翅果油树根瘤超微结构及其内生菌的观察

作者用光学显微镜,透射电镜和扫描电镜对翅果油树(Eldaeagnus mollis D.)根瘤侵染细胞的超微结构及其内生菌的形态进行了观察研究。翅果油树根瘤中的内生菌具有五种不同的发育形态:菌丝、固氮泡囊、孢囊、孢囊孢子和拟类菌体。内生菌的这些不同形态以及它们在共生固氮中的作用,本文也作了讨论。     

Production of mycelial biomass and exo-polymer by <Emphasis Type="Italic">Hericium erinaceus</Emphasis> CZ-2: Optimization of nutrients levels using response surface methodology

The Doehlert experimental design was used to optimize the production of mycelial biomass and exopolymer from Hericium erinaceus CZ-2 in this study. Statistical analysis showed that the linear and quadric terms of 3 variables: corn flour, yeast extract, and corn steep liquor had significant effects. The optimized combination of these 3 variables was confirmed through validation experiments. The optimal conditions for higher production of mycelial biomass (19.92 g/L) were estimated when the media composition concentrations were set as: 30.85 g/L, corn flour; 2.81 g/L, yeast extract; 16.9 mL/L, corn steep liquor; 10 g/L, glucose; 1 g/L, KH₂PO₄; and 0.5 g/L, MgSO₄·7H₂O; while a maximal exo-polymer yield (1.653 g/L) could be achieved when setting concentrations of: 32.71 g/L, corn flour; 2.35 g/L, Yeast extract; 14.42 mL/L, Corn steep liquor; 10 g/L, glucose; 1 g/L, KH₂PO₄; and 0.5 g/L, MgSO₄·7H₂O. The upscale production was also investigated using a 15 L fermentor using the optimized medium.     

A strategy for fusion expression and preparation of functional glucagon-like peptide-1 (GLP-1) analogue by introducing an enterokinase cleavage site

KGLP-1, a 31-amino acid glucagon-like peptide-1 (GLP-1) analogue, has a great therapeutic potential for anti-diabetes. In this work, a strategy for expression and purification of functional KGLP-1 peptide has been established. KGLP-1 cDNA was fused with glutathione S-transferase (GST), with an enterokinase cleavage site in the fusion junction. The recombinant fusion protein GST–KGLP-1 was affinity purified via the GST-tag, and then digested with enterokinase. The resulting GST part as well as the enzymes were eliminated by ultra-filtration followed by size exclusion chromatograph. The yield of purified KGLP-1 was approximately 12.1 mg/L, with purity of 96.18 %. The recombinant KGLP-1 was shown to have similar bioactivity as native GLP-1 when evaluated in a Chinese hamster ovary cell line expressing a GLP-1 receptor-egfp reporter gene.     

新疆伊犁地区侵染蚕豆和三叶草的豌豆花叶病毒的鉴定

从伊犁地区采集的蚕豆花叶病和三叶草花叶病植株获得的病毒分离物,经接种子鉴别寄主,可系统侵染蚕豆、三叶草、豌豆,局部侵染苋色藜和菜豆。可通过蚕豆蚜进行非持久性传播,不通过种子传播。电镜下,病毒粒体呈线条状,平均长度为756nm。在汁液中的热钝化温度是55℃。体外存活期3天。在感病蚕豆叶超簿切片中,可观察到风轮状内含体。血清反应结果证明,该病毒与马铃薯Y病毒、菜豆黄色花叶病毒和菜豆普通花叶病毒有一定相关性。根据上述特性认为,从伊黎地区蚕豆花叶和三叶草花叶植株得到的病毒分离物,为豌豆花叶病毒(PMV)。     

水孔蛋白在细胞延长、盐胁迫和光合作用中的作用

水孔蛋白属于一个高度保守的、能够进行跨生物膜水分运输的通道蛋白MIP家族。水孔蛋白作为膜水通道,在控制细胞和组织的水含量中扮演重要角色。本研究的重点是属于PIP亚家族的GhPIP1;2和属于TIP亚家族的γTIP1在植物细胞延长中的作用。使用特异基因探针的Northern杂交和实时荧光PCR技术证明GhPIP1;2和GhγTIP1主要在棉花纤维延长过程中显著表达,且最高表达量在开花后5d。在细胞延长过程中,GhPIP1;2和GhγTIP1表达显著,表明它们在促使水流迅速进入液泡这一过程中扮演重要角色。而且也研究了盐胁迫植物中钙离子对水孔蛋白的影响。分别或一起用NaCl或CaCl2处理原生质体或细胞质膜。结果发现在盐胁迫条件下,水渗透率值在原生质体和质膜颗粒中都下降了,同时PIP1水孔蛋白的含量也下降了,表明NaCl对水孔蛋白的功能和含量有抑制作用。同时也观察了Ca2+的两种不同的作用。感知胁迫的胞质中游离钙离子浓度的增加可能导致水孔蛋白的关闭。而过剩的钙离子将导致水孔蛋白的上游调控。同时实验已经证明大麦的一类水孔蛋白-HvPIP2;1有更高的水和CO2转移率。本研究的目标是确定负责转运水和CO2的关键水孔蛋白...     

