Isolation, characterization, and application of the novel polyvalent bacteriophage vB_EcoM_XAM237 against pathogenic Escherichia coli

A novel polyvalent broad-spectrum phage, vB_EcoM_XAM237 (XAM237), was isolated from pig farm sewage. It can simultaneously lyse multiple strains of pathogenic Escherichia coli (E. coli), demonstrating a broad host range. When the enteropathogenic E. coli (EPEC) strain E711 was used as the host bacterium, the phage XAM237 exhibited a short latent period, high stability at different temperatures and pH values and good tolerance to chloroform. Moreover, phage XAM237 can efficiently adsorb and lyse host bacteria in vitro. Whole-genome sequencing revealed that XAM237 is a double-stranded DNA (dsDNA) phage consisting of 170 541 bp with a G + C content of 35%. Phylogenetic analysis confirmed that XAM237 belongs to the family Straboviridae, genus Tequatrovirus. In addition, the genome of XAM237 did not contain genes related to lysogenicity, virulence or antimicrobial resistance. The effects of phage XAM237 in treating EPEC infections in vivo were evaluated in a mouse model. Phage XAM237 was able to reduce the number of colonized aEPEC strain E711 in the small intestine, liver, spleen, and kidney. This study suggested that phage XAM237 may be a promising candidate biologic agent for controlling pathogenic E. coli infections

Correction to “Interlayer Exciton−Phonon Coupling in MoSe2/WSe2 Heterostructures”

Corrections to Table 2 in the original article are as follows: Table 2. Deformation Potentials for the A1gM and A1gW Heterostructure Eigenvectors on the MoSe2 and WSe2 Bands at K (° = M, W)

Ein neues Bruchstück aus den sogenannten Heidnischen Märtyrerakten

Digitalisat der Ausgabe von 1930, erschienen 202

From visual representations to perceptual decisions: investigating neural mechanisms underlying visual recognition and perceptual decision making

