Search

Typhoid toxin is a virulence factor for the bacterial pathogen Salmonella Typhi, which causes typhoid fever in humans. After its synthesis by intracellular bacteria, typhoid toxin is secreted into the lumen of the Salmonella-containing vacuole by a secretion mechanism strictly dependent on TtsA, a specific muramidase that facilitates toxin transport through the peptidoglycan layer. Here we show that substrate recognition by TtsA depends on a discrete domain within its carboxy terminus, which targets the enzyme to the bacterial poles to recognize YcbB-edited peptidoglycan. Comparison of the atomic structures of TtsA bound to its substrate and that of a close homolog with different specificity identified specific determinants involved in substrate recognition. Combined with structure-guided mutagenesis and in vitro and in vivo crosslinking experiments, this study provides an unprecedented view of the mechanisms by which a muramidase recognizes its peptidoglycan substrate to facilitate protein secretion. [ABSTRACT FROM AUTHOR]

Chronic intraocular leptospiral infection is the most common cause for recurrent uveitis in equids. History and a combination of typical ophthalmological findings can lead to suspected diagnosis ofleptospiral induced uveitis. Testing intraocular fluids had been shown to be the most valuable tool for providing evidence of an intraocular leptospiral infection. The most appropriate treatment for recurrences of leptospiral uveitis is vitrectomy, whereas vitrectomy in non-leptospiral uveitis cases is less successful in regard of avoiding further damage to effected eyes. However, in cases in which clinical and ophthalmological findings are not typical for leptospiral induced uveitis, preoperative testing of aqueous fluid can be indicated to evaluate an indication for vitrectomy. Until now, for save sampling of aqueous humour, a general anaesthesia was necessary for paracentesis of the anterior chamber, and a second was necessary for vitrectomy in case of leptospira-positive laboratory results (either antibodies using microscopic agglutination tests (MAT), enzyme-linked immunosorbent assays (ELISA) or polymerase chain reactions (PCR) detecting LipL32). A quick ELISA test, the SNAP® Lepto, has recently been made available to detect antibodies directed against LipL32 of pathogenic leptospires in any species. In order to evaluate the SNAP® Lepto and to test whether it is effective with intraocular samples (aqueous and vitreous humour) from horses, 118 samples from equine eyes suffering from recurrent uveitis and 120 samples from equine control eyes were taken and tested with SNAP® Lepto (detecting antibodies directed against LipL32), MAT (detecting antibodies directed against ten different serovars) and PCR (detecting the LipL32 antigen). If one of these tests was positive, an intraocular leptospiral infection was assumed.The result was that SNAP® Lepto was positive in 114 out of 118 intraocular samples (97 %) from horses suffering from recurrent uveitis. SNAP® Lepto was even superior to MAT, with a sensitivity of 0.97 (MAT 0.93). PCR was positive with fluids from eyes suffering from uveitis in 70% of samples. There were no positive PCR results in any SNAP® Lepto-negative samples from uveitic eyes and the MAT was positive in four SNAP® Lepto-negative samples. On the other hand, SNAP® Lepto gave a positive result in eight MAT-negative samples from eyes with uveitis. Furthermore, none of the antibody tests was positive regarding any sample from the control eyes, and PCR was positive in one single sample from a control eye. It can be concluded that SNAP® Lepto, which gives a result within 10 minutes, is a valuable test method for detecting antibodies directed against LipL32 in intraocular fluids from horses. In the case of a negative result, MAT and PCR can be performed subsequently to reduce false negative results. [ABSTRACT FROM AUTHOR]

Gross domestic product (GDP) represents a widely used metric to compare economic development across time and space. GDP estimates have been routinely assembled only since the beginning of the second half of the 20th century, making comparisons with prior periods cumbersome or even impossible. In recent years various efforts have been put forward to re-estimate national GDP for specific years in the past centuries and even millennia, providing new insights into past economic development on a snapshot basis. In order to make this wealth of data utilizable across research disciplines, we here present a first continuous and consistent data set of GDP time series for 195 countries from 1850 to 2009, based mainly on data from the Maddison Project and other population and GDP sources. The GDP data are consistent with Penn World Tables v8.1 and future GDP projections from the Shared Socio-economic Pathways (SSPs), and are freely available at http://doi.org/10. 5880/pik.2018.010 (Geiger and Frieler, 2018). To ease usability, we additionally provide GDP per capita data and further supplementary and data description files in the online archive. We utilize various methods to handle missing data and discuss the advantages and limitations of our methodology. Despite known shortcomings this data set provides valuable input, e.g., for climate impact research, in order to consistently analyze economic impacts from pre-industrial times to the future. [ABSTRACT FROM AUTHOR]

Gross Domestic Product (GDP) represents a widely used metric to compare economic development across time and space. GDP estimates have been routinely assembled only since the beginning of the second half of the 20th century, making comparisons with prior periods cumbersome or even impossible. In recent years various efforts have been put forward to re-estimate national GDP for specific years in the past centuries and even millennia, providing new insights of past economic development on a snapshot basis. In order to make this wealth of data utilizable across research disciplines, we here present a first continuous and consistent data set of GDP time series for 195 countries from 1850 to 2009, based mainly on data from the Maddison Project and other population and GDP sources. The GDP data is consistent with Penn World Tables v8.1 and future GDP projections from the Shared Socioeconomic Pathways (SSPs), and freely available at https://doi.org/10.5880/pik.2017.003. To ease usability, we additionally provide GPD per capita data and further supplementary and data description files in the online archive. We utilize various methods to handle missing data and discuss the advantages and limitations of our methodology. Despite known shortcomings this data set provides valuable input e.g. for climate impact research in order to consistently analyze economic impacts from pre-industrial times to the future. [ABSTRACT FROM AUTHOR]

