Characterization ofCampylobacter jejuni lipopolysaccharide

Lipopolysaccharides were isolated from dehydratedCampylobacter jejuni by combination of the phenol-chloroform-petroleum ether and phenol-water extraction techniques. Biochemical characterizations of lipopolysaccharide were performed on the two fractions of highest purity. Neutral sugar analyses detected galactose, glucose, trace amounts of mannose, and an unidentified deoxy-hexose. The primary amino sugars were galactosamine, glucosamine, and glucosamine-phosphate. Chemical analyses of other lipopolysaccharide components included phosphate, 3-deoxy-d-manno-octulosonic acid (KDO), and fatty acids. The predominant fatty acids were 3-hydroxytetradecanoic and hexadecanoic acids with lesser amounts of tetradecanoic acid. 3-Hydroxytetradecanoic acids were bound to lipid A by both amide and ester linkages.     

Characterization of the antigens involved in serotyping strains ofCampylobacter jejuni by passive hemagglutination

Components of outer membrane preparations, heated saline extracts, and phenolwater lipopolysaccharide extracts obtained from strains ofCampylobacter jejuni representing seven passive hemagglutination serotypes (Penner serotypes 1–4, 13, 16, and 50) were electrophoresed in sodium dodecyl sulfate-polyacrylamide gels. Tests of gel eluates demonstrated that lipopolysaccharide antigens are involved in serotypingC. jejuni by passive hemagglutination and that other cell surface components have no activity. This finding was confirmed by hemagglutination inhibition. In the typing ofC. jejuni by passive hemagglutination, each serotype is probably defined by the presence of one or more specific lipopolysaccharides. These findings may lead to a clarification of the serotyping nomenclature for those systems that depend on passive hemagglutination. It is recommended that a single internationally agreed numbering system be adopted for lipopolysaccharides derived fromC. jejuni.     

Pathogenicity ofCampylobacter jejuni in intraperitoneally or intravenously inoculated ferrets

Ferret kits inoculated intravenously (IV) withCampylobacter jejuni after pretreatment with parenteral iron developed more severe systemic signs and more prolonged bacteremia than untreated inoculated controls. Watery diarrhea began in both groups 2–16 h after inoculation and lasted less than 48 h.C. jejuni was cultured from rectal swabs 2–8 h after inoculation, and gut colonization persisted up to 15 days, suggesting that colonization does not necessarily induce diarrhea. Gut colonization occurred as rapidly after IV inoculation of ferrets in which the common bile duct had been ligated as it did in unligated controls.C. jejuni apparently reached the intestinal lumen by mucosal invasion from the bloodstream. Bacteremia following natural infection could thus result in repeated passages ofC. jejuni across the gut wall, exposing the mucosa to both the bacterial cells and their metabolic products. Histological evidence of an inflammatory response in the mucosa, without severe epithelial damage, suggests a toxin-mediated secretory diarrhea.     

Genomic characterization ofCampylobacter jejuni by field inversion gel electrophoresis

The genome ofCampylobacter jejuni was characterized by field inversion gel electrophoresis (FIGE) after digestion with three rare-cutting restriction endonucleases. The restriction enzymesSac II (5-CCGCGG),Sal I (5-GTCGAC), andSma I (5-CCCGGG) were found to produce 13, 5, and 8 fragments respectively from theC. jejuni genome. The fragment sizes ranged from 1.6 kb to 1300 kb, which gaveC. jejuni a genome size of approximately 1900 kb. Furthermore, thegly A and rRNA genes ofC. jejuni were localized to specific fragments by use of Southern analysis, and thegly A gene was shown to be closely linked to one of the three rRNA genes.     

Cloning and sequence analysis of the flagellin gene ofCampylobacter jejuni TGH9011

Flagella are essential for motility and have been implicated to be one of the pathogenic determinants. The flagellum ofCampylobacter jejuni is a polymeric structure of a 62-kd protein. Using a high-affinity flagellin antibody to screen a lambda gt 11 phage genomic expression library ofC. jejuni strain TGH9011 (Serotype LIO36), a recombinant phage clone lambda gt 11RK that expresses theC. jejuni flagellin protein was isolated. The recombinant lambda gt 11 RK produced a 56-kd protein upon induction with isopropylthiogalactoside, which reacted specifically with anti-flagellin antibody. The flagellin gene was sequenced, and comparative analysis of the nucleotide and amino acid sequence identified a region of the flagellin that shows hypervariability among differentCampylobacter species and strains.     

Genetic differences in the levator ani muscle weight between inbred and congenic mouse strains.

