Colonization factors of diarrheagenicE. coli and their intestinal receptors

WhileEscherichia coli is common as a commensal organism in the distal ileum and colon, the presence of colonization factors (CF) on pathogenic strains ofE. coli facilitates attachment of the organism to intestinal receptor molecules in a species- and tissue-specific fashion. After the initial adherence, colonization occurs, and the involvement of additional virulence determinants leads to illness. EnterotoxigenicE. coli (ETEC) is the most extensively studied of the five categories ofE. coli that cause diarrheal disease, and has the greatest impact on health worldwide. ETEC can be isolated from domestic animals and humans. The biochemistry, genetics, epidemiology, antigenic characteristics, and cell and receptor binding properties of ETEC have been extensively described. Another major category, enteropathogenicE. coli (EPEC), has virulence mechanisms, primarily effacement and cytoskeletal rearrangement of intestinal brush borders, that are distinct from ETEC. An EPEC CF receptor has been purified and characterized as a sialidated transmembrane glycoprotein complex directly attached to actin, thereby associating CF-binding with host-cell response. Three, additional categories ofE. coli diarrheal disease, their colonization factors and their host cell receptors are discussed. It appears that biofilms exist in the intestine in a manner similar to oral bacterial biofilms, and thatE. coli is part of these biofilms as both commensals and pathogens.Abbreviations CF colonization factor - CFA Colonization Factor Antigen - CS coli-surface-associated antigen - EAggEC enteroaggregativeE. coli - ECDD E. coli diarrheal disease - EHEC enterohemorrhagicE. coli - EIEC enteroinvasiveE. coli - EPEC enteropathogenicE. coli - ETEC enterotoxigenicE. coli - Gal galactose - GalNAc N-acetyl galactosamine - LT heat-labile toxin - NeuAc N-acetyl neuraminic acid - PCF Putative colonization factor - RBC red blood cells - SLT Shiga-like toxin - ST heat-stable toxin     

Bacteriological evaluation of groups of beef carcasses before the wash at six Alberta abattoirs

K.W.F. JERICHO, J.A. BRADLEY AND G.C. KOZUB. 1994. A method has been developed for the bacteriological evaluation of groups of beef carcasses which can be used to measure the degree of control over hygiene during hide removal and carcass dressing in abattoirs. This method, which enumerates aerobic mesophilic bacteria automatically using a hydrophobic grid membrane filter, was applied at six abattoirs. Two hundred excision samples (5 × 5 × 0.5 cm) were taken at 10 sites on the external surface of a group of 20 carcasses (five carcasses were sampled on each of four consecutive daily visits) for group-carcass evaluation at each abattoir. For each abattoir, the mean log₁₀ Most Probable Number of Growth Units (MPNGU) and between-carcass variance component were obtained for each site and the average over sites. Using the average within-abattoir variance of this study and previously published studies involving 76 additional carcasses (Jericho et al. 1993), it was determined that 20 carcasses are more than adequate to estimate the mean log₁₀ MPNGU per cm² within 0.5 units at a site. The distribution of the log₁₀ MPNGU per cm² over the 10 sites was compared for the abattoirs, and sites were found to cluster into 2–4 homogenous groups. The means over sites of log₁₀ MPNGU per cm² for the abattoirs ranged from 1.52 to 2.64 and were unrelated to line speed     

Molecular drift of the bride of sevenless (boss) gene in Drosophila

DNA sequences were determined for three to five alleles of the bride-of- sevenless (boss) gene in each of four species of Drosophila. The product of boss is a transmembrane receptor for a ligand coded by the sevenless gene that triggers differentiation of the R7 photoreceptor cell in the compound eye. Population parameters affecting the rate and pattern of molecular evolution of boss were estimated from the multinomial configurations of nucleotide polymorphisms of synonymous codons. The time of divergence between D. melanogaster and D. simulans was estimated as approximately 1 Myr, that between D. teissieri and D. yakuba as approximately 0.75 Myr, and that between the two pairs of sibling species as approximately 2 Myr. (The boss genes themselves have estimated divergence times approximately 50% greater than the species divergence times.) The effective size of the species was estimated as approximately 5 x 10(6), and the average mutation rate was estimated as 1-2 x 10(-9)/nucleotide/generation. The ratio of amino acid polymorphisms within species to fixed differences between species suggests that approximately 25% of all possible single-step amino acid replacements in the boss gene product may be selectively neutral or nearly neutral. The data also imply that random genetic drift has been responsible for virtually all of the observed differences in the portion of the boss gene analyzed among the four species.      

Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene

We have analyzed the conserved regions of the gene coding for the circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria parasite. The closest evolutionary relative of P. falciparum, the agent of malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is consistent with the hypothesis that P. falciparum is an ancient human parasite, associated with humans since the divergence of the hominids from their closest hominoid relatives. Three other human Plasmodium species are each genetically indistinguishable from species parasitic to nonhuman primates; that is, for the DNA sequences included in our analysis, the differences between species are not greater than the differences between strains of the human species. The human P. malariae is indistinguishable from P. brasilianum, and P. vivax is indistinguishable from P. simium; P. brasilianum and P. simium are parasitic to New World monkeys. The human P. vivax-like is indistinguishable from P. simiovale, a parasite of Old World macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are evolutionarily recent human parasites, the first two at least acquired only within the last several thousand years, and perhaps within the last few hundred years, after the expansion of human populations in South America following the European colonizations. We estimate the rate of evolution of the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year. The divergence between the P. falciparum and P. reichenowi lineages is accordingly dated 8.9 Myr ago. The divergence between the three lineages leading to the human parasites is very ancient, about 100 Myr old between P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between P. falciparum and the other two.      

Oligomeric forms of the membrane-bound acetylcholine receptor disclosed upon extraction of the M(r) 43,000 nonreceptor peptide

Oligomeric forms of the acetylcholine receptor are directly visualized by electron microscopy in receptor-rich membranes from torpedo marmorata. The receptor structures are quantitatively correlated with the molecular species so far identified only after detergent solubilization, and further related to the polypeptide composition of the membranes and changes thereof. The structural identification is made possibly by the increased fragility of the membranes after extraction of nonreceptor peptides and their subsequent disruption upon drying onto hydrophilic carbon supports. Receptor particles in native membranes depleted of nonreceptor peptides appear as single units of 7-8 nm, and double and multiple aggregates thereof. Particle doublets having a main-axis diameter of 19 +/- 3 nm predominate in these membranes. Linear aggregates of particles similar to those observed in rotary replicas of quick-frozen fresh electrolytes (Heuser, J.E. and S. R. Salpeter. 1979, J. Cell Biol. 82: 150-173) are also present in the alkaline-extracted membranes. Chemical modifications of the thiol groups shift the distribution of structural species. Dithiothreitol reduction, which renders almost exclusively the 9S, monomeric receptor form, results in the observation of the 7-8 nm particle in isolated form. The proportion of doublets increases in membranes alkylated with N-ethylmaleimide. Treatment with 5,5’-dithiobis-(nitrobenzoic acid) increases the proportion of higher oligomeric species, and particle aggregates (n=oligo) predominate. The nonreceptor v-peptide (doublet of M(r) 43,000) appears to play a role in the receptor monomer-polymer equilibria. Receptor protein and v-peptide co-aggregate upon reduction and reoxidation of native membranes. In membranes protected ab initio with N- ethylmaleimide, only the receptor appears to self-aggregate. The v-peptide cannot be extracted from these alkylated membranes, though it is easily released from normal, subsequently alkylated or reduced membranes. A stabilization of the dimeric species by the nonreceptor v-peptide is suggested by these experiments. Monospecific antibodies against the v-peptide are used in conjunction with rhodamine- labeled anti-bodies in an indirect immunoflourescence assay to map the vectorial exposure of the v-peptide. When intact membranes, v-peptide depleted and “holey” native membranes (treated with 0.3 percent saponin) are compared, maximal labeling is obtained with the latter type of membranes, suggesting a predominantly cytoplasmic exposure of the antigenic determinants of the v-peptide in the membrane. The influence of the v-peptide in the thiol-dependent interconversions of the receptor protein and the putative topography of the peptide are analyzed in the light of the present results.     