Tropical cyclones pose a major risk to societies worldwide with about 22 million directly-affected people and damages of $29 billion on average per year over the last 20 years. While data on observed cyclones tracks (location of the center) and wind speeds is publically available these data sets do not contain information about the spatial extent of the storm and people or assets exposed. Here, we apply a simplified wind field model to estimate the areas exposed to wind speeds above 34, 64, and 96 knots. Based on available spatially-explicit data on population densities and Gross Domestic Product (GDP) we estimate 1) the number of people and 2) the sum of assets exposed to wind speeds above these thresholds accounting for temporal changes in historical distribution of population and assets (TCE-hist) and assuming fixed 2015 patterns (TCE-2015). The associated country-event level exposure data (TCE-DAT) covers the period 1950 to 2015 and is freely available at http://doi.org/10.5880/pik.2017.005. It is considered key information to 1) assess the contribution of climatological versus socio-economic drivers of changes in exposure to tropical cyclones, 2) estimate changes in vulnerability from the difference in exposure and reported damages and calibrate associated damage functions, and 3) build improved exposure-based predictors to estimate higher-level societal impacts such as long-term effects on GDP, employment, or migration. We validate the adequateness of our methodology by comparing our exposure estimate to estimated exposure obtained from reported wind fields available since 1988 for the United States. We expect that the free availability of the underlying model and TCE-DAT will make research on tropical cyclone risks more accessible to non-experts and stakeholders. [ABSTRACT FROM AUTHOR]

Although Staphylococcus aureus is not a classical intracellular pathogen, it can survive within phagocytes and many other cell types. However, the pathogen is also able to escape from cells by mechanisms that are only partially understood. We analysed a series of isogenic S. aureus mutants of the USA300 derivative JE2 for their capacity to destroy human macrophages from within. Intracellular S. aureus JE2 caused severe cell damage in human macrophages and could efficiently escape from within the cells. To obtain this full escape phenotype including an intermittent residency in the cytoplasm, the combined action of the regulatory systems Sae and Agr is required. Mutants in Sae or mutants deficient in the Sae target genes lukAB and pvl remained in high numbers within the macrophages causing reduced cell damage. Mutants in the regulatory system Agr or in the Agr target gene psmα were largely similar to wild-type bacteria concerning cell damage and escape efficiency. However, these strains were rarely detectable in the cytoplasm, emphasizing the role of phenol-soluble modulins (PSMs) for phagosomal escape. Thus, Sae-regulated toxins largely determine damage and escape from within macrophages, whereas PSMs are mainly responsible for the escape from the phagosome into the cytoplasm. Damage of macrophages induced by intracellular bacteria was linked neither to activation of apoptosis-related caspase 3, 7 or 8 nor to NLRP3-dependent inflammasome activation. [ABSTRACT FROM AUTHOR]

The control of rRNA synthesis and, thereby, translation is vital for adapting to changing environmental conditions. The decrease of rRNA is a common feature of the stringent response, which is elicited by the rapid synthesis of (p)ppGpp. Here we analysed the properties and regulation of one representative rRNA operon of Staphylococcus aureus under stringent conditions and during growth. The promoters, P1 and P2, are severely downregulated at low intracellular guanosine triphosphate (GTP) concentrations either imposed by stringent conditions or in a guanine auxotroph guaBA mutant. In a (p)ppGpp0 strain, the GTP level increased under stringent conditions, and rRNA transcription was upregulated. The correlation of the intracellular GTP levels and rRNA promoter activity could be linked to GTP nucleotides in the initiation region of both promoters at positions between +1 and +4. This indicates that not only transcriptional initiation, but also the first steps of elongation, requires high concentrations of free nucleotides. However, the severe downregulation of rRNA in post-exponential growth phase is independent of (p)ppGpp, the composition of the initiation region and the intracellular nucleotide pool. In summary, rRNA transcription in S. aureus is only partially and presumably indirectly controlled by (p)ppGpp. [ABSTRACT FROM AUTHOR]

The stringent response is a conserved global regulatory mechanism that is related to the synthesis of (p)ppGpp nucleotides. Gram-positive bacteria, such as Staphylococcus aureus, possess three (p)ppGpp synthases: the bifunctional RSH (RelA/SpoT homolog) protein, which consists of a (p)ppGpp synthase and a (p)ppGpp hydrolase domain, and two truncated (p)ppGpp synthases, designated RelP and RelQ. Here, we characterized these two small (p)ppGpp synthases. Biochemical analyses of purified proteins and in vivo studies revealed a stronger synthetic activity for RelP than for RelQ. However, both enzymes prefer GDP over GTP as the pyrophosphate recipient to synthesize ppGpp. Each of the enzymes was shown to be responsible for the essentiality of the (p)ppGpp hydrolase domain of the RSH protein. The staphylococcal RSH-hydrolase is an efficient enzyme that prevents the toxic accumulation of (p)ppGpp. Expression of (p)ppGpp synthases in a hydrolase-negative background leads not only to growth arrest but also to cell death. Transcriptional analyses showed that relP and relQ are strongly induced upon vancomycin and ampicillin treatments. Accordingly, mutants lacking relP and relQ showed a significantly reduced survival rate upon treatments with cell wall-active antibiotics. Thus, RelP and RelQ are active (p)ppGpp synthases in S. aureus that are induced under cell envelope stress to mediate tolerance against these conditions. [ABSTRACT FROM AUTHOR]

