饲喂益生素雏鸡新城疫疫苗免疫后外周血液的体液免疫变化

为了研究益生素与疫苗的体液免疫增强联合效应,应用免疫SPA菌体花环法、间接ELISA法对饲喂益生素雏鸡ND疫苗免疫后,其外周血液B淋巴细胞数量、IgG、IgM和IgA含量的动态变化进行了较全面系统地研究。结果发现,应用益生素的雏鸡ND疫苗免疫后7d内,其上述被检指标显著高于ND疫苗单独免疫雏鸡(p0.05),表明益生素可提高雏鸡外周血液对ND疫苗的体液免疫应答能力。益生素Ⅰ组雏鸡外周血液的体液免疫指标又略高于益生素Ⅱ组雏鸡,说明益生素Ⅰ的疫苗免疫增强效果优于益生素Ⅱ。     

Nuclear Replacement of In Vitro‐Matured Porcine Oocytes by a Serial Centrifugation and Fusion Method

The objective of the present study was to establish a method for nuclear replacement in metaphase‐II (M‐II) stage porcine oocytes. Karyoplasts containing M‐II chromosomes (K) and cytoplasts without chromosomes (C) were produced from in vitro‐matured oocytes by a serial centrifugation method. The oocytes were then reconstructed by fusion of one karyoplast with 1, 2, 3 or 4 cytoplasts (K + 1C, K + 2C, K + 3C and K + 4C, respectively). Reconstructed oocytes, karyoplasts without fusion of any cytoplast (K) and zona‐free M‐II oocytes (control) were used for experiments. The rates of female pronucleus formation after parthenogenetic activation in all groups of reconstructed oocytes (58.2–77.4%) were not different from those of the K and control groups (58.2% and 66.0%, respectively). In vitro fertilization was carried out to assay the fertilization ability and subsequent embryonic development of the reconstructed oocytes. The cytoplast : karyoplast ratio did not affect the fertilization status (penetration and male pronuclear formation rates) of the oocytes. A significantly high monospermy rate was found in K oocytes (p < 0.05, 61.6%) compared with the other groups (18.2–32.8%). Blastocyst formation rates increased significantly as the number of the cytoplasts fused with karyoplasts increased (p < 0.05, 0.0–15.3%). The blastocyst rate in the K + 4C group (15.3%) was comparable with that of the control (17.8%). Total cell numbers in both the K + 3C and K + 4C groups (16.0 and 15.3 cells, respectively) were comparable with that of the control (26.2 cells). Our results demonstrate that a serial centrifugation and fusion (Centri‐Fusion) is an effective method for producing M‐II chromosome transferred oocytes with normal fertilization ability and in vitro development. It is suggested that the number of cytoplasts fused with a karyoplast plays a critical role in embryonic development.     

Biomechanical Comparison of the Trocar Tip Point and the Hollow Ground Tip Point for Smooth External Skeletal Fixation Pins

Objective —To compare the insertional characteristics of external fixator pins with hollow ground (HG), modified HG, and trocar (T) points.
Study Design —An acute, in vitro biomechanical evaluation.
Sample Population—Thirteen radii from canine cadavers.
Methods —A total of 16 T-tipped and 16 HG-tipped pins were inserted into 8 canine radii. Ten pins of each modification of the HG tip (length of the cutting edge reduced by 0.127 mm and 0.254 mm, respectively) were inserted into another five radii. All pins were inserted with low-speed power drilling and 80 N drilling load. Differences between peak tip temperature, drilling energy, and pullout force were determined for each pin type at both diaphyseal and metaphyseal locations.
Results —HG-tipped pins showed a 40% lower tip temperature in diaphyseal bone, a 25% reduction in drilling energy in diaphyseal bone, and a reduction of pullout force in both diaphyseal (65%) and metaphyseal (50%) bone compared with T-tipped pins. HG 0.254-mm pins generated higher tip temperatures and had greater pullout than HG pins in diaphyseal bone.
Conclusions —The HG tip was a more efficient design; however, the reduction in pullout force suggests that, because a better hole was drilled, radial preload is reduced. Reduction of the cutting edge by 0.254 mm increased the pullout force but also increased the temperatures.
Clinical Relevance —Thermal and microstructural damage are reduced by the HG tip, but pin-bone interface stability is also compromised. The use of a tip with 0.254 mm reduction in the cutting edge may optimize the biological and mechanical factors at the pin-bone interface.     

不同强度干旱胁迫对红砂种子萌发的影响

采用培养皿纸上发芽床实验设计,设置PEG6000 0(CK)、25 g/L、50 g/L、75 g/L、100 g/L、125 g/L、150g/L、200 g/L、250 g/L、300g/L 10个干旱胁迫处理,NaCl 0(CK)、50 mmol/L 2个处理,研究了不同干旱胁迫条件下红砂种子的萌发率、萌发势、萌发指数、活力指数等指标的变化特点。结果表明,PEG6000浓度低于75 g/L时萌发率随PEG6000浓度升高有上升的趋势,但高于125 g/L时萌发率随着PEG6000浓度的升高而下降,直至0;种子能够萌发的最高PEG6000浓度为200 g/L。干旱胁迫对种子胚芽生长有抑制作用,但轻度干旱可促进初生根生长。PEG6000浓度高于100时可以显著延缓种子的初始发芽时间,降低种子的发芽势。NaCl处理对红砂种子萌发率无显著影响,但对萌发指数、萌发势、和活力指数均有显著影响。     