Mesenchymal stem cells modified with angiopoietin-1 improve remodeling in a rat model of acute myocardial infarction

We used human angiopoietin-1 (hAng1)-modified mesenchymal stem cells (MSCs) to treat acute myocardial infarction (AMI) in rats. The hAng1 gene was transfected into cultured rat MSCs using an adenoviral vector. Five million hAng-transfected MSCs (MSC(Ang1)) or green fluorescent protein transfected MSCs (MSC(GFP)) or PBS only (PBS group) were injected intramyocardially into the inbred Lewis rat hearts immediately after myocardial infarction. MSC(Ang1) survived in the infarcted myocardium, and expressed hAng1 at both mRNA and protein levels. The vascular density was higher in the MSC(Ang1) and MSC(GFP) groups than in the PBS group. The measurements of infarcted ventricular wall thickness, infarction area, and left ventricular diameter indicated that heart remodeling was inhibited and heart function was improved in both the MSC(Ang1) and MSC(GFP) groups. However, in contrast to the MSC(GFP) group, the MSC(Ang1) group showed enhanced angiogenesis and arteriogenesis (by 11-35%), infarction area was reduced by 30% and the left ventricular wall was 46% thicker (P<0.05). The results indicated that hAng1-modified MSCs improved heart function, followed by angiogenic effects in salvaging ischemic myocardium and reduced cardiac remodeling.     

模拟降水量变化对荒漠草原土壤酶活性的影响及其相关因素分析

为明确荒漠草原土壤酶活性对降水格局改变的响应机制, 该研究基于宁夏荒漠草原降水量不同梯度变化(减少50%、减少30%、自然降水、增加30%和增加50%)的野外试验(2014年开始试验), 于2016年5-7月采样, 测定分析不同降水梯度2年后对土壤酶活性的影响, 并分析酶活性与植物生物量、微生物生物量C∶N∶P生态化学计量特征以及土壤理化性质的关系。结果表明: (1)与自然降水量相比, 减少30%降水量对3种土壤酶活性均无显著影响, 减少50%降水量显著降低了土壤蔗糖酶活性(^P < 0.05); 增加降水量显著提高了土壤蔗糖酶和磷酸酶活性(^P < 0.05), 但对脲酶活性无显著影响。(2)减少降水量对植物生物量影响较小(尤其减少30%降水量), 但不同程度地降低了微生物生物量C、N、P, 提高了微生物生物量C∶N和C∶P; 增加降水量则不同程度提高了植物生物量及微生物生物量C、N、P。(3)土壤蔗糖酶和磷酸酶活性随植物及微生物生物量增加而增加; 对土壤酶活性影响显著的土壤因子包括: 含水量、NO₃^- N、NH₄⁺ N、C∶P、有机C、全N、C∶N和pH (P < 0.05)。研究认为, 减少降水量(尤其是减少30%降水量)对土壤酶活性影响较小, 增加降水量促进了植物的生长、刺激微生物活性, 进而提高了土壤酶活性, 但随着植物生物量增加, 土壤有机C输入增多, 磷酸酶活性相应增强并促进了有机P的矿化, 导致土壤微生物P限制增加。     

鸡肉源沙门氏菌对喹诺酮和氟喹诺酮类抗生素耐药状况及相关基因

【目的】研究分离于陕西、河南、四川和北京四省(市)鸡肉源沙门氏菌对喹诺酮和部分氟喹诺酮类抗生素的药敏性及相关耐药基因,更好地了解耐药性的产生和传播途径,确保食品安全。【方法】用琼脂稀释法测定沙门氏菌的药敏性,用PCR和基因序列测定法确定耐药沙门氏菌中与(氟)喹诺酮类抗生素耐药相关的喹诺酮类抗性决定区基因突变及质粒携带的耐药基因。【结果】390株沙门氏菌中,63.59%的菌株对萘啶酮酸产生抗性,21.28%、16.67%和14.62%的菌株分别对环丙沙星、左氧氟沙星和加替沙星产生抗性。248株萘啶酮酸抗性菌中,aac(6’)-Ib-cr、qnrA、qnrB和qnrS基因的检出率分别为20.16%、10.89%、10.08%和1.61%。83株耐环丙沙星的菌株中,gyrA和parC基因的点突变共199个;其中gyrA基因中以Ser83Phe和Asp87Gly双突变最为常见,其次分别为Ser83Phe和Asp87Asn双突变、Ser83Tyr、Ser83Phe、Asp87Gly;parC基因的65个点突变均为Ser80Arg突变。【结论】四省市中鸡肉源沙门氏菌耐药状况严重,其解旋酶和拓扑异构酶基因突变及质粒携带的耐药基因是导致沙门氏菌耐药的重要机制。     

我国1999—2003年间ALV—J野毒株gp85基因变异趋势

通过接种鸡胚成纤维细胞（CEF）、间接免疫荧光试验（IFA）和聚合酶链式反应（PCR）,连续五年从全国各地的送检病料中分离到14株J亚群白血病病毒（ALV-J）。为了动态观察ALV-J囊膜表面结构蛋白（GP85）的变异情况,对这14株野毒株的囊膜糖蛋白基因（env）进行了克隆和测序,将它们与HPRS-103株的GP85的氨基酸序列进行了比较,结果表明：ALV-J的囊膜表面结构蛋白发生了很大的变异,而且这些变异主要集中在高变区hr1、hr2和vr3;这些野毒株GP85的氨基酸序列的同源性在86．6％～100％之间（从同一鸡场中分离到的两株ALV-J即BJ00302与BJ0303的同源性为100％,其它毒株之间的同源性均小于100％）;有义突变与沉默突变的比例显示这3个高变区极有可能是免疫选择压作用的位点。