Quentin Perraud
Apr 1, 2020; 19:589-607
Research

Bacteria secrete siderophores to access iron, a key nutrient poorly bioavailable and the source of strong competition between microorganisms in most biotopes. Many bacteria also use siderophores produced by other microorganisms (exosiderophores) in a piracy strategy. Pseudomonas aeruginosa, an opportunistic pathogen, produces two siderophores, pyoverdine and pyochelin, and is also able to use a panel of exosiderophores. We first investigated expression of the various iron-uptake pathways of P. aeruginosa in three different growth media using proteomic and RT-qPCR approaches and observed three different phenotypic patterns, indicating complex phenotypic plasticity in the expression of the various iron-uptake pathways. We then investigated the phenotypic plasticity of iron-uptake pathway expression in the presence of various exosiderophores (present individually or as a mixture) under planktonic growth conditions, as well as in an epithelial cell infection assay. In all growth conditions tested, catechol-type exosiderophores were clearly more efficient in inducing the expression of their corresponding transporters than the others, showing that bacteria opt for the use of catechol siderophores to access iron when they are present in the environment. In parallel, expression of the proteins of the pyochelin pathway was significantly repressed under most conditions tested, as well as that of proteins of the pyoverdine pathway, but to a lesser extent. There was no effect on the expression of the heme and ferrous uptake pathways. Overall, these data provide precise insights on how P. aeruginosa adjusts the expression of its various iron-uptake pathways (phenotypic plasticity and switching) to match varying levels of iron and competition.

Twenty-seven years after signing Barry Bonds to a then-record free-agent contract, the Giants are in the market for yet another superstar outfielder. San Francisco's interest in Bryce Harper remained a prominent topic of conversation during Saturday's FanFest at Oracle Park, with CEO Larry Baer weighing in on the potential franchise-altering benefits of landing a marquee player.

Research Event

McMillan, Peter -- Travel.

Breslau : E. Morgenstern, 1882.

Berlin : G. Reimer, 1893.

Berlin : G. Reimer, 1863.

Berlin : G. Reimer, 1876.

Berlin : Hirschwald, 1875.

Tübingen : Mohr, 1911.

Stuttgart : F. Enke, 1883.

Berlin : Hirschwald, 1894.

Jena : G. Fischer, 1900.

Berlin : A. Hirschwald, 1892-1893.

Berlin : A. Hirschwald, 1899.

Leipzig : Roszberg, 1884.

Hamburg : Wilhelm Mauke, 1871.

Berlin : Nicolai, 1842.

Berlin : H. Steinitz, 1894.

Berlin : A. Hirschwald, 1864.

Berlin : S. Karger, 1894.

Jena : G. Fischer, 1897.

Berlin : S. Karger, 1894.

Leipzig : Franz Deuticke, 1897.

Berlin : A. Hirschwald, 1896.

Berlin : A. Hirschwald, 1900.

Berlin : J. Springer, 1893.

Berlin : J. Springer, 1887.

Berlin : A. Hirschwald, 1854.

Leipzig : Toeplitz & Deuticke, 1887.

Berlin : Hirschwald, 1905.

Wurzburg : Verlagsbuchhandlung, 1895.

Bingen am Rhein : Selbstverlag des Verfassers, 1885.

Edinburgh : printed for William Creech, 1787.

Leipzig : G. Thieme, 1893.

Jessica A. Gorski
Aug 1, 2002; 22:6309-6314
BRIEF COMMUNICATION

The freedom fighter may have once used the structure to conspire against English forces

Do some armchair traveling and see the breathtaking vistas of all 50 states while learning about their histories

An abstract aerial view of a sand dune at sunset at Imperial Sand Dunes, Glamis, California.

The post Aero Design Series – Stock Wheel – Part 1: Intro and Initial Mockup appeared first on SOLIDWORKS Education Blog.

The post Aero Design Series- Stock Wheel – Part 2: Front Plane Sketch and Revolve appeared first on SOLIDWORKS Education Blog.

The post Aero Design Series – Stock Wheel – Part 3: Saving and Renaming appeared first on SOLIDWORKS Education Blog.

The post Aero Design Series – Stock Wheel – Part 4: Right Plane Cutouts appeared first on SOLIDWORKS Education Blog.

An adolescent girl with a history of frequent electronic cigarette use of nicotine was hospitalized with severe necrotizing pneumonia. Blood cultures obtained before the administration of empirical broad-spectrum intravenous antibiotics had positive results for the growth of Fusobacterium necrophorum. The pathogen is an uncommon but well-known cause of anaerobic pneumonia with unique features that are collectively referred to as Lemierre syndrome or postanginal sepsis. The syndrome begins as a pharyngeal infection. Untreated, the infection progresses to involve the ipsilateral internal jugular vein, resulting in septic thrombophlebitis with direct spread from the neck to the lungs causing multifocal necrotizing pneumonia. The teenager we present in this report had neither a preceding pharyngeal infection nor Doppler ultrasonographic evidence for the presence of deep neck vein thrombi, leading us to explore alternative mechanisms for her pneumonia. We propose the possibility that her behavior of frequent vaping led to sufficient pharyngeal irritation such that F necrophorum colonizing her oropharynx was inhaled directly into her lungs during electronic cigarette use. Preexisting, but not yet recognized, vaping-related lung injury may have also contributed to her risk of developing the infection. The patient was hospitalized for 10 days. At follow-up one month later, she still became short of breath with minimal exertion.