Role of hydrogen peroxide in stress-induced programmed cell death during somatic embryogenesis in Fraxinus mandshurica

We examined how reactive oxygen species, in the form of hydrogen peroxide (H2O2), affect osmotic stress–induced programmed cell death during somatic embryogenesis from cotyledon explants of Manchurian ash (Fraxinus mandshurica Rupr.). We found that substantial osmotic stress was essential for Manchurian ash somatic cells to obtain embryogenic competence. The explant cells displayed hallmarks of programmed cell death, chromatin condensation, and DNA fragmentation to oligonucleotides during somatic embryogenesis. Increasing concentrations of plant growth regulators and sucrose in the medium increased osmotic stress thereby inducing H2O2 accumulation in the explant cells. We found that H2O2 concentration was significantly decreased in explant cells when the induction medium was modified, i.e., when reducing the concentration of sucrose, which reduces the osmotic pressure of the medium, or by withdrawing plant growth regulators at mid-culture. These treatments also decreased the proportion of explant cells undergoing programmed cell death. Accordingly, a decreased rate of somatic embryo induction was observed. These results show that PCD occurred during tissue browning and death of some explant cells during somatic embryogenesis in F. mandshurica. The ROS contributed to PCD in abiotic stress stimulated F. mandshurica cells.

Effects of a nitric oxide donor and nitric oxide scavengers on Sorbus pohuashanensis embryo germination

The effects of an exogenous nitric oxide donor(sodium nitroprusside, SNP), a NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxode(PTIO) and carboxy-PTIO potassium salt(c PTIO) on the embryo germination of Sorbus pohuashanensis were studied in a petri dish test. SNP at 0.5–5 mmol L-1 increased germination percentage, mean time to germination, germination index and germination energy compared with the control to different degrees. Treatment with 2 mmol L-1 SNP improved germination most significantly; embryo germination percentage for mother tree 1(91.11%) and mother tree 2(64.44%) were much higher than the control. In addition,excessive SNP levels did not enhance embryo germination.Combined treatment with SNP and an NO scavenger delayed embryo germination. Treatment with c PTIO inhibited embryo germination; germination percentage was 42.22% and was lower than that of the control. These results show that low concentrations of exogenous NO can enhance the embryo germination of S. pohuashanensis,providing a simple, effective way for promoting germination of S. pohuashanensis.

Aflatoxin B1, zearalenone and deoxynivalenol in feed ingredients and complete feed from different Province in China

Background： The current study was carried out to provide a reference for monitory of aflatoxin B_1（AFB_1）,zearalenone（ZEN） and deoxynivalenol（DON） contamination in feed ingredients and complete feeds were collected from different Province in China from 2013 to 2015.Methods： A total of 443 feed ingredients, including 220 corn, 24 wheat, 24 domestic distillers dried grains with soluble（DDGS）, 55 bran, 20 wheat shorts and red dog, 37 imported DDGS, 34 corn germ meal and 29 soybean meal as well as 127 complete feeds including 25 pig complete feed（powder）, 90 pig complete feed（pellet）, six duck complete feed and six cattle complete feed were randomly collected from different Province in China,respectively, by high-performance chromatography in combined with UV or fluorescence analysis.Results： The incidence rates of AFB_1, ZEN and DON contamination of feed ingredients and complete feeds were80.8, 92.3 and 93.9 %, respectively. The percentage of positive samples for DON ranged from 66.7 to 100 %.Domestic DDGS and imported DDGS presented the most serious contamination AFB_1, ZEN and DON contamination levels of feeds ranged from 61.5 to 100 %, indicated that serious contamination over the studied 3-year period.Conclusion： The current data provide clear evidence that AFB_1, ZEN and DON contamination of feed ingredients and complete feeds in different Province in China is serious and differs over past 3-year. The use of corn, domestic DDGS, imported DDGS and corn germ meal, which may be contaminated with these three mycotoxins, as animal feed may triggered a health risk for animal. Feeds are most contaminated with DON followed by ZEN and AFB_1.Mycotoxins contamination in feed ingredients and complete feeds should be monitored routinely in China.

