456 research outputs found
Hepatic Cytochrome P-450. A Proton Magnetic Relaxation Study of Microsomal, Solubilized and Partially Reconstituted Enzyme System
The longitudiJ:ial proton magnetic relaxation times, Ti, were
measured from -5 to 40 °c for microsomal, solubilized and reconstituted
cytochrome P-450 obtained from phenobarbital-induced rat
livers. The paramagnetic contribution to the rates was derived by
subtraction of the rates measured on dithionite-CO-reduced samples.
The same values were obtained for microsomal P-450 on
reduction with NADPH. PMR titratio.n by KCN yielded a dissociation
constant of about 30 mM. This is three orders of magnitude larger
than for metmyoglobin. It is concluded that the measured PMR
rates are most likely due to the P-450 (and P-420) haem-iron while
the 300/o non-haem iron found in both the microsomal and s olubilized
P-450 is .ineffective for the PMR rates. These rates increase
several times on isotopic dilution (D20 for H20) with the microsomes
and diminish for the solubilized samples. Microsomes show 170/o
residual, encaged, H20. Most of their paramagnetic PMR rate is due
to the parama.gnetic iron located on the outside of microsomes.
This is demonstrated by measurements with deuterated samples to
which 190/o H20 had been added. Hence, the solubilized P-450 is
homogeneous regarding PMR, but the microsomes are not
Hepatic Cytochrome P-450. A Proton Magnetic Relaxation Study of Microsomal, Solubilized and Partially Reconstituted Enzyme System
The longitudiJ:ial proton magnetic relaxation times, Ti, were
measured from -5 to 40 °c for microsomal, solubilized and reconstituted
cytochrome P-450 obtained from phenobarbital-induced rat
livers. The paramagnetic contribution to the rates was derived by
subtraction of the rates measured on dithionite-CO-reduced samples.
The same values were obtained for microsomal P-450 on
reduction with NADPH. PMR titratio.n by KCN yielded a dissociation
constant of about 30 mM. This is three orders of magnitude larger
than for metmyoglobin. It is concluded that the measured PMR
rates are most likely due to the P-450 (and P-420) haem-iron while
the 300/o non-haem iron found in both the microsomal and s olubilized
P-450 is .ineffective for the PMR rates. These rates increase
several times on isotopic dilution (D20 for H20) with the microsomes
and diminish for the solubilized samples. Microsomes show 170/o
residual, encaged, H20. Most of their paramagnetic PMR rate is due
to the parama.gnetic iron located on the outside of microsomes.
This is demonstrated by measurements with deuterated samples to
which 190/o H20 had been added. Hence, the solubilized P-450 is
homogeneous regarding PMR, but the microsomes are not
Solvent Proton Magnetic Relaxation in Solution of Rabbit Liver Cytochrome P450. On the Corfelation Time for the Electron Proton Dipole-Dipole Interaction
Structural parameters can be derived from PMR measurements
if the correlation time fdr the spin interactions is known. The relaxation
rates induced by the ferric haem-iron of cyt P450 were
found to be frequency independent from 10 to 37 MHz. The possible
limits for the correlation time according to Solomon\u27s theory are
discussed with regard to the possible existence of a water molecule
at the sixth coordination site of the haem-iron. No definite conclusion
could be reached in this respect, but the results are definetely
in favour of a haem environment which can accomodate several
water molecules exchanging quickly with the bulk of solvent
Solvent Proton Magnetic Relaxation in Solution of Rabbit Liver Cytochrome P450. On the Corfelation Time for the Electron Proton Dipole-Dipole Interaction
Structural parameters can be derived from PMR measurements
if the correlation time fdr the spin interactions is known. The relaxation
rates induced by the ferric haem-iron of cyt P450 were
found to be frequency independent from 10 to 37 MHz. The possible
limits for the correlation time according to Solomon\u27s theory are
discussed with regard to the possible existence of a water molecule
at the sixth coordination site of the haem-iron. No definite conclusion
could be reached in this respect, but the results are definetely
in favour of a haem environment which can accomodate several
water molecules exchanging quickly with the bulk of solvent
Genetic diversity among cowpea cultivars as revealed by ISSR and DAF markers.