To successfully interact with the environment, humans must robustly encode sensory inputs into neural representations and translate these representations into adaptive behavior. In this thesis, I conducted three empirical studies targeting particular neural mechanisms entailed in this transition from sensory inputs to perceptual decisions. In Study 1, I probed the robustness of core visual processing mechanisms by characterizing and comparing the neural dynamics of object recognition for natural photographs and abstracted line drawings. This revealed that core visual processing mechanisms in the brain are robust to the abstraction of substantial amounts of visual information, such as in line drawings. In Study 2, I investigated the influence of feedback processing on object representations by comparing the neural dynamics of object recognition for stimuli that were either rapidly followed by a masking stimulus or followed only after a substantial delay. This revealed that feedback processing fundamentally shapes visual representations in the brain, first in early than in high-level visual cortex. Feedback enhances the persistence of visual representations, causes a shift in the representational format in high-level visual cortex, and affects distinct spectro-temporal windows in the theta to beta frequency bands. Finally, in Study 3, I examined the link between neural representations of real-world scenes and behavior under varying task demands. The findings showed that distinct visual representations in the brain are behaviorally relevant depending on the task, that mid-level visual features underlie these behaviorally relevant representations, and that visual representations can interfere with behavior given task demands that do not align with the represented information. By demonstrating the robustness of core visual processing mechanisms to visual abstractions and by characterizing how feedback processing dynamically shapes visual processing, the findings in Study 1 and 2 provide complimentary insights into the neural mechanisms that enable robust encoding of visual information. By identifying and characterizing visual representations relevant for behavior across different task demands, Study 3 provides novel insights into the translation of sensory information into perceptual decisions. Collectively, these results contribute to a large body of research on visual recognition and perceptual decision making, provide potential new theoretical frameworks for understanding the underlying mechanisms, and guide the way for future research that directly tests and refines these theories.Um erfolgreich mit der Umwelt zu interagieren, müssen Menschen sensorische Reize robust enkodieren und die resultierenden Repräsentationen in Verhalten umwandeln. In dieser Dissertation habe ich drei empirischen Studie durchgeführt, um spezifische neuronale Mechanismen zu untersuchen, die diesem Übergang von sensorischen Reizen zu Wahrnehmungsentscheidungen zugrunde liegen. In Studie 1 habe ich die Robustheit grundlegender visueller Verarbeitungsmechanismen untersucht, indem ich die neuronale Dynamik der Objekterkennung für natürliche Fotografien und abstrahierte Strichzeichnungen charakterisiert und verglichen habe. Die Ergebnisse zeigten, dass grundlegende visuelle Verarbeitungsmechanismen robust gegenüber der Abstraktion großer Mengen visueller Informationen sind, wie es in Strichzeichnungen der Fall ist. In Studie 2 untersuchte ich den Einfluss von Feedbackverarbeitung auf Objektrepräsentationen, indem ich die neuronale Dynamik der Objekterkennung für Stimuli verglich, die entweder schnell von einem Maskierungsreiz gefolgt wurden oder erst nach einer längeren Verzögerung. Die Ergebnisse zeigten, dass Feedback die visuellen Repräsentationen im Gehirn grundlegend beeinflusst, zunächst im frühen und später im höheren visuellen Kortex. Feedback erhöht die Beständigkeit visueller Repräsentationen, führt zu einer Veränderung im Repräsentationsformat im höheren visuellen Kortex und beeinflusst spezifische spektral-temporale Fenster in den Theta- bis Beta-Frequenzbändern. Abschließend habe ich in Studie 3 den Zusammenhang zwischen neuronalen Repräsentationen realer Szenenbilder und dem Verhalten während verschiedener Aufgaben untersucht. Die Ergebnisse zeigten, dass unterschiedliche visuelle Repräsentationen im Gehirn je nach Aufgabe verhaltensrelevant sind, dass visuelle Informationen mittlerer Komplexität diesen Repräsentationen zugrunde liegen und dass visuelle Repräsentationen mit Verhalten interferieren können, wenn die Aufgabenanforderungen nicht mit der repräsentierten Information übereinstimmen. Durch die Demonstration der Robustheit grundlegender visueller Verarbeitunsgsmechanismen gegenüber visueller Abstraktion und die Charakterisierung, wie Feedback visuelle Verarbeitung dynamisch formt, liefern die Ergebnisse aus Studie 1 und 2 komplementäre Einblicke in die neuronalen Mechanismen, die die robuste Enkodierung visueller Informationen ermöglichen. Durch die Identifizierung und Charakterisierung verhaltensrelevanter visueller Repräsentationen, liefert Studie 3 neue Erkenntnisse über die Umwandlung von sensorischen Reizen in Wahrnehmungsentscheidungen. Insgesamt tragen diese Ergebnisse zu einem breiten Forschungsfeld zu visueller Objekterkennung und Wahrnehmungsentscheidungen bei, liefern neue theoretische Anhaltspunkte für das Verständnis der zugrundeliegenden neuronalen Mechanismen und können zukünftige Forschung anleiten, die diese Theorien direkt testet