We develop a diagrammatic scattering theory for interacting bosons in a three-dimensional, weakly disordered potential. Based on a microscopic N-body scattering theory, we identify the relevant diagrams including elastic and inelastic collision processes that are sufficient to describe diffusive quantum transport. By taking advantage of the statistical properties of the weak disorder potential, we demonstrate how the N-body dynamics can be reduced to a nonlinear integral equation of Boltzmann type for the single-particle diffusive flux. Our theory reduces to the Gross–Pitaevskii mean field description in the limit where only elastic collisions are taken into account. However, even at weak interaction strength, inelastic collisions lead to energy redistribution between the bosons—initially prepared all at the same single-particle energy—and thereby induce thermalization of the single-particle current. In addition, we include also weak localization effects and determine the coherent corrections to the incoherent transport in terms of the coherent backscattering signal. We find that inelastic collisions lead to an enhancement of the backscattered cone in a narrow spectral window for increasing interaction strength. [ABSTRACT FROM AUTHOR]

The stringent response is initiated by rapid (p)ppGpp synthesis, which leads to a profound reprogramming of gene expression in most bacteria. The stringent phenotype seems to be species specific and may be mediated by fundamentally different molecular mechanisms. In Staphylococcus aureus, (p)ppGpp synthesis upon amino acid deprivation is achieved through the synthase domain of the bifunctional enzyme RSH (RelA/SpoT homolog). In several firmicutes, a direct link between stringent response and the CodY regulon was proposed. Wild-type strain HG001, rshSyn, codY and rshSyn, codY double mutants were analyzed by transcriptome analysis to delineate different consequences of RSH-dependent (p)ppGpp synthesis after induction of the stringent response by amino-acid deprivation. Under these conditions genes coding for major components of the protein synthesis machinery and nucleotide metabolism were down-regulated only in rsh positive strains. Genes which became activated upon (p)ppGpp induction are mostly regulated indirectly via de-repression of the GTP-responsive repressor CodY. Only seven genes, including those coding for the cytotoxic phenol-soluble modulins (PSMs), were found to be up-regulated via RSH independently of CodY. qtRT-PCR analyses of hallmark genes of the stringent response indicate that an RSH activating stringent condition is induced after uptake of S. aureus in human polymorphonuclear neutrophils (PMNs). The RSH activity in turn is crucial for intracellular expression of psms. Accordingly, rshSyn and rshSyn, codY mutants were less able to survive after phagocytosis similar to psm mutants. Intraphagosomal induction of psmα1-4 and/or psmβ1,2 could complement the survival of the rshSyn mutant. Thus, an active RSH synthase is required for intracellular psm expression which contributes to survival after phagocytosis. [ABSTRACT FROM AUTHOR]

We develop a diagrammatic scattering theory for interacting bosons in a three-dimensional, weakly disordered potential. We show how collisional energy transfer between the bosons induces the thermal-ization of the inelastic single-particle current which, after only a few collision events, dominates over the elastic contribution described by the Gross-Pitaevskii ansatz. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyzes coherent backscattering of intense laser light by two randomly placed distant atoms. Starting from the general two-atom master equation, we analytically derive the elastic and inelastic background and interference components of the double scattering spectrum. By expressing the final results in terms of single-atom observables, the two-atom problem is shown to be equivalent to a description in terms of single atoms under bichromatic driving. [ABSTRACT FROM AUTHOR]

The article presents a study which focused on a better representation of the long-term impacts of extreme weather events on economic growth. Topics discussed include effect of insurance on economic recovery, impact of growth losses on shock heterogeneity, and role of better insurance coverage in mitigating climate change-induced growth losses.

OBJECTIVE: To assess the histological injury and intestinal microperfusion measured by laser Doppler flowmetry and spectrophotometry (LDFS) of the small intestine orad to a strangulation during colic surgery. ANIMALS: Horses with naturally occurring small intestinal strangulations undergoing colic surgery were included. METHODS: In this prospective clinical trial, intestinal tissue oxygen saturation (tSO2) and tissue blood flow (tBF) were measured by LDFS orad to the strangulation following release of the strangulation (n = 18). The number of horses with postoperative reflux (POR) and the cases that survived until discharge were compared between groups using Fisher's exact test (P < .05). Intestinal biopsies were taken in cases that underwent intestinal resection or intraoperative euthanasia (n = 28). Measurements were compared between injured and noninjured segments with a Mann-Whitney U or t test. RESULTS: The tSO2 and tBF of the orad intestine were lower than previously reported in healthy horses. Horses with low tSO2 of < 35% were significantly more likely to suffer from POR (6/6 cases) compared to cases with tSO2 > 69% (1/6). The number of horses that survived were not statistically different between these groups (2/6 and 6/6). All horses with mucosal injury developed POR (6/6), which was significantly more likely compared to horses without mucosal injury (3/13). No significant difference in tSO2 or tBF could be found between the segments with and without histological injury. CLINICAL RELEVANCE: The results suggest that measuring tSO2 in the orad segment during colic surgery may aid in predicting postoperative issues. [ABSTRACT FROM AUTHOR]

