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Number of results: 28
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Abstract

Function of duck (Anas platyrhynchos) major histocompatibility complex class I (Anpl-MHC I) molecules in binding peptides is through the peptide binding groove (PBG), which is thought to be influenced by the high polymorphism of α1 and α2 domains. However, little is known about the polymorphism of Anpl-MHC I peptide binding domain (PBD), especially in the domestic duck. Here, we analyzed the polymorphism of forty-eight Anpl-MHC I α1 and α2 domains from domestic duck breeds previously reported. All sequences were analyzed through multiple sequence alignment and a phylogenetic tree was constructed. The coefficient of variance of the peptide binding domains (PBDs) from WS, CV, JD, and SX duck breeds was estimated based on the Wu-Kabat variability index, followed by the location of the highly variable sites (HVSs) on reported crystal structure models. Analysis of α1 and α2 domains showed common features of classical MHC class I and high polymorphism, especially in α1 domain. The constructed phylogenetic tree showed that PBDs of domestic ducks did not segregate based on breeds and had a close phylogenetic relationship, even with wild ducks. In each breed, HVSs were mostly located in the PBG, suggesting that they might determine peptide-binding characteristics and subsequently influence peptide presentation and recognition. The combined results of sequence data and crystal structure provide novel valuable insights into the polymorphism and diversity of Anpl-MHC I PBDs that will facilitate further studies on disease resistance differences between duck breeds and the development of cytotoxic T-lymphocyte (CTL) epitope vaccines suited for preventing diseases in domestic ducks.
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Abstract

The welfare and healthy growth of poultry under intensive feeding conditions are closely related to their living environment. In spring, the air quality considerably decreases due to reduced ventilation and aeration in cage systems, which influences the meat quality and health of broilers during normal growth stages. In this study, we analyzed the airborne bacterial communities in PM2.5 and PM10 in cage broiler houses at different broiler growth stages under intensive rearing conditions based on the high-throughput 16S rDNA sequencing technique. Our results revealed that PM2.5, PM10 and airborne microbes gradually increased during the broiler growth cycle in poultry houses. Some potential or opportunistic pathogens, including Acinetobacter, Pseudomonas, Enterococcus, Microbacterium, etc., were found in the broiler houses at different growth stages. Our study evaluated variations in the microbial communities in PM2.5 and PM10 and potential opportunistic pathogens during the growth cycle of broilers in poultry houses in the spring. Our findings may provide a basis for developing technologies for air quality control in caged poultry houses.
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Abstract

Senecavirus A (SVA) the only member of the Senecavirus genus within the Picornaviridae family, is an emerging pathogen causing swine idiopathic vesicular disease and epidemic transient neonatal losses. Here, SVA strain (CH-HNKZ-2017) was isolated from a swine farm exhibiting vesicular disease in Henan Province of Central China. A phylogenetic analysis based on complete genome sequence indicated that CH-HNKZ-2017 was closely related to US-15-40381IA, indica- ting that a new SVA isolate had emerged in China.
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Abstract

Isothermal hot compression experiments were carried out using the Gleeble-1500D thermal mechanical simulator. The flow stress of the Cu-1%Zr and Cu-1%Zr-0.15%Y alloys was studied at hot deformation temperature of 550°C, 650°C, 750°C, 850°C, 900°C and the strain rate of 0.001 s–1, 0.01 s–1, 0.1 s–1, 1 s–1, 10 s–1. Hot deformation activation energy and constitutive equations for two kinds of alloys with and without yttrium addition were obtained by correlating the flow stress, strain rate and deformation temperature. The reasons for the change of hot deformation activation energy of the two alloys were analyzed. Dynamic recrystallization microstructure evolution for the two kinds of alloys during hot compression deformation was analyzed by optical and transmission electron microscopy. Cu-1%Zr and Cu-1%Zr-0.15%Y alloys exhibit similar behavior of hot compression deformation. Typical dynamic recovery occurs during the 550-750°C deformation temperature, while dynamic recrystallization (DRX) occurs during the 850-900°C deformation temperature. High Zr content and the addition of Y significantly improved Cu-1%Zr alloy hot deformation activation energy. Compared with hot deformation activation energy of pure copper, hot deformation activation energy of the Cu-1%Zr and Cu-1%Zr-0.15%Y alloys is increased by 54% and 81%, respectively. Compared with hot deformation activation energy of the Cu-1%Zr alloy, it increased by 18% with the addition of Y. The addition of yttrium refines grain, advances the dynamic recrystallization critical strain point and improves dynamic recrystallization.
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Abstract