Significant differences in relative weight of the levator ani muscle (LAW) between inbred and congenic mouse strains, differing genetically only by the major histocompatibility H-2 complex were found. It is assumed that a genetic factor (Hom-1), identical or closely associated wi th the H-2 complex, is one of the genes which influence LAW. These experiments suggest that for assay methods for myotropic activity of androgens groups of animals may be used with a homogenous genotype.     

Detection and identification ofCampylobacter coli andCampylobacter jejuni by two-step polymerase chain reaction

Flagellin gene was used as target sequence to detect and distinguishC. coli andC. jejuni by a “nested PCR” technique. The method shows a high level of sensitivity and specificity. Application of this rapid diagnostic tool could provide further information about epidemiological and pathogenetic implications of each of these two microorganisms.     

Penetration ofCampylobacter jejuni at different storage temperatures in membranes and contents of cracked eggs

Summary Campylobacter jejuni 79-193 penetrates the inner, outer membrane and ultimately the contents of cracked eggs more at 4°C (after equilibration at 42°C for 10 min) than at 42°C or 25°C. The number of eggs showing penetration byC. jejuni decreased with time.

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Pénétration de Campylobacter jejuni à différentes températures dans les membranes et contenus d'oeux félés

Résumé Campylobacter jejuni pénètre les membranes externe, interne et finalement le contenu d'oeux félés davantage à 4°C (après équilibration à 42°C pendant 10 min.) qu'à 25 ou 42°C. Le nombre d'oeux montrant la pénétration parC. jejuni décroît avec le temps.

     

特异区段替换小鼠性发育表型的研究

目的了解性发育相关数量性状基因座(quantitative trait locus,QTL)(DXMit68-rs29053133)在近交系小鼠A/J和C3H/HeJ(C3H)中是否存在影响表型的序列差异,以帮助对候选基因进行筛选。方法利用A/J和C3H构建了针对该区段的特异区段替换系小鼠,并对其雌鼠的性发育相关性状进行研究。结果 A/J和C3H在这一QTL中染色体的序列差异,没有引起相关性状的明显差异。结论研究结果显示,A/J和C3H小鼠中该QTL区段中存在序列差异的基因并不是引起性发育表型产生差异的候选基因。     

Applications of congenic strains in the mouse

The sequencing of the human and the mouse genomes has shown that the chromosomes of these two species contain approximately 30,000 genes. The biological systems that can be studied in an individual or in a tissue result from complex interactions within this multitude of genes. Before describing these interactions, it is necessary to understand the function of each gene. In the mouse, congenic strains are developed to introduce a chromosomal segment in a given inbred genetic background. One can then compare the biological effects of different alleles at the same locus in the same genetic background or the effect of a given allele in different genetic backgrounds. One can also introduce into different congenic strains with the same genetic background genes which control a complex genetic trait, then combine these genes by appropriate crosses to study their interactions. Although the chromosomal segment transferred into a congenic strain usually contains up to several hundreds of genes, molecular markers can be used to reduce this number as well as the number of crosses required for the development of congenic strains.     

Analyzing complex traits with congenic strains

Congenic strains continue to be a fundamental resource for dissecting the genetic basis of complex traits. Traditionally, genetic variants (QTLs) that account for phenotypic variation in a panel of congenic strains are sought first by comparing phenotypes for each strain to the host (reference) strain, and then by examining the results to identify a common chromosome segment that provides the best match between genotype and phenotype across the panel. However, this “common-segment” method has significant limitations, including the subjective nature of the genetic model and an inability to deal formally with strain phenotypes that do not fit the model. We propose an alternative that we call “sequential” analysis and that is based on a unique principle of QTL analysis where each strain, corresponding to a single genotype, is tested individually for QTL effects rather than testing the congenic panel collectively for common effects across heterogeneous backgrounds. A minimum spanning tree, based on principles of graph theory, is used to determine the optimal sequence of strain comparisons. For two traits in two panels of congenic strains in mice, we compared results for the sequential method with the common-segment method as well as with two standard methods of QTL analysis, namely, interval mapping and multiple linear regression. The general utility of the sequential method was demonstrated with analysis of five additional traits in congenic panels from mice and rats. Sequential analysis rigorously resolved phenotypic heterogeneity among strains in the congenic panels and found QTLs that other methods failed to detect.     

Experimental allergic encephalomyelitis in congenic strains of mice

Inbred mice and lines congenic to them for the major histocompatibility complex were similar in susceptibility to EAE except for moderate differences in two pairs. TheH-2 haplotypesq, s, andb occurred in inbred strains and in congenic lines of high, medium, or low susceptibility. It is concluded that the major histocompatibility complex does not control susceptibility to EAE in mice. Furthermore, the low susceptibility of DBA/1J mice was not enhanced by poly A-U.