Wide Distribution of a High-Virulence Borrelia burgdorferi Clone in Europe and North America

We found substantial population differentiation and recent trans-Atlantic dispersal of a high-virulence B. burgdorferi clone

Mitochondrial ROS prime the hyperglycemic shift from apoptosis to necroptosis.

We have previously identified a shift from TNF-α-induced apoptosis to necroptosis that occurs under hyperglycemic conditions. This shift involves the downregulation or silencing of caspases and concurrent upregulation of necroptotic proteins leading to activation of the necrosome. In addition, under hyperglycemic conditions in vivo, this shift in cell death mechanisms exacerbates neonatal hypoxia-ischemia (HI) brain injury. Here, we identify two major factors that drive the hyperglycemic shift to necroptosis: (1) reactive oxygen species (ROS) and (2) receptor-interacting protein kinase 1 (RIP1). ROS, including mitochondrial superoxide, led to the oxidation of RIP1, as well as formation and activation of the necrosome. Concurrently, ROS mediate a decrease in the levels and activation of executioner caspases-3, -6, and -7. Importantly, hyperglycemia and mitochondrial ROS result in the oxidation of RIP1 and loss of executioner caspases prior to death receptor engagement by TNF-α. Moreover, RIP1 partially controlled levels of mitochondrial ROS in the context of hyperglycemia. As a result of its regulation of ROS, RIP1 also regulated necrosome activation and caspase loss. Mitochondrial ROS exacerbated neonatal HI-brain injury in hyperglycemic mice, as a result of the shift from apoptosis to necroptosis

Magmatism, serpentinization and life: Insights through drilling the Atlantis Massif (IODP Expedition 357)

IODP Expedition 357 used two seabed drills to core 17 shallow holes at 9 sites across Atlantis Massif ocean core complex (Mid-Atlantic Ridge 30°N). The goals of this expedition were to investigate serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. More than 57 m of core were recovered, with borehole penetration ranging from 1.3 to 16.4 meters below seafloor, and core recovery as high as 75% of total penetration in one borehole. The cores show highly heterogeneous rock types and alteration associated with changes in bulk rock chemistry that reflect multiple phases of magmatism, fluid-rock interaction and mass transfer within the detachment fault zone. Recovered ultramafic rocks are dominated by pervasively serpentinized harzburgite with intervals of serpentinized dunite and minor pyroxenite veins; gabbroic rocks occur as melt impregnations and veins. Dolerite intrusions and basaltic rocks represent the latest magmatic activity. The proportion of mafic rocks is volumetrically less than the amount of mafic rocks recovered previously by drilling the central dome of Atlantis Massif at IODP Site U1309. This suggests a different mode of melt accumulation in the mantle peridotites at the ridge-transform intersection and/or a tectonic transposition of rock types within a complex detachment fault zone. The cores revealed a high degree of serpentinization and metasomatic alteration dominated by talc-amphibole-chlorite overprinting. Metasomatism is most prevalent at contacts between ultramafic and mafic domains (gabbroic and/or doleritic intrusions) and points to channeled fluid flow and silica mobility during exhumation along the detachment fault. The presence of the mafic lenses within the serpentinites and their alteration to mechanically weak talc, serpentine and chlorite may also be critical in the development of the detachment fault zone and may aid in continued unroofing of the upper mantle peridotite/gabbro sequences. New technologies were also developed for the seabed drills to enable biogeochemical and microbiological characterization of the environment. An in situ sensor package and water sampling system recorded real-time variations in dissolved methane, oxygen, pH, oxidation reduction potential (Eh), and temperature and during drilling and sampled bottom water after drilling. Systematic excursions in these parameters together with elevated hydrogen and methane concentrations in post-drilling fluids provide evidence for active serpentinization at all sites. In addition, chemical tracers were delivered into the drilling fluids for contamination testing, and a borehole plug system was successfully deployed at some sites for future fluid sampling. A major achievement of IODP Expedition 357 was to obtain microbiological samples along a west–east profile, which will provide a better understanding of how microbial communities evolve as ultramafic and mafic rocks are altered and emplaced on the seafloor. Strict sampling handling protocols allowed for very low limits of microbial cell detection, and our results show that the Atlantis Massif subsurface contains a relatively low density of microbial life

Characterization and Vaccine Potential of Outer Membrane Vesicles Produced by Haemophilus parasuis.

