Search results for "Hemolysin"

Whole-genome characterization of Shewanella algae strain SYT3 isolated from seawater reveals insight into hemolysis.

2018

Aim: To describe the genomic characteristics of seawater-borne hemolytic Shewanella algae and its resistance genes. Materials & methods: Whole genome sequence of S. algae SYT3 was determined using llumina MiSeq platform. Multiple-database-based analysis was performed to identify the genetic background of its hemolytic activity and the antibiotic resistance genes. Results: S. algae SYT3 possesses a homolog of the hly operon involved in the synthesis of hemolysin. We also identified candidate genes associated with resistance to β-lactam antibiotics (bla OXA-55) and fluoroquinolone (qnrA3). Conclusion: The study provides an insight into the hemolytic activity of S. algae. Our findings als…

2018

Photobacterium damselae subsp. damselae (Pdd) is an emerging pathogen of marine animals that sometimes causes serious infections in humans. Two related pore forming toxins, phobalysins P and C, and damselysin, a phospholipase D, confer strong virulence of Pdd in mice. Because infections by Pdd are typically caused following exposure of wounds to sea water we investigated how salinity impacts toxin activity, swimming, and association of Pdd with epithelial cells. These activities were low when bacteria were pre-cultured in media with 3.5% NaCl, the global average salinity of sea water. In contrast, lower salinity increased swimming of wild type Pdd peaking at 2% NaCl, hemolysis, and associat…

Ephestia kuehniella tolerance to Bacillus thuringiensis Cry1Aa is associated with reduced oligomer formation

2016

The basis of the different susceptibility of Ephestia kuehniella to the Cry1Aa and Cry1Ac δ-endotoxins from Bacillus thuringiensis kurstaki BNS3 was studied. Both toxins bound specifically to the BBMV of E. kuehniella. The result of the ligand blot showed that Cry1Ac bound to three putative receptors of about 100, 65 and 80 kDa and Cry1Aa interacted only with a 100 kDa protein. Pronase digestion of the BBMV-bound toxins was used to analyze the toxin insertion. Both toxins inserted into the BBMV as monomers however, a 14 kDa peptide of α4-α5 which correspond to the oligomeric form of this peptide was detected in case of Cry1Ac only. Analysis of the in vitro oligomerisation of these toxins in…

Dissecting the role of ADAM10 as a mediator of Staphylococcus aureus α-toxin action

2016

Staphylococcus aureus is a leading cause of bacterial infections in humans, including life-threatening diseases such as pneumonia and sepsis. Its small membrane-pore-forming α-toxin is considered an important virulence factor. By destroying cell–cell contacts through cleavage of cadherins, the metalloproteinase ADAM10 (a disintegrin and metalloproteinase 10) critically contributes to α-toxin-dependent pathology of experimental S. aureus infections in mice. Moreover, ADAM10 was proposed to be a receptor for α-toxin. However, it is unclear whether the catalytic activity or specific domains of ADAM10 are involved in mediating binding and/or subsequent cytotoxicity of α-toxin. Also, it is not k…

The usefulness of a mathematical model of exposure for environmental risk assessment

2011

We respond to the Comment of Lang et al . [[1][1]] regarding our mathematical model [[2][2]] of exposure of non-target Lepidoptera to Bt -maize pollen expressing Cry1Ab within Europe. Lang et al . remark on the degree to which the model was subject to uncertainty. Perry et al . [[2][2]] did indeed

A mathematical model of exposure of nontarget Lepidoptera to Bt-maize pollen expressing Cry1Ab within Europe

2010

Genetically modified (GM) maize MON810 expresses a Cry1Ab insecticidal protein, derived from Bacillus thuringiensis ( Bt ), toxic to lepidopteran target pests such as Ostrinia nubilalis . An environmental risk to non-target Lepidoptera from this GM crop is exposure to harmful amounts of Bt -containing pollen deposited on host plants in or near MON810 fields. An 11-parameter mathematical model analysed exposure of larvae of three non-target species: the butterflies Inachis io (L.), Vanessa atalanta (L.) and moth Plutella xylostella (L.), in 11 representative maize cultivation regions in four European countries. A mortality–dose relationship was integrated with a dose–distance relationship t…

The Vibrio choleare haemolysin anion channel is required for cell vacuolation and death

2002

SummarySeveral strains of Vibrio cholerae secrete ahaemolytic toxin of 63kDa, termed V. cholerae cytolysin (VCC). This toxin causes extensive vacuo-lation and death of cells in culture and forms ananion-selective channel in planar lipid bilayers and incells. Here, we identify inhibitors of the VCC anionchannel and show that the formation of the anionchannel is necessary for the development of the vacuoles and for the cell death induced by this toxin. Using markers of cell organelles, we show that vacuoles derive from different intracellular com-partments and we identify the contribution of lateendosomes and of the trans -Golgi network in vacuolebiogenesis.Introduction The Gram-negative bact…

Effects ofBacillus thuringiensisCry1Ab and Cry3Aa endotoxins on predatory Coleoptera tested through artificial diet-incorporation bioassays

2009

AbstractTraditional approaches to studying the effects of genetically modified (GM) crops on beneficial insects involve either field assays, comparing insect population levels between control and GM crops or tritrophic bioassays with contaminated insects – usually larvae or eggs of Lepidoptera – as preys. Here, we report the results of a bioassay using an artificial diet, suitable for predatory Coleoptera, to supplyBacillus thuringiensis(Bt) solubilized Cry1Ab and Cry3Aa as well as trypsin-activated Cry1Ab toAtheta coriariaandCryptolaemus montrouzieriadults and young larvae ofAdalia bipunctata. Water, solubilization buffer and trypsin-treated solubilization buffer were used as controls. In …

Conductance and Ion Selectivity of a Mesoscopic Protein Nanopore Probed with Cysteine Scanning Mutagenesis

2005

Nanometer-scale proteinaceous pores are the basis of ion and macromolecular transport in cells and organelles. Recent studies suggest that ion channels and synthetic nanopores may prove useful in biotechnological applications. To better understand the structure-function relationship of nanopores, we are studying the ion-conducting properties of channels formed by wild-type and genetically engineered versions of Staphylococcus aureus alpha-hemolysin (alphaHL) reconstituted into planar lipid bilayer membranes. Specifically, we measured the ion selectivities and current-voltage relationships of channels formed with 24 different alphaHL point cysteine mutants before and after derivatizing the c…

Studies on the natural hemolytic system of the annelid worm Spirographis spallanzanii viviani (Polychaeta).

1981

Abstract Hemolytic activity in the hemolymph of Spirographis spallanzanii was estabilished against Bufo, sheep, calf, rabbit, rat, human A, B, O erythrocytes. Chemico-physical treatments suggest that the hemolytic factor could be a thermo-labile protein whose activity requires calcium ions and which is active over broad pH and temperature ranges. Some of these properties and the sigmoidal curve obtained by plotting the quantity of hemolymph against the percentage of hemolysis, produce some analogies with the mammalian lytic system.