Background: More intense tropical cyclones (TCs) are expected in the future under a warming climate scenario, but little is known about their mortality effect pattern across countries and over decades. We aim to evaluate the TC-specific mortality risks, periods of concern (POC) and characterize the spatiotemporal pattern and exposure-response (ER) relationships on a multicountry scale. Methods and findings: Daily all-cause, cardiovascular, and respiratory mortality among the general population were collected from 494 locations in 18 countries or territories during 1980 to 2019. Daily TC exposures were defined when the maximum sustained windspeed associated with a TC was ≥34 knots using a parametric wind field model at a 0.5° × 0.5° resolution. We first estimated the TC-specific mortality risks and POC using an advanced flexible statistical framework of mixed Poisson model, accounting for the population changes, natural variation, seasonal and day of the week effects. Then, a mixed meta-regression model was used to pool the TC-specific mortality risks to estimate the overall and country-specific ER relationships of TC characteristics (windspeed, rainfall, and year) with mortality. Overall, 47.7 million all-cause, 15.5 million cardiovascular, and 4.9 million respiratory deaths and 382 TCs were included in our analyses. An overall average POC of around 20 days was observed for TC-related all-cause and cardiopulmonary mortality, with relatively longer POC for the United States of America, Brazil, and Taiwan (>30 days). The TC-specific relative risks (RR) varied substantially, ranging from 1.04 to 1.42, 1.07 to 1.77, and 1.12 to 1.92 among the top 100 TCs with highest RRs for all-cause, cardiovascular, and respiratory mortality, respectively. At country level, relatively higher TC-related mortality risks were observed in Guatemala, Brazil, and New Zealand for all-cause, cardiovascular, and respiratory mortality, respectively. We found an overall monotonically increasing and approximately linear ER curve of TC-related maximum sustained windspeed and cumulative rainfall with mortality, with heterogeneous patterns across countries and regions. The TC-related mortality risks were generally decreasing from 1980 to 2019, especially for the Philippines, Taiwan, and the USA, whereas potentially increasing trends in TC-related all-cause and cardiovascular mortality risks were observed for Japan. Conclusions: The TC mortality risks and POC varied greatly across TC events, locations, and countries. To minimize the TC-related health burdens, targeted strategies are particularly needed for different countries and regions, integrating epidemiological evidence on region-specific POC and ER curves that consider across-TC variability. Author summary: Why was this study done?: Tropical cyclones (TCs), among the most destructive and costliest climate extreme events, are expected to be more intense due to climate change. Despite the widely acknowledged hazards, a consistent and quantitative assessment of the mortality risks of TC across countries is lacking. Such quantitative and comparable evidence across countries is urgently required to better understand the health effects and respond to the potentially increasing hazards. No previous studies have characterized the periods of concern (POC), exposure-response (ER) relationship, and temporal trends of the TC health risks, directly relevant to more precise and effective preparedness and mitigation strategies. What did the researchers do and find?: Using mortality data from 494 TC-exposed locations in 18 countries or territories, we quantified the TC-specific mortality risks and POC of the 382 TC events that affected these locations. The ER relationships and temporal trends were then characterized for each country or territory. TC exposure was associated with a prolonged elevated risk of all-cause, cardiovascular, and respiratory mortality, with an overall average POC of around 20 days. The TC mortality risks and POC varied greatly across TC events, locations, and countries. Overall, the mortality risks increased approximately linearly with increasing TC-related maximum sustained windspeed or cumulative rainfall. Most studied countries or territories witnessed a decreasing TC-related mortality risks from 1980 to 2019, especially for the Philippines, Taiwan, and the USA, while potentially increasing TC-related all-cause and cardiovascular mortality risks were observed for Japan. What do these findings mean?: TC events can exhibit significant variations in their risk patterns, and future risk assessments may need to better account for this large across-TC variability. Targeted and evidence-based disaster management and preparedness strategies need to be developed for different countries to more effectively mitigate the TC hazards. Key study limitations include potential exposure misclassification errors, residual confounding, and limited generalizability. [ABSTRACT FROM AUTHOR]

The stringent response is characterized by (p)ppGpp synthesis resulting in repression of translation and reprogramming of the transcriptome. In Staphylococcus aureus, (p)ppGpp is synthesized by the long RSH (RelA/SpoT homolog) enzyme, RelSau or by one of the two short synthetases (RelP, RelQ). RSH enzymes are characterized by an N-terminal enzymatic domain bearing distinct motifs for (p)ppGpp synthetase or hydrolase activity and a C-terminal regulatory domain (CTD) containing conserved motifs (TGS, DC and ACT). The intramolecular switch between synthetase and hydrolase activity of RelSau is crucial for the adaption of S. aureus to stress (stringent) or non-stress (relaxed) conditions. We elucidated the role of the CTD in the enzymatic activities of RelSau. Growth pattern, transcriptional analyses and in vitro assays yielded the following results: i) in vivo, under relaxed conditions, as well as in vitro, the CTD inhibits synthetase activity but is not required for hydrolase activity; ii) under stringent conditions, the CTD is essential for (p)ppGpp synthesis; iii) RelSau lacking the CTD exhibits net hydrolase activity when expressed in S. aureus but net (p)ppGpp synthetase activity when expressed in E. coli; iv) the TGS and DC motifs within the CTD are required for correct stringent response, whereas the ACT motif is dispensable, v) Co-immunoprecipitation indicated that the CTD interacts with the ribosome, which is largely dependent on the TGS motif. In conclusion, RelSau primarily exists in a synthetase-OFF/hydrolase-ON state, the TGS motif within the CTD is required to activate (p)ppGpp synthesis under stringent conditions. [ABSTRACT FROM AUTHOR]

In ecotoxicology, evaluation of toxicities and no observed effect concentrations (NOEC) of test compounds in experimental fish is commonly based on molecular-, biochemical- and analytical chemistry analyses of organ/tissue samples and the assessment of (histo-) pathological lesions. Standardization of organ/tissue sampling locations, sample numbers, and sample processing contributes to warrant the reproducibility and inter- and intra-study comparability of analysis results. The present article provides the first comprehensive tissue sampling guidelines specifically adapted to rainbow trout (Oncorhynchus mykiss) as a frequently used fish species in ecotoxicological studies. A broad spectrum of ~40 different organs and tissues is covered. Appropriate sampling locations, sample sizes and sample numbers for subsequent routine histopathological evaluation (all organs/tissue) and for molecular analyses (~30 organs/tissues) are described in detail and illustrated with schematic drawings and representative macroscopic and histological images. These field-proven sampling guidelines were developed based on the pertinent literature and practical experience in ecotoxicological fish studies. They are intended to serve as a standard reference for any routine ecotoxicological study using rainbow trout as a test system. A broad application of the featured tissue sampling procedures will help to improve the reproducibility of analyses and to reduce inter- and intra-study variability induced by sampling bias and (normal) inter-sample morphological variation, and will therefore provide a robust basis for reliable characterization of toxicity and NOEC identification of diverse test substances and aquatic pollutants. [ABSTRACT FROM AUTHOR]