Haemophilus parasuis is a Gram-negative bacterium that colonizes the upper respiratory tract of swine and is capable of causing a systemic infection, resulting in high morbidity and mortality. H. parasuis isolates display a wide range of virulence and virulence factors are largely unknown. Commercial bacterins are often used to vaccinate swine against H. parasuis, though strain variability and lack of cross-reactivity can make this an ineffective means of protection. Outer membrane vesicles (OMV) are spherical structures naturally released from the membrane of bacteria and OMV are often enriched in toxins, signaling molecules and other bacterial components. Examination of OMV structures has led to identification of virulence factors in a number of bacteria and they have been successfully used as subunit vaccines. We have isolated OMV from both virulent and avirulent strains of H. parasuis, have examined their protein content and assessed their ability to induce an immune response in the host. Vaccination with purified OMV derived from the virulent H. parasuis Nagasaki strain provided protection against challenge with a lethal dose of the bacteria

<i>H</i>. <i>parasuis</i> CFU and OMV totals.

<p>Experimental growth conditions, CFU and OMV yields.</p

Transcription of cytokine mRNA by porcine alveolar macrophages following stimulation with OMV.

<p>Real-time RT-PCR was used to evaluate cytokine mRNA levels in alveolar macrophages 18 h after incubation with <i>E</i>. <i>coli</i> LPS (10 μg/ml), live <i>H</i>. <i>parasuis</i> (MOI 2:1), Plate OMV (1 μg), Liquid OMV (1 μg) and Liquid Sonicate (1 μg). Data is expressed as the fold-change in mRNA relative to mock-treated cells. (* = p<0.05, ** = p<0.01, *** = p<0.005).</p

Density gradient purification of vesicles.

<p>A. D74 Liquid OMV density fractions 1–12, B. D74 Plate OMV density fractions 1–12, C. D74 Liquid Sonicate density fractions 1–12, D. Nagasaki Liquid OMV density fractions 1–12, E. Nagasaki Plate OMV density fractions 1–12, F. Nagasaki Liquid Sonicate density fractions 1–12. Iodixinol concentrations by lane, 1 = 15%, 2 = 20%, 3–4 = 25%, 5–6 = 30%, 7–8 = 35%, 9–10 = 40%, 11–12 = 45%. Bars indicate fractions combined for OMV recovery.</p

Protein profiles and Western blot of <i>H</i>. <i>parasuis</i> samples.

<p>A. SDS-PAGE of D74 whole cell lysate (Lane 1), D74 liquid OMV (Lane 2), D74 plate OMV (Lane 3), D74 sonicate (Lane 4), Nagasaki whole cell lysate (Lane 5), Nagasaki liquid OMV (Lane 6), Nagasaki plate OMV (Lane 7), Nagasaki plate sonicate (Lane 8) (20 μg/well). B. Same wells and concentration as A, Western blot probed with sera from Nagasaki bacterin immunized pigs (1:1K dilution).</p

NSAF values of top proteins from liquid and plate isolated OMV.

<p>Top proteins (NSAF> = 0.02 for at least one experimental condition) from Nagasaki plate isolated OMV (NPO), D74 plate isolated OMV (DPO), Nagasaki liquid isolated OMV (NLO) and D74 liquid isolated OMV (DLO).</p

<i>H</i>. <i>parasuis</i> purified OMV and sonicate protein localization.

<p>A. Unique and shared proteins from liquid and plate isolated OMV, B. Protein localization as predicted by the pSORTb 3.0 and CELLO2GO programs. NSAF = Normalized Spectral Abundance Factor.</p