246 research outputs found
Aquaporin gene expression and apoplastic water flow in bur oak (Quercus macrocarpa) leaves in relation to the light response of leaf hydraulic conductance
It has previously been shown that hydraulic conductance in bur oak leaves (Quercus macrocarpa Michx.), measured with the high pressure flow meter technique (HPFM), can significantly increase within 30 min following exposure to high irradiance. The present study investigated whether this increase could be explained by an increase in the cell-to-cell pathway and whether the response is linked to changes in the transcript level corresponding to aquaporin genes. Four cDNA sequences showing high similarity to members of the aquaporin gene family from other plant species were characterized from bur oak leaves and the expression levels of these cDNA sequences were examined in leaves by quantitative real-time PCR (QRT-PCR). No change was found in the relative transcript abundance corresponding to these four putative aquaporin genes in leaves with light-induced high hydraulic conductance (exposed to high irradiance) compared to leaves with low hydraulic conductance (exposed to low irradiance). However, in sun leaves that were exposed to different light levels prior to leaf collection (full sunlight, shade, and covered with aluminium foil for 16 h), the relative transcript levels of two of the putative aquaporin genes increased several-fold in shaded leaves compared to the sun-exposed or covered leaves. When the leaves were pressure-infiltrated with the apoplastic tracer dye trisodium 3-hydroxy-5,8,10-pyrenetrisulphonate (PTS3, 0.02%), there was no change in the PTS3 concentration of leaf exudates collected in ambient light or in high irradiance, but there was a small apoplastic acidification. There was also no change in PTS3 concentration between the leaves infiltrated under high irradiance with 0.02% PTS3 or with 0.1 mM HgCl2 in 0.02% PTS3. The results suggest that the putative aquaporin genes that were identified in the present study probably do not play a role in the light responses of hydraulic conductance at the transcript level, but they may function in regulating water homeostasis in leaves adapted to different light conditions. In addition, it is shown that high irradiance induced changes in the pH of the apoplast and that there does not appear to be a significant shift to the cell-to-cell mediated water transport in bur oak leaves exposed to high irradiance as measured by the apoplastic tracer dye
NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array
NectarCAM is a camera proposed for the medium-sized telescopes of the
Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV
to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the
heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog
to Digital converter. The camera will be equipped with 265 7-photomultiplier
modules, covering a field of view of 8 degrees. Each module includes the
photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and
Ethernet transceiver. The recorded events last between a few nanoseconds and
tens of nanoseconds. The camera trigger will be flexible so as to minimize the
read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data
rate of more than 4 kHz with less than 5\% dead time. The camera concept, the
design and tests of the various subcomponents and results of thermal and
electrical prototypes are presented. The design includes the mechanical
structure, cooling of the electronics, read-out, clock distribution, slow
control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter
We present a study of showers initiated by electrons, pions, kaons, and
protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE
scintillator-tungsten analogue hadronic calorimeter. The data were recorded at
the CERN Super Proton Synchrotron in 2011. The analysis includes measurements
of the calorimeter response to each particle type as well as measurements of
the energy resolution and studies of the longitudinal and radial shower
development for selected particles. The results are compared to Geant4
simulations (version 9.6.p02). In the study of the energy resolution we include
previously published data with beam momenta from 1 GeV to 10 GeV recorded at
the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
The spatial development of hadronic showers in the CALICE scintillator-steel
analogue hadron calorimeter is studied using test beam data collected at CERN
and FNAL for single positive pions and protons with initial momenta in the
range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron
showers are parametrised with two-component functions. The parametrisation is
fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics
lists from Geant4 version 9.6. The parameters extracted from data and simulated
samples are compared for the two types of hadrons. The response to pions and
the ratio of the non-electromagnetic to the electromagnetic calorimeter
response, h/e, are estimated using the extrapolation and decomposition of the
longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to
JINS
Reproducibility of measurements of potential doubling time of tumour cells in the multicentre National Cancer Institute protocol T92-0045
We compared the flow cytometric measurement and analysis of the potential doubling time (Tpot) between three centres involved in the National Cancer Institute (NCI) protocol T92-0045. The primary purpose was to understand and minimize the variation within the measurement. A total of 102 specimens were selected at random from patients entered into the trial. Samples were prepared, stained, run and analysed in each centre and a single set of data analysed by all three centres. Analysis of the disc data set revealed that the measurement of labelling index (LI) was robust and reproducible. The estimation of duration of S-phase (Ts) was subject to errors of profile interpretation, particularly DNA ploidy status, and analysis. The LI dominated the variation in Tpot such that the level of final agreement, after removal of outliers and ploidy agreement, reached correlation coefficients of 0.9. The sample data showed poor agreement within each of the components of the measurement. There was some improvement when ploidy was in agreement, but correlation coefficients failed to exceed values of 0.5 for Tpot. The data suggest that observer-associated analysis of Ts and tissue processing and tumour heterogeneity were the major causes of variability in the Tpot measurement. The first two aspects can be standardized and minimized, but heterogeneity will remain a problem with biopsy techniques. © 1999 Cancer Research Campaig
In Vitro vs In Silico Detected SNPs for the Development of a Genotyping Array: What Can We Learn from a Non-Model Species?
