773 research outputs found
Flour proteins linked to quality traits in an Australian doubled haploid wheat population
The Cranbrook/Halberd doubled haploid population has provided a unique opportunity to examine in detail the contributions made by a number of different high molecular weight (HMW) and low molecular weight (LMW) glutenin alleles to the dough properties in a set of homogeneous lines of wheat. A range of different instruments was employed, including Farinograph, Extensograph, Do-Corder, Resistograph, and GRL/EasyMix, to study the dough rheology of the lines from 3 sites over 2 years. Correlation studies showed that 2 basic parameters (dough strength and extensibility) were measured by these different instruments. The results presented are mainly from the Extensograph, which is a major Australian standard for determining release and marketing classification of Australian wheats.
Approaches to investigate the data include bulk segregant analysis, distribution of protein alleles in the population, and multiple linear regression. As expected, the HMW glutenin alleles made a major contribution to dough strength, with a minor, but not insignificant, contribution from the LMW glutenin alleles. From a knowledge of their glutenin alleles, a glutenin strength score (GSS) was devised to allow breeders to rank the dough strength of various lines. The GSS scoring system is based on both HMW and LMW glutenin alleles, adding to a total out of 10. Extensibility, on the other hand, was predominantly influenced by protein levels in the flour and environmental conditions such as site and season. However, the LMW glutenin alleles make a significant genetic contribution to the extensibility, which can be assessed by using a glutenin extensibility score. These two glutenin quality scores currently include only the alleles present in the parents, Cranbrook and Halberd, but this could be expanded to include a wider range of alleles by analysis of the quality data from other doubled haploid populations. These quality scores would then be an extremely useful tool for assessing the potential quality of parental and early generation germplasm in wheat breeding programs, by a knowledge of the allelic composition of their HMW and LMW glutenins
A Model for the Elasticity of Compressed Emulsions
We present a new model to describe the unusual elastic properties of
compressed emulsions. The response of a single droplet under compression is
investigated numerically for different Wigner-Seitz cells. The response is
softer than harmonic, and depends on the coordination number of the droplet.
Using these results, we propose a new effective inter-droplet potential which
is used to determine the elastic response of a monodisperse collection of
disordered droplets as a function of volume fraction. Our results are in
excellent agreement with recent experiments. This suggests that anharmonicity,
together with disorder, are responsible for the quasi-linear increase of
and observed at .Comment: RevTeX with psfig-included figures and a galley macr
Inhibition of osteocyte apoptosis prevents the increase in osteocytic receptor activator of nuclear factor κB ligand (RANKL) but does not stop bone resorption or the loss of bone induced by unloading
"This research was originally published in Journal of Biological Chemistry. Lilian I. Plotkin, Arancha R. Gortazar, Hannah M. Davis, Keith W. Condon, Hugo Gabilondo, Marta Maycas, Matthew R. Allen, and Teresita Bellido. Inhibition of Osteocyte Apoptosis Prevents the Increase in Osteocytic Receptor Activator of Nuclear Factor κB Ligand (RANKL) but Does Not Stop Bone Resorption or the Loss of Bone Induced by Unloading*. Journal of Biological Chemistry. 2015; 290:18934-18942. © the American Society for Biochemistry and Molecular Biology."Apoptosis of osteocytes and osteoblasts precedes bone resorption and bone loss with reduced mechanical stimulation, and receptor activator of NF-κB ligand (RANKL) expression is increased with unloading in mice. Because osteocytes are major RANKL producers, we hypothesized that apoptotic osteocytes signal to neighboring osteocytes to increase RANKL expression, which, in turn, increases osteoclastogenesis and bone resorption. The traditional bisphosphonate (BP) alendronate (Aln) or IG9402, a BP analog that does not inhibit resorption, prevented the increase in osteocyte apoptosis and osteocytic RANKL expression. The BPs also inhibited osteoblast apoptosis but did not prevent the increase in osteoblastic RANKL. Unloaded mice exhibited high serum levels of the bone resorption marker C-telopeptide fragments of type I collagen (CTX), elevated osteoclastogenesis, and increased osteoclasts in bone. Aln, but not IG9402, prevented all of these effects. In addition, Aln prevented the reduction in spinal and femoral bone mineral density, spinal bone volume/tissue volume, trabecular thickness, mechanical strength, and material strength induced by unloading. Although IG9402 did not prevent the loss of bone mass, it partially prevented the loss of