Molecular typing and spread of Clavibacter michiganensis subsp. michiganensis in greenhouses in Japan

Clavibacter michiganensis subsp. michiganensis (CMM) strains collected between 2005-2008 from greenhouses in different locations in Okayama Prefecture, Japan, were fingerprinted by repetitive sequence-based polymerase chain reaction (rep-PCR) with ERIC and BOX primers. One hundred and eighty strains from eight different locations in Okayama were differentiated into four haplotypes (A to D) based on rep-PCR. Regardless of the year of isolation, location or cultivar of tomato, the strains in each greenhouse and location belonged to the same haplotype, suggesting the strains originated from the previous greenhouse population. Based on Morisita's index of dispersion ( I _δ ), the distribution of diseased plants in the greenhouses, where disbudding and defoliation using either scissors or by hand were carried out in the same direction to promote the spread of CMM, occurred in an aggregated distribution in a quadrant along a row of plants, but the distribution of diseased plants indicated a random distribution in a quadrant along a furrow of plants (two adjoining rows of plants). These results showed that disbudding and defoliation contribute highly to the secondary spread of bacterial canker in commercial greenhouses.     

动物源金黄色葡萄球菌生物被膜形成能力与分子分型关系研究

[目的]调查产生生物被膜的金黄色葡萄球菌流行病学特征,探究生物被膜形成能力与分子型之间的相关性,为治疗动物金黄色葡萄球菌感染提供理论依据.[方法]以广东省兽药研制与安全评价重点实验室保存的98株金黄色葡萄球菌为研究对象,用结晶紫半定量法测定所有菌株生物被膜形成能力,将产膜菌株进行22种常见抗菌药的最小抑菌浓度测定,通过...     

Clonal structure in Ichthyobacterium seriolicida,the causative agent of bacterial haemolytic jaundice in yellowtail,Seriola quinqueradiata,inferred from molecular epidemiological analysis

Bacterial haemolytic jaundice caused by Ichthyobacterium seriolicida has been responsible for mortality in farmed yellowtail, Seriola quinqueradiata, in western Japan since the 1980s. In this study, polymorphic analysis of I. seriolicida was performed using three molecular methods: amplified fragment length polymorphism (AFLP) analysis, multilocus sequence typing (MLST) and multiple‐locus variable‐number tandem repeat analysis (MLVA). Twenty‐eight isolates were analysed using AFLP, while 31 isolates were examined by MLST and MLVA. No polymorphisms were identified by AFLP analysis using EcoRI and MseI, or by MLST of internal fragments of eight housekeeping genes. However, MLVA revealed variation in repeat numbers of three elements, allowing separation of the isolates into 16 sequence types. The unweighted pair group method using arithmetic averages cluster analysis of the MLVA data identified four major clusters, and all isolates belonged to clonal complexes. It is likely that I. seriolicida populations share a common ancestor, which may be a recently introduced strain.     

Prevalence and antimicrobial resistance of Campylobacter and Salmonella in layer flocks in Honshu,Japan

Campylobacter and non-typhoidal Salmonella are the major causes of bacterial gastrointestinal infections in humans. Although antimicrobial therapy is typically not recommended in many cases of these infections, it may be life-saving in patients with severe symptoms. Since chicken eggs and meat derived from layers are destined for human consumption, we investigated the prevalence and antimicrobial resistance of these two bacterial genera in 82 layer flocks at chicken processing plants in Honshu, Japan. Campylobacter was isolated from 77 flocks (93.9%). Resistance to ampicillin, tetracycline, and ciprofloxacin was documented in 42.3 (30/71), 16.9 (12/71), and 14.1% (10/71) of Campylobacter jejuni, respectively. Multilocus-sequence typing identified ST4389 and ST5262 as the most frequent C. jejuni sequence types. In C. coli, resistance to ampicillin, tetracycline, and ciprofloxacin was found in 20.0 (7/35), 20.0 (7/35), and 25.7% (9/35), respectively. The most frequent sequence type in C. coli was ST8292. Erythromycin resistance was not observed among Campylobacter species. Salmonella was isolated from 14 flocks (17.1%). The two most frequent serovars were Salmonella Corvallis and S. Braenderup. Neither S. Enteritidis nor S. Infantis were isolated. Streptomycin resistance was observed in six isolates (26.1%), and all isolates were susceptible to cefotaxime and ciprofloxacin. Thus, chicken eggs and meat derived from layers are possible sources of these bacterial infections in humans. The antimicrobial susceptibility of these isolates was maintained, reflecting restrictions on the use of antimicrobial agents on layers.     