Immune cells affect endothelial cells of the small intestine in steady state

Endothelzellen sind an der Aufrechterhaltung der Gewebehomöostase des Dünndarms beteiligt. Diese werden unterteilt in Blut-Endothelzellen (BECs), die die innerste Schicht der Blutgefäße bilden, und lymphatische Endothelzellen (LECs), die am Aufbau der Lymphgefäße beteiligt sind. Neben den klassischen Funktionen der Endothelzellen, wie der Barrierefunktion und dem Stoffaustausch, bestehen Hinweise, dass sie auch mit Zellen des Immunsystems interagieren. Immunzellen treten mit nicht-hämatopoetischen Zellen in Kontakt, wie beispielsweise Epithelzellen. So können Zellen der Typ-3-Immunantwort via IL-22 die Regeneration von Epithelzellen aktivieren. Indizien sprechen dafür, dass Komponenten des Immunsystems, insbesondere der Typ-3-Immunantwort, mit Endothelzellen interagieren und die Angiogenese beeinflussen. Bis dato existiert keine Studie über die Verteilung von Endothelzellen und bestimmten Immunzellen im steady state des Dünndarms und der Interaktion dieser Zellen. Das Ziel dieser Studie ist, die Verteilung von Endothel- und Immunzellen im steady state des Dünndarms zu charakterisieren, die Bedeutung von Immunzellen, vornehmlich solcher, die an der Typ-3-Immunantwort beteiligt sind, für das Vorkommen von Endothelzellen zu ermitteln und schließlich Signalwege, die an der Interaktion dieser Zelltypen beteiligt sind, näher zu beleuchten. Konventionelle Labormäuse, sowie transgene Mäuse wurden eingesetzt, um das Vorkommen verschiedener Zelltypen in verschiedenen Abschnitten des Dünndarms im steady state zu erforschen. Mit Durchflusszytometrie und Immunfluoreszenz wurden Mauslinien, denen verschiedene Immunzellen fehlen oder in ihrer Funktion eingeschränkt sind, analysiert. Veränderungen der Genexpression im Dünndarmgewebe der Mäuse wurden mittels RT-qPCR analysiert. Die Ergebnisse zeigten, dass Endothel- und Immunzellen in unterschiedlichen Abschnitten des Dünndarms in unterschiedlicher Frequenz vorkamen. BECs waren am zahlreichsten im Jejunum und LECs im Ileum zu finden. Eine gemeinsame Häufung von BECs und RORgt+ T-Zellen wurde festgestellt, wobei auch mikroskopisch eine räumliche Nähe dieser Zelltypen zu sehen war. In Mäusen denen Rag1 oder Rorc(gt) fehlt, wurden weniger BECs und LECs im Dünndarm, insbesondere in den proximalen Abschnitten, detektiert. In den Untersuchungen wurden Hinweise gefunden, dass Th17-Zellen für eine erhöhte Anzahl an Endothelzellen verantwortlich sind. IL-22 wurde als potenzieller Mediator dieser Interaktion identifiziert, möglicherweise indem es das Gleichgewicht von angiogenetischen und angiostatischen Einflüssen zugunsten der Angiogenese verschiebt. In den Ergebnissen der RT-qPCR konnte eine geringere Expression angiogenetischer Gene in Mauslinien mit reduzierter Anzahl an Endothelzellen nachgewiesen werden. Zusammenfassend scheinen Komponenten der Typ-3-Immunität die Formation beziehungsweise Aufrechterhaltung des Gefäßnetzwerkes zu stimulieren.Endothelial cells are critically involved in the maintenance of tissue homeostasis of the small intestine. Among endothelial cells, blood endothelial cells (BECs), which form the innermost layer of blood vessels, are discriminated from lymphatic endothelial cells (LECs), which are involved in the construction of lymphatic vessels. In addition to the classical functions of endothelial cells, such as barrier function and substance exchange, there is increasing evidence that they also interact with cells of the immune system. Conversely, immune cells are now known to communicate with non-haematopoietic cells, such as epithelial cells. Cells of the type 3 immune response can activate epithelial cell regeneration via IL-22. There is circumstantial evidence that components of the immune system, particularly the type 3 immune response, cooperate with endothelial cells and affect angiogenesis. A study of the distribution of endothelial cells and certain immune cells in the steady state of the small intestine and their interaction does not yet exist. The aim of this study is to characterize the distribution of endothelial cells and immune cells in the steady state of the small intestine, to determine the importance of immune cells, particularly those involved in the type 3 immune response, for the presence of endothelial cells, and finally to elucidate the signalling pathways involved in this interaction. Conventional laboratory mice, as well as transgenic mice, were used to investigate the presence of different cell types in different segments of the small intestine in steady state. Mouse lines lacking various immune cells or having impaired function of the same were analyzed using flow cytometry and immunofluorescence. RT-qPCR was performed to detect changes on the expressional level in small intestinal tissue of the mice. The results of this work showed that endothelial cells and immune cells are present at different frequencies in different sections of the small intestine. BECs were most numerous in the jejunum and LECs in the ileum. A common accumulation of BECs and RORgt+ T cells was observed, and a spatial proximity of these cell types was also evident microscopically. In mice lacking Rag1 or Rorc(gt), fewer BECs and LECs were detected in the small intestine, particularly in its proximal sections. In studies presented in this work, evidence was found, that it is Th17 cells that provide for increased numbers of endothelial cells. IL-22 was identified as a potential mediator of this interaction possibly by shifting the balance of angiogenic and angiostatic influences on endothelial cells in favor of angiogenesis. RT-qPCR results demonstrated lower expression of angiogenic genes in mouse lines with reduced numbers of endothelial cells. In conclusion, components of type 3 immunity appear to stimulate the formation and maintenance of the vascular network