BIOLATINA 2010. Autoria: DAMASCENO-SILVA, K. J. [i.e. SILVA, K. J. D. e]
Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin
The transiting planet WASP-12 b was identified as a potential target for
transit timing studies because a departure from a linear ephemeris was reported
in the literature. Such deviations could be caused by an additional planet in
the system. We attempt to confirm the existence of claimed variations in
transit timing and interpret its origin. We organised a multi-site campaign to
observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre
telescopes. We obtained 61 transit light curves, many of them with
sub-millimagnitude precision. The simultaneous analysis of the best-quality
datasets allowed us to obtain refined system parameters, which agree with
values reported in previous studies. The residuals versus a linear ephemeris
reveal a possible periodic signal that may be approximated by a sinusoid with
an amplitude of 0.00068+/-0.00013 d and period of 500+/-20 orbital periods of
WASP-12 b. The joint analysis of timing data and published radial velocity
measurements results in a two-planet model which better explains observations
than single-planet scenarios. We hypothesize that WASP-12 b might be not the
only planet in the system and there might be the additional 0.1 M_Jup body on a
3.6-d eccentric orbit. A dynamical analysis indicates that the proposed
two-planet system is stable over long timescales.Comment: Accepted for publication in A&
The semen microbiome and its relationship with local immunology and viral load in HIV infection
Semen is a major vector for HIV transmission, but the semen HIV RNA viral load (VL) only correlates moderately with the blood VL. Viral shedding can be enhanced by genital infections and associated inflammation, but it can also occur in the absence of classical pathogens. Thus, we hypothesized that a dysregulated semen microbiome correlates with local HIV shedding. We analyzed semen samples from 49 men who have sex with men (MSM), including 22 HIV-uninfected and 27 HIV-infected men, at baseline and after starting antiretroviral therapy (ART) using 16S rRNA gene-based pyrosequencing and quantitative PCR. We studied the relationship of semen bacteria with HIV infection, semen cytokine levels, and semen VL by linear regression, non-metric multidimensional scaling, and goodness-of-fit test. Streptococcus, Corynebacterium, and Staphylococcus were common semen bacteria, irrespective of HIV status. While Ureaplasma was the more abundant Mollicutes in HIV-uninfected men, Mycoplasma dominated after HIV infection. HIV infection was associated with decreased semen microbiome diversity and richness, which were restored after six months of ART. In HIV-infected men, semen bacterial load correlated with seven pro-inflammatory semen cytokines, including IL-6 (p = 0.024), TNF-α (p = 0.009), and IL-1b (p = 0.002). IL-1b in particular was associated with semen VL (r(2)  = 0.18, p = 0.02). Semen bacterial load was also directly linked to the semen HIV VL (r(2) = 0.15, p = 0.02). HIV infection reshapes the relationship between semen bacteria and pro-inflammatory cytokines, and both are linked to semen VL, which supports a role of the semen microbiome in HIV sexual transmission
The semen microbiome and its relationship with local immunology and viral load in HIV infection
Semen is a major vector for HIV transmission, but the semen HIV RNA viral load (VL) only correlates moderately with the blood VL. Viral shedding can be enhanced by genital infections and associated inflammation, but it can also occur in the absence of classical pathogens. Thus, we hypothesized that a dysregulated semen microbiome correlates with local HIV shedding. We analyzed semen samples from 49 men who have sex with men (MSM), including 22 HIV-uninfected and 27 HIV-infected men, at baseline and after starting antiretroviral therapy (ART) using 16S rRNA gene-based pyrosequencing and quantitative PCR. We studied the relationship of semen bacteria with HIV infection, semen cytokine levels, and semen VL by linear regression, non-metric multidimensional scaling, and goodness-of-fit test. Streptococcus, Corynebacterium, and Staphylococcus were common semen bacteria, irrespective of HIV status. While Ureaplasma was the more abundant Mollicutes in HIV-uninfected men, Mycoplasma dominated after HIV infection. HIV infection was associated with decreased semen microbiome diversity and richness, which were restored after six months of ART. In HIV-infected men, semen bacterial load correlated with seven pro-inflammatory semen cytokines, including IL-6 (p = 0.024), TNF-α (p = 0.009), and IL-1b (p = 0.002). IL-1b in particular was associated with semen VL (r2 = 0.18, p = 0.02). Semen bacterial load was also directly linked to the semen HIV VL (r2 = 0.15, p = 0.02). HIV infection reshapes the relationship between semen bacteria and pro-inflammatory cytokines, and both are linked to semen VL, which supports a role of the semen microbiome in HIV sexual transmission
The transcription factor STAT6 mediates direct repression of inflammatory enhancers and limits activation of alternatively polarized macrophages
The molecular basis of signal-dependent transcriptional activation has been extensively studied in macrophage polarization, but our understanding remains limited regarding the molecular determinants of repression. Here we show that IL-4-activated STAT6 transcription factor is required for the direct transcriptional repression of a large number of genes during in vitro and in vivo alternative macrophage polarization. Repression results in decreased lineage-determining transcription factor, p300, and RNA polymerase II binding followed by reduced enhancer RNA expression, H3K27 acetylation, and chromatin accessibility. The repressor function of STAT6 is HDAC3 dependent on a subset of IL-4-repressed genes. In addition, STAT6-repressed enhancers show extensive overlap with the NF-κB p65 cistrome and exhibit decreased responsiveness to lipopolysaccharide after IL-4 stimulus on a subset of genes. As a consequence, macrophages exhibit diminished inflammasome activation, decreased IL-1β production, and pyroptosis. Thus, the IL-4-STAT6 signaling pathway establishes an alternative polarization-specific epigenenomic signature resulting in dampened macrophage responsiveness to inflammatory stimuli
Genomic characterization of phosphoprotein phosphatase gene family in vitis vinifera.
O trabalho objetivou identificar e caracterizar genes que codificam proteĂnas da famĂlia PPP no genoma de V. vinifera
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