2,174 research outputs found
Baboon endogenous virus genome: Molecular cloning and structural characterization of nondefective viral genomes from DNA of a baboon cell strain
Several heterogeneities in the baboon endogenous virus (BaEV) genomes that are present in the DNA of normal baboon tissues and the baboon cell strain BEF-3 have been described previously. To study these genomes, we cloned BaEV proviruses from BEF-3 cellular DNA into the vector Charon 4A. Of the four full-length clones isolated, one was nondefective as determined by transfection. The sequence of a portion of this clone was found to code for amino acids 61-91 in the p30 region of the gag gene. This identification allowed us to align the restriction map with the BaEV genetic map. One heterogeneity, a BamHI site 2.4 kilobases (kb) from the proviral 5' end, was located close to the gag-pol junction; another, a BamHI site 1.4 kb from the 5' end of the genome, corresponded to the gag p30 coding sequence for amino acids 32-34; and a third, a Xho I site, was near the 3' end of the pol gene. To select the nondefective BaEV genomes from BEF-3 cells, we infected permissive cells with virus produced by BEF-3 cells and also transfected BEF-3 cellular DNA into permissive cells. The BaEV genomes in the permissive recipient cultures were then analyzed by restriction enzyme analysis. These nondefective genomes were found to be heterogeneous with respect to the gag-pol BamHI site and the Xho I site, but all were found to contain the BamHI site 1.4 kb from the 5' end of the genome
Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models
We present a 1620 A image of the nearby globular cluster NGC 6752 obtained
with the Ultraviolet Imaging Telescope (UIT) during the Astro-2 mission of the
Space Shuttle Endeavour in 1995 March. An ultraviolet-visible color-magnitude
diagram (CMD) is derived for 216 stars matched with the visible photometry of
Buonanno et al. (1986). This CMD provides a nearly complete census of the hot
horizontal branch (HB) population with good temperature and luminosity
discrimination for comparison with theoretical tracks. The observed data show
good agreement with the theoretical zero-age horizontal branch (ZAHB) of
Sweigart (1996) for an assumed reddening of E(B-V) = 0.05 and a distance
modulus of 13.05. The observed HB luminosity width is in excellent agreement
with the theoretical models and supports the single star scenario for the
origin of extreme horizontal branch (EHB) stars. However, only four stars can
be identified as post-EHB stars, whereas almost three times this many are
expected from the HB number counts. If this effect is not a statistical
anomaly, then some non-canonical effect may be decreasing the post-EHB
lifetime. The recent non-canonical models of Sweigart (1996), which have
helium-enriched envelopes due to mixing along the red giant branch, cannot
explain the deficit of post-EHB stars, but might be better able to explain
their luminosity distribution.Comment: 14 pages, AASTeX, includes 4 EPS figures ApJ Letters accepte
A rapid method for assessing the RNA-binding potential of a protein
In recent years, evidence has emerged for the existence of many diverse types of RNA, which play roles in a wide range of biological processes in all kingdoms of life. These molecules generally do not, however, act in isolation, and identifying which proteins partner with RNA is a major challenge. Many methods, in vivo and in vitro, have been used to address this question, including combinatorial or high-throughput approaches, such as systematic evolution of ligands, cross-linking and immunoprecipitation and RNA immunoprecipitation combined with deep sequencing. However, most of these methods are not trivial to pursue and often require substantial optimization before results can be achieved. Here, we demonstrate a simple technique that allows one to screen proteins for RNA-binding properties in a gel-shift experiment and can be easily implemented in any laboratory. This assay should be a useful first-pass tool for assessing whether a protein has RNA- or DNA-binding properties, prior to committing resources to more complex procedure
A study of protein and amino nutrition of growing pigs.
