降水量及N添加对宁夏荒漠草原土壤C:N:P生态化学计量特征和植被群落组成的影响

为了解降水格局改变和大气氮(N)沉降增加背景下土壤碳(C)∶N∶磷(P)平衡关系的改变是否会影响到荒漠草原植被群落组成, 基于2017年在宁夏荒漠草原设立的降水量(降水量减少50%、降水量减少30%、自然降水量、降水量增加30%和降水量增加50%)、N添加(0和5 g·m^-2·yr^-1)及其交互作用的野外试验, 初步分析了土壤C∶N∶P生态化学计量特征和植物群落组成的变化趋势以及二者的关系。结果表明, 增加降水量降低了土壤有机C、全N和N∶P。N添加及其与降水量的交互作用对土壤C∶N∶P生态化学计量特征的影响较小; 适量增加降水量刺激了多数植物生长, 提高了群落多样性。过量增加降水量导致猪毛蒿种群生物量急增, 且N添加对降水量效应有促进作用, 从而降低了群落多样性; 土壤含水量、全N、有机C和N∶P与种群生物量关系较为密切, 土壤含水量、有机C、C∶P和C∶N与多样性指数存在较强的相关关系。以上结果意味着降水量会通过调控土壤水分有效性, 改变土壤与植物之间N和P的满足程度, 从而对植物生长策略和群落多样性产生影响; 短期N添加对土壤养分有效性影响较小。因此, 还需通过长期的原位试验, 对N添加及其与降水量交互作用下土壤C∶N∶P计量平衡与植物群落组成的关系进行深入探讨。     

Oxalate-degrading capacities of lactic acid bacteria in canine feces

In this study, lactic acid bacteria in canine feces were isolated and identified, and their oxalate-degrading capacities were evaluated. The oxalate-degrading capacities were determined for 24 of 47 (51.06%) lactic acid bacteria isolates. Of these, 8 isolates [Leuconostoc mesenteroides (RL75), Lactococcus garvieae (CD2), Lactococcus subsp. lactis (CS21), Enterococcus faecium (CL71 and CL72), and Enterococcus faecalis (CD14, CS62, and CD12)] degraded more than 5% of the oxalate present, while the others degraded less than 5% of the oxalate in vitro. Isolates that degraded more than 5% of the oxalate present were selected for further examination. The oxalate-degrading capacities of individual isolates, a mixture of Enterococcus, a mixture of Lactococcus, and a mixture of the eight isolates were evaluated in media containing different concentrations of glucose (sufficient, insufficient, or no glucose). In comparison with the control medium, all of the individual isolates and mixtures of isolates could degrade oxalate in all three groups (P<0.05). In most cases, the isolates growing in medium with 20 g/L of glucose had higher oxalate-degrading capacities than those growing in medium with 2.5 g/L of glucose or no glucose. The mixture of all isolates showed higher oxalate-degrading capacity than the individual isolates and other mixtures. The oxalate-degrading capacities of the isolates were isolate dependent.     

应用Excel软件分析敌敌畏农药对两广二号家蚕的安全间隔期

应用Excel软件中的曲线方程分析判断敌敌畏农药对两广二号家蚕的安全间隔期。结果表明：敌敌畏1000倍液的安全间隔期是6d多,其数学模型为幂函数曲线方：y=88．0653x-1834本方法克服以往家蚕的农药安全期无数学模型可循或使用的BASIC方法陈旧繁杂的缺点,也避免英文统计软件SPSS难以在农村普及的不足,是一种计...     

β-carotene attenuates weaning-induced apoptosis via inhibition of PERK-CHOP and IRE1-JNK/p38 MAPK signalling pathways in piglet jejunum

Weaning may cause oxidative injury, immune response impairment, apoptosis and other injuries in piglets. Oxidative and endoplasmic reticulum stress (ERS) can elicit inflammatory responses, and persistent oxidative and ERS also may lead to apoptotic cascades, which is associated with the pathogenesis of multiple diseases. β-carotene, a natural carotenoid, has potential anti-inflammatory and antioxidant functions. However, the effect of β-carotene on apoptosis in weaned piglets and the detailed molecular mechanism remain unclear. In this study, we found that β-carotene decreased malondialdehyde (MDA) levels and increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in piglet serum. β-carotene could inhibit the mRNA levels of caspase-3 significantly, but had no significant inhibitory effect of the mRNA levels of caspase-9 and caspase-12 in the piglet jejunum. In addition, β-carotene decreased the activation of GRP78, CHOP, and JNK/p38 MAPK and the ratio of Bax/Bcl-2. Furthermore, β-carotene had a significant influence on the activation of ERS and apoptosis-related signals in TG-induced IPEC-J2. In the present study, β-carotene pre-treatment attenuated the ratio of Bax/Bcl-2 and prevented TG-induced increases in the level of PERK-CHOP and IRE1-JNK/p38 MAPK pathway activation in a dose-dependent manner. Overall, these findings indicate that β-carotene may protect weaning-induced apoptosis through inhibiting ERS.     

