supplementation on intestinal morphology, Arg transporters and metabolism, and the potential protective mechanism of Arg supplementation in piglets under oxidative stress. A total of thirty-six weaned piglets were randomly allocated to six groups with six replicates and fed a base diet (0·95 % Arg,) or base diet supplemented with 0·8 % and 1·6 % l-Arg for 1 week, respectively. Subsequently, a challenge test was conducted by intraperitoneal injection of diquat, an initiator of radical production, or sterile saline. The whole trial lasted 11 d. The diquat challenge significantly decreased plasma Arg concentration at 6 h after injection (P<0·05), lowered villus height in the jejunum and ileum (P<0·05) as well as villus width and crypt depth in the duodenum, jejunum and ileum (P<0·05). Oxidative stress significantly increased cationic amino acid transporter (CAT)-1, CAT-2 and CAT-3, mRNA levels (P<0·05), decreased arginase II (ARGII) and inducible nitric oxide synthase mRNA levels, and increased TNF- α mRNA level in the jejunum (P<0·05). Supplementation with Arg significantly decreased crypt depth (P<0·05), suppressed CAT-1 mRNA expression induced by diquat (P<0·05), increased ARGII and endothelial nitric oxide synthase mRNA levels (P<0·05), and effectively relieved the TNF- α mRNA expression induced by diquat in the jejunum (P<0·05). It is concluded that oxidative stress decreased Arg bioavailability and increased expression of inflammatory cytokines in the jejunum, and that Arg supplementation has beneficial effects in the jejunum through regulation of the metabolism of Arg and suppression of inflammatory cytokine expression in piglets.

Adaptation of gut microbiome to different dietary non-starch polysaccharide fractions in a porcine model

SCOPE Dietary fibers, consisting of nonstarch polysaccharides (NSPs) were found to modulate the gut microbiota. However, little is known about the role of a separated fiber fraction. Here, we describe a response in gut microbiome to different fiber fractions using a porcine model. METHODS AND RESULTS Ileal and cecal digesta were collected from pigs fed with fiber-free diet (FFD) or diet containing 5% cellulose (CEL), xylan (XYL) or β-glucan (GLU). We observed an elevated 16S rRNA gene copies in ileum and cecum digesta after NSP ingestion. Interestingly, we found that cecum digesta contained higher bacterial diversity than ileum digesta. Moreover, NSPs had no significant influence on overall diversity, but acutely altered the abundance of specific bacteria. Importantly, NSPs decreased the abundance of phylum Firmicutes, but increased the phylum Proteobacteria in ileal samples. Among the NSP-treated groups, pigs on CEL-containing diet had exclusively higher abundance of Lactobacillus spp. in the ileum. Whereas, the GLU-treated samples had more Clostridium spp. CONCLUSION This study not only indicated how the gut microbiome adapts to the three major NSP fractions, but the results also contribute to our understanding of the role of dietary fibers in modulating gut microbiota and health.