End of Project ReportProtein nutrition of the pig is concerned primarily with supplying the amino acid
requirements for fast, efficient growth and development of a lean carcass. In addition,
surplus protein contributes to a high level of nitrogen excretion in manure which is a
problem in complying with the Nitrates Directive. Metabolism of the excess protein /
nitrogen in the pig involves creation of urea and this process depresses the efficiency of
energy utilisation. As the pig grows, its requirement for individual amino acids falls but
the optimum ratio changes. Providing a diet with the correct levels and balance of the
principal amino acids is expected to improve performance.
Improvements in genetics and changes in management such as slaughter weight require
that the amino acid requirements be reassessed periodically. The objective of this study
was to examine response of pigs to variation in dietary lysine in several weight ranges
with the concentrations of the other principal amino acids held constant.
Entire males had superior FCR to females in all trials except 15 to 30kg, but differences
in dietary lysine requirements did not occur until the finishing stage. At heavier
weights, response of male and female pigs began to diverge at lysine concentrations
greater than 10.7 g/kg (ADG) and 9.7 g/kg (FCR).
There appeared to be a need to increase the threonine to lysine ratio in the diet from
0.60 to 0.70 when lysine concentration was reduced from 12.0 to 9.5 g/kg as weight of
the pig increased.
Providing the same mean lysine content (11.1 g/kg) to pigs from 38 to 97 kg in a series
of five diets declining in lysine concentration compared with a single diet did not affect
performance, or reduce N excretion. However, lowering the overall mean lysine
concentration from 11g/kg to 10.0 g/kg reduced overall N excretion by 13 %, without a
negative effect on pig performance. Pigs which were offered a low lysine diet in the
early stage of growth exhibited a compensatory response during realimentation on a
high lysine diet but it was not sufficient to equal the overall performance of pigs
previously offered a lysine-adequate diet. Nitrogen excretion was reduced by 23 % while the low lysine diet was fed in the initial period but there was no residual effect on
N excretion during realimentation.Teagasc Walsh Fellowship ProgrammeNational Development
Programme Funds (NDP
Quasi-elastic and inelastic inclusive electron scattering from an oxygen jet target
The results of an experiment on inclusive electron scattering from an oxygen
jet target, performed in a wide range of energy and momentum transfer covering
both quasi-elastic and (1232) resonance regions, are reported. In the
former region the theoretical predictions, obtained including effects of
nucleon-nucleon correlations in both initial and final states, give a good
description of the experimental data. In the inelastic region a broadening as
well as a damping of the resonant part of the cross section with respect to the
free nucleon case is observed. The need of more detailed calculations including
nuclear structure effects on the electroproduction cross section of nucleon
resonances is highlighted.Comment: to appear in Nucl. Phys.
Intersubband decay of 1-D exciton resonances in carbon nanotubes
We have studied intersubband decay of E22 excitons in semiconducting carbon
nanotubes experimentally and theoretically. Photoluminescence excitation line
widths of semiconducting nanotubes with chiral indicess (n, m) can be mapped
onto a connectivity grid with curves of constant (n-m) and (2n+m). Moreover,
the global behavior of E22 linewidths is best characterized by a strong
increase with energy irrespective of their (n-m) mod(3)= \pm 1 family
affiliation. Solution of the Bethe-Salpeter equations shows that the E22
linewidths are dominated by phonon assisted coupling to higher momentum states
of the E11 and E12 exciton bands. The calculations also suggest that the
branching ratio for decay into exciton bands vs free carrier bands,
respectively is about 10:1.Comment: 4 pages, 4 figure
Initial correlations effects on decoherence at zero temperature
We consider a free charged particle interacting with an electromagnetic bath
at zero temperature. The dipole approximation is used to treat the bath
wavelengths larger than the width of the particle wave packet. The effect of
these wavelengths is described then by a linear Hamiltonian whose form is
analogous to phenomenological Hamiltonians previously adopted to describe the
free particle-bath interaction. We study how the time dependence of decoherence
evolution is related with initial particle-bath correlations. We show that
decoherence is related to the time dependent dressing of the particle. Moreover
because decoherence induced by the T=0 bath is very rapid, we make some
considerations on the conditions under which interference may be experimentally
observed.Comment: 16 pages, 1 figur
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