琼脂扩散沉淀反应检测菌毛抗原的初步研究

用琼脂护散沉淀反应检测了大肠杆菌菌毛抗原。结果表明,用巴比妥钠－ＨＣｌ缓冲液制备的琼脂平板,在菌毛孔与抗菌毛血清孔之间出现一种明显的沉淀线,而用８０ｇ／Ｌ的ＮａＣｌ配制的琼脂板在菌毛幻与抗菌毛血清孔之间则无沉淀线。由此提示,用巴比妥钠－ＨＣｌ缓冲液制备的琼脂平板右用来检测细菌菌毛抗原。     

猪脱碘酶3基因定位及对生产性状的潜在影响

为确定猪脱碘酶3(DIO3)基因能否作为某些生产性状的候选基因,本研究设计猪DIO3基因特异引物,采用辐射杂种细胞系,将其定位在猪7号染色体微卫星SW764附近。通过比较猪QTL数据库,发现该座位存在7个分别影响猪肌纤维直径、内脂率、胴体长、胴体质量、皮质醇水平调控的QTL,结果表明DIO3基因可作为猪肉质性状、胴体性状和应激相关性状的候选基因。     

外源基因在原核生物和真核生物中的表达(英文)

[目的]研究外源基因在原核生物和真核生物中的表达。[方法]将带有目的基因的表达载体pTYB2-WF转化大肠杆菌ER2566,用IPTG诱导植酸酶基因表达。用SDS-PAGE验证植酸酶融合蛋白表达情况,并进一步对融合蛋白进行纯化。用毕赤酵母表达系统表达植酸酶基因phyA;构建酵母整合载体pPIC9K-phyA,转化毕赤酵母GS115,构建工程菌GS115-pPIC9K-phyA。[结果]在甲醇的诱导下表达植酸酶,经酶活力的测定,其植酸酶活力达7.3μ/ml,构建了毕赤酵母工程菌GS115-pPIC9K-phyA。[结论]甲醇酵母表达机制在分子生物学以及工业应用领域发挥作用。     

猪胚胎冷冻保存研究进展

胚胎冷冻保存技术在大多数哺乳动物上已获得成功,牛胚胎冷冻已经进入商业化应用阶段。猪胚胎由于其特殊的低温生物学特性,冷冻保存研究进展缓慢。本文综述了猪胚胎在冷冻过程中的细胞生物学变化,以及近几年猪胚胎冷冻保存研究所取得的显著进展。     

应用测试片快速检测食品中的大肠杆菌O157：H7

目的应用大肠杆菌O157:H7测试片快速检测食品中的大肠杆菌O157:H7。方法对大肠杆菌O157:H7测试片的各项指标及影响因素进行测试,并将其应用于食品检测。结果大肠杆菌O157:H7测试片的检测灵敏度高,其对纯菌的检测低限可达3cfu/mL;特异性较强,与鼠伤寒沙门氏菌、志贺氏菌等21种非目的菌无交叉反应;快速,24h内可报告阴性检测结果。应用该测试片检测各种食品206份,检测结果与SN标准的符合率达到98.5%。结论应用测试片检测食品中的大肠杆菌O157:H7具有快速、方便、经济、无需昂贵设备等优点。该测试片可适应于食品中大肠杆菌O157:H7的快速初筛。     

Occurrence of Salmonella,Campylobacter, Yersinia enterocolitica,Escherichia coli O157 and Listeria monocytogenes in Swine

The objective of this study was to investigate the occurrence of major bacterial foodborne pathogens in swine. In total, 359 samples from manure storage tanks (91) and fresh pooled faeces (268) obtained from finisher (110), sows (78) and weanlings (80) were collected and tested. Campylobacter, Salmonella, Yersinia enterocolitica, Escherichia coli O157 and Listeria monocytogenes were isolated from 36.5%, 31.5%, 5.8%, 3.3% and 3.3% of samples respectively. All E. coli O157 isolates found on 10 farms were tested but none was determined to be E. coli O157:H7. Salmonella and Campylobacter were more likely to be detected from stored manure rather than from fresh faecal samples. Yersinia enterocolitica tended to be detected more commonly from fresh samples than from manure pits. Listeria monocytogenes was not recovered from manure pits or from sow faecal samples and only infrequently found in the faeces of weanling pigs and finisher pigs. The proportion of positive samples showed a seasonal change. Salmonella was twice as likely not be recovered in winter, whereas the chance of culturing Campylobacter was higher in winter. The 113 Salmonella isolates recovered on 24 farms and the four most common serovars were Salmonella Typhimurium var. Copenhagen (31.0%), Salmonella Derby (12.4%), S. Typhimurium (10.6%) and Salmonella Agona (10.6%). Of 131 Campylobacter isolates recovered on 21 farms, 118 isolates were Campylobacter coli and 13 isolates could not be speciated. Fifteen of 21 Y. enterocolitica isolates found on 15 farms were detected in finisher pigs. The sero/biogroups of Y. enterocolitica were O3/biotype 4 (16 isolates), O6,30/biotype 1A (three isolates), O5/biotype 1A (one isolate) and O8/biotype 1B (one isolate). These findings provide baseline information on the distribution of important zoonotic pathogens in swine and indicate that pigs should be considered as a possible source of foodborne diseases in humans.     

