C型肉毒梭菌毒素杀灭高原鼠兔试验

<正> 有史以来,鼠类就与人类为敌。鼠类给人类带来的巨大灾难,绝不亚于其他自然灾旱,鼠患危害之烈,已受到全世界的普遍关注。夏河县草场高原鼠兔(Ochotona curzoniae Hodgson)危害面积达43.3万亩,占整个鼠害总面积的37.98％。由于高原鼠兔啃食牧草嫩茎、叶、花、种子及根茎,抑制了优良牧草的生长发育,减少了草场可利用面积。同时,高原鼠兔频繁活动,挖洞形成大片“黑土滩”,造成草     

C型肉毒梭菌毒素的稳定性测定

本文介绍了对C型肉毒梭茵毒素稳定性的测定结果。结果为:稀释后的毒素对温度十分敏感,在5℃保存24小时,毒力开始下降.后随温度上升,毒力大幅度下降,但阳光照射与否,对毒素毒力影响不大。因此,我省用毒饵法在当年10月到翌年4月杀灭高原鼠免,在4—5月杀灭高原鼢鼠,能保证杀鼠效力。     

C型肉毒梭菌毒素毒饵稳定性的试验研究

C型肉毒梭菌毒素毒饵在天然草地上放置6天内,试鼠高原鼠兔死亡率为90～100％;8～10天逐渐分解为基本无毒。试鼠死亡高峰期为采食毒饵后3～4天,并且5天内已接触过毒素的试鼠不产生明显的耐药性。     

D型肉毒毒素灭高原鼠兔试验

0.1%、0.15%和0.2%浓度的D型肉毒毒素毒饵对高原鼠兔Ochotona curzoniae的灭洞率分别为:71.4%、76.5%和83%.在5%显著水平上,3个浓度之间灭杀效果差异不显著.试验结果表明,3个浓度的D型肉毒毒素对高原鼠兔的灭杀效果与0.1%的C型肉毒毒素相当.     

抗℃型肉毒毒素单克隆抗体的研究

用透村培养法制备的Ｃ型肉毒毒素的类毒素，免疫ＢＡＬＢ／Ｃ小鼠，取其脾细胞与小鼠骨髓瘤细胞系ＳＰ２／０融合。经ＨＡＴ选择培养基选择培养，其细胞融合率平均为７４．５％。用间按ＥＬＩＳＡ法筛选后，共获得９４孔产生抗Ｃ型肉毒毒素抗体的杂交瘤阳性孔。选其中１Ｃ２、１Ｄ１２、１Ｅ８、１Ｇ６、１Ｇ１１、２Ｂ１２、２Ｃ１１、２Ｅ１２、２Ｇ１１、２Ｈ３、３Ａ４、３Ｃ５、３Ｄ３、３Ｆ７、３Ｈ６共１５孔用有限稀释法进行     

一起狐狸C型肉毒毒素中毒的诊治

肉毒毒素是由厌氧的肉毒梭菌在生长繁殖过程中产生的一种细菌外毒素,能引起动物发生肉毒中毒。根据毒素抗原性的不同,可将肉毒梭菌及其毒素分为A、B、C、D、E、F和G型7个型。其中A、B、E及F型为人的中毒型别,C和D型为动物的中毒型别。C型肉毒梭菌在自然界广泛分布,饮食被C型肉毒梭菌特别是C型肉毒毒素污染的水或草料的动物有可能发生C型肉毒中毒。     

A型肉毒毒素基因的克隆及序列分析

目的:克隆肉毒梭菌(Clostridium botulinum)A型肉毒毒素(BoNTa)编码基因。方法:提取肉毒梭菌国际标准株(62A)基因组DNA,根据肉毒梭菌BoNTa基因(GenBank登录号M30196)序列设计引物,采用LA-PCR方法,扩增出目的基因片段,与pMD18-T载体连接,通过酶切鉴定、测序分析克隆到的A型肉毒毒素基因序列。结果:该基因片段与Genbank中的BoNTa基因序列(GenBank登录号M30196)一致性为100%,预测氨基酸序列一致性为100%。结论:成功克隆肉毒梭菌的A型肉毒毒素基因序列,为肉毒梭菌的快速检测,以及进一步用基因工程方法生产A型肉毒毒素奠定了基础。     

黄芩素对感染鼠伤寒沙门氏菌小鼠的影响

试验研究黄芩素对感染鼠伤寒沙门氏菌(STM)小鼠的影响.将80只小鼠分为空白组、STM组、黄芩素+STM组和黄芩素组.结果 显示:STM使感染小鼠的存活率明显下降,小鼠血清中炎性因子水平明显增高,脏器指数降低,肝脏和脾脏组织呈现明显的病理改变.黄芩素可使感染STM小鼠的存活率明显升高,小鼠血清中炎性因子水平降低,脏器指...     