The Meq Genes of Nigerian Marek’s Disease Virus (MDV) Field Isolates Contain Mutations Common to Both European and US High Virulence Strains

Background: Marek’s disease (MD) is a pathology affecting chickens caused by Marek’s disease virus (MDV), an acute transforming alphaherpesvirus of the genus Mardivirus. MD is characterized by paralysis, immune suppression, and the rapid formation of T-cell (primarily CD4+) lymphomas. Over the last 50 years, losses due to MDV infection have been controlled worldwide through vaccination; however, these live-attenuated vaccines are non-sterilizing and potentially contributed to the virulence evolution of MDV field strains. Mutations common to field strains that can overcome vaccine protection were identified in the C-terminal proline-rich repeats of the oncoprotein Meq (Marek’s EcoRI-Q-encoded protein). These mutations in meq have been found to be distinct to their region of origin, with high virulence strains obtained in Europe differing from those having evolved in the US. The present work reports on meq mutations identified in MDV field strains in Nigeria, arising at farms employing different vaccination practices. Materials and Methods: DNA was isolated from FTA cards obtained at 12 farms affected by increased MD in the Plateau State, Nigeria. These sequences included partial whole genomes as well as targeted sequences of the meq oncogenes from these strains. Several of the meq genes were cloned for expression and their localization ability to interact with the chicken NF-IL3 protein, a putative Meq dimerization partner, were assessed. Results: Sequence analysis of the meq genes from these Nigerian field strains revealed an RB1B-like lineage co-circulating with a European Polen5-like lineage, as well as recombinants harboring a combination of these mutations. In a number of these isolates, Meq mutations accumulated in both N-terminal and C-terminal domains. Discussion: Our data, suggest a direct effect of the vaccine strategy on the selection of Meq mutations. Moreover, we posit the evolution of the next higher level of virulence MDVs, a very virulent plus plus pathotype (vv++)

Same, but different: Variations in fragment ions among stereoisomers of a 17α-methyl steroid in gas chromatography/electron ionization mass spectrometry

Rationale Gas chromatography/electron ionization mass spectrometry (GC/EI-MS) is a well-established tool for the identification of unknown compounds such as new metabolites of xenobiotics. But it reaches the limits of confident structural assignment if it comes to stereoisomers. This work helps to overcome this difficulty by getting a deeper comprehension of composition of so far unspecific and also characteristic fragment ions in general and comparison among stereoisomers. Methods Unit mass resolution mass spectra of various isotopologues of four 17α-methyl steroid diastereomers obtained by selectively introducing [2H9]-trimethylsilyl (TMS) groups or chemical syntheses were systematically compared. The impact of stereochemistry on variations of relative abundances has been assessed by statistical comparison from repeated measurements. Additionally, characterization of m/z 318 with high-resolution MS using gas chromatography/quadrupole time-of-flight MS (GC/QTOF-MS) was performed. Results The formation of fragment ions from TMS-derivatives after cleavage of methyl or TMS groups ([M-CH3]+, [M-TMSOH]•+, [M-CH3-TMSOH]+, [M-2x90]•+, [M-2x90-CH3]+) rarely arises from only one position in the molecule and composition of fragment ion signals is highly influenced by the stereochemistry of the A-ring at C3 and C5 of the steroid. Similarly, the formation of the characteristic fragment ion m/z 143 most likely consists of two different ways of formation. A possible structure for fragment ion m/z 318 was postulated. Conclusions Stereoisomers showed differing fragmentation behaviors based on their configuration. These observations further illustrate that variations among stereoisomers in EI-MS fragmentation is no random underlying process but instead a pattern which needs to be understood in its complexity. This easily accessible technical approach can be applied on different molecule structures to further investigate the field of isomeric assignment in GC/EI-MS