The two-component system SaeRS of Staphylococcus aureus is closely involved in the regulation of major virulence factors. However, little is known about the signals leading to saeRS activation. A total of four overlapping transcripts (T1 to T4) from three different transcription starting points are expressed in the sae operon. We used a β-galactosidase reporter assay to characterize the putative promoter regions within the saeRS upstream region. The main transcript T2 is probably generated by endoribonucleolytic processing of the T1 transcript. Only two distinct promoter elements (P1 and P3) could be detected within the saeRS upstream region. The P3 promoter, upstream of saeRS, generates the T3 transcript, includes a cis-acting enhancer element and is repressed by saeRS. The most distal P1 promoter is strongly autoregulated, activated by agr, and repressed by sigma factor B. In strain Newman a mutation within the histidine kinase SaeS leads to a constitutively activated sae system. Evaluation of different external signals revealed that the P1 promoter in strain ISP479R and strain UAMS-1 is inhibited by low pH and high NaCl concentrations but activated by hydrogen peroxide. The most prominent induction of P1 was observed at subinhibitory concentrations of α-defensins in various S. aureus strains, with the exception of strain ISP479R and strain COL. P1 was not activated by the antimicrobial peptides LL37 and daptomycin. In summary, the results indicate that the sensor molecule SaeS is activated by alteration within the membrane allowing the pathogen to react to phagocytosis related effector molecules. [ABSTRACT FROM AUTHOR]

As a facultative intracellular pathogen, Salmonella enterica serovar Typhimurium is one of the leading causes of food-borne diseases in humans. With the ingestion of fecal contaminated food or water, S. Typhimurium reaches the intestine. Here, the pathogen efficiently invades intestinal epithelial cells of the mucosal epithelium by the use of multiple virulence factors. Recently, chitinases have been described as emerging virulence factors of S. Typhimurium that contribute to the attachment and invasion of the intestinal epithelium, prevent immune activation, and modulate the host glycome. Here we find that the deletion of chiA leads to diminished adhesion and invasion of polarized intestinal epithelial cells (IEC) compared to wild-type S. Typhimurium. Interestingly, no apparent impact on interaction was detected when using non-polarized IEC or HeLa epithelial cells. In concordance, we demonstrate that chiA gene and ChiA protein expression was solely induced when bacteria gain contact with polarized IEC. The induction of chiA transcripts needs the specific activity of transcriptional regulator ChiR, which is co-localized with chiA in the chitinase operon. Moreover, we established that after chiA is induced, a major portion of the bacterial population expresses chiA, analyzed by flow cytometry. Once expressed, we found ChiA in the bacterial supernatants using Western blot analyses. ChiA secretion was completely abolished when accessory genes within the chitinase operon encoding for a holin and a peptidoglycan hydrolase were deleted. Holins, peptidoglycan hydrolases, and large extracellular enzymes in close proximity have been described as components of the bacterial holin/peptidoglycan hydrolase-dependent protein secretion system or Type 10 Secretion System. Overall, our results confirm that chitinase A is an important virulence factor, tightly regulated by ChiR, that promotes adhesion and invasion upon contact with polarized IEC and is likely secreted by a Type 10 Secretion System (T10SS). Author summary: Being considered as one of the key global causes of diarrheal diseases, Salmonella can cause diseases from mild salmonellosis to life-threatening diseases depending on host factors and the serotypes of Salmonella. Within the species Salmonella enterica, serovar Typhimurium is the most important human food-borne bacterial pathogen contracted through the consumption of contaminated food or drinking water. Highly adapted, S. Typhimurium owns a plethora of tightly regulated virulence factors, which when needed, are secreted by specific secretion systems to facilitate bacterial infection. Besides classical virulence factors such as toxins, S. Typhimurium also takes advantage of metabolic enzymes degrading various substrates important for colonization. Here, we demonstrate that chitinase A produced by S. Typhimurium is specifically induced and promotes adhesion and invasion of polarized intestinal epithelial cells. The gene encoding for chitinase A is organized within a defined operon that includes three other important genes. One encodes for the transcriptional regulator ChiR, which we show is essential for the induction of chitinase A expression upon contact with polarized intestinal epithelial cells. The other two encode for a holin and a peptidoglycan hydrolase, components of a Type 10 Secretion System, which is responsible for the active secretion of chitinase A in S. Typhimurium. [ABSTRACT FROM AUTHOR]

Bacteria respond to ever-changing environments through several adaptive strategies. This includes mechanisms leading to a high degree of phenotypic variability within a genetically homogeneous population. In Staphylococcus aureus, the capsular polysaccharide (CP) protects against phagocytosis, but also impedes adherence to endothelial cells and/or matrix proteins. We analysed the regulation of core biosynthesis genes (capA-P) necessary for CP synthesis using single-cell assays (immunofluorescence and promoter-activity). In persistent human carriers, we found a distinct subpopulation of nasal S. aureus to be CP positive. In vitro, cap expression is also heterogeneous and strongly growth-phase dependent. We asked whether this peculiar expression pattern (earlyOff/lateHeterogen) is orchestrated by the quorum system Agr. We show that the Agr-driven effector molecule RNAIII promotes cap expression largely via inactivation of the repressor Rot. High NaCl, deletion of CodY or Sae also resulted in higher cap expression but did not change the earlyOFF/ lateHeterogen expression pattern. Activity of the quorum system itself is largely homogenous and does not account for the observed heterogeneity of cap expression or the strictly growth phase dependent expression. Our findings are in contrast to the prevailing view that quorum sensing is the main driving force for virulence gene expression when bacterial cell densities increase. [ABSTRACT FROM AUTHOR]