日粮添加水苏糖对肉仔鸡鼠伤寒沙门氏菌感染控制效果的研究

试验研究了添加不同梯度水苏糖对肉鸡鼠伤寒沙门氏菌攻毒的控制效果。试验选用1日龄体重相近(45.52±1.48)g的健康AA肉鸡公雏72只,随机分为3个处理,设6个重复,每个重复4只。在玉米-大豆浓缩蛋白日粮基础上分别添加0、0.4%和0.8%水平的水苏糖。结果表明:日粮添加水苏糖降低了肉鸡体重;肉鸡肠道沙门氏菌控制效果不显著,第19天时,0.4%水苏糖添加组的大肠杆菌数显著高于其他2组(P<0.05),乳酸菌各处理之间差异不显著;pH值与盲肠指数无差异(P>0.05)。以上研究表明,该梯度水苏糖不能控制肉鸡沙门氏菌感染,对肉鸡无保护作用。     

Effect of carbohydrates on Salmonella typhimurium colonization in broiler chickens

The effect of carbohydrates in the drinking water of broiler chickens on Salmonella typhimurium colonization was evaluated. Results indicate that mannose and lactose (2.5%) significantly (P less than 0.05) reduced intestinal colonization of S. typhimurium by at least one-half, as compared with dextrose, maltose, and sucrose. Lactose and mannose also significantly reduced (P less than 0.01) the mean log10 number of S. typhimurium in the cecal contents. Although mannose was the most effective sugar at blocking colonization, lactose may be more practical because it is effective and costs much less than mannose. Provision of carbohydrates in the drinking water had no significant effect on weight gain.     

Single or double vaccination schedules in sheep against experimental infection with Salmonella typhimurium or Salmonella bovismorbificans

Extract

Sir: - We wish to draw the attention of veterinarians to the presence of the sarcoptiform mite Trixacarus caviae as the cause of a pruritic skin condition in guinea pigs.     

植物诱变育种研究进展

简述了诱变育种的发展现状,系统介绍了辐射诱变、化学诱变和航天诱变的特点、诱变机理、生物学效应及其在植物育种中的应用。     

Reduction of Salmonella typhimurium concentration in broiler chickens by milk or whey

Whey (5%) in the feed of chicks for the first 10 days of life reduced the mean log10 number of viable S. typhimurium from 5.68 in control chickens to 3.38 in whey-fed chickens. Lactose in drinking water or reconstituted dry milk (5% wt: vol) in drinking water reduced the mean log10 number of S. typhimurium to 2.60 and 2.11, respectively. Milk (5% wt: wt) in feed was not effective in reducing S. typhimurium colonization. The lack of effect of milk in the feed is believed to be because not enough lactose was provided at the 5% (wt: wt) concentration. Lactose in whey or nonfat dried milk offers alternatives to the use of pure lactose in preventing or lowering S. typhimurium numbers in young broiler chickens.     

Effect of reticuloendotheliosis virus on the response of chickens to Salmonella typhimurium infection

Groups of 25 chickens free of maternal antibody to reticuloendotheliosis virus (REV) were inoculated with either third or seventh passage REV at either one or seven days of age. Some of the birds inoculated at day 1 with REV were inoculated with Salmonella typhimurium either concurrently or six or 13 days later while some of those inoculated with REV at day 7 were inoculated concurrently with S typhimurium. At day old, infection with S typhimurium alone caused the death of 12 of 25 chicks whereas in the dual infection, using the third passage REV, 18 of 25 birds died. Similarly no seven or 14 day old chickens died when challenged with S typhimurium alone, but previous day-old infection with REV caused a respective mortality of eight of 25 and five of 25 birds. With the seventh passage REV a similar pattern was seen. At day old S typhimurium infection alone killed seven of 25 birds whereas combined with virus the mortality was 14 of 25 and while S typhimurium alone killed none of 25 chicks infected at seven days old, the mortality in birds also infected with REV was 14 of 25. Combined virus and bacterial infections did not increase the proportion of feathering defects in birds surviving S typhimurium infections. There was a significantly higher proportion of feathering defects in birds infected with third passage virus compared with seventh passage virus. Although a higher proportion of birds had antibody responses to REV in the seventh than in the third passage group, there was no discernible difference in the effect the different viruses had on chickens' susceptibility to S typhimurium.