葡萄组织培养快速繁殖及微茎尖培养研究

通过对葡萄组织培养快速繁殖和微茎尖培养的接种、继代繁殖、生根及移栽等关键技术的研究,筛选出适于多种品种生长的广潜培养基.采用价格便宜的化学试剂等代用品配制培养基,使其成本降低46.3%至58.2%.其茎段培养方法已应用于繁殖珍贵的葡萄品种苗木,微茎尖培养将为培育无病毒苗提供技术准备.     

Deletional tolerance mediated by extrathymic Aire-expressing cells

The prevention of autoimmunity requires the elimination of self-reactive T cells during their development and maturation. The expression of diverse self-antigens by stromal cells in the thymus is essential to this process and depends, in part, on the activity of the autoimmune regulator (Aire) gene. Here we report the identification of extrathymic Aire-expressing cells (eTACs) resident within the secondary lymphoid organs. These stromally derived eTACs express a diverse array of distinct self-antigens and are capable of interacting with and deleting na?ve autoreactive T cells. Using two-photon microscopy, we observed stable antigen-specific interactions between eTACs and autoreactive T cells. We propose that such a secondary network of self-antigen-expressing stromal cells may help reinforce immune tolerance by preventing the maturation of autoreactive T cells that escape thymic negative selection.     

从DNA水平上分析香菇不同菌株的遗传差异

本文选取了10个中国香菇野生种和2个栽培种.采用RAPD技术进行遗传差异测定.16个随机引物共扩增出118条DNA带,在此基础上分析并构建了遗传相关聚类图.结果表明,我国的香菇野生资源存在着较大的遗传差异,10个野生种菌株之间的遗传相似性在50%～80 %之间.     

Erysipelothrix rhusiopathiae bloodstream infection – A 22‐year experience at Mayo Clinic,Minnesota

Erysipelothrix rhusiopathiae is a facultatively anaerobic Gram‐positive bacillus found mostly in swine, fish and sheep. E. rhusiopathiae classically causes cutaneous eruptions in butchers, fish handlers and veterinarians. Based solely on case reports, 90% of E. rhusiopathiae bloodstream infections (BSI) have been associated with infective endocarditis (IE). To assess the true frequency of IE in E. rhusiopathiae BSI as well as other clinical associations, we performed a retrospective cohort analysis of E. rhusiopathiae BSI at Mayo Clinic. This is a single‐centre, retrospective study conducted between 1/1/1994 and 20/6/2016 at Mayo Clinic in Rochester, MN. Medical records were reviewed for demographics, E. rhusiopathiae BSI, anti‐microbial susceptibilities, incidence of IE, patient comorbidities, intensive care unit (ICU) admission and duration of antibiotics. Five cases of E. rhusiopathiae BSI were identified. Risk factors included animal exposures, immunosuppression, diabetes and kidney disease. All cases involved penicillin‐sensitive strains and high‐grade BSI. Four cases showed no signs of IE on transesophageal echocardiogram. All patients recovered fully with intravenous antibiotics. Our retrospective review illustrates that E. rhusiopathiae can cause invasive BSI in the absence of IE and that the previously reported 90% association between BSI and IE may be overestimated due to reporting bias. E. rhusiopathiae should be suspected in any patient with Gram‐positive bacilli in blood cultures and the aforementioned risk factors. A limitation of our study was the low sample size, and future studies may involve multicentre collaborations and the use of polymerase chain reaction (PCR) or serologic testing to increase the number of diagnoses..     

刈割次数对菊芋生物量及营养价值影响研究

为探讨不同刈割次数对菊芋产量及营养价值的影响,以自选品种青芋1号、青芋2号菊芋为试验材料,采用两种不同刈割次数分别测定不同品种的产量,粗蛋白、粗脂肪、粗纤维、粗灰分、钙、磷、无氮浸出物含量,结果表明:随着刈割次数的增加,两个品种的总生物量和地上部生物量增加,地下部生物量减少;在苗高170 cm时刈割1次的菊芋秸秆中粗蛋白、粗脂肪、粗灰分以及钙磷、总糖含量高于对照及刈割两次的秸秆。为达到生物量最大值,菊芋应该选择在苗高120 cm时留茬30 cm刈割1次,苗子长到120 cm再刈割1次;为了达到最佳营养价值时期刈割则可以选择在苗高170 cm时刈割。     

