Role of a single noncoding nucleotide in the evolution of an epidemic African clade of Salmonella

Salmonella enterica serovar Typhimurium ST313 is a relatively newly emerged sequence type that is causing a devastating epidemic of bloodstream infections across sub-Saharan Africa. Analysis of hundreds ofSalmonellagenomes has revealed that ST313 is closely related to the ST19 group ofSTyphimurium that cause gastroenteritis across the world. The core genomes of ST313 and ST19 vary by only ∼1,000 SNPs. We hypothesized that the phenotypic differences that distinguish AfricanSalmonellafrom ST19 are caused by certain SNPs that directly modulate the transcription of virulence genes. Here we identified 3,597 transcriptional start sites of the ST313 strain D23580, and searched for a gene-expression signature linked to pathogenesis ofSalmonellaWe identified a SNP in the promoter of thepgtEgene that caused high expression of the PgtE virulence factor in AfricanS.Typhimurium, increased the degradation of the factor B component of human complement, contributed to serum resistance, and modulated virulence in the chicken infection model. We propose that high levels of PgtE expression by AfricanSTyphimurium ST313 promote bacterial survival and dissemination during human infection. Our finding of a functional role for an extragenic SNP shows that approaches used to deduce the evolution of virulence in bacterial pathogens should include a focus on noncoding regions of the genome

IgG1 Is Required for Optimal Protection after Immunization with the Purified Porin OmpD from Salmonella Typhimurium

In mice, the IgG subclass induced after Ag encounter can reflect the nature of the Ag. Th2 Ags such as alum-precipitated proteins and helminths induce IgG1, whereas Th1 Ags, such as Salmonella Typhimurium, predominantly induce IgG2a. The contribution of different IgG isotypes to protection against bacteria such as S. Typhimurium is unclear, although as IgG2a is induced by natural infection, it is assumed this isotype is important. Previously, we have shown that purified S. Typhimurium porins including outer membrane protein OmpD, which induce both IgG1 and IgG2a in mice, provide protection to S. Typhimurium infection via Ab. In this study we report the unexpected finding that mice lacking IgG1, but not IgG2a, are substantially less protected after porin immunization than wild-type controls. IgG1-deficient mice produce more porin-specific IgG2a, resulting in total IgG levels that are similar to wild-type mice. The decreased protection in IgG1-deficient mice correlates with less efficient bacterial opsonization and uptake by macrophages, and this reflects the low binding of outer membrane protein OmpD-specific IgG2a to the bacterial surface. Thus, the Th2-associated isotype IgG1 can play a role in protection against Th1-associated organisms such as S. Typhimurium. Therefore, individual IgG subclasses to a single Ag can provide different levels of protection and the IgG isotype induced may need to be a consideration when designing vaccines and immunization strategies

The Vlochos Archaeological Project: Report on the 2016– 2018 seasons of Greek-Swedish archaeological work at Vlochos, Thessaly

The Vlochos Archaeological Project (2016–2018) was a Greek-Swedish archaeological investigation of the remains of the ancient urban site at Vlochos in western Thessaly, Greece. Employing a wide array of noninvasive methods, the project succeeded in completely mapping the visible remains, which had previously not been systematically investigated. The extensive remains of multi-period urban fortifications, a ClassicalHellenistic city, a Roman town, and a Late Antique fortress were identified, evidence of the long history of habitation on this site. Since comparatively little fieldwork has been conducted in the region, the results significantly increase our knowledge of the history and archaeology of Thessaly

Exploring Appraisal, Emotional, Informational, and Instrumental Support for Novice Agricultural Education Teachers in California: A Phenomenological Study

The purpose of this qualitative study was to understand the perceived emotional, appraisal, informational, and instrumental support for the novice, secondary agricultural teachers in the state of California. The theory guiding this study was social support theory as it frames the social support constructs to be explored. With 10 novice agricultural teachers across the state of California serving as study participants, data collection included a questionnaire, individual interviews, and focus groups. Data were analyzed by a seven-step, modified Van Kamm data analysis procedure. Findings, which will be disseminated to the agricultural education research community and leaders in California’s agricultural education system, indicate that novice agriculture teachers in California consistently receive informational support from an array of school-related sources. Although provided through numerous school-related sources, the accessibility of other social support constructs varied among study participants. Implications and recommendations for agricultural education are shared

