90 research outputs found
Not for You ; Only for Ticketmaster: Do Ticketmaster\u27s Exclusive Agreements with Concert Venues Violate Federal Antitrust Law?
Quantitative predictions on auxin-induced polar distribution of PIN proteins during vein formation in leaves
The dynamic patterning of the plant hormone auxin and its efflux facilitator
the PIN protein are the key regulator for the spatial and temporal organization
of plant development. In particular auxin induces the polar localization of its
own efflux facilitator. Due to this positive feedback auxin flow is directed
and patterns of auxin and PIN arise. During the earliest stage of vein
initiation in leaves auxin accumulates in a single cell in a rim of epidermal
cells from which it flows into the ground meristem tissue of the leaf blade.
There the localized auxin supply yields the successive polarization of PIN
distribution along a strand of cells. We model the auxin and PIN dynamics
within cells with a minimal canalization model. Solving the model analytically
we uncover an excitable polarization front that triggers a polar distribution
of PIN proteins in cells. As polarization fronts may extend to opposing
directions from their initiation site we suggest a possible resolution to the
puzzling occurrence of bipolar cells, such we offer an explanation for the
development of closed, looped veins. Employing non-linear analysis we identify
the role of the contributing microscopic processes during polarization.
Furthermore, we deduce quantitative predictions on polarization fronts
establishing a route to determine the up to now largely unknown kinetic rates
of auxin and PIN dynamics.Comment: 9 pages, 4 figures, supplemental information included, accepted for
publication in Eur. Phys. J.
Quantifying loopy network architectures
Biology presents many examples of planar distribution and structural networks
having dense sets of closed loops. An archetype of this form of network
organization is the vasculature of dicotyledonous leaves, which showcases a
hierarchically-nested architecture containing closed loops at many different
levels. Although a number of methods have been proposed to measure aspects of
the structure of such networks, a robust metric to quantify their hierarchical
organization is still lacking. We present an algorithmic framework, the
hierarchical loop decomposition, that allows mapping loopy networks to binary
trees, preserving in the connectivity of the trees the architecture of the
original graph. We apply this framework to investigate computer generated
graphs, such as artificial models and optimal distribution networks, as well as
natural graphs extracted from digitized images of dicotyledonous leaves and
vasculature of rat cerebral neocortex. We calculate various metrics based on
the Asymmetry, the cumulative size distribution and the Strahler bifurcation
ratios of the corresponding trees and discuss the relationship of these
quantities to the architectural organization of the original graphs. This
algorithmic framework decouples the geometric information (exact location of
edges and nodes) from the metric topology (connectivity and edge weight) and it
ultimately allows us to perform a quantitative statistical comparison between
predictions of theoretical models and naturally occurring loopy graphs.Comment: 17 pages, 8 figures. During preparation of this manuscript the
authors became aware of the work of Mileyko at al., concurrently submitted
for publicatio
A Computational Clonal Analysis of the Developing Mouse Limb Bud
A comprehensive spatio-temporal description of the tissue movements underlying organogenesis would be an extremely useful resource to developmental biology. Clonal analysis and fate mappings are popular experiments to study tissue movement during morphogenesis. Such experiments allow cell populations to be labeled at an early stage of development and to follow their spatial evolution over time. However, disentangling the cumulative effects of the multiple events responsible for the expansion of the labeled cell population is not always straightforward. To overcome this problem, we develop a novel computational method that combines accurate quantification of 2D limb bud morphologies and growth modeling to analyze mouse clonal data of early limb development. Firstly, we explore various tissue movements that match experimental limb bud shape changes. Secondly, by comparing computational clones with newly generated mouse clonal data we are able to choose and characterize the tissue movement map that better matches experimental data. Our computational analysis produces for the first time a two dimensional model of limb growth based on experimental data that can be used to better characterize limb tissue movement in space and time. The model shows that the distribution and shapes of clones can be described as a combination of anisotropic growth with isotropic cell mixing, without the need for lineage compartmentalization along the AP and PD axis. Lastly, we show that this comprehensive description can be used to reassess spatio-temporal gene regulations taking tissue movement into account and to investigate PD patterning hypothesis
Detection of a novel gammaherpesvirus (genus Rhadinovirus) in wild muntjac deer in Northern Ireland
This study represents the initial part of an investigation into the potential for non-native, wild, free-living muntjac deer (Muntiacus reevesi) to carry viruses that could be a threat to livestock. A degenerate PCR assay was used to screen a range of tissues from muntjac deer culled in Northern Ireland for the presence of herpesviral nucleic acids. This was followed by sequencing of PCR amplicons and phylogenetic analysis. We report the detection of a novel gammaherpesvirus most closely related to a type 2 ruminant rhadinovirus from mule deer. It remains to be determined if this new virus is pathogenic to deer or presents a risk to food security through the susceptibility of domestic livestock
Clinic-epidemiological evaluation of ulcers in patients with leprosy sequelae and the effect of low level laser therapy on wound healing: a randomized clinical trial
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Urinary tract infections and antibiotic use in pregnancy - qualitative analysis of online forum content
Background Antibiotics are standard treatment for asymptomatic and symptomatic urinary tract infections (UTIs) in pregnancy. Their overuse, however, can contribute to antimicrobial resistance (AMR) and expose the foetus to drugs that might affect its development. Preventative behaviours are currently the best option to reduce incidences of UTIs and to avoid the use of antibiotics in pregnancy. The aim of this study was to explore women’s experiences of UTIs in pregnancy to develop an understanding of their concerns and to optimise and encourage behaviours that facilitate appropriate use of antibiotics.
Methods
An online pregnancy forum in the United Kingdom (UK) was used to collect data on women’s discussions of UTIs. A total of 202 individual threads generated by 675 different usernames were selected for analysis. The data was organised using NVivo 11® software and then analysed qualitatively using inductive thematic analysis.
Results
Women’s perceptions of UTIs and antibiotic use in pregnancy were driven by their pre-natal attachment to the foetus. UTIs were thought to be common and high risk in pregnancy, which meant that antibiotics were viewed as essential in the presence of suspected symptoms. The dominant view about antibiotics was that their use was safe and of little concern in pregnancy. Women reported an emotional reaction to developing a UTI. They coped by seeking information about behaviour change strategies to assist with recovery and through emotional support from the online forum.
Conclusions
Women face dual risks when they experience UTIs; the risk from the infection and the risk from antibiotic treatment. Pre-natal attachment to the foetus is highlighted in the decision making process. The focus is on the shorter term risk from UTIs while undermining the longer term risks from antibiotic use, especially the risk of AMR. A balanced view needs to be presented, and evidence-based infection prevention strategies should be promoted, to women to ensure appropriate antibiotic use in pregnancy, to address the global challenge of AMR
Genetic Control of Organ Shape and Tissue Polarity
A combination of experimental analysis and mathematical modelling shows how the genetic control of tissue polarity plays a fundamental role in the development and evolution of form
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