Search results for " Toxins"

Transcription analysis of the genes tcdA-E of the pathogenicity locus of Clostridium difficile.

1997

To analyse the transcription pattern of the five tcdA-E genes of the pathogenicity locus (PaLoc) of Clostridium difficile a protocol was established to purify RNA from strain VPI10463. Transcription analysis of the five tcdA-E genes showed that they were all transcribed. In the early exponential phase, a high level of tcdC and low levels of tcdA,B,D,E transcripts were detectable; this was inverted in the stationary phase, suggesting that TcdC might have a negative influence on transcription of the other genes. Three transcription initiation sites, one for tcdA and two for tcdB were determined by primer extension analysis. Readthrough transcripts from outside the locus were not obtainable, s…

Clostridium difficile toxin A carries a C-terminal repetitive structure homologous to the carbohydrate binding region of streptococcal glycosyltransf…

1990

A detailed analysis of the 8130-bp open reading frame (ORF) of gene toxA and of an upstream ORF designated utxA, indicates the presence of a transcription terminator stem-loop for toxA, promoter sequences, and Shine-Dalgarno boxes for toxA and utxA. No transcription terminator between toxA and utxA is suggested by the sequence. ToxA contains two domains, one-third (C-terminal) with a repetitive structure and the residual two-thirds with no repetitions. The 2499-bp sequence encoding the repetitive structure is composed of nine groups of different short repetitive oligodeoxyribonucleotides (SRONs). A combination of these SRONs codes for five groups of combined repetitive oligopeptides (CROPs)…

Clostridium difficile heterogeneously impacts intestinal community architecture but drives stable metabolome responses

2015

Clostridium difficile-associated diarrhoea (CDAD) is caused by C. difficile toxins A and B and represents a serious emerging health problem. Yet, its progression and functional consequences are unclear. We hypothesised that C. difficile can drive major measurable metabolic changes in the gut microbiota and that a relationship with the production or absence of toxins may be established. We tested this hypothesis by performing metabolic profiling on the gut microbiota of patients with C. difficile that produced (n=6) or did not produce (n=4) toxins and on non-colonised control patients (n=6), all of whom were experiencing diarrhoea. We report a statistically significant separation (P-value o0…

Expression of P, S, and F1C adhesins by cytotoxic necrotizing factor1-producing Escherichia coli from septicemic and diarrheic pigs

1997

Nineteen papC-positive cytotoxic necrotizing factor 1 (CNF1)-producing Escherichia coli isolates from pigs with septicemia or diarrhea were tested for the presence of pap-, sfa-, and afa-related sequences encoding P/Prs, S/F1C, and Dr/AFA adhesins respectively. Production of adhesins by isolates was tested by mannose-resistant hemagglutination (MRHA), sialidase treatment of erythrocytes and particle agglutination tests. Production of P, S, and F1C fimbriae by isolates was also examined by immunofluorescence. All isolates were pap+ by PCR. Eighteen isolates (95%) were MRHA for ovine and human A erythrocytes and exhibited GalNac-GalNac receptor specificity associated with class III P(Prs) adh…

Vibrio cholerae cytolysin: assembly and membrane insertion of the oligomeric pore are tightly linked and are not detectably restricted by membrane fl…

2000

AbstractHemolytic strains of Vibrio cholerae secrete a cytolysin that, upon binding as a monomer, forms pentameric pores in animal cell membranes. Pore formation is inhibited at low temperature and in the absence of cholesterol. We here posed the following questions: firstly, can oligomerization be observed in the absence of pore formation? Secondly, is membrane fluidity responsible for the effect of temperature or of cholesterol upon pore formation? The first issue was approached by chemical cross-linking, by electrophoretic heteromer analysis, and by electron microscopy. None of these methods yielded any evidence of a non-lytic pre-pore oligomer. The second question was addressed by the u…

Staphyloccal alpha toxin

1998

Mode of action of Bacillus thuringiensis PS86Q3 strain in hymenopteran forest pests

2001

The mode of action of Cry toxins has been described principally in lepidopteran insects as a multistep process. In this work we describe the mode of action of a Cry toxin active in the common pine sawfly Diprion pini (Hymenoptera, Diprionidae), considered a major forest pest in Europe. Strain PS86Q3 contains a long bipyramidal crystal composed of five major proteins. The N-terminal sequence shows that the 155 kDa protein corresponds to Cry5B toxin and the other proteins belong to the Cry5A subgroup. PCR analysis indicates the presence of cry5Ac and cry5Ba genes, suggesting that Cry5A protein should be Cry5Ac. Activation of protoxins with trypsin or with midgut content from D. pini and Cepha…

Molecular and Insecticidal Characterization of a Cry1I Protein Toxic to Insects of the Families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae

2006

ABSTRACT The most notable characteristic of Bacillus thuringiensis is its ability to produce insecticidal proteins. More than 300 different proteins have been described with specific activity against insect species. We report the molecular and insecticidal characterization of a novel cry gene encoding a protein of the Cry1I group with toxic activity towards insects of the families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae. PCR analysis detected a DNA sequence with an open reading frame of 2.2 kb which encodes a protein with a molecular mass of 80.9 kDa. Trypsin digestion of this protein resulted in a fragment of ca. 60 kDa, typical of activated Cry1 proteins. The deduced sequen…

Use of Bacillus thuringiensis toxins for control of the cotton pest earias insulana (Boisd.) (Lepidoptera: Noctuidae)

2006

ABSTRACT Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana . At a concentration of 100 μg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 μg/ml (for Cry9Ca and Cry1Ia, …

A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins

2018

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The Europea…