LPS和LT对肠黏膜VEC内分泌NO和ET的影响

研究LPS和LT引起肠黏膜微血管内皮细胞(VEC)损伤的作用机制。将所培养的肠黏膜VEC 60个孔分为空白对照组、LPS(1μg/mL)组和LT(50μg/mL)组3个组,每个组又分4个不同时间段:3h、6h、9h、12h。结果LPS导致肠黏膜VEC分泌NO明显升高,3 h后达到高峰,随后逐渐降低,而ET分泌急剧升高,9 h后达到高峰。LT导致肠黏膜VEC分泌NO明显升高,3 h达到高峰,随后逐渐降低,而ET在6 h前明显降低,随后逐渐升高到正常水平。     

Generation of a cold-adapted PRRSV with a nucleotide substitution in the ORF5 and numerous mutations in the hypervariable region of NSP2

A cold-adapted porcine reproductive and respiratory syndrome virus (CA-VR2332) was generated from the modified live virus strain VR2332. CA-VR2332 showed impaired growth when cultured at 37°C with numerous mutations (^S731^F, ^E819^D, ^G975^E, and ^D1014^N) in the hypervariable region of the NSP2, in which the mutation ^S731^F might play a vital role in viral replication at 30°C. Conserved amino acid sequences of the GP5 protein suggests that CA-VR2332 is a promising candidate for producing an effective vaccine against PRRSV infection. Further studies on replication and immunogenicity in vivo are required to evaluate the properties of CA-VR2332.     

绿盲蝽为害对不同空间位置桃叶生理指标的影响

为明确绿盲蝽为害不同时期桃树的应激反应发生发展过程,采用生化测定方法分析了桃树上、中、下部不同受害程度叶片内的可溶性糖、蛋白质、游离氨基酸含量以及防御性酶活性的变化。结果表明,绿盲蝽为害后,随着时间的延长,受轻度为害的桃树叶片内可溶性糖含量由28.61 mg/g减少至19.21 mg/g,蛋白质含量由1.29 mg/g先增加至2.01 mg/g,后减少至1.66 mg/g,游离氨基酸含量由0.49 mg/g增加至0.72 mg/g;而受重度为害的叶片内可溶性糖和蛋白质的含量均先减少后增加,游离氨基酸含量则先增加后减少。防御性酶活性随绿盲蝽为害程度的加重也发生了不同程度的变化,随着时间的延长,受轻度为害的叶片内超氧化物歧化酶活性降低,过氧化物酶和过氧化氢酶活性有所升高;而受重度为害的叶片内超氧化物歧化酶活性先降低后升高,过氧化物酶活性升高,过氧化氢酶活性降低。说明不同位置桃树叶片对绿盲蝽的为害胁迫产生了应激反应,通过调整其体内各种防御性物质的含量,对绿盲蝽为害产生诱导抗性,且与为害程度有一定的相关性。     

Inclusion of wheat aleurone in gestation diets improves postprandial satiety,stress status and stillbirth rate of sows

This study investigated the effects of different amounts of wheat aleurone (WA) (0, 15%, 30%) inclusion in gestation diets on the reproductive performance, postprandial satiety, stress status and stereotypic behaviors of sows. A total of 84 Landrace × Yorkshire sows (parity 4.87 ± 1.32) at breeding were randomly allotted to one of the three isoenergetic and isonitrogenous dietary treatments based on parity and body weight. The results showed that, compared with the control (0), sows fed the WA diet had a higher serum concentration of peptide YY (PYY) (P < 0.05) and glucagon like peptide-1 (GLP-1) (P < 0.05) and a lower concentration of saliva cortisol (P < 0.01). Importantly, compared with the control group, only the 15% WA group had a higher concentration of the total antioxidant capacity (T-AOC) (P < 0.05), lower proportions of sitting (P = 0.05) and stillbirth rates (P < 0.01). Accordingly, the production cost per piglet born alive ($ 6.9 vs. $ 7.6) or per piglet born healthy ($ 7.4 vs. $ 7.9) declined in the 15% WA group versus the control group. Overall, 15% WA inclusion in gestation diets contributed to enhancing postprandial satiety, alleviating stress status and decreasing stillbirth rate of sows. This study provides a reference for the application of WA as a partial substitute for conventional feed ingredients to improve sows’ reproductive performance.