TY  - JOUR
A1  - Tuchscherr, Lorena
A1  - Bischoff, Markus
A1  - Lattar, Santiago M.
A1  - Noto Llana, Mariangeles
A1  - Pförtner, Henrike
A1  - Niemann, Silke
A1  - Geraci, Jennifer
A1  - Van de Vyver, Hélène
A1  - Fraunholz, Martin J.
A1  - Cheung, Ambrose L.
A1  - Herrmann, Mathias
A1  - Völker, Uwe
A1  - Sordelli, Daniel O.
A1  - Peters, Georg
A1  - Loeffler, Bettina
T1  - Sigma factor SigB is crucial to mediate Staphylococcus aureus adaptation during chronic infections
JF  - PLoS Pathogens
N2  - Staphylococcus aureus is a major human pathogen that causes a range of infections from acute invasive to chronic and difficult-to-treat. Infection strategies associated with persisting S. aureus infections are bacterial host cell invasion and the bacterial ability to dynamically change phenotypes from the aggressive wild-type to small colony variants (SCVs), which are adapted for intracellular long-term persistence. The underlying mechanisms of the bacterial switching and adaptation mechanisms appear to be very dynamic, but are largely unknown. Here, we analyzed the role and the crosstalk of the global S. aureus regulators agr, sarA and SigB by generating single, double and triple mutants, and testing them with proteome analysis and in different in vitro and in vivo infection models. We were able to demonstrate that SigB is the crucial factor for adaptation in chronic infections. During acute infection, the bacteria require the simultaneous action of the agr and sarA loci to defend against invading immune cells by causing inflammation and cytotoxicity and to escape from phagosomes in their host cells that enable them to settle an infection at high bacterial density. To persist intracellularly the bacteria subsequently need to silence agr and sarA. Indeed agr and sarA deletion mutants expressed a much lower number of virulence factors and could persist at high numbers intracellularly. SigB plays a crucial function to promote bacterial intracellular persistence. In fact, \(\Delta\)sigB-mutants did not generate SCVs and were completely cleared by the host cells within a few days. In this study we identified SigB as an essential factor that enables the bacteria to switch from the highly aggressive phenotype that settles an acute infection to a silent SCV-phenotype that allows for long-term intracellular persistence. Consequently, the SigB-operon represents a possible target to develop preventive and therapeutic strategies against chronic and therapy-refractory infections.
KW  - gene regulator agr
KW  - endothelial cells
KW  - modulates virulence
KW  - death pathway sar locus
KW  - factor B
KW  - small-colony variants
KW  - alpha-toxin
KW  - epithelial cells
KW  - in vitro
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143419
VL  - 11
IS  - 4
ER  - 
TY  - JOUR
A1  - De Palma, Adriana
A1  - Abrahamczyk, Stefan
A1  - Aizen, Marcelo A.
A1  - Albrecht, Matthias
A1  - Basset, Yves
A1  - Bates, Adam
A1  - Blake, Robin J.
A1  - Boutin, Céline
A1  - Bugter, Rob
A1  - Connop, Stuart
A1  - Cruz-López, Leopoldo
A1  - Cunningham, Saul A.
A1  - Darvill, Ben
A1  - Diekötter, Tim
A1  - Dorn, Silvia
A1  - Downing, Nicola
A1  - Entling, Martin H.
A1  - Farwig, Nina
A1  - Felicioli, Antonio
A1  - Fonte, Steven J.
A1  - Fowler, Robert
A1  - Franzen, Markus Franzén
A1  - Goulson, Dave
A1  - Grass, Ingo
A1  - Hanley, Mick E.
A1  - Hendrix, Stephen D.
A1  - Herrmann, Farina
A1  - Herzog, Felix
A1  - Holzschuh, Andrea
A1  - Jauker, Birgit
A1  - Kessler, Michael
A1  - Knight, M. E.
A1  - Kruess, Andreas
A1  - Lavelle, Patrick
A1  - Le Féon, Violette
A1  - Lentini, Pia
A1  - Malone, Louise A.
A1  - Marshall, Jon
A1  - Martínez Pachón, Eliana
A1  - McFrederick, Quinn S.
A1  - Morales, Carolina L.
A1  - Mudri-Stojnic, Sonja
A1  - Nates-Parra, Guiomar
A1  - Nilsson, Sven G.
A1  - Öckinger, Erik
A1  - Osgathorpe, Lynne
A1  - Parra-H, Alejandro
A1  - Peres, Carlos A.
A1  - Persson, Anna S.
A1  - Petanidou, Theodora
A1  - Poveda, Katja
A1  - Power, Eileen F.
A1  - Quaranta, Marino
A1  - Quintero, Carolina
A1  - Rader, Romina
A1  - Richards, Miriam H.
A1  - Roulston, T’ai
A1  - Rousseau, Laurent
A1  - Sadler, Jonathan P.
A1  - Samnegård, Ulrika
A1  - Schellhorn, Nancy A.
A1  - Schüepp, Christof
A1  - Schweiger, Oliver
A1  - Smith-Pardo, Allan H.
A1  - Steffan-Dewenter, Ingolf
A1  - Stout, Jane C.
A1  - Tonietto, Rebecca K.
A1  - Tscharntke, Teja
A1  - Tylianakis, Jason M.
A1  - Verboven, Hans A. F.
A1  - Vergara, Carlos H.
A1  - Verhulst, Jort
A1  - Westphal, Catrin
A1  - Yoon, Hyung Joo
A1  - Purvis, Andy
T1  - Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases
JF  - Scientific Reports
N2  - Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises.
KW  - bee community
KW  - land-use change
KW  - intensification
KW  - geographic biases
KW  - taxonomic biases
KW  - global dataset
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167642
VL  - 6
ER  -