98 research outputs found
Brightest Cluster Galaxies and Core Gas Density in REXCESS Clusters
We investigate the relationship between brightest cluster galaxies (BCGs) and
their host clusters using a sample of nearby galaxy clusters from the
Representative XMM Cluster Structure Survey (REXCESS). The sample was imaged
with the Southern Observatory for Astrophysical Research (SOAR) in R band to
investigate the mass of the old stellar population. Using a metric radius of
12h^-1 kpc, we found that the BCG luminosity depends weakly on overall cluster
mass as L_BCG \propto M_cl^0.18+-0.07, consistent with previous work. We found
that 90% of the BCGs are located within 0.035 r_500 of the peak of the X-ray
emission, including all of the cool core (CC) clusters. We also found an
unexpected correlation between the BCG metric luminosity and the core gas
density for non-cool core (non-CC) clusters, following a power law of n_e
\propto L_BCG^2.7+-0.4 (where n_e is measured at 0.008 r_500). The correlation
is not easily explained by star formation (which is weak in non-CC clusters) or
overall cluster mass (which is not correlated with core gas density). The trend
persists even when the BCG is not located near the peak of the X-ray emission,
so proximity is not necessary. We suggest that, for non-CC clusters, this
correlation implies that the same process that sets the central entropy of the
cluster gas also determines the central stellar density of the BCG, and that
this underlying physical process is likely to be mergers.Comment: 16 pages, 8 figures, accepted Astrophysical Journa
H i in Virgoâs âRed and Deadâ Dwarf EllipticalsâA Tidal Tail and Central Star Formation
A mouse model reproducing the pathophysiology of neonatal group B streptococcal infection
Group B streptococcal (GBS) meningitis remains a devastating disease. The absence of an animal model reproducing the natural infectious process has limited our understanding of the disease and, consequently, delayed the development of effective treatments. We describe here a mouse model in which bacteria are transmitted to the offspring from vaginally colonised pregnant females, the natural route of infection. We show that GBS strain BM110, belonging to the CC17 clonal complex, is more virulent in this vertical transmission model than the isogenic mutant BM110âcylE, which is deprived of hemolysin/cytolysin. Pups exposed to the more virulent strain exhibit higher mortality rates and lung inflammation than those exposed to the attenuated strain. Moreover, pups that survive to BM110 infection present neurological developmental disability, revealed by impaired learning performance and memory in adulthood. The use of this new mouse model, that reproduces key steps of GBS infection in newborns, will promote a better understanding of the physiopathology of GBS-induced meningitis.The authors gratefully acknowledge the help of Encarnaca̧ Ìo Ribeiro for excellent technical assistance, Joana Tavares for assisting with IVIS Lumina LT, Susana Roque for the
luminex instrument experiments, the Molecular Microbiology group at i3S for microscope use, and the Portuguese architect and artist Gil Ferreira da Silva for the artworks
included in the last figure. This work was supported by funds from Foundation for
Science and Technology (FCT), European Regional Development Fund (FEDER) and
Compete under project POCI-01-0145-FEDER-016607 (PTDC/IMI-MIC/1049/2014)
and from the project NORTE-01-0145-FEDER-000012, supported by Norte Portugal
Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). T.S.
and A.M. were supported by Investigador FCT (IF/00875/2012 and IF/00753/2014),
POPH and Fundo Social Europeu. E.B.A. and C.C.P. hold postdoctoral fellowships from
FCT (PTDC/IMI-MIC/1049/2014 and SFRH/BPD/91962/2012). Ar.F. and P.T.C. were
supported by Laboratoire dâExcellence (LABEX) Integrative Biology of Emerging Infectious Diseases (grant ANR-10-LABX-62-IBEID).info:eu-repo/semantics/publishedVersio
Cognitive performance in patients with Mild Cognitive Impairment and Alzheimer's disease with white matter hyperintensities: An exploratory analysis
Yellow light emission of Vibrio fischeri strain Y-1: purification and characterization of the energy-accepting yellow fluorescent protein.
A strain of luminous bacteria, Vibrio fischeri Y-1, emits yellow light rather than the blue-green emission typical of other luminous bacteria. The yellow emission has been postulated previously to result from energy transfer from an electronically excited species formed in the bacterial luciferase-catalyzed reaction to a secondary emitter protein, termed the yellow fluorescent protein (YFP). We report here the purification of YFP to homogeneity without loss of the chromophore. The protein was found to be a homodimer of Mr 22,000 subunits with one weakly bound FMN per subunit. The FMN-protein complex was stabilized by 10% (vol/vol) glycerol in the buffers, allowing purification of the active holo-YFP. The protein migrated as a single spot with an isoelectric point of approximately 6.5 on two-dimensional polyacrylamide gel electrophoresis and gave an N-terminal sequence of Met-Phe-Lys-Gly-Ile-Val-Glu-Gly-Ile-Gly-Ile-Ile-Glu-Lys-Ile. Addition of purified YFP to a reaction in which luciferase was supplied with FMNH2 (reduced FMN) by a NADH:FMN oxidoreductase resulted in a dramatic enhancement in the intensity of bioluminescence and an additional peak in the emission spectrum at about 534 nm. The resulting bimodal bioluminescence emission spectrum had peaks at 484 nm, apparently due to emission from the luciferase-flavin complex, and at 534 nm, corresponding to the fluorescence emission maximum of YFP. This bimodal spectrum closely matched the emission spectrum in vivo
Reductive detoxification as a mechanism of fungal resistance to singlet oxygen-generating photosensitizers.
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