猪血多肽对建鲤抗氧化能力和免疫功能的影响

本试验旨在从体外和体内水平评估猪血多肽(peptides from swine blood,PSB)对建鲤(Cyprinus carpio var.Jian)抗氧化能力和免疫功能的影响。在体外试验中,制备建鲤外周血白细胞和头肾巨噬细胞,然后暴露在含有不同浓度(0、10、20、40、80μg/m L)猪血多肽的培养基中作用24 h,采用WST-1法测定外周血白细胞的增殖能力,氯化硝基四氮唑蓝(NBT)还原法和格里斯(Griess)试剂显色法分别测定头肾巨噬细胞氮呼吸爆发和氧呼吸爆发活性;在体内试验中,分别将0、0.5、1.0、2.0和5.0 g/kg猪血多肽添加到基础饲料中饲喂建鲤,在恒温循环水系统中进行8周的饲养试验,分别在饲喂第1、2、4、8周采集血样,检测血清中生化指标、抗氧化指标及免疫指标的变化。结果表明:在体外试验中,猪血多肽浓度为20、40和80μg/m L时,可以显著或极显著提高建鲤外周血白细胞的增殖能力(P<0.05或P<0.01);猪血多肽浓度为40和80μg/m L时,可以显著或极显著增强建鲤头肾巨噬细胞氮呼吸爆发和氧呼吸爆发活性(P<0.05或P<0.01)。在体内试验中,用添加5.0 g/kg猪血多肽的饲料饲喂建鲤后,第4和8周血清中3种生化指标[白蛋白(ALB)、总蛋白(TP)、碱性磷酸酶(AKP)]含量/活性、3种抗氧化酶[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)]活性和3种免疫因子[白介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)、补体4(C4)]含量均显著升高(P<0.05);此外,第8周血清中补体3(C3)含量亦显著升高(P<0.05)。由此得出,猪血多肽能够增强建鲤的抗氧化能力和免疫功能。     

禽源致病性大肠杆菌分离株R质粒的研究

从本室临床分离到的２０株禽源大肠杆菌，经药敏试验筛选到四株抗性菌株提取质粒ＤＮＡ，电泳分析表明菌株各存在数量不等（１－４个）的质粒ＤＮＡ条带。分别用试剂盒回收出５种大小不同的Ｒ质粒，分别转化大肠杆菌ＤＨ５α；但只有２０．５ｋｇ、９．４ｋｂ两种质粒转化成功，并获得了相应的抗药性，用含９．４ｋｂ质粒转化的大肠杆菌攻毒，可致死小鼠，说明该质粒可能携带有毒性基因。     

Comparative Research on Serogroups Distribution and Antimicrobial Resistance of Escherichia coil Isolates from Poultry in Different Areas of China

A total of 241 Escherichia coli(E. coli)isolates from 349 avian samples(292 from cloacae,29 from feed and water,28 from dust and padding)were collected from Northeast,South,North,and Central China in recent years.The percentage of isolation was 69.1%.There are 67 serogroups each with 1-2 isolates distributed in different regions.and some of these regions had the preponderant serogroups.Antimicrobial-resistance(AR)of E. coli was so severe that the majority were multi-AR.Fifty percent strains were resistant to 10-19 antimicrobial drugs.Overall,the isolates represented resistance to nalidixic acid(88.1%),tetracycline(85.7%),sulfamethoxazole(81.0%),trimethoprim-sulfamethpxazole(77.1%),ampicillin (76.2%),amoxilline(74.3%),streplomycin(66.2%),fluoroquinolones(57.1-66.7%),chloramphenicol(52.9%),gentamicin (39.0%),and kanamycin(36.2%).The isolates were sensitive to cefalexin,amoxilline-clavulanic acid,amikacin,and florfenicol with all AR rate of 0-19.5%only.The results showed that the AR was more severe in chicken farms in which the antibiotics were used broadly and repeatedly.This study indicated the AR characterization of E. coli in different areas of China.It will be a foundation for studying AR mechanism and regulating the usage of antimicrobial in the poultry industry.     

抗大肠杆菌O157单克隆抗体制备过程中杂交瘤细胞的观测

采用细胞活力测定、形态学观察和遗传学检测的方法,研究了在用常规方法制备大肠杆菌O157单克隆抗体过程中,融合前后的细胞在细胞活力、细胞形态以及染色体数量的差异.结果表明,与凯骨髓瘤细胞相比,杂交瘤细胞的细胞活力和细胞形态无明显变化;当脾细胞与凯骨髓瘤细胞融合形成杂交瘤细胞后,其染色体数目接近两亲本细胞染色体数目之和.