In line with the key role of methionine in protein biosynthesis initiation and many cellular processes most microorganisms have evolved mechanisms to synthesize methionine de novo. Here we demonstrate that, in the bacterial pathogen Staphylococcus aureus, a rare combination of stringent response-controlled CodY activity, T-box riboswitch and mRNA decay mechanisms regulate the synthesis and stability of methionine biosynthesis metICFE-mdh mRNA. In contrast to other Bacillales which employ S-box riboswitches to control methionine biosynthesis, the S. aureus metICFE-mdh mRNA is preceded by a 5′-untranslated met leader RNA harboring a T-box riboswitch. Interestingly, this T-box riboswitch is revealed to specifically interact with uncharged initiator formylmethionyl-tRNA (tRNAifMet) while binding of elongator tRNAMet proved to be weak, suggesting a putative additional function of the system in translation initiation control. met leader RNA/metICFE-mdh operon expression is under the control of the repressor CodY which binds upstream of the met leader RNA promoter. As part of the metabolic emergency circuit of the stringent response, methionine depletion activates RelA-dependent (p)ppGpp alarmone synthesis, releasing CodY from its binding site and thereby activating the met leader promoter. Our data further suggest that subsequent steps in metICFE-mdh transcription are tightly controlled by the 5′ met leader-associated T-box riboswitch which mediates premature transcription termination when methionine is present. If methionine supply is limited, and hence tRNAifMet becomes uncharged, full-length met leader/metICFE-mdh mRNA is transcribed which is rapidly degraded by nucleases involving RNase J2. Together, the data demonstrate that staphylococci have evolved special mechanisms to prevent the accumulation of excess methionine. We hypothesize that this strict control might reflect the limited metabolic capacities of staphylococci to reuse methionine as, other than Bacillus, staphylococci lack both the methionine salvage and polyamine synthesis pathways. Thus, methionine metabolism might represent a metabolic Achilles' heel making the pathway an interesting target for future anti-staphylococcal drug development. [ABSTRACT FROM AUTHOR]

The saePQRS system of Staphylococcus aureus controls the expression of major virulence factors and encodes a histidine kinase (SaeS), a response regulator (SaeR), a membrane protein (SaeQ), and a lipoprotein (SaeP). The widely used strain Newman is characterized by a single amino acid change in the sensory domain of SaeS (Pro18 in strain Newman [SaeSP], compared with Leu18 in other strains [SaeSL]). SaeSP determines activation of the class I sae target genes (coa, fnbA, eap, sib, efb, fib, sae), which are highly expressed in strain Newman. In contrast, class II target genes (hla, hlb, cap) are not sensitive to the SaeS polymorphism. The SaeSL allele (saeSL) is dominant over the SaeSP allele, as shown by single-copy integration of saePQRSL in strain Newman, which results in severe repression of class I target genes. The differential effect on target gene expression is explained by different requirements for SaeR phosphorylation. From an analysis of saeS deletion strains and strains with mutated SaeR phosphorylation sites, we concluded that a high level of SaeR phosphorylation is required for activation of class I target genes. However, a low level of SaeR phosphorylation, which can occur independent of SaeS, is sufficient to activate class II target genes. Using inducible saeRS constructs, we showed that the expression of both types of target genes is independent of the saeRS dosage and that the typical growth phase-dependent gene expression pattern is not driven by SaeRS. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus reacts to changing environmental conditions such as heat, pH, and chemicals through global regulators such as the sae (S. aureus exoprotein expression) two-component signaling system. Subinhibitory concentrations of some antibiotics were shown to increase virulence factor expression. Here, we investigated the S. aureus stress response to sublethal concentrations of a commonly used biocide (Perform), by real-time quantitative PCR (qRT-PCR), promoter activity assay, sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, and a flow cytometric invasion assay. Perform, acting through the production of reactive oxygen species, generally downregulated expression of extracellular proteins in strains 6850, COL, ISP479C but upregulated these proteins in strain Newman. Upregulated proteins were sae dependent. The Perform component SDS, but not paraquat (another oxygen donor), mimicked the biocide effect. Eap (extracellular adherence protein) was most prominently augmented. Upregulation of eap and sae was confirmed by qRT-PCR. Promoter activity of sae P1 was increased by Perform and SDS. Both substances enhanced cellular invasiveness, by 2.5-fold and 3.2-fold, respectively. Increased invasiveness was dependent on Eap and the sae system, whereas agr, sarA, sigB, and fibronectin-binding proteins had no major effect in strain Newman. This unique response pattern was due to a point mutation in SaeS (the sensor histidine kinase), as demonstrated by allele swapping. Newman saePQRSISP479C behaved like ISP479C, whereas saePQRSNewman rendered ISP479C equally responsive as Newman. Taken together, the findings indicate that a point mutation in SaeS of strain Newman was responsible for increased expression of Eap upon exposure to sublethal Perform and SDS concentrations, leading to increased Eap-dependent cellular invasiveness. This may be important for understanding the regulation of virulence in S. aureus. [ABSTRACT FROM AUTHOR]

Abstract: Tissue Doppler was performed to assess physiological ranges of mechanical synchronicity in 47 patients aged 38 to 81 y with normal coronary angiograms, ECG recordings and echocardiographic findings. Maximal time delays between two different left ventricular (LV) walls in long axis time-to-peak tissue displacement (TD_D), respectively in time-to-peak strain (TD_S), time-to-peak strain rate (TD_SR), time-to-peak systolic (TD_VS) and early diastolic (TD_VE) velocities of basal and midwall segments were determined as values corrected for heart rate in a 16-segment LV model and in the right ventricle (RV). Strain (TD_S: LV = 212 ± 108 ms, RV = 195 ± 15 ms) and strain rate (TD_SR: LV = 183 ± 67 ms, RV = 120 ± 60 ms) showed the highest dyssynchrony values (TD_D: LV = 110 ± 96 ms, RV = 42 ± 38 ms; TD_VS: LV = 82 ± 47 ms, RV = 36 ± 36 ms; TD_VE: LV = 73 ± 36 ms, RV = 46 ± 20 ms) in both ventricles. There was no significant association between a certain LV wall and the occurrence of the earliest, respectively latest peak values of any parameter. (E-mail: poerner@t-online.de) [Copyright &y& Elsevier]

