94 research outputs found
An investigation of the PsbS protein isolated from spinach chloroplast membranes.
Dissipation of excess light energy in plant photosynthetic membranes plays an
important role in the response of plants to the environment, providing short-term
balancing between the intensity of sunlight and photosynthetic capacity. The carotenoid
zeaxanthin and the photosystem Il subunit PsbS play vital roles in this process, but the
mechanism of their action is largely unexplained. This thesis reports a novel procedure
for the extraction of the PsbS protein from spinach thylakoids, including a detailed
account of the developmental process and characterisation of the isolated protein. The
ability of the PsbS protein to bind xanthophyll cycle carotenoids in vitro was assessed,
leading to the observation that the isolated protein was able to bind exogenous
zeaxanthin, the binding resulting in a strong red shift in the absorption spectrum, and
the appearance of characteristic features in the resonance Raman spectrum and a distinct
circular dichroism spectrum, indicating pigment-protein, as well as specific pigmentpigment,
interaction. A strong shift in the absorption spectrum of PsbS phenylalanine
residues after zeaxanthin binding was observed. It is concluded that zeaxanthin binding
to PsbS is the origin of the well known energy dissipation-related 535-nm absorption
change. The ability of this PsbS-zeaxanthin complex to affect the rate of chlorophyll
fluorescence quenching of the major LHcn antenna protein is detailed, revealing an
increase in the rate of quenching, whilst the magnitude of quenching remained constant.
The altered properties of zeaxanthin and PsbS after in vitro reconstitution and their
subsequent effect on LHCnb provide the first direct indication about how they regulate
energy dissipation
Antibody-based detection of protein phosphorylation status to track the efficacy of novel therapies using nanogram protein quantities from stem cells and cell lines
This protocol describes a highly reproducible antibody-based method that provides protein level and phosphorylation status information from nanogram quantities of protein cell lysate. Nanocapillary isoelectric focusing (cIEF) combines with UV-activated linking chemistry to detect changes in phosphorylation status. As an example application, we describe how to detect changes in response to tyrosine kinase inhibitors (TKIs) in the phosphorylation status of the adaptor protein ​CrkL, a major substrate of the oncogenic tyrosine kinase ​BCR-​ABL in chronic myeloid leukemia (CML), using highly enriched CML stem cells and mature cell populations in vitro. This protocol provides a 2.5 pg/nl limit of protein detection (<0.2% of a stem cell sample containing <104 cells). Additional assays are described for phosphorylated tyrosine 207 (pTyr207)-​CrkL and the protein tyrosine phosphatase ​PTPRC/​CD45; these assays were developed using this protocol and applied to CML patient samples. This method is of high throughput, and it can act as a screen for in vitro cancer stem cell response to drugs and novel agents
Two Clusters with Radio-quiet Cooling Cores
Radio lobes inflated by active galactic nuclei at the centers of clusters are
a promising candidate for halting condensation in clusters with short central
cooling times because they are common in such clusters. In order to test the
AGN-heating hypothesis, we obtained Chandra observations of two clusters with
short central cooling times yet no evidence for AGN activity: Abell 1650 and
Abell 2244. The cores of these clusters indeed appear systematically different
from cores with more prominent radio emission. They do not have significant
central temperature gradients, and their central entropy levels are markedly
higher than in clusters with stronger radio emission, corresponding to central
cooling times ~ 1 Gigayear. Also, there is no evidence for fossil X-ray
cavities produced by an earlier episode of AGN heating. We suggest that either
(1) the central gas has not yet cooled to the point at which feedback is
necessary to prevent it from condensing, possibly because it is conductively
stabilized, or (2) the gas experienced a major heating event Gyr in
the past and has not required feedback since then. The fact that these clusters
with no evident feedback have higher central entropy and therefore longer
central cooling times than clusters with obvious AGN feedback strongly suggests
that AGNs supply the feedback necessary to suppress condensation in clusters
with short central cooling times.Comment: ApJ Letter, in pres
Health outcomes of a subsidised fruit and vegetable program for Aboriginal children in northern New South Wales
Objective: To evaluate the impact of a fruit and vegetable subsidy program on short-term health outcomes of disadvantaged Aboriginal children.Design, setting and participants: A before-and-after study involving clinical assessments, health record audits and blood testing of all children aged 0–17 years (n = 167) from 55 participating families at baseline and after 12 months at three Aboriginal community-controlled health services in New South Wales. All assessments were completed between December 2008 and September 2010.Intervention: A weekly box of subsidised fruit and vegetables linked to preventive health services and nutrition promotion at an Aboriginal Medical Service.Main outcome measures: Change in episodes of illness, health service and emergency department attendances, antibiotic prescriptions and anthropometry.Results: There was a significant decrease in oral antibiotics prescribed (− 0.5 prescriptions/year; 95% CI, − 0.8 to − 0.2) during 12 months of participation in the program compared with the 12 months before the program. The proportion of children classified as overweight or obese at baseline was 28.3% (38/134) and the proportion in each weight category did not change (P = 0.721) after 12 months. A small but significant increase in mean haemoglobin level (3.1 g/L; 95% CI, 1.4–4.8 g/L) was shown, although the proportion with iron deficiency (baseline, 41%; follow-up, 37%; P = 0.440) and anaemia (baseline, 8%; follow-up, 5%; P = 0.453) did not change significantly.Conclusion: This fruit and vegetable subsidy program was associated with improvements in some indicators of short-term health status among disadvantaged Aboriginal children. A controlled trial is warranted to investigate the sustainability and feasibility of healthy food subsidy programs in Australia