铬对肉仔鸡生长性能、免疫功能和胴体品质的影响

用21日龄Arbor Acress(AA)肉公鸡336只,研究饲粮中添加铬对肉仔鸡生长性能、免疫功能和胴体品质的影响。将试验鸡只共分为8个处理组,分别添加源于氯化铬的铬2．0、4．0、6．0、8.0、10．0、12．0和14．0mg/kg。结果表明:饲粮中添加2．0mg/kg铬显著提高了肉仔鸡胸腺重(P<0．10),降低了腹脂率(P<0．10),4．0、6．0mg/kg铬显著提高了全净膛率(P< 0．10),各试验组显著提高了T淋巴细胞转化率(P<0．10);饲粮中添加铬对其余指标则无显著影响(P>0．10)。     

猪繁殖与呼吸综合征病毒强弱毒株嵌合感染性克隆的构建及鉴定

查明猪繁殖与呼吸综合征病毒(PRRSV)致病性大幅增高的机制,进而研制用于防治流行PRRSV变异株的高效疫苗无疑是兽医工作者的当务之急.在弱毒株APRRS的全长感染性克隆pAPRRS以及我室构建的高致病性HP PRRSV感染性克隆pJX143的基础上,构建了nsp2替换的强弱毒PRRSV嵌合感染性克隆.将构建的嵌合克隆转染MA104,4d后观察到典型的CPE.通过RT-PCR和免疫荧光证明获得了一系列强弱毒株之间的嵌合病毒.这些嵌合病毒的构建成功和相应反向遗传操作平台的建立及应用,为研发预防HP PRRSV的高效嵌合疫苗奠定了基础.该类嵌合感染性cDNA克隆也为解析目前流行的HP PRRSV毒力因子和高致病力机制奠定了基础.     

依普黄酮对笼养蛋鸡骨质疏松症骨组织病理变化的影响

本试验选用200只24周龄健康海蓝褐蛋鸡,随机分为4组:对照组(基础日粮中含钙3.55%)、低钙组(日粮含钙1.27%)、试验Ⅰ组(8mg依普黄酮/kg低钙日粮)和试验Ⅱ组(20mg依普黄酮/kg低钙日粮),观察依普黄酮对笼养蛋鸡骨质疏松症骨组织病理变化的影响。结果显示,与低钙组相比,试验Ⅰ、Ⅱ组骨髓腔面积分别显著下降7.81%(P0.05)和10.26%(P0.05),骨皮质平均厚度分别显著升高23.78(P0.05)和27.60(P0.05),并且骨小梁增厚、变密,骨陷窝变浅,成骨细胞增多,破骨细胞减少。结果表明,低钙日粮中添加依普黄酮能显著改善蛋鸡骨质疏松症的临床症状,与其促进成骨细胞生成,抑制破骨细胞活性,使其骨量增加,骨结构得到改善密切相关。     

植物乳杆菌微胶囊化的研究

为了保证足够的乳酸菌在动物肠道中发挥益生作用,试验以海藻酸钠、脱脂奶粉、乳糖为壁材,采用挤压包埋和冷冻干燥结合的方法对植物乳杆菌进行微胶囊化研究。通过正交试验找到最佳的微胶囊化条件及载体的添加量。结果表明,海藻酸钠浓度为3％,脱脂奶粉浓度为4％,乳糖浓度为6％,CaCl₂浓度为2％时,制备的微胶囊中活菌数最高,达到7.67×10¹⁰ CFU/g,且产品具有耐酸性。     

Development of A Dual Real-time PCR for the Rapid Detection of Listeria monocytogenes

To establish a rapid assay for Listeria monocytogenes(LM) detection,a Real-time PCR method was developed targeting iap gene of LM.The results showed that the test for 15 bacteria strains,only LM was positive,indicated that the method had high specificity.In addition,the sensitivity of Real-time PCR was 6.5 CFU/mL.Stability and reproducibility of the test showed that the coefficient of variation for the same sample repeat the Ct values were less than 2%.Furthermore,a total of 3 positive samples for LM were detected from 139 clinical samples by the method,which was in accordance with the testing result by GB 478930-2010 standard detection protocol.Therefore,the Real-time PCR method provides a novel rapid,sensitive and good repeatability detection method for LM infection.     

DNA甲基化酶抑制剂5-Aza-CdR对多能基因及甲基化相关基因在徒手克隆胚胎中表达模式的影响

本试验通过实时荧光定量PCR方法对多能基因Oct4和Nanog及DNA甲基化相关基因Dnmt1和Tets在徒手克隆（handmade cloning,HMC）胚胎中的表达模式进行初步研究,并探讨5-Aza-CdR处理重构胚对这些基因表达模式的影响。结果显示,Oct4、Nanog和Tet3的表达在2细胞时期达到顶峰,Dnmt1和Tet2基因的表达随HMC胚胎发育而下降,而Tet1基因随HMC胚胎发育表达上升。使用5-Aza-CdR处理重构胚没有改变Oct4、Tet1和Tet3基因的表达模式,使Nanog基因在胚胎发育初期表达增加,Dnmt1和Tet2基因在胚胎发育初期表达降低。研究初步确立了Oct4、Nanog、Dnmt1和Tets基因在HMC胚胎的表达模式,5-Aza-CdR对重构胚的处理可对HMC胚胎的甲基化模式产生影响。