Antigen presentation by MHC-II is shaped by competitive and cooperative allosteric mechanisms of peptide exchange

Major histocompatibility complex class II (MHC-II) presents antigens to T helper cells. The spectrum of presented peptides is regulated by the exchange catalyst human leukocyte antigen DM (HLA-DM), which dissociates peptide-MHC-II complexes in the endosome. How susceptible a peptide is to HLA-DM is mechanistically not understood. Here, we present a data-driven mathematical model for the conformational landscape of MHC-II that explains the wide range of measured HLA-DM susceptibilities and predicts why some peptides are largely HLA-DM-resistant. We find that the conformational plasticity of MHC-II mediates both allosteric competition and cooperation between peptide and HLA-DM. Competition causes HLA-DM susceptibility to be proportional to the intrinsic peptide off-rate. Remarkably, diverse MHC-II allotypes with conserved HLA-DM interactions show a universal linear susceptibility function. However, HLA-DM-resistant peptides deviate from this susceptibility function; we predict resistance to be caused by fast peptide association with MHC-II. Thus, our study provides quantitative insight into peptide and MHC-II allotype parameters that shape class-II antigen presentation

Mobilization against forced domestic work in Peru

Organized domestic workers have recently been at the forefront of political campaigns in Peru to promote legislative reforms concerning forced labor. This empirical case study investigates how the international labor norm concerning forced labor is disseminated, appropriated and politically mobilized at the national level. It thereby examines the dynamics and cultural embedding of the appropriation process and its implications for labor regulation, policy responses and trade union actions. The research delves into the ways and spaces in which international and national actors, the International Labour Organisation and national domestic workers’ trade unions, translate the international norms into their local context, adapt and negotiate them. I argue that the mobilization against forced domestic labor is embedded in the period of reconfiguration of the domestic work sector in Peru and that it is oriented toward internationally institutionalized categorizations and indicators. By employing the theoretical lens of vernacularization, a contextualizing examination of the labor policy actors, their positions and knowledge bases, as well as an analysis of decisive moments, spaces, technologies and developments of communicative actions, enables a sociological understanding of the emergence and manifestation of the mobilization against forced domestic work. The process of vernacularization creates a localized version of international norms that retains elements of the original while incorporating local specificities in the implementation. It creates a space where different forms of knowledge interact – local knowledge and transnational technicized knowledge. This research adds a nuanced understanding of the intersection between internationalization of ‘universal’ labor standards, knowledge production, and trade union mobilization within a feminized and racialized sector

Klebsiella pneumoniae Glycoconjugate Vaccine Leads Based on Semi‐Synthetic O1 and O2ac Antigens

Klebsiella pneumoniae (KP) is a common opportunistic pathogen that emerged as a new critical threat to human health, due to its hypervirulence and widespread resistance against many antibiotics, including carbapenems. Alternative intervention strategies such as vaccines are not available. Cell‐surface lipopolysaccharides (LPS) and capsular polysaccharides (CPS) are attractive targets for vaccine development. We present a method to synthesize LPS substructures, covering over 70 % of virulent KP strains that were used to characterize the antibody repertoire of infected patients. Thereby, glycoconjugate vaccine leads against the Klebsiella pneumoniae serotypes O1, O2a, O2afg and O2ac have been identified