Background: There is considerable interest in the high-throughput discovery and genotyping of single nucleotide polymorphisms (SNPs) to accelerate genetic mapping and enable association studies. This study provides an assessment of EST-derived and resequencing-derived SNP quality in maritime pine (Pinus pinaster Ait.), a conifer characterized by a huge genome size (~23.8 Gb/C). [br/]
Methodology/Principal Findings: A 384-SNPs GoldenGate genotyping array was built from i/ 184 SNPs originally detected in a set of 40 re-sequenced candidate genes (in vitro SNPs), chosen on the basis of functionality scores, presence of neighboring polymorphisms, minor allele frequencies and linkage disequilibrium and ii/ 200 SNPs screened from ESTs (in silico SNPs) selected based on the number of ESTs used for SNP detection, the SNP minor allele frequency and the quality of SNP flanking sequences. The global success rate of the assay was 66.9%, and a conversion rate (considering only polymorphic SNPs) of 51% was achieved. In vitro SNPs showed significantly higher genotyping-success and conversion rates than in silico SNPs (+11.5% and +18.5%, respectively). The reproducibility was 100%, and the genotyping error rate very low (0.54%, dropping down to 0.06% when removing four SNPs showing elevated error rates). [br/]
Conclusions/Significance: This study demonstrates that ESTs provide a resource for SNP identification in non-model species, which do not require any additional bench work and little bio-informatics analysis. However, the time and cost benefits of in silico SNPs are counterbalanced by a lower conversion rate than in vitro SNPs. This drawback is acceptable for population-based experiments, but could be dramatic in experiments involving samples from narrow genetic backgrounds. In addition, we showed that both the visual inspection of genotyping clusters and the estimation of a per SNP error rate should help identify markers that are not suitable to the GoldenGate technology in species characterized by a large and complex genome
High-throughput SNP genotyping in the highly heterozygous genome of Eucalyptus: assay success, polymorphism and transferability across species
<p>Abstract</p> <p>Background</p> <p>High-throughput SNP genotyping has become an essential requirement for molecular breeding and population genomics studies in plant species. Large scale SNP developments have been reported for several mainstream crops. A growing interest now exists to expand the speed and resolution of genetic analysis to outbred species with highly heterozygous genomes. When nucleotide diversity is high, a refined diagnosis of the target SNP sequence context is needed to convert queried SNPs into high-quality genotypes using the Golden Gate Genotyping Technology (GGGT). This issue becomes exacerbated when attempting to transfer SNPs across species, a scarcely explored topic in plants, and likely to become significant for population genomics and inter specific breeding applications in less domesticated and less funded plant genera.</p> <p>Results</p> <p>We have successfully developed the first set of 768 SNPs assayed by the GGGT for the highly heterozygous genome of <it>Eucalyptus </it>from a mixed Sanger/454 database with 1,164,695 ESTs and the preliminary 4.5X draft genome sequence for <it>E. grandis</it>. A systematic assessment of <it>in silico </it>SNP filtering requirements showed that stringent constraints on the SNP surrounding sequences have a significant impact on SNP genotyping performance and polymorphism. SNP assay success was high for the 288 SNPs selected with more rigorous <it>in silico </it>constraints; 93% of them provided high quality genotype calls and 71% of them were polymorphic in a diverse panel of 96 individuals of five different species.</p> <p>SNP reliability was high across nine <it>Eucalyptus </it>species belonging to three sections within subgenus Symphomyrtus and still satisfactory across species of two additional subgenera, although polymorphism declined as phylogenetic distance increased.</p> <p>Conclusions</p> <p>This study indicates that the GGGT performs well both within and across species of <it>Eucalyptus </it>notwithstanding its nucleotide diversity ≥2%. The development of a much larger array of informative SNPs across multiple <it>Eucalyptus </it>species is feasible, although strongly dependent on having a representative and sufficiently deep collection of sequences from many individuals of each target species. A higher density SNP platform will be instrumental to undertake genome-wide phylogenetic and population genomics studies and to implement molecular breeding by Genomic Selection in <it>Eucalyptus</it>.</p
A modified Inflammatory Bowel Disease questionnaire and the Vaizey Incontinence questionnaire are simple ways to identify patients with significant gastrointestinal symptoms after pelvic radiotherapy