strength, suggesting a contribution of osteocyte viability to strength independent of bone mass. These results demonstrate that osteocyte apoptosis leads to increased osteocytic RANKL. However, blockade of these events is not sufficient to restrain osteoclast formation, inhibit resorption, or stop bone loss induced by skeletal unloadingThis work was supported, in whole or in part, by National Institutes of Health Grants R01DK076007 and ARRA supplement S10-RR023710 (to T. B.) and R01AR053643 (to L. I. P.). This work was also supported by Veterans Affairs Merit Award I01BX002104 (to T. B.) and an IUSM Biomedical Research grant (to L. I. P.) and by scholarships from the Conchita Rábago Foundation (to A. R. G. and M. M.), the European Molecular Biology Organization (to M. M.), and Universidad Autónoma de Madrid (to H. G
Close encounters of a rotating star with planets in parabolic orbits of varying inclination and the formation of Hot Jupiters
(abbreviated) We extend the theory of close encounters of a planet on a
parabolic orbit with a star to include the effects of tides induced on the
central rotating star. Orbits with arbitrary inclination to the stellar
rotation axis are considered. We obtain results both from an analytic treatment
and numerical one that are in satisfactory agreement. These results are applied
to the initial phase of the tidal circularisation problem. We find that both
tides induced in the star and planet can lead to a significant decrease of the
orbital semi-major axis for orbits having periastron distances smaller than 5-6
stellar radii (corresponding to periods days after the
circularisation has been completed) with tides in the star being much stronger
for retrograde orbits compared to prograde orbits. We use the simple Skumanich
law for the stellar rotation with its rotational period equal to one month at
the age of 5Gyr. The strength of tidal interactions is characterised by
circularisation time scale, defined as a time scale of evolution of
the planet's semi-major axis due to tides considered as a function of orbital
period after the process of tidal circularisation has been completed.
We find that the ratio of the initial circularisation time scales corresponding
to prograde and retrograde orbits is of order 1.5-2 for a planet of one Jupiter
mass and four days. It grows with the mass of the planet, being
of order five for a five Jupiter mass planet with the same . Thus, the
effect of stellar rotation may provide a bias in the formation of planetary
systems having planets on close orbits around their host stars, as a
consequence of planet-planet scattering, favouring systems with retrograde
orbits. The results may also be applied to the problem of tidal capture of
stars in young stellar clusters.Comment: to be published in Celestial Mechanics and Dynamical Astronom
Selectivity and functional diversity in arbuscular mycorrhizas of co-occurring fungi and plants from a temperate deciduous woodland
1 The arbuscular mycorrhizal (AM) fungi colonizing plants at a woodland site in North Yorkshire (UK) have been characterized from the roots of five plant species (Rubus fruticosus agg. L., Epilobium angustifolium L., Acer pseudoplatanus L., Ajuga reptans L. and Glechoma hederacea L.), and identified using small-subunit rRNA (SSUrRNA) gene amplification and sequencing. 2 Interactions between five plant species from the site and four co-occurring glomalean fungi were investigated in artificial one-to-one AM symbioses. Three of the fungi were isolated from the site; the fourth was a culture genetically similar to a taxon found at the site. Phosphorus uptake and growth responses were compared with non-mycorrhizal controls. 3 Individual fungi colonized each plant with different spatial distribution and intensity. Some did not colonize at all, indicating incompatibility under the conditions used in the experiments. 4 Glomus hoi consistently occupied a large proportion of root systems and outperformed the other fungi, improving P uptake and enhancing the growth of four out of the five plant species. Only G. hoi colonized and increased P uptake in Acer pseudoplatanus, the host plant with which it associates almost exclusively under field conditions. Colonization of all plant species by Scutellospora dipurpurescens was sparse, and beneficial to only one of the host plants (Teucrium scorodonia). Archaeospora trappei and Glomus sp. UY1225 had variable effects on the host plants, conferring a range of P uptake and growth benefits on Lysimachia nummularia and T. scorodonia, increasing P uptake whilst not affecting biomass in Ajuga reptans and Glechoma hederacea, and failing to form mycorrhizas with A. pseudoplatanus. 5 These experimental mycorrhizas show that root colonization, symbiont compatibility and plant performance vary with each fungus-plant combination, even when the plants and fungi naturally co-exist. 6 We provide evidence of physical and functional selectivity in AM. The small number of described AM fungal species (154) has been ascribed to their supposed lack of host specificity, but if the selectivity we have observed is the general rule, then we may predict that many more, probably hard-to-culture glomalean species await discovery, or that members of species as currently perceived may be physiologically or functionally distinct