Climate modelling output that was provided under the latest Coupled Model Intercomparison Project (CMIP6) shows significant changes in model-specific Equilibrium Climate Sensitivity (ECS) as compared to CMIP5. The newer versions of many Global Climate Models (GCMs) report higher ECS values that result in stronger global warming than previously estimated. At the same time, the multi-GCM spread of ECS is significantly larger than under CMIP5. Here, we analyse how the differences between CMIP5 and CMIP6 affect climate projections for Germany. We use the statistical-empirical downscaling method EPISODES in order to downscale GCM data for the scenario pairs RCP4.5/SSP2-4.5 and RCP8.5/SSP5-8.5. We use data sets of the GCMs CanESM, EC-Earth, MPI-ESM, and NorESM. The results show that the GCM-specific changes in the ECS also have an impact at the regional scale. While the temperature signal under regional climate change remains comparable for both CMIP generations in the MPI-ESM chain, the temperature signal increases by up to 3 °C for the RCP8.5/SSP5-8.5 scenario pair in the EC-Earth chain. Changes in precipitation are less pronounced and they only show notable differences at the seasonal scale. The reported changes in the climate signal will have direct consequences for society. Climate change impacts previously projected for the high-emission RCP8.5 scenario might occur equally under the new SSP2-4.5 scenario. [ABSTRACT FROM AUTHOR]

The article presents the discussion on highlighting a severe threat to the safety of young generations and call for drastic emission reductions. Topics include standard scientific paradigm for assessing climate change in discrete time windows or at discrete levels of warming; encapsulating spatiotemporal changes in climate hazards, population density, cohort size, and life expectancy; and wildfires, crop failures, droughts, river floods, heat waves, and tropical cyclones.

In Paris, France, December 2015, the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) invited the Intergovernmental Panel on Climate Change (IPCC) to provide a "special report in 2018 on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways". In Nairobi, Kenya, April 2016, the IPCC panel accepted the invitation. Here we describe the response devised within the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) to provide tailored, cross-sectorally consistent impact projections to broaden the scientific basis for the report. The simulation protocol is designed to allow for (1) separation of the impacts of historical warming starting from pre-industrial conditions from impacts of other drivers such as historical land-use changes (based on pre-industrial and historical impact model simulations); (2) quantification of the impacts of additional warming up to 1.5 °C, including a potential overshoot and longterm impacts up to 2299, and comparison to higher levels of global mean temperature change (based on the lowemissions Representative Concentration Pathway RCP2.6 and a no-mitigation pathway RCP6.0) with socio-economic conditions fixed at 2005 levels; and (3) assessment of the climate effects based on the same climate scenarios while accounting for simultaneous changes in socio-economic conditions following the middle-of-the-road Shared Socioeconomic Pathway (SSP2, Fricko et al., 2016) and in particular differential bioenergy requirements associated with the transformation of the energy system to comply with RCP2.6 compared to RCP6.0.With the aim of providing the scientific basis for an aggregation of impacts across sectors and analysis of cross-sectoral interactions that may dampen or amplify sectoral impacts, the protocol is designed to facilitate consistent impact projections from a range of impact models across different sectors (global and regional hydrology, lakes, global crops, global vegetation, regional forests, global and regional marine ecosystems and fisheries, global and regional coastal infrastructure, energy supply and demand, temperature-related mortality, and global terrestrial biodiversity). [ABSTRACT FROM AUTHOR]

Typhoid toxin is a unique A 2 B 5 exotoxin and an important virulence factor for Salmonella Typhi, the cause of typhoid fever. In the decade since its initial discovery, great strides have been made in deciphering the unusual biological program of this toxin, which is fundamentally different from related toxins in many ways. Purified typhoid toxin administered to laboratory animals causes many of the symptoms of typhoid fever, suggesting that typhoid toxin is a central factor in this disease. Further advances in understanding the biology of this toxin will help guide the development of badly needed diagnostics and therapeutic interventions that target this toxin to detect, prevent or treat typhoid fever. [ABSTRACT FROM AUTHOR]

A detailed study of twin-, large-angle and small-angle grain boundaries over a small volume of multi-crystalline silicon is presented on the basis of electron backscatter diffraction and synchrotron X-ray topography (SXRT) measurements. Identical areas (ca 6 mm2) of two nearest neighbour wafers from a directional solidified Si column were analysed in order to gain information about the evolution of grain boundaries during the crystal growth process. Therefore, the emphasis was placed on the evolution of one particular grain and its neighbouring grains. In the case of 'straight line' Σ3 grain boundaries, no change is observed if the twin plane corresponds to a {211} plane. Significant changes are found for non-straight line boundaries: while curved Σ3 grain boundaries are formed and eliminated very frequently, the Σ9 and Σ27a grain boundaries undergo only minor changes. By means of SXRT imaging, it is shown that the microstructure of the analysed grain exhibits numerous small-angle grain boundaries with angles in the range between 0.003 and 0.02엯, corresponding to a theoretical dislocation density of the order of 107-108 cm-2. The experiments give evidence that the small-angle grain boundaries with the larger angles extend, while those with smaller angles vanish during growth. [ABSTRACT FROM AUTHOR]