Relationship between H_(2)O_(2) accumulation and NO synthesis during osmotic stress:promoted somatic embryogenesis of Fraxinus mandshurica

Osmotic stress promotes somatic embryogenesis of Fraxinus mandshurica,which leads to accumulation of reactive oxygen species(ROS).The single pieces of cotyledons of F.mandshurica were used as explants to induce somatic embryogenesis in osmotic-stress medium.Furthermore,the hydrogen peroxide H_(2)O_(2) content of explanted cells was varied by adding exogenous H_(2)O_(2) or catalase solution to assess the effects of the exogenous H_(2)O_(2)on somatic embryogenesis,intracellular H_(2)O_(2)accumulation,and the relationship between signaling mediated by ROS or reactive nitrogen species.The results revealed that exogenous H_(2)O_(2)(100?300μmol L^(–1))increased the number of somatic embryos.On 60th day of exogenous H_(2)O_(2)(200μmol L^(–1))treatment,the number of somatic embryos of explants treated,which was 136.54%,was higher than the control.Moreover,exogenous H_(2)O_(2)(100μmol L^(–1))significantly increased the intracellular H_(2)O_(2)content and enhanced the activities of superoxidase dismutase and peroxidase.Finally,exogenous H_(2)O_(2)(100μmol L^(–1))activated the intracellular non-enzymatic pathway for nitric oxide(NO)synthesis.The somatic embryogenesis in broadleaf trees increases with the change of endogenic ROS content,and depends on the upregulation of antioxidant enzymes.Both H_(2)O_(2)and NO,as signaling molecules,were found to be involved in the process of somatic embryogenesis in broadleaf trees.In the process of exogenous H_(2)O_(2)promoting somatic embryogenesis,NO synthesis depended on non-enzymatic reactions.These results provide a scientific basis for resolving the mechanism by which ROS levels are regulated during somatic embryogenesis of broadleaf trees and establish a reasonable and efficient technology system for regulating somatic embryogenesis of trees.

Effects of different levels of urea supplementation on nutrient intake and growth performance in growing camels fed roughage based complete pellet diets

The utilization of urea in camels has beneficial and negative effects. The aims of this study were to investigate the effects of different levels of urea supplementation on nutrients intake, digestibility,growth performance, feed efficiency and economics in growing camels fed roughage based complete pellet diets. In the present study, eighteen growing camels with an average live body weight of306.17 ± 2.05 kg were randomly assigned in three treatments: T1 = roughage complete pellet diet without urea,T2 = T1 plus 1% urea,and T3 = T1 plus 2% urea. The results showed that the urea supplementation significantly affected average daily feed and nutrient intake of dry matter(DM), organic matter(OM), crude protein(CP), neutral detergent fiber(NDF), and acid detergent fiber(ADF)(P < 0.05).On the contrary, the average daily intake of nitrogen free extract(NFE) and water were not influenced by increasing urea supplementation(P > 0.05). Similarly, digestion coefficient of DM, CP, ether extract(EE),crude fiber(CF) and ADF was influenced by increasing urea level(P < 0.05), while the digestion coefficient of OM, NFE and NDF was not affected by increasing urea level(P > 0.05). The intake of digestive nutrients was similar among all treatment groups. Total body live weight gain and average daily gain were significantly higher in urea supplemented groups(P < 0.05) than in the control group. The supplementation of urea at 1% in low quality roughage complete pellet diets significantly improved(P < 0.05) the feed efficiency. In conclusion,these results indicated that the incorporation of urea at 1% in roughage based complete pellet diets could positively improve nutrients intake, digestibility, growth performance and feed conversion efficiency of growing camels.

Compensation effects of coated cysteamine on meat quality, amino acid composition, fatty acid composition, mineral content in dorsal muscle and serum biochemical indices in finishing pigs offered reduced trace minerals diet

Dear Editor.Trace mineral elements(ME)and amino acids have been demonstrated to be essential bioelements in animal nutrition.If there is a deficiency in ME,a number of biological functions in animals may be affected,including physical growth,psychomotor development,and immunity.Supplementation of pig diets with ME is known to improve the animals'growth,reproduction,and their immunity against oxidative stress and cell damage.

Imbalanced dietary methionine-to-sulfur amino acid ratio can affect amino acid profiles, antioxidant capacity, and intestinal morphology of piglets