In order to predict the distribution of shrinkage porosity in steel ingot efficiently and accurately, a criterion R√L and a method to obtain its threshold value were proposed. The criterion R√L was derived based on the solidification characteristics of steel ingot and pressure gradient in the mushy zone, in which the physical properties, the thermal parameters, the structure of the mushy zone and the secondary dendrite arm spacing were all taken into consideration. The threshold value of the criterion R√L was obtained with combination of numerical simulation of ingot solidification and total solidification shrinkage rate. Prediction of the shrinkage porosity in a 5.5 ton ingot of 2Cr13 steel with criterion R√L>0.21 m・℃1/2・s -3/2 agreed well with the results of experimental sectioning. Based on this criterion, optimization of the ingot was carried out by decreasing the height-to-diameter ratio and increasing the taper, which successfully eliminated the centreline porosity and further proved the applicability of this criterion.
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Abstract

Objective: This study aimed to investigate developmental changes of the thymus and intra- thymic IL-1β, IL-6 and TNF-α expression in weaned Sprague-Dawley rats induced by lipopolysac- charide. Methods: Forty healthy weaned rats aged 26 days and weighing 83±4 g were randomly and equally divided into two groups. The lipopolysaccharide group was treated daily with a single injection of lipopolysaccharide for 10 consecutive days, and the saline group was treated with an equal volume of sterilized saline. On the 1st, 4th, 7th and 10th day, histological changes and distribu- tion of IL-1β-, IL-6- and TNF-α-positive cells were detected in the thymus by hematoxylin-eosin and immunohistochemistry staining, respectively. Subsequently, the expression levels of IL-1β, IL-6 and TNF-α were evaluated in the thymus by the ELISA method. Results: Thymus weight and index were significantly smaller in lipopolysaccharide-treated rats than in saline-treated rats (p<0.05), but no substantial changes were found in the thymus microstructure after lipopolysaccharide induction. Moreover, a large number of IL-1β-, IL-6- and TNF-α-positive cells were observed with brownish-yellow color and mainly distributed in the thy- mus parenchyma, both integrated optical density and average optical density increased signifi- cantly in lipopolysaccharide-treated rats than those in saline-treated rats. Compared with the saline group, most of the thymic homogenates had higher levels of IL-1β, IL-6 and TNF-α in the lipopolysaccharide group on different days. Conclusion: These findings indicate that the thymus atrophied after lipopolysaccharide induction in weaned Sprague-Dawley rats, and excessive production of intrathymic IL-1β, IL-6 and TNF-α was probably involved in the atrophic process.
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Abstract