HLA-C, DRB1 and DQB1 alleles involved in genetic predisposition to psoriasis vulgaris in the Slovak population

Psoriasis vulgaris is a complex chronic skin disease with immunological and genetic background. The most important predisposing genetic factors in psoriasis are genes of the human leukocyte antigen (HLA) region. Accumulative evidence has shown that several HLA alleles are closely associated with psoriasis; however, they tend to vary in different racial and ethnic backgrounds. One hundred forty-seven unrelated Slovak patients with psoriasis vulgaris (average age at onset 28?±?14 years) were genotyped for the HLA-C, DQB1 and DRB1 alleles by the polymerase chain reaction using sequence-specific primers. Allele frequencies observed in the group of psoriatic patients were compared to those obtained in the ethnically matched control group comprising 194 subjects with no history of psoriasis. Susceptibility to psoriasis vulgaris in our study group is significantly associated with HLA-C*06 (odds ratio (OR)?=?3.85), DRB1*07 (OR?=?2.56) and DQB1*02 (OR?=?1.09), respectively, whereas DRB*01 (OR?=?0.05) is associated negatively. Hereby, we provide the first report on the association of HLA-C, DRB1 and DQB1 alleles with psoriasis in the Slovak population. Our findings confirm HLA-C*06 and DRB1*07 as the most important genetic risk factors for psoriasis. However, the role of HLA genes as causative in the pathogenesis of the disease remains unclear. Identification of genetic factors that increase the risk of psoriasis is a precondition that helps to elucidate the pathogenesis of this troubling disease and identify targets for a more specific and effective therapy.     

Conjugation of the 1BL/1RS translocation with qualitative and quantitative traits in the common wheat T.aestivum

The review considers the effect of the rye 1BL/1RS translocation in the common wheat genome on qualitative and quantitative traits: grain quality, resistance to diseases, productivity and adaptivity, parthenogenesis, regeneration in anther culture, frequency of chromosome aberrations and frequency of cross-pollination. Data on special features of transmission of the 1BL/1RS translocation through male and female gametes are presented.     

Recombination frequency in the locus Gli-D1 of common wheat T. aestivum L

The recombination frequency at the gliadin locus Gli-D1 of common wheat was determined by the maximum likelihood method. Recombination was observed between the gene encoding the fastest omega-component of the allele Gli-D1j, and the genes encoding the other omega-gliadins of this allele. The frequency of recombination was 0.65 +/- 0.18% for the cross between the near-isogenic lines of winter common wheat with respect to gliadin loci Gli-D1-4 and Gli-B1-3 and 0.78 +/- 0.45% for the cross between the varieties Yunnat and B-16.     

TGF-β1 suppresses IL-6-induced STAT3 activation through regulation of Jak2 expression in prostate epithelial cells

Chronic inflammation plays an important role in the initiation and progression of various human diseases including benign prostatic hyperplasia or prostate cancer. Here we show that the proinflammatory cytokine interleukin-6 (IL-6) has prosurvival effects and chronically activates the Jak2/STAT3 signalling pathway in a model of benign prostatic hyperplasia (BPH-1). We demonstrate that the antiinflammatory cytokine transforming growth factor-β1 (TGF-β1), which also permanently activates its canonical signalling pathway through SMAD proteins in BPH-1 cells, modifies the effects of IL-6 on cell proliferation. Importantly, TGF-β1 inhibits IL-6 signal transduction by decreasing the phosphorylation levels of STAT3. This effect is associated with decreased expression of Jak2 at both mRNA and protein levels. Moreover, we showed that TGF-β1 inhibits IL-6-induced expression of the cancer-associated gene MUC1. These observations demonstrated a novel interaction between TGF-β1 and IL-6 signalling and suggested another mechanism of how defects in TGF-β signalling, frequently associated with prostate pathologies, can contribute to the disruption of tissue homeostasis.     

Identification of DNA sequence variation in Campylobacter jejuni strains associated with the Guillain-Barré syndrome by high-throughput AFLP analysis

Background  

Campylobacter jejuni is the predominant cause of antecedent infection in post-infectious neuropathies such as the Guillain-Barré (GBS) and Miller Fisher syndromes (MFS). GBS and MFS are probably induced by molecular mimicry between human gangliosides and bacterial lipo-oligosaccharides (LOS). This study describes a new C. jejuni-specific high-throughput AFLP (htAFLP) approach for detection and identification of DNA polymorphism, in general, and of putative GBS/MFS-markers, in particular.