S taphylococcus aureus is a Gram-positive human pathogen that is readily internalized by professional phagocytes such as macrophages and neutrophils but also by non-professional phagocytes such as epithelial or endothelial cells. Intracellular bacteria have been proposed to play a role in evasion of the innate immune system and may also lead to dissemination within migrating phagocytes. Further, S . aureus efficiently lyses host cells with a battery of cytolytic toxins. Recently, phenol-soluble modulins ( PSM) have been identified to comprise a genus-specific family of cytolytic peptides. Of these the PSMα peptides have been implicated in killing polymorphonuclear leucocytes after phagocytosis. We questioned if the peptides were active in destroying endosomal membranes to avoid lysosomal killing of the pathogen and monitored integrity of infected host cell endosomes by measuring the acidity of the intracellular bacterial microenvironment via flow cytometry and by a reporter recruitment technique. Isogenic mutants of the methicillin-resistant S . aureus ( MRSA) strains USA300 LAC, USA400 MW2 as well as the strongly cytolytic methicillin-sensitive strain 6850 were compared with their respective wild type strains. In all three genetic backgrounds, PSMα mutants were unable to escape from phagosomes in non-professional (293, HeLa, EAhy.926) and professional phagocytes ( THP-1), whereas mutants in PSMβ and δ-toxin as well as β-toxin, phosphatidyl inositol-dependent phospholipase C and Panton Valentine leucotoxin escaped with efficiencies of the parental strains. S . aureus replicated intracellularly only in presence of a functional PSMα operon thereby illustrating that bacteria grow in the host cell cytoplasm upon phagosomal escape. [ABSTRACT FROM AUTHOR]

The Staphylococcus aureus regulatory saePQRS system controls the expression of numerous virulence factors, including extracellular adherence protein (Eap), which amongst others facilitates invasion of host cells. The saePQRS operon codes for 4 proteins: the histidine kinase SaeS, the response regulator SaeR, the lipoprotein SaeP and the transmembrane protein SaeQ. S. aureus strain Newman has a single amino acid substitution in the transmembrane domain of SaeS (L18P) which results in constitutive kinase activity. SDS was shown to be one of the signals interfering with SaeS activity leading to inhibition of the sae target gene eap in strains with SaeSL but causing activation in strains containing SaeSP. Here, we analyzed the possible involvement of the SaeP protein and saePQ region in SDS-mediated sae/eap expression. We found that SaePQ is not needed for SDS-mediated SaeS signaling. Furthermore, we could show that SaeS activity is closely linked to the expression of Eap and the capacity to invade host cells in a number of clinical isolates. This suggests that SaeS activity might be directly modulated by structurally non-complex environmental signals, as SDS, which possibly altering its kinase/phosphatase activity. [ABSTRACT FROM AUTHOR]

In this work, the electrical characteristics of grain boundaries (GBs) in multicrystalline silicon with and without iron contamination are analyzed by fixed voltage current maps and local I/V curves using conductive AFM (cAFM). I/V characteristics reveal the formation of a Schottky contact between the AFM tip and the sample surface. The impact of both, the polarity of the applied voltage and the illumination by the AFM laser on the behavior of GBs was analyzed systematically. Depending on the polarity of the applied voltage and the iron content of the sample, grain boundaries alter significantly the recorded current flow compared to the surrounding material. The results also show a clear influence of the AFM laser light on the electrical behavior of the grain boundaries. Conductive AFM measurements are furthermore compared to data obtained by electron beam induced current (EBIC), indicating that cAFM provides complimentary information. [ABSTRACT FROM AUTHOR]

Tropical cyclones (TC) are among the most damaging extreme weather events, regularly displacing millions of people. Global warming is expected to intensify tropical cyclones and the damages they cause. Although adaptation options are limited, forecasting the impact of single tropical cyclones or the intensity of a whole tropical cyclone season is of great interest. While the skill of dynamical forecast models of lead times up to a week has steadily improved, forecasts with longer lead times remain challenging due to the uncertainty in tropical cyclone genesis events. Warm sea surface temperatures (SST) and low vertical wind shear (VWS) are well established as favorable conditions for TC formation. Using causal discovery algorithms, we confirm that relationship and identify suitable precursor regions for seasonal TC genesis prediction for the Atlantic basin. Our predictive model exhibits high skill with two months lead time before the Atlantic hurricane season. In line with previous findings, our approach reveals the established factors: Atlantic multidecadal oscillation (AMO) favoring TC genesis through warm SST conditions and El Niño southern oscillation (ENSO) influencing VWS. Although TC formation is to some extend a probabilistic phenomenon, we find that basic climate variables as mean sea level pressure over the Pacific and Atlantic SSTs can help to estimate the total amount of such events. [ABSTRACT FROM AUTHOR]

The repressor CodY is reported to inhibit metabolic genes mainly involved in nitrogen metabolism. We analyzed codY mutants from three unrelated Staphylococcus aureus strains (Newman, UAMS-1, and RN1HG). The mutants grew more slowly than their parent strains in a chemically defined medium. However, only codY mutants were able to grow in medium lacking threonine. An excess of isoleucine resulted in growth inhibition in the wild type but not in the codY mutants, indicating that isoleucine plays a role in CodY-dependent repression. Prototypic CodY-repressed genes including the virulence regulator agr are repressed after up-shift with isoleucine. The CodY-dependent repression of agr is consistent with the concomitant influence of CodY on typical agr-regulated genes such as cap, spa, fnbA, and coa. However, some of these virulence genes (e.g., cap, fnbA, and spa) were also regulated by CodY in an agr-negative background. Microarray analysis revealed that the large majority of CodY-repressed genes were involved in amino acid metabolism; CodY-activated genes were mainly involved in nucleotide metabolism or virulence. In summary, CodY in S. aureus not only acts as a repressor for genes involved in nitrogen metabolism but also contributes to virulence gene regulation by supporting as well as substituting for agr function. [ABSTRACT FROM AUTHOR]