MDAP-2 is a new antibacterial peptide with a unique structure that was isolated from house- flies. However, its biological characteristics and antibacterial mechanisms against bacteria are still poorly understood. To study the biological characteristics, antibacterial activity, hemolytic activi- ty, cytotoxicity to mammalian cells, and the secondary structure of MDAP-2 were detected; the results showed that MDAP-2 displayed high antibacterial activity against all of the tested Gram-negative bacteria. MDAP-2 had lower hemolytic activity to rabbit red blood cells; only 3.4% hemolytic activity was observed at a concentration of 800μg/ml. MDAP-2 also had lower cytotoxicity to mammalian cells; IC50 values for HEK-293 cells, VERO cells, and IPEC-J2 cells were greater than 1000 μg/ml. The circular dichroism (CD) spectra showed that the peptide most- ly has α-helical properties and some β-fold structure in water and in membrane-like conditions. MDAP-2 is therefore a promising antibacterial agent against Gram-negative bacteria. To deter- mine the antibacterial mechanism(s) of action, fluorescent probes, flow cytometry, and transmis- sion electron microscopy (TEM) were used to study the effects of MDAP-2 on membrane perme- ability, polarization ability, and integrity of Gram-negative bacteria. The results indicated that the peptide caused membrane depolarization, increased membrane permeability, and destroyed membrane integrity. In conclusion, MDAP-2 is a broad-spectrum, lower hemolytic activity, and lower cytotoxicity antibacterial peptide, which is mainly effective on Gram-negative bacteria. It exerts its antimicrobial effects by causing bacterial cytoplasm membrane depolarization, increas- ing cell membrane permeability and disturbing the membrane integrity of Gram-negative bacte- ria. MDAP-2 may offer a new strategy to for defense against Gram-negative bacteria.
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Abstract

Heterogeneous nuclear ribonucleoprotein K (hnRNP K), is a multifunctional protein that participates in a variety of regulatory processes of signal transduction and gene expression. To further characterize the significance of hnRNP K in different male germ cells, we investigated the expression profiles of hnRNP K at different developmental stages in pig and rat testes, and conducted a comparative analysis of expression patterns between these two species. In porcine testis development, both the mRNA and protein level of hnRNP K were down-regulated from 3 months to 8 months. However, the expression level of hnRNP K was abundant across the embryonic period in rats, and decreased gradually from 0 day post partum (dpp) to 14 dpp, then increased with the highest level presenting at 90 dpp. Immunolocalization analysis further confirmed the differential expression and localization of hnRNP K protein during testis development in pigs and rats. The results showed that hnRNP K was widely distributed in gonocytes, spermatogonia, sertoli cells and Leydig cells. The dynamic expression profile of hnRNP K may imply its crucial and potential roles in the development of the testis, which will provide a theoretical basis for the future study of molecular mechanism regulation of spermatogenesis.
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Abstract

Twinned dendrites in Al-Zn alloy with high Zn content (40% wt.%) were successfully prepared by directional solidification. At different directional solidification rates (1000 and 1500 μm/s), microstructures and growth orientation variations of Al twinned dendrite and non-twinned dendrite were characterized. By using the inverted trapezoidal graphite sleeve at 1000 μm/s, Al twinned dendrite were formed to developed feather crystal structures in longitudinal section. Its primary and secondary twinned dendrite were grew along [110] direction. Moreover the deviation angle between [110] direction of Al twinned dendrite and the heat flow direction was about 27.15°. While not using the inverted trapezoidal graphite sleeve at 1000 and 1500 μm/s, Al dendrite was the non-twinned dendrite and the twinned dendrite was not appeared. The experimental results showed that the higher temperature gradient, a certain pulling rate and convection environment were the formation conditions of twinned dendrites.
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Abstract

Culture gas atmosphere is one of the most important factors affecting embryo development in vitro. The main objective of this study was to compare the effects of CO concentration on the subsequent pre-implantation developmental capacity of pig embryos in vitro, including embryos obtained via parthenogenesis, in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI). Pig embryos were developed in four different CO2 concentrations in air: 3%, 5%, 10%, or 15%. The cleavage rate of pig parthenogenetic, IVF, or ICSI embryos developed in CO2 concen- trations under 5% was the highest. There were no significant differences in the oocyte cleavage rate in ICSI embryos in CO2 concentrations under 3% and 5% (p>0.05). However, as CO2 levels increased (up to 15%) the blastocyst output on day 7, from parthenogenetic, IVF, and ICSI em- bryos, decreased to 0%. These findings demonstrate that CO2 positively affects the developmen- tal capacity of pig embryos. However, high or low CO2 levels do not significantly improve the developmental capacity of pig embryos. The best results were obtained for all of the pig embryos at a 5% CO2 concentration.
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