Animal protein sources such as fishmeal and plasma powder are excellent and indispensable sources of energy,amino acid s,and minerals in animal production.Amino acid imbalance,especially methionine-to-sulfur amino acid(Met:SAA)ratio,caused by an imbalance of animal protein meal leads to growth restriction.This study was conducted to evaluate the effects of imbalanced Met:SAA ratio supplementation of different animal protein source diets on growth performance,plasma amino acid profiles,antioxidant capacity and intestinal morphology in a piglet model.Twenty-four weaned piglets(castrated males;BW=10.46±0.34 kg),assigned randomly into 3 groups(8 piglets/group),were fed for 28 d.Three experimental diets of equal energy and crude protein levels were as follows:1)a corn-soybean basal diet with a Met:SAA ratio at 0.51(BD);2)a plasma powder diet with a low Met:SAA ratio at 0.41(L-MR);3)a fishmeal diet with a high Met:SAA ratio at0.61(H-MR).Results revealed that compared to BD,L-MR significantly decreased(P<0.05)the activities of plasma total antioxidant capacity and glutathione peroxidase,plasma amino acid profiles,and significantly reduced(P<0.05)villus height and crypt depth in the duodenum and jejunum.Additionally,L-MR significantly reduced(P<0.05)the mRNA expression level of solute carrier family 7 member 9(SIC7 A9)in the ileum,and significantly increased(P<0.05)mRNA expression levels of zonula occludens-1(ZO-1)in the duodenum,and Claudin-1,ZO-1,sodium-coupled neutral amino acid transporters 2(SNAT2)and SIC7 A7 in the j ejunum.HMR significantly increased(P<0.05)plasma SAA levels,and significantly reduced(P<0.05)average daily feed intake,villus height,and villus height-to-crypt depth(VH:CD)ratio in the ileum compared to BD.In conclusion,L-MR may result in oxidative stress and villous atrophy but proves beneficial in improving intestinal barrier function and the activity of amino acid transporters for compensatory growth.H-MR may impair intestinal growth and development for weaned piglets.The research provides a guidance on the adequate Met:SAA ratio(0.51)supplementation in diet structure for weaned piglets.

Reduced dietary nitrogen with a high Lys:CP ratio restricted dietary N excretion without negatively affecting weaned piglets

We hypothesized that balancing the content of exogenous amino acids, especially lysine, to reduce protein content in swine diets could reduce nitrogen(N) pollution associated with animal husbandry. Two experiments(45 d each experiment) were performed on weaned piglets(Duroc x Landrace x Yorkshire,28 d of age) to test this and to determine the optimal lysine to crude protein(Lys:CP) ratio in diet. In Exp. 1,12 piglets(6 replicates [n = 6]) were fed diets containing different levels of CP(17% and 20%) but the same level of Lys, Increased CP content resulted in significant increases(P < 0.05) of average daily gain(ADG), average daily feed intake(ADFI), and body weight(BW);but did not affect the feed to gain ratio. In Exp. 2,24 piglets(8 replicates [n = 8]) were fed 1 of 3 diets as follows: 1) 20% CP with a regular Lys:CP ratio(6.23%, control);2) 17% CP with a reduced Lys:CP ratio(6.14%, LL);or 3) 17% CP with a standard Lys:CP ratio(7.32%, SL). The ADG, final BW, serum concentrations of growth hormone and insulin-like growth factor-1, villus height in the jejunum, and villus height to crypt depth ratio were the lowest in piglets fed LL diet, whereas blood urea N concentration was the lowest and the value of lipase activity was the highest in the piglets fed SL diet. The SL diet did not affect growth performance,intestinal morphology, or serum hormone concentrations, indicating that reduced dietary N with a high Lys:CP ratio can efficiently reduce dietary N excretion without negatively affecting weaned piglets.

A water-soluble β-glucan improves growth performance by altering gut microbiome and health in weaned pigs

Beta-glucan has been shown to have a beneficial effect on gastrointestinal health.This experiment was conducted to investigate the effects ofβ-glucan isolated from Agrobacterium sp.ZX09 on growth performance and intestinal health of weaning pigs.A total of 108 weaned pigs(21 d of age;6.05±0.36 kg)were randomly divided into 3 groups(6 pens/group;6 pigs/pen),and the groups were each treated with the following diets:1)basal diet,2)basal diet supplemented with 20 mg/kg olaquindox,3)basal diet supplemented with 200 mg/kgβ-glucan,for 21 d.Compared with the control group,pigs fed with200 mg/kgβ-glucan had greaterBW,average daily gain and duodenal villus height to crypt depth ratio(P<0.05).Olaquindox increased the duodenal or jejunal villus height of pigs compared withβ-glucan.Compared with the control group,β-glucan tended to increase the occludin mRNA expression in the jejunum(0.05<P<0.10).Beta-glucan enriched the beneficial microbiota in the ileum of pigs(P<0.05).In conclusion,β-glucan may promote growth performance by improving intestinal health and increasing beneficial microbiota of weaned pigs.The study results will provide valuable theoretical guidance for the utilization ofβ-glucan in weaned pigs.