羊梭菌病快速鉴别PCR方法的建立及初步应用

根据GenBank已公布的产气荚膜梭菌和腐败梭菌的α毒素基因序列,分别设计并合成针对2种α毒素基因的特异性引物,通过扩增条件的优化,建立快速鉴别产气荚膜梭菌和腐败梭菌的双重PCR方法。特异性试验显示,产气荚膜梭菌和腐败梭菌参考菌株均扩增出了相应的预期目的条带,而大肠埃希菌、沙门菌、金黄色葡萄球菌和链球菌则均未能扩增出相应条带。灵敏度试验结果显示,产气荚膜梭菌和腐败梭菌基因组DNA最低检测量分别为17.95pg/μL和1.261pg/μL。应用该方法对样品进行检测,其中5份为产气荚膜梭菌阳性。成功建立了特异性强、敏感性高的双重PCR方法,可以有效进行产气荚膜梭菌和腐败梭菌的快速鉴别,对羊梭菌病病原快速鉴定及流行病学调查具有重要意义。     

Magnetic resonance imaging appearance of the brain and cervical spinal cord in an edema disease affected pig

A 7‐week‐old male pig was presented with signs of a central nervous system disorder. An MRI of the head and cervical spine was performed immediately after euthanasia. The MRI revealed multifocal bilaterally symmetric T2‐weighted hyperintense lesions in the brain and spinal cord, likely due to a toxic metabolic process. Histopathological examination supported the MRI findings and confirmed the diagnosis of edema disease due to Shiga‐like toxin produced by Escherichia coli. This is the first case published of the MRI findings in an edema disease affected pig.     

Chronic granulomatous pneumonia and lung rupture secondary to aspiration of activated charcoal in a French Bulldog

A 4‐year‐old, spayed female French Bulldog was presented for respiratory distress and suspected aspiration pneumonia after oral administration of activated charcoal for possible ingestion of a suspected toxic dose of trazodone. The patient had a moderate volume of pleural effusion, which contained free and intracellular black particulate matter consistent with charcoal. Due to presumed charcoal aspiration with subsequent lung rupture, the right middle and right caudal lung lobes were surgically removed. Histology revealed abundant black debris consistent with charcoal and severe granulomatous inflammation. Based on the clinical, gross, and histologic findings, a diagnosis of severe, chronic, locally extensive, aspiration pneumonia and lung rupture with secondary pleuritis and mediastinitis due to charcoal aspiration was made. Aspiration pneumonia is the main complication of activated charcoal administration, which can incite extensive, granulomatous inflammation in the respiratory tract. To the authors’ knowledge, this is the first report describing the cytologic and histologic findings associated with inadvertent charcoal aspiration in a veterinary species.     

利用胚性细胞悬浮系研究香蕉枯萎病抗性离体筛选技术

以香蕉(Musa spp. AAA group)胚性细胞悬浮系(Embryogenic Cell Suspension,ECS)为试材,进行抗枯萎病离体筛选技术研究。首先测试不同的γ射线(60Co)辐射剂量对ECS植株再生能力的影响;在此基础上,以不同浓度的枯萎病病原菌毒素粗滤液(FOC)为选择压力,研究FOC对ECS植株再生能力的影响,并进行离体抗性筛选。结果表明,ECS的植株再生能力与辐射剂量之间呈负相关,半致死剂量为70～80Gy。同样地,未经辐射处理的ECS其植株再生能力也随着FOC体积分数的增加而急剧下降,但经辐射处理过的ECS其植株再生能力与CK相比成倍地增加;当FOC体积分数达到12%后,只有从经80Gy辐射后的ECS获得了再生植株。这表明ECS耐FOC的能力随着辐射剂量的增加而增强。     

Attribution of human infections with Shiga toxin‐producing Escherichia coli (STEC) to livestock sources and identification of source‐specific risk factors,The Netherlands (2010–2014)

Shiga toxin‐producing Escherichia coli (STEC) is a zoonotic pathogen of public health concern whose sources and transmission routes are difficult to trace. Using a combined source attribution and case–control analysis, we determined the relative contributions of four putative livestock sources (cattle, small ruminants, pigs, poultry) to human STEC infections and their associated dietary, animal contact, temporal and socio‐econo‐demographic risk factors in the Netherlands in 2010/2011–2014. Dutch source data were supplemented with those from other European countries with similar STEC epidemiology. Human STEC infections were attributed to sources using both the modified Dutch model (mDM) and the modified Hald model (mHM) supplied with the same O‐serotyping data. Cattle accounted for 48.6% (mDM) and 53.1% (mHM) of the 1,183 human cases attributed, followed by small ruminants (mDM: 23.5%; mHM: 25.4%), pigs (mDM: 12.5%; mHM: 5.7%) and poultry (mDM: 2.7%; mHM: 3.1%), whereas the sources of the remaining 12.8% of cases could not be attributed. Of the top five O‐serotypes infecting humans, O157, O26, O91 and O103 were mainly attributed to cattle (61%–75%) and O146 to small ruminants (71%–77%). Significant risk factors for human STEC infection as a whole were the consumption of beef, raw/undercooked meat or cured meat/cold cuts. For cattle‐attributed STEC infections, specific risk factors were consuming raw meat spreads and beef. Consuming raw/undercooked or minced meat were risk factors for STEC infections attributed to small ruminants. For STEC infections attributed to pigs, only consuming raw/undercooked meat was significant. Consuming minced meat, raw/undercooked meat or cured meat/cold cuts were associated with poultry‐attributed STEC infections. Consuming raw vegetables was protective for all STEC infections. We concluded that domestic ruminants account for approximately three‐quarters of reported human STEC infections, whereas pigs and poultry play a minor role and that risk factors for human STEC infection vary according to the attributed source.     

