盐碱胁迫下黑麦草生长及离子微区分布特征

盐碱生境通过离子毒害和渗透胁迫等抑制植物的生长发育。离子微区分布调控主要通过调整盐分在不同部位的分布来减轻Na⁺等高浓度离子对重要组织器官的毒害作用,是盐碱胁迫下植物生存的重要策略之一。为探究黑麦草在盐碱胁迫下的离子微区分布特征,本研究通过水培法,采用不同盐碱浓度(0、50、100、200 mmol·L^-1)培养液处理黑麦草植株,考察其生长、离子吸收、运输选择性和微区分布变化,揭示黑麦草对盐碱胁迫的适应机制。结果表明:1) 盐碱胁迫下,植株的相对含水率、叶绿素含量逐渐降低,电解质外渗率显著升高;当盐碱浓度大于100 mmol·L^-1时,根长、株高和生物量均显著降低,即黑麦草的耐盐阈值是100~200 mmol·L^-1;2) 盐碱浓度为50 mmol·L^-1时,植株根中K⁺/Na⁺较空白升高了48.3%,Ca²⁺/Na⁺升高了54.1%,说明黑麦草根部可通过增强K⁺、Ca²⁺的吸收来维持细胞渗透压并缓解高浓度Na⁺的毒性;3) 在50~200 mmol·L^-1的盐碱浓度下,黑麦草叶片中可溶性组分及细胞壁中Na⁺的相对含量较对照显著增加,但细胞器内Na⁺的相对含量降低,说明叶部将Na⁺富集在液泡和细胞壁中,以减少Na⁺对细胞器的毒害作用;4) 叶片微观结构的SEM电镜图片显示,盐碱胁迫下叶片表皮增厚、导管数量减少和孔径缩小。综上所述,盐碱胁迫下黑麦草不同器官的适应机理不同,根部主要通过强化K⁺、Ca²⁺的吸收,降低对Na⁺的吸收,并将Na⁺区隔化在液泡中以降低离子毒害和维持渗透调节,而叶片主要通过将Na⁺区隔在液泡及细胞壁中,以及微观结构的变化来保护细胞器免受离子毒害。本研究可为黑麦草的耐盐碱适应机制及其在盐碱土上的种植提供理论依据。     

猪圆环病毒3型TaqMan-MGB荧光定量PCR方法的建立及应用

为建立猪圆环病毒3型(PCV3)荧光定量PCR检测方法,本研究根据GenBank中PCV3基因序列设计特异性引物和探针,经过反应体系和条件优化,建立了特异性检测PCV3的TaqMan-MGB荧光定量PCR方法。该检测方法在4.78×10~1拷贝/μL～4.78×10~9拷贝/μL质粒标准品范围内均有良好的线性关系;该方法特异性试验结果显示,其与多种常见猪病病毒均无交叉反应,特异性良好;本研究建立的方法敏感性是常规PCR方法的100倍,敏感性较高;批内批间重复性试验变异系数均小于2.3%,重复性良好。对临床样品的检测结果显示,该方法对PCV3的检出率高于常规PCR方法,并且PCV3阳性样品多存在混合感染情况。该方法的建立为PCV3的实验室诊断及流行病学调查提供了快速、准确的检测手段。     

Effect of Different Domestic Alfalfa Adding Content on Nutritional Quality of Local Fresh Milk

Domestic alfalfa supply has the obvious price advantage in the local dairy farms,but its feasible amount of feeding and the effect on the quality of fresh milk are still unclear for a lack of scientific experimental evidence. The alfalfa growed in Daqing city, Heilongjiang province was used in the present study,and one-year feeding experiment was performed to analyze the effect of alfalfa on the quality of fresh milk in the local 9 large-scale dairy farms. The results showed that compared with control group,the nutrient of fresh milk were not significantly improred when the amout of alfalfa was 3 kg/d (P >0.05).While the cude protein and dry matter of fresh milk were significantly increased (P <0.05) when the amount of alfalfa addition in the diet was 6 kg/d, but the milk fat and lactose percentage were not significantly affected (P <0.05). Moreover,the alfalfa addition in diet resulted in a significantly increase of unsaturated fatty acid percentage (P <0.05) and optimization of fatty acid composition of the fresh milk. In conclusion,it was helpful to improve the nutritional quality of fresh milk by changing the alfalfa amount of 3 kg/d,which was commonly used at present in dairy farms,to be 6 kg/d.     

