Constitutive Expressor of Pathogenesis-Related Genes5 affects cell wall biogenesis and trichome development

<p>Abstract</p> <p>Background</p> <p>The Arabidopsis thaliana <it>CONSTITUTIVE EXPRESSOR OF PATHOGENESIS-RELATED GENES5 </it>(<it>CPR5</it>) gene has been previously implicated in disease resistance, cell proliferation, cell death, and sugar sensing, and encodes a putative membrane protein of unknown biochemical function. Trichome development is also affected in <it>cpr5 </it>plants, which have leaf trichomes that are reduced in size and branch number.</p> <p>Results</p> <p>In the work presented here, the role of <it>CPR5 </it>in trichome development was examined. Trichomes on <it>cpr5 </it>mutants had reduced birefringence, suggesting a difference in cell wall structure between <it>cpr5 </it>and wild-type trichomes. Consistent with this, leaf cell walls of <it>cpr5 </it>plants contained significantly less paracrystalline cellulose and had an altered wall carbohydrate composition. We also found that the effects of <it>cpr5 </it>on trichome size and endoreplication of trichome nuclear DNA were epistatic to the effects of mutations in <it>triptychon </it>(<it>try</it>) or overexpression of <it>GLABRA3</it>, indicating that these trichome developmental regulators are dependant on <it>CPR5 </it>function for their effects on trichome expansion and endoreplication.</p> <p>Conclusion</p> <p>Our results suggest that <it>CPR5 </it>is unlikely to be a specific regulator of pathogen response pathways or senescence, but rather functions either in cell wall biogenesis or in multiple cell signaling or transcription response pathways.</p

SIAMESE cooperates with the CDH1-like protein CCS52A1 to establish endoreplication in Arabidopsis thaliana trichomes

Endoreplication, also known as endoreduplication, is a phyogenetically widespread modified version of the cell cycle in which DNA replication is not followed by cell division. The SIAMESE (SIM) gene of Arabidopsis thaliana encodes the founding member of a novel class of plant-specific cyclin-dependent kinase (CDK) inhibitors and is a key regulator of endoreplication during the development of trichomes (shoot epidermal hairs). Here, we have identified mutations in the CCS52A1 gene as genetic modifiers of the multicellular trichome phenotype of sim mutants. Loss-of-function ccs52A1 mutations dramatically enhance the multicellularity of sim mutants trichomes in double mutants, whereas overexpression of CCS52A1 completely suppresses the sim mutant phenotype. CCS52A1 encodes a CDH1/FZR-like protein, a class of proteins that function as activators of the anaphase-promoting complex. Unicellular ccs52A1 trichomes become multicellular upon overexpression of B-type cyclin, consistent with repression of the accumulation of mitotic cyclins in the developing trichome by CCS52A1. As these M-phase-specific cyclins are known to accumulate in sim mutant trichomes, our data suggest that CCS52A1 and SIM cooperate in repressing accumulation of mitotic cyclins to establish the trichome endocycle. Comparison with endoreplication pathways in Drosophila and mammals indicates that while these organisms all use similar components to initiate endoreplication, the components are deployed differently in each organism. Copyright © 2010 by the Genetics Society of America

BRANCHLESS TRICHOMES links cell shape and cell cycle control in Arabidopsis trichomes

Endoreplication, also called endoreduplication, is a modified cell cycle in which DNA is repeatedly replicated without subsequent cell division. Endoreplication is often associated with increased cell size and specialized cell shapes, but the mechanism coordinating DNA content with shape and size remains obscure. Here we identify the product of the BRANCHLESS TRICHOMES (BLT) gene, a protein of hitherto unknown function that has been conserved throughout angiosperm evolution, as a link in coordinating cell shape and nuclear DNA content in endoreplicated Arabidopsis trichomes. Loss-of-function mutations in BLT were found to enhance the multicellular trichome phenotype of mutants in the SIAMESE (SIM) gene, which encodes a repressor of endoreplication. Epistasis and overexpression experiments revealed that BLT encodes a key regulator of trichome branching. Additional experiments showed that BLT interacts both genetically and physically with STICHEL, another key regulator of trichome branching. Although blt mutants have normal trichome DNA content, overexpression of BLT results in an additional round of endoreplication, and blt mutants uncouple DNA content from morphogenesis in mutants with increased trichome branching, further emphasizing its role in linking cell shape and endoreplication. © 2011. Published by The Company of Biologists Ltd

Functional conservation in the SIAMESE-RELATED family of cyclin-dependent kinase inhibitors in land plants

© 2015 American Society of Plant Biologists. All rights reserved. The best-characterized members of the plant-specific SIAMESE-RELATED (SMR) family of cyclin-dependent kinase inhibitors regulate the transition from the mitotic cell cycle to endoreplication, also known as endoreduplication, an altered version of the cell cycle in which DNA is replicated without cell division. Some other family members are implicated in cell cycle responses to biotic and abiotic stresses. However, the functions of most SMRs remain unknown, and the specific cyclin- dependent kinase complexes inhibited by SMRs are unclear. Here, we demonstrate that a diverse group of SMRs, including an SMR from the bryophyte Physcomitrella patens, can complement an Arabidopsis thaliana siamese (sim) mutant and that both Arabidopsis SIM and P. patens SMR can inhibit CDK activity in vitro. Furthermore, we show that Arabidopsis SIM can bind to and inhibit both CDKA;1 and CDKB1;1. Finally, we show that SMR2 acts to restrict cell proliferation during leaf growth in Arabidopsis and that SIM, SMR1/LGO, and SMR2 play overlapping roles in controlling the transition from cell division to endoreplication during leaf development. These results indicate that differences in SMR function in plant growth and development are primarily due to differences in transcriptional and posttranscriptional regulation, rather than to differences in fundamental biochemical function