Status of young-of-the-year brown trout (Salmo trutta fario) in Swiss streams: factors influencing YOY trout recruitment

As part of the Swiss Fischnetz project (network for declining fish yields in Switzerland) studies were carried out to investigate the decline in catches of brown trout . Insufficient YOY ( young-of-the-year ) recruitment of brown trout due to different abiotic and/or biotic factors was hypothesized as a potential cause of this decline. Quantitative assessments of fish ecology parameters and habitat measurements were carried out at 97 river sites over a two-year period. The main objectives of this study were to document the occurrence and abundance of naturally reproduced YOY trout and to develop an understanding of environmental factors responsible for the observed YOY density. A general linear model (GLM) was used to analyse the influence of selected environmental abiotic and biotic parameters on YOY density. Successful recruitment of YOY trout was observed in all but three of the sites studied. Abundance was correlated with abiotic and biotic factors , such as river width, slope, altitude, substratum condition, and the occurrence of proliferative kidney disease (PKD). The results highlight the importance of small streams for natural YOY recruitment of brown trout and their function as a source of individuals for downstream river sections

Novel (R₂PC₂H₄PR₂)M⁰−COT Complexes (M = Pd, Pt) Having Semiaromatic η²-COT or Dianionic η²(1,4)-COT Ligands

The complexes (R2PC2H4PR2)Pd(C2H4) (R = iPr, tBu) react with COT by displacement of the ethene ligand to afford the novel mononuclear complexes (R2PC2H4PR2)Pd(η2-C8H8) (R = iPr (1a), tBu (1b)). The COT ligand of 1a,b is semiaromatic; i.e., it is planar with alternating C-C and C=C bonds as expected for the monoanion [C8H8]-. Treatment of 1a,b with (R2PC2H4PR2)Pd-alkene complexes generates the dinuclear derivatives {(R2PC2H4PR2)Pd}2(μ-η2,η2-C8H8) (R = iPr (2a), tBu(2b)). The complexes 2a,b are labile; elimination of the COT ligand from 2a gives rise to homoleptic Pd2(μ-dippe)2. Reaction of (dippe)PtCl2 with (tmeda)2Li2COT or displacement of the alkene ligands in {(dippe)Pt}2(µ-η2,η2-C8H12) (4) or (dippe)Pt(C2H4) (5) by COT produces (dippe)Pt(η2-C8H8) (6a), which in the solid state also has a semiaromatic COT ligand. In solution, complex 6a is in equilibrium with the novel isomeric form (dippe)PtII{η2(1,4)-C8H8} (6b). The complexes are characterized by IR, MS, and solution and solid-state NMR

Assessing the decline of brown trout (Salmo trutta) in Swiss rivers using a Bayesian probability network

A Bayesian probability network has been developed to integrate the various scientific findings of an interdisciplinary research project on brown trout and their habitat in Switzerland. The network is based on a dynamic, age-structured population model, which is extended to include the effect of natural and anthropogenic influence factors. These include gravel bed conditions, water quality, disease rates, water temperature, habitat conditions, stocking practices, angler catch and flood frequency. Effect strength and associated uncertainty are described by conditional probability distributions. These conditional probabilities were developed using experimental and field data, literature reports, and the elicited judgment of involved scientists. The model was applied to brown trout populations at 12 locations in four river basins. Model testing consisted of comparing predictions of juvenile and adult density under current conditions to the results of recent population surveys. The relative importance of the various influence factors was then assessed by comparing various model scenarios, including a hypothetical reference condition. A measure of causal strength was developed based on this comparison, and the major stress factors were analyzed according to this measure for each location. We found that suboptimal habitat conditions are the most important and ubiquitous stress factor and have impacts of sufficient magnitude to explain the reduced fish populations observed in recent years. However, other factors likely contribute to the declines, depending on local conditions. The model developed in this study can be used to provide these site-specific assessments and predict the effect of candidate management measures. (c) 2005 Elsevier B.V. All rights reserved