转Bt基因棉Bt毒蛋白的ELISA检测方法的研究(英文)

利用纯化的Ｂｔ毒素蛋白（６７ｋＤａ）作为标准蛋白和免疫抗原,建立了检测转基因抗虫棉植株内Ｂｔ毒蛋白含量的抗体夹心ＥＬＩＳＡ方法。检测极限１μｇ·Ｌ－ １,线性范围１－ １５μｇ·Ｌ－ １,板内误差Ｃ．Ｖ．＜ ５％ ,板间误差Ｃ．Ｖ．＜ ５％ ,平均样品回收率９４．９４％ 。经稀释度试验等质量控制试验,表明所建立的ＥＬＩＳＡ方法是可靠的,可用于转基因棉花植株中Ｂｔ毒素蛋白含量的测定。     

Correlation between fusaric acid production and virulence of isolates ofFusarium oxysporum that causes potato dry rot in South Africa

Summary Virulence of 12Fusarium oxysporum isolates was determined on three potato cultivars Late Harvest, BP1 and Kimberley Choice. The production of fusaric acid by the 12F. oxysporum isolates was also determined. The aim of the study was to determine whether a correlation exists between fusaric acid production and virulence ofF. oxysporum isolates. Late Harvest was the most tolerant and BP1 the most susceptible cultivar. Virulence ranking, order of theF. oxysporum isolates with the different cultivars corresponded with the mean of value of the ranking order for all three cultivars. A correlation was found between virulence of isolates and fusaric acid production except for Late Harvest. Fusaric acid production may play a major role in the development of dry rot in potato tubers.     

水稻白叶枯病菌及其毒素引起烟草叶片组织坏死机制的研究

 水稻白叶枯病菌JXO Ⅲ细胞悬浮液及其分泌的毒素溶液接种到烟草叶片中,都能在烟草叶片上产生快速的坏死反应。引起坏死反应所需的最短时间分别为接种后8 h和0.5 h。低浓度的JXOⅢ(< 107 cfu/ml)接种后36~48 h内形成褪绿斑,而低浓度的毒素(< 2.5 mg/ml)接种后随时间延长在接点无任何可见变化。依文斯蓝(Evans blue)染色发现,毒素和JXOⅢ分别在接种后0.5 h和6 h内细胞大量死亡。叶圆片法测定表明,接种毒素后2 h内烟草细胞膜透性迅速上升,接种JXOⅢ后9 h细胞膜透性开始明显上升。毒素处理的烟草叶片中LOX、POX、SOD、CAT活性水平较对照降低,而JXOⅢ处理中上述酶活性较对照有不同程度的增加。蛋白质合成抑制剂环己酰亚胺,RNA合成抑制剂放线菌素D和钙离子通道阻断剂氯化镧分别以7.1×10^-5 M、1×10^-4 M和1×10^-3 M浓度有效地抑制JXOⅢ在烟草上形成坏死反应,这些抑制剂对毒素在烟草上的坏死反应则没有影响。     

球形芽孢杆菌杀蚊毒素的作用方式和蚊虫的抗性特征

球形芽孢杆菌（Bacillussphaericus）是一种对蚊幼虫有毒杀作用的好气芽孢杆菌。高毒力菌株在芽孢形成过程中能产生有51．4和41．9kDa蛋白组成的伴孢晶体。蚊幼虫取食芽孢／晶体混合物后,晶体蛋白被降解形成活性蛋白而结合到中肠上皮细胞的特异性结合位点上,最后导致蚊幼虫死亡;低毒力菌株和部分高毒力菌株在其营养体生长阶段可产生可溶性的100、30．5和38．5kDa的Mix毒素（Mtx1、Mtx2和Mix3）。该毒素同晶体毒素和其它杀虫毒素无同源性,其杀蚊作用机理不详。在实验室和野外长期高选择性压力下,蚊幼虫会通过中肠上皮细胞二元毒素特异性结合位点的改变而对球形芽孢杆菌产生不同水平的抗性,其抗性特性是由位于染色体上的单一隐性基因决定的。本文简述了球形芽孢杆菌的杀蚊毒素的作用方式及抗性蚊虫的抗性特性。     

C型产气荚膜梭菌β毒素基因克隆与核苷酸序列分析

用ＰＣＲ技术,从含Ｃ型产气荚膜梭菌β毒素基因质粒ｐＢ１２中扩增出了０．９５Ｋｂ的β毒素基因,然后用限制性核酸内切酶ＢａｍＨＩ和ＥｃｏＲＩ对其进行双酶切处理,最后将其定向连接在事先经同样内切酶处理的载体ｐＥＴ－２８ｃ（＋）中的相应位点上,转化至受体菌ＢＬ２１（ＤＥ３）中。经ＢａｍＨＩ和ＥｃｏＲＩ双酶切分析和核苷酸序列分析,证明重组质粒ｐＸＥＴＢ２含有产气荚膜梭菌β毒素基因,确定了其全部的核苷酸序列,并且具有正确的阅读框架