Star Formation, Radio Sources, Cooling X-ray Gas, and Galaxy Interactions in the Brightest Cluster Galaxy in 2A0335+096
We present deep emission-line imaging taken with the SOAR Optical Imaging
Camera of the brightest cluster galaxy (BCG) in the nearby (z=0.035) X-ray
cluster 2A0335+096. We analyze long-slit optical spectroscopy, archival VLA,
Chandra X-ray, and XMM UV data. 2A0335+096 is a bright, cool-core X-ray
cluster, once known as a cooling flow. Within the highly disturbed core
revealed by Chandra X-ray observations, 2A0335+096 hosts a highly structured
optical emission-line system. The redshift of the companion is within 100 km/s
of the BCG and has certainly interacted with the BCG, and is likely bound to
it. The comparison of optical and radio images shows curved filaments in
H-alpha emission surrounding the resolved radio source. The velocity structure
of the emission-line bar between the BCG nucleus and the companion galaxy
provides strong evidence for an interaction between the two in the last ~50
Myrs. The age of the radio source is similar to the interaction time, so this
interaction may have provoked an episode of radio activity. We estimate a star
formation rate of >7 solar mass/yr based on the Halpha and archival UV data, a
rate similar to, but somewhat lower than, the revised X-ray cooling rate of
10-30 solar masses/year estimated from XMM spectra by Peterson & workers. The
Halpha nebula is limited to a region of high X-ray surface brightness and cool
X-ray temperature. The detailed structures of H-alpha and X-ray gas differ. The
peak of the X-ray emission is not the peak of H-alpha emission, nor does it lie
in the BCG. The estimated age of the radio lobes and their interaction with the
optical emission-line gas, the estimated timescale for depletion and
accumulation of cold gas, and the dynamical time in the system are all similar,
suggesting a common trigger mechanism.Comment: Accepted AJ, July 2007 publication. Vol 134, p. 14-2
Pahs, Ionized Gas, and Molecular Hydrogen in Brightest Cluster Galaxies of Cool Core Clusters of Galaxies
We present measurements of 5-25 {\mu}m emission features of brightest cluster
galaxies (BCGs) with strong optical emission lines in a sample of 9 cool-core
clusters of galaxies observed with the Infrared Spectrograph on board the
Spitzer Space Telescope. These systems provide a view of dusty molecular gas
and star formation, surrounded by dense, X-ray emitting intracluster gas. Past
work has shown that BCGs in cool-core clusters may host powerful radio sources,
luminous optical emission line systems, and excess UV, while BCGs in other
clusters never show this activity. In this sample, we detect polycyclic
aromatic hydrocarbons (PAHs), extremely luminous, rotationally-excited
molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne
II] and [Ne III]), and infrared continuum emission from warm dust and cool
stars. We show here that these BCGs exhibit more luminous forbidden neon and H2
rotational line emission than star-forming galaxies with similar total infrared
luminosities, as well as somewhat higher ratios of 70 {\mu}m / 24 {\mu}m
luminosities. Our analysis suggests that while star formation processes
dominate the heating of the dust and PAHs, a heating process consistent with
suprathermal electron heating from the hot gas, distinct from star formation,
is heating the molecular gas and contributing to the heating of the ionized gas
in the galaxies. The survival of PAHs and dust suggests that dusty gas is
somehow shielded from significant interaction with the X-ray gas.Comment: 27 preprint pages, 18 figures, accepted by Astrophysical Journa
Encoding NF-κB temporal control in response to TNF: distinct roles for the negative regulators IκBα and A20
TNF-induced NF-κB activity shows complex temporal regulation whose different phases lead to distinct gene expression programs. Combining experimental studies and mathematical modeling, we identify two temporal amplification steps—one determined by the obligate negative feedback regulator IκBα—that define the duration of the first phase of NF-κB activity. The second phase is defined by A20, whose inducible expression provides for a rheostat function by which other inflammatory stimuli can regulate TNF responses. Our results delineate the nonredundant functions implied by the knockout phenotypes of iκbα and a20, and identify the latter as a signaling cross-talk mediator controlling inflammatory and developmental responses
Knowledge, attitudes and practices towards dog-bite related rabies in para-medical staff at rural primary health centres in Baramati, western India
The lack of awareness regarding rabies amongst rural primary care health staff and their adverse practices towards the management of dog-bite wounds is a major contributor to the high incidence of rabies infection and subsequent human mortality in India. A Knowledge,
Attitudes and Practices survey was carried out involving 54 nursing and non-nursing staff working in 18 rural Primary Health centres and sub-centres around Baramati town of Pune district in Western India. Multivariable logistic regression models were constructed to assess
factors that influenced knowledge of rabies and practices towards management of dog-bite related wounds. The more experienced and better-educated workers were found to have a good awareness of rabies (OR 3.4, 95%CI 1.0–12.1) and good practices towards dog-bite wound management (OR 5.6, 95%CI 1.2–27.0). Surprisingly, non-nursing staff were significantly more knowledgeable about rabies (OR 3.5, 95%CI 1.0–12.3), but their practices towards dog-bite wound management were inadequate (OR 0.18, 95%CI 0.04–0.8) compared to the nursing staff. It is recommended that a mandatory training module for primary
care health staff be developed and implemented to improve their knowledge regarding rabies and management of dog-bite wounds to reduce the incidence of human rabies in
rural India
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