The reaction center triplet state of the photosynthetic bacterium Rhodobacter sphaeroides R26: Electron spin echo spectroscopy of a single crystal
Transitions in the Horizontal Transport of Vertically Vibrated Granular Layers
Motivated by recent advances in the investigation of fluctuation-driven
ratchets and flows in excited granular media, we have carried out experimental
and simulational studies to explore the horizontal transport of granular
particles in a vertically vibrated system whose base has a sawtooth-shaped
profile. The resulting material flow exhibits novel collective behavior, both
as a function of the number of layers of particles and the driving frequency;
in particular, under certain conditions, increasing the layer thickness leads
to a reversal of the current, while the onset of transport as a function of
frequency occurs gradually in a manner reminiscent of a phase transition. Our
experimental findings are interpreted here with the help of extensive, event
driven Molecular Dynamics simulations. In addition to reproducing the
experimental results, the simulations revealed that the current may be reversed
as a function of the driving frequency as well. We also give details about the
simulations so that similar numerical studies can be carried out in a more
straightforward manner in the future.Comment: 12 pages, 18 figure
Interacting entropy-corrected holographic dark energy with apparent horizon as an infrared cutoff
In this work we consider the entropy-corrected version of interacting
holographic dark energy (HDE), in the non-flat universe enclosed by apparent
horizon. Two corrections of entropy so-called logarithmic 'LEC' and power-law
'PLEC' in HDE model with apparent horizon as an IR-cutoff are studied. The
ratio of dark matter to dark energy densities , equation of state parameter
and deceleration parameter are obtained. We show that the cosmic
coincidence is satisfied for both interacting models. By studying the effect of
interaction in EoS parameter, we see that the phantom divide may be crossed and
also find that the interacting models can drive an acceleration expansion at
the present and future, while in non-interacting case, this expansion can
happen only at the early time. The graphs of deceleration parameter for
interacting models, show that the present acceleration expansion is preceded by
a sufficiently long period deceleration at past. Moreover, the thermodynamical
interpretation of interaction between LECHDE and dark matter is described. We
obtain a relation between the interaction term of dark components and thermal
fluctuation in a non-flat universe, bounded by the apparent horizon. In
limiting case, for ordinary HDE, the relation of interaction term versus
thermal fluctuation is also calculated.Comment: 20 pages, 8 figures, figures changed, some Ref. is added, changed
some sentences, accepted by General relativity and gravitation (GERG
Cosmological Evolution Across Phantom Crossing and the Nature of the Horizon
In standard cosmology, with the evolution of the universe, the matter density
and thermodynamic pressure gradually decreases. Also in course of evolution,
the matter in the universe obeys (or violates) some restrictions or energy
conditions. If the matter distribution obeys strong energy condition (SEC), the
universe is in a decelerating phase while violation of SEC indicates an
accelerated expansion of the universe. In the period of accelerated expansion
the matter may be either of quintessence nature or of phantom nature depending
on the fulfilment of the weak energy condition (WEC) or violation of it. As
recent observational evidences demand that the universe is going through an
accelerated expansion so mater should be either quintessence or phantom in
nature. In the present work we study the evolution of the universe through the
phantom barrier (i.e. the dividing line between the quintessence and phantom
era) and examine how apparent and event horizon change across the barrier.
Finally, we investigate the possibility of occurrence of any singularity in
phantom era.Comment: 7 pages and 4 figure
Phase Diagram of the Heisenberg Spin Ladder with Ring Exchange
We investigate the phase diagram of a generalized spin-1/2 quantum
antiferromagnet on a ladder with rung, leg, diagonal, and ring-exchange
interactions. We consider the exactly soluble models associated with the
problem, obtain the exact ground states which exist for certain parameter
regimes, and apply a variety of perturbative techniques in the regime of strong
ring-exchange coupling. By combining these approaches with considerations
related to the discrete Z_4 symmetry of the model, we present the complete
phase diagram.Comment: 17 pages, 10 figure
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