中华鳖弗氏柠檬酸杆菌的鉴定及病理组织观察

为确定2020年10月湖北一中华鳖发病的病原体及病原特征,实验从该养殖场患病中华鳖个体肝脏中分离获得1株优势菌A3,经理化性状及16S rRNA序列鉴定,表明菌株A3属于柠檬酸杆菌。进一步通过recN序列鉴定,发现A3与布氏柠檬酸杆菌recN碱基一致性为95.58%~96.01%,与柠檬酸杆菌属其他种的recN碱基一致性均低于93.72%,表明菌株A3为柠檬酸杆菌属潜在新种。人工回归感染实验证实菌株A3是引起本次中华鳖患病的病原菌。与嗜水气单胞菌相比,A3感染病程偏慢但致死率较高。药敏实验结果显示,菌株A3对美罗培南等10种抗生素敏感,对氟苯尼考等9种抗生素耐药。多位点序列分型(MLST)鉴定显示,菌株A3属于新序列型(ST)。对柠檬酸杆菌多位点序列分型的7个管家基因序列进行级联并构建系统发育树,结果显示,柠檬酸杆菌的进化与菌株的分离源及分离地点没有明显关系;菌株A3与分离自欧洲人源的ST120型菌株Citfre2580亲缘关系最近。本研究对中华鳖的病原进行了分离鉴定,并阐述了一种更可靠的柠檬酸杆菌鉴定方法,旨在引起人们对柠檬酸杆菌致病性的重视,为水产品健康养殖提供一定的参考依据。     

鸡白痢、鸡伤寒沙门菌分子分型方法的验证

为验证鸡白痢、鸡伤寒沙门菌分子分型方法的准确性,本研究以3株鸡白痢、鸡伤寒沙门菌国际参考菌株和306株国内分离株为研究对象,采用5种已知的分子分型方法开展验证性实验。结果发现,基于特定基因可变区的2种分型方法具有良好的特异性,其检测结果与生化分型结果一致,而3种基于特定基因单核苷酸多态性的分型方法则出现假阳性或假阴性的结果。上述结果表明,鸡白痢、鸡伤寒沙门菌分子分型方法的准确性仍需进一步验证。     

Application of RAPD and SI-typing techniques to confirm genetic integrity of radish (Raphanus sativus L.) varieties

The random amplified polymorphic DNA (RAPD) and self-incompatibility (SI) typing techniques were applied to settle a lawsuit between a Seed Company and a farmer concerning seed impurity in radish (Raphanus sativus L.). After sowing “Halra Woldong” (HW) a winter radish variety, two morphologically different radish plants grew. Genomic DNA from each of the two types were prepared and analyzed using ninety-six RAPD markers and four variety-specific markers were found. The polymorphic RAPD band patterns were compared with those of the twenty Korean radish varieties. The genetic integrity of the two varieties in question was identified and further confirmed by SI-typing of S-locus glycoprotein (SLG) and S-locus receptor kinase (SRK) genes.     

多杀性巴氏杆菌检测、鉴定和分型研究进展

多杀性巴氏杆菌(Pm)可以引起多种畜禽疾病,给养殖业造成巨大的经济损失。为了系统的了解Pm检测、鉴定和分型技术的发展,论文主要对Pm的分类地位、鉴定和分型的传统方法以及分子生物学方法,诸如种特异性PCR、荚膜分型PCR、产毒素Pm的PCR鉴定、16 S rRNA基因测序法、DNA杂交、大分子图谱、限制性酶切分析和核糖体分型、随机扩增DNA片段多态性、脉冲场凝胶电泳及其他各种基因分型技术等进行了综述。     

鸡传染性支气管炎病毒分型研究进展

鸡传染性支气管炎严重危害养禽业,其病原传染性支气管炎病毒血清型/基因型复杂,不同血清型/基因型之间免疫交叉保护效果差。IBV毒株的分型对于实施有效的疫病控制、病原研究、流行病学调查及研究病毒的演化意义重大。文章就IBV分型的最新研究进展进行综述,为IBV相关研究提供参考。     

A human major histocompatibility complex (MHC) DNA probe recognizes goat genes

A human major histocompatibility complex (MHC) class II (DR-β) probe was hybridized with restriction enzyme digest of genomic DNA from 14 goats. Nine of the animals belonged to one family. Digestion of the DNA with the restriction enzyme Eco RI gave 7 fragments in 13 animals and 6 fragments in the last animal. No other polymorphism could be detected. Bam HI digestion gave from 3 to 6 fragments which displayed a considerable polymorphism. In the family studied, polymorphic fragments were inherited together with serologically defined lymphocyte antigen specificities believed to be coded for by MHC class I genes.