微生态制剂对仔鸡生产性能和免疫功能的影响

研究表明，用不同的微生态制剂饲喂仔鸡，均能促进免疫器官的生长发育，提高免疫器官指数；能明显提高循环抗体的水平和红细胞的免疫功能，因而能促进仔鸡的生长发育，降低料肉比。     

The siderophore-interacting protein is involved in iron acquisition and virulence of Riemerella anatipestifer strain CH3

Riemerella anatipestifer causes epizootic infectious disease in poultry and serious economic losses especially to the duck industry. However, little is known regarding the molecular basis of its pathogenesis. The ability to acquire iron under low-iron conditions is related to the virulence of a variety of bacterial pathogens. In this study, a sip (Riean_1281) deletion mutant CH3Δsip was constructed and characterized for iron-limited growth, biofilm formation, and pathogenicity to ducklings. Results showed that siderophore-interacting protein (SIP) was involved in iron utilization and the sip deletion significantly reduced biofilm formation and adherence to and invasion of Vero cells. In addition, the sip gene was absent in 1 of 24 (4.17%) virulent strains and 2 of 3 (66.7%) avirulent strains of R. anatipestifer, and the sip gene from six R. anatipestifer strains, which belong to serotypes 1, 2, and 10, respectively, shared 100% amino acid identities to those of R. anatipestifer strains DSM15868 and RA-GD. These results suggested that siderophore-mediated iron acquisition may be an important iron-uptake pathway in R. anatipestifer. Animal experiments indicated that the median lethal dose of the CH3Δsip mutant in ducklings was about 35-fold higher than that of the wild-type CH3 strain. Thus, our results demonstrated that R. anatipestifer SIP was involved in iron acquisition and necessary for its optimal virulence.     

中国肉类消费全景图和大趋势

中国食物消费进入新阶段,口粮消费下降,以肉为主的动物性产品消费量的增加是未来消费的主要趋势。本文描绘中国肉类消费全景图,并展望我国肉类消费的大趋势。分析认为,我国城镇居民肉类消费仍处在稳步增长阶段,农村居民肉类消费还有成倍增长的空间。     

锌在养猪业中的应用

本文概述了锌在猪体内的分布、存在形式、代谢需要量与生理作用,阐述不同锌源对猪的生产性能的影响及其应用现状,揭示了合理利用锌源、降低生产成本、减轻对环境污染的重要性。     

MiR‐330‐5p negatively regulates ovine preadipocyte differentiation by targeting branched‐chain aminotransferase 2

The differentiation of preadipocytes into adipose tissues is tightly regulated by various factors including microRNAs and cytokines. This article aims to study the effect of miR‐330‐5p on expression of BCAT2 in ovine preadipocytes. Ovine preadipocytes were isolated, and we found that the miR‐330‐5p expression decreased gradually during the early differentiation of ovine preadipocytes, while BCAT2 expression increased. BCAT2 was identified as a direct target of miR‐330‐5p, ectopic expression of miR‐330‐5p could change the expression of both BCAT2 mRNA and protein. Silencing BCAT2 had the same inhibition effects as overexpressing miR‐330‐5p on the preadipocyte differentiation, but overexpressing BCAT2 had the converse effects. Taken together, we demonstrated that miR‐330‐5p is a negative regulator of differentiation by targeting BCAT2, and clarified the role of BCAT2 and miR‐330‐5p during preadipocyte differentiation.     

猪伪狂犬病病毒gE抗体胶体金免疫层析检测方法的建立及应用

以纯化的抗人红细胞单链抗体(ScFv)-猪伪狂犬病病毒(PRV)gE蛋白双功能融合蛋白为诊断抗原和胶体金标记物,以羊抗猪IgG包被硝酸纤维膜作为质控带,制作检测猪伪狂犬病毒gE抗体的双抗原胶体金试纸条。利用方阵滴定试验筛选出金标抗原最佳工作浓度为17.6μg,检测线诊断抗原最佳标记量为1.76μg,血清最佳稀释度为1∶10,作用时间15 min,与猪瘟病毒(CSFV)、猪细小病毒(PPV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪乙型脑炎病毒(JEV)、猪布鲁菌(Brucella)阳性血清和PRVgE缺失疫苗接种的猪免疫血清检测线均不出现红色条带,与PRV标准阳性血清反应检测线出现红色条带。试纸条操作简单,肉眼于15 min内可判定结果;试纸条在室温保存6个月,其特异性和敏感性没有明显变化;与美国IDEXX和法国LSI gE-ELISA抗体检测诊断试剂盒检测结果比较,1 164份猪血清的符合率均为90.55%。制备的胶体金试纸条具有操作简便、敏感性和特异性较高的特点,可用于PRV野毒感染的快速筛查。