Galaxy Zoo: CANDELS barred discs and bar fractions

The formation of bars in disc galaxies is a tracer of the dynamical maturity of the population. Previous studies have found that the incidence of bars in discs decreases from the local Universe to z ~ 1, and by z > 1 simulations predict that bar features in dynamically mature discs should be extremely rare. Here, we report the discovery of strong barred structures in massive disc galaxies at z ~ 1.5 in deep rest-frame optical images from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey. From within a sample of 876 disc galaxies identified by visual classification in Galaxy Zoo, we identify 123 barred galaxies. Selecting a subsample within the same region of the evolving galaxy luminosity function (brighter than L*), we find that the bar fraction across the redshift range 0.5 ≤ z ≤ 2 (fbar = 10.7+6.3 -3.5 per cent after correcting for incompleteness) does not significantly evolve.We discuss the implications of this discovery in the context of existing simulations and our current understanding of the way disc galaxies have evolved over the last 11 billion yearsPeer reviewedFinal Accepted Versio

Joint hypermobility links neurodivergence to dysautonomia and pain

Objectives: Autism, attention deficit hyperactivity disorder (ADHD), and tic disorder (Tourette syndrome; TS) are neurodevelopmental conditions that frequently co-occur and impact psychological, social, and emotional processes. Increased likelihood of chronic physical symptoms, including fatigue and pain, are also recognized. The expression of joint hypermobility, reflecting a constitutional variant in connective tissue, predicts susceptibility to psychological symptoms alongside recognized physical symptoms. Here, we tested for increased prevalence of joint hypermobility, autonomic dysfunction, and musculoskeletal symptoms in 109 adults with neurodevelopmental condition diagnoses. Methods: Rates of generalized joint hypermobility (GJH, henceforth hypermobility) in adults with a formal diagnosis of neurodevelopmental conditions (henceforth neurodivergent group, n = 109) were compared to those in the general population in UK. Levels of orthostatic intolerance and musculoskeletal symptoms were compared to a separate comparison group (n = 57). Age specific cut-offs for GJH were possible to determine in the neurodivergent and comparison group only. Results: The neurodivergent group manifested elevated prevalence of hypermobility (51%) compared to the general population rate of 20% and a comparison population (17.5%). Using a more stringent age specific cut-off, in the neurodivergent group this prevalence was 28.4%, more than double than the comparison group (12.5%). Odds ratio for presence of hypermobility in neurodivergent group, compared to the general population was 4.51 (95% CI 2.17–9.37), with greater odds in females than males. Using age specific cut-off, the odds ratio for GJH in neurodivergent group, compared to the comparison group, was 2.84 (95% CI 1.16–6.94). Neurodivergent participants reported significantly more symptoms of orthostatic intolerance and musculoskeletal skeletal pain than the comparison group. The number of hypermobile joints was found to mediate the relationship between neurodivergence and symptoms of both dysautonomia and pain. Conclusions: In neurodivergent adults, there is a strong link between the expression of joint hypermobility, dysautonomia, and pain, more so than in the comparison group. Moreover, joint hypermobility mediates the link between neurodivergence and symptoms of dysautonomia and pain. Increased awareness and understanding of this association may enhance the management of core symptoms and allied difficulties in neurodivergent people, including co-occurring physical symptoms, and guide service delivery in the future

The Astropy Problem

The Astropy Project (http://astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Despite this, the project has always been and remains to this day effectively unfunded. Further, contributors receive little or no formal recognition for creating and supporting what is now critical software. This paper explores the problem in detail, outlines possible solutions to correct this, and presents a few suggestions on how to address the sustainability of general purpose astronomical software

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

Galaxy Zoo: CANDELS barred discs and bar fractions

The formation of bars in disc galaxies is a tracer of the dynamical maturity of the population. Previous studies have found that the incidence of bars in discs decreases from the local Universe to z ∼ 1, and by z>1 simulations predict that bar features in dynamically mature discs should be extremely rare. Here, we report the discovery of strong barred structures in massive disc galaxies at z ∼ 1.5 in deep rest-frame optical images from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey. From within a sample of 876 disc galaxies identified by visual classification in Galaxy Zoo, we identify 123 barred galaxies. Selecting a subsample within the same region of the evolving galaxy luminosity function (brighter than L*), we find that the bar fraction across the redshift range 0.5 ≤ z ≤ 2 ( $f_{{\rm bar}} = 10.7^{+6.3}_{-3.5}$ per cent after correcting for incompleteness) does not significantly evolve. We discuss the implications of this discovery in the context of existing simulations and our current understanding of the way disc galaxies have evolved over the last 11 billion year