HeLa-cell adherence patterns and actin aggregation of enteropathogenic Escherichia coli (EPEC) and Shiga-toxin-producing E. coli (STEC) strains carrying different eae and tir alleles

A collection of 69 eae-positive strains expressing 29 different intimin types and eight tir alleles was characterized with respect to their adherence patterns to HeLa cells, ability to promote actin accumulation in vitro, the presence of bfpA alleles in positive strains, and bundle-forming pilus (BFP) expression. All of the nine typical enteropathogenic Escherichia coli (tEPEC) studied harbored the enteropathogenic E. coli adherence factor (EAF) plasmid, as shown by PCR and/or EAF probe results. In addition, they were positive for bfpA, as shown by PCR, and BFP expression, as confirmed by immunofluorescence (IFL) and/or immunoblotting (IBL) assays. Localized adherence (LA) was exclusively displayed by those nine tEPEC, while localized-adherence-like (LAL) was the most frequent pattern among atypical EPEC (aEPEC) and Shiga-toxinproducing E. coli (STEC). All LA and LAL strains were able to cause attaching and effacing (AE) lesions, as established by means of the FAS test. There was a significant association between the presence of tir allele α1 and bfpA-positive strains, and consequently, with the LA pattern. However, intimin type or bfpA was not associated with the adherence pattern displayed in HeLa cells. Among the eight bfpA alleles detected, a new type (β10; accession number FN391178) was identified in a strain of serotype O157:H45, and a truncated variant (β3.2-t; accession number FN 391181) in four strains belonging to different pathotypes. [Int Microbiol 2009; 12(4):243-251

XHIP-II: Clusters and associations

Context. In the absence of complete kinematic data it has not previously been possible to furnish accurate lists of member stars for all moving groups. There has been an unresolved dispute concerning the apparent inconsistency of the Hipparcos parallax distance to the Pleiades. Aims. To find improved candidate lists for clusters and associations represented among Hipparcos stars, to establish distances, and to cast light on the Pleiades distance anomaly. Methods. We use a six dimensional fitting procedure to identify candidates, and plot CMDs for 20 of the nearest groups. We calculate the mean parallax distance for all groups. Results. We identify lists of candidates and calculated parallax distances for 42 clusters and 45 associations represented within the Hipparcos catalogue. We find agreement between parallax distance and photometric distances for the most important clusters. For single stars in the Pleiades we find mean parallax distance 125.6 \pm 4.2 pc and photometric distance 132 \pm 3 pc calibrated to nearby groups of similar in age and composition. This gives no reason to doubt either the Hipparcos database or stellar evolutionary theory.Comment: Accepted for publication in Astronomy Letters, 10 pages, 2 fig

Discussion of the De Generatione Sonorum, a treatise on sound and phonetics by Robert Grosseteste

Here I am proposing a translation and discussion of the De Generatione Sonorum, one of the short scientific treatises written by Robert Grosseteste. The subject is the sound and the phonetics. In this treatise we find a discussion of oscillations and elasticity of materials and the description of some motions and their combinations to

A Contract for the Advance Sale of Wine

Edition of a sale of wine in advance from Byzantine Egypt (P.Vindob. inv. G 40267). Notable features include the guarantee clause and the supply of jars by the seller, both of which are put in a wider context

Exposure to two antigenically distinct SARS-CoV-2 variants broadens neutralization patterns.

Previous exposure to one severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant influences neutralizing antibody responses induced by subsequent exposures. Consecutive exposures predominantly back-boost pre-existing immunity and expand cross-neutralizing antibodies while de novo variant-specific responses are poorly induced. In this study, we analyzed neutralizing antibodies against a panel of variants in plasma samples from individuals after exactly two exposures: twice pre-Omicron variant (either two dose vaccinated or infected and one dose vaccinated), pre-Omicron followed by early Omicron variant, or twice early Omicron variant. We found that exposure to two antigenically distinct variants, either pre-Omicron followed by Omicron or two different Omicron variants, increased the neutralization breadth. However, no significant cross-neutralization against the genetically closely related human coronavirus SARS-CoV was induced. Using depletion experiments, we showed that the first exposed variant strongly influences the specificity of antibodies. The second exposure primarily expanded cross-reactive antibodies rather than inducing a variant-specific response against the later variant, highlighting the phenomenon of immune imprinting in the context of SARS-CoV-2. Overall, our results indicate that multiple exposures to SARS-CoV-2 improve cross-neutralization against a variety of variants, but also underscore the lack of de novo antibody production against the more recently encountered variant