Cloning,Expression and Bioinformatics Analysis of Enterococcus faecalis from Northeast Black Bear

In order to detect Enterococcus faecalis endocarditis antigen (EfaA) of bear that was used to disclose the infected Northeast Black bear immediately, a pair of PCR primers was synthesized by EfaA gene of Enterococcus faecalis that was recorded in GenBank (accession number:U03756.1) and the target fragment was 689 bp. The PCR product was cloned by pMD19-T vector, then was transferred to Escherichia coli DH5α competent cells and the positive clones were filtered. Recombinant plasmid (pMD19-T-EfaA) was extracted. Identification of PCR and digestion, sequencing, the structure prediction of proteins were operated. The results showed that EfaA gene was cloned successfully, and the gene homology with ATCC 29212 was 100.0%. pMD19-T-EfaA was constructed successfully, structure of proteins was predicted. This study provided theoretical basis for diagnostic methods of Enterococcus faecalis and laid basis for prevention and control of Northeast Black bear disease.     

猪圆环病毒2型山东分离株全基因组的克隆与序列分析

根据猪圆环病毒2型(PCV-2)全基因组序列,设计一对特异性引物,从疑似断奶仔猪多系统衰竭综合征(PMWS)病料中扩增出PCV-2基因组DNA,将基因片段克隆于pMD18-T载体,筛选获得含有相应片段的阳性重组质粒pMD18-T-PCV-2。对筛选出的阳性质粒进行测序。结果表明,PCV山东株的全基因组为1 767 bp,与国内外毒株核苷酸同源性高达99.6%。     

饲养空间对昆明小鼠产仔数、子代成活数及体重的影响

为了研究饲养空间对昆明小鼠产仔数、子代成活数和体重的影响,随机选择32只合笼后的雌鼠平均分配在两种自主设计的鼠箱中,实验组鼠箱底面积为(10×20)cm2,对照组鼠箱底面积为(20×30)cm2.记录雌鼠产仔数,每周记录成活仔鼠数和仔鼠体重至28日龄.在试验两水平下产仔数差异不显著(P>0.05);仔鼠成活数在21日龄...     

青贮时间及添加剂对高寒牧区燕麦-箭筈豌豆混播捆裹青贮发酵品质的影响

为了探讨青藏高原高寒牧区燕麦与箭筈豌豆混播捆裹青贮的可行性,为该地区草产品加工提供技术依据,在甘南州夏河县研究了青贮时间与添加剂对燕麦与箭筈豌豆混播捆裹青贮品质的影响。在燕麦灌浆期、箭筈豌豆开花期刈割,添加玉米粉(4%)、尿素(0.4%)、Synlac Dry(0.002 g/kg)和Sila-Max 200 (0.0025 g/kg),以直接青贮为对照(CK),进行捆裹青贮。分别在青贮第40,80,120天开包取样,每处理各时间点3个重复,测定其营养指标、发酵指标和主要微生物类群数量。结果表明:青贮时间对燕麦与箭筈豌豆混播捆裹青贮品质影响显著。由于高寒牧区秋冬季气温很低,完成青贮发酵所需的时间明显增加,在青贮80 d左右发酵才能完成。添加尿素显著提高了青贮料的粗蛋白含量,但同时其氨态氮含量在青贮40,80和120 d时一直保持最高值,较对照分别增加了73.70%、189.60%和185.27%;pH值下降缓慢,青贮120 d后pH仍在4.2以上。添加玉米粉效果明显优于添加尿素。和非生物型添加剂相比,乳酸菌制剂的青贮效果更佳,不仅促进了发酵进程,而且提高了青贮发酵品质。添加Sila-Max 200青贮效果优于添加Synlac Dry,其LAB 数量在青贮40 d后较对照增加了9.88%,乳酸含量增加了110.77%,pH值显著(P<0.05)下降;在青贮80 d后乳酸含量仍为对照的2倍,显著(P<0.05)高于其他3个处理,pH已降至4.1以下。因此,在青藏高原高寒地区,燕麦与箭筈豌豆混播在燕麦灌浆期、箭筈豌豆开花期刈割,添加Sila-Max 200后捆裹青贮80 d即可获得优质的青贮料。     

2012～2017年我国部分地区规模化猪场PRV野毒流行病学调查

为了监测我国规模化猪场伪狂犬病病毒(Pseudorabies virus,PRV)野毒感染情况,本研究采用伪狂犬g E抗体ELISA检测试剂盒对2012年2月~2017年7月送检的我国11个省份925个规模化猪场的44809份猪血清样品进行PRV野毒抗体检测。结果显示,925个猪场中有508个野毒阳性猪场,占检测猪场总数的54.91%,检出9153份阳性猪血清,平均阳性率为20.42%。其中种猪的野毒感染情况最明显,检出率较高,阳性率为23.19%;育肥猪的阳性检出率最低为17.22%。调查表明,我国规模化猪场猪群中仍存在PRV野毒感染。同时,本调查分析了不同地区、不同日龄猪的PRV野毒感染情况及该病的流行趋势,为我国伪狂犬病的净化提供思路。