After radiotherapy for pelvic cancer, chronic gastrointestinal problems may affect quality of life (QOL) in 6–78% of patients. This variation may be due to true differences in outcome in different diseases, and may also represent the inadequacy of the scales used to measure radiotherapy-induced gastrointestinal side effects. The aim of this study was to assess whether outcome measures used for nonmalignant gastrointestinal disease are useful to detect gastrointestinal morbidity after radiotherapy. Results obtained from a Vaizey Incontinence questionnaire and a modified Inflammatory Bowel Disease questionnaire (IBDQ) – both patient completed – were compared to those from a staff administered Late Effects on Normal Tissue (LENT) – Subjective, Objective, Management and Analytic (SOMA) questionnaire in patients who had completed radiotherapy for a pelvic tumour at least 3 months previously. In all, 142 consecutive patients were recruited, 72 male and 70 female, median age 66 years (range 26–90 years), a median of 27 (range 3–258) months after radiotherapy. In total, 62 had been treated for a gynaecological, 58, a urological and 22, a gastrointestinal tract tumour. Of these, 21 had undergone previous gastrointestinal surgery and seven suffered chronic gastrointestinal disorders preceding their diagnosis of cancer. The Vaizey questionnaire suggested that 27% patients were incontinent for solid stools, 35% for liquid stools and 37% could not defer defaecation for 15 min. The IBDQ suggested that 89% had developed a chronic change in bowel habit and this change significantly affected 49% patients: 44% had more frequent or looser bowel movements, 30% were troubled by abdominal pain, 30% were troubled by bloating, 28% complained of tenesmus, 27% were troubled by their accidental soiling and 20% had rectal bleeding. At least 34% suffered emotional distress and 22% impairment of social function because of their bowels. The small intestine/colon SOMA median score was 0.1538 (range 0–1) and the rectal SOMA median score was 0.1428 (range 0–1). Pearson's correlations for the IBDQ score and small intestine/colon SOMA score was −0.630 (P<0.001), IBDQ and rectum SOMA −0.616 (P<0.001), IBDQ and Vaizey scores −0.599 (P<0.001), Vaizey and small intestine/colon SOMA 0.452 (P<0.001) and Vaizey and rectum SOMA 0.760 (P<0.001). After radiotherapy for a tumour in the pelvis, half of all patients develop gastrointestinal morbidity, which affects their QOL. A modified IBDQ and Vaizey questionnaire are reliable in assessing new gastrointestinal symptoms as well as overall QOL and are much easier to use than LENT SOMA
The late radiotherapy normal tissue injury phenotypes of telangiectasia, fibrosis and atrophy in breast cancer patients have distinct genotype-dependent causes
The relationship between late normal tissue radiation injury phenotypes in 167 breast cancer patients treated with radiotherapy and: (i) radiotherapy dose (boost); (ii) an early acute radiation reaction and (iii) genetic background was examined. Patients were genotyped at single nucleotide polymorphisms (SNPs) in eight candidate genes. An early acute reaction to radiation and/or the inheritance of the transforming growth factor-β1 (TGFβ1 −509T) SNP contributed to the risk of fibrosis. In contrast, an additional 15 Gy electron boost and/or the inheritance of X-ray repair cross-complementing 1 (XRCC1) (R399Q) SNP contributed to the risk of telangiectasia. Although fibrosis, telangiectasia and atrophy, all contribute to late radiation injury, the data suggest that they have distinct underlying genetic and radiobiological causes. Fibrosis risk is associated with an inflammatory response (an acute reaction and/or TGFβ1), whereas telangiectasia is associated with vascular endothelial cell damage (boost and/or XRCC1). Atrophy is associated with an acute response, but the genetic predisposing factors that determine the risk of an acute response or atrophy have yet to be identified. A combined analysis of two UK breast cancer patient studies shows that 8% of patients are homozygous (TT) for the TGFβ1 (C-509T) variant allele and have a 15-fold increased risk of fibrosis following radiotherapy (95% confidence interval: 3.76–60.3; P=0.000003) compared with (CC) homozygotes
Involvement of Pinus taeda MYB1 and MYB8 in phenylpropanoid metabolism and secondary cell wall biogenesis: a comparative in planta analysis
The involvement of two R2R3-MYB genes from Pinus taeda L., PtMYB1 and PtMYB8, in phenylpropanoid metabolism and secondary cell wall biogenesis was investigated in planta. These pine MYBs were constitutively overexpressed (OE) in Picea glauca (Moench) Voss, used as a heterologous conifer expression system. Morphological, histological, chemical (lignin and soluble phenols), and transcriptional analyses, i.e. microarray and reverse transcription quantitative PCR (RT-qPCR) were used for extensive phenotyping of MYB-overexpressing spruce plantlets. Upon germination of somatic embryos, root growth was reduced in both transgenics. Enhanced lignin deposition was also a common feature but ectopic secondary cell wall deposition was more strongly associated with PtMYB8-OE. Microarray and RT-qPCR data showed that overexpression of each MYB led to an overlapping up-regulation of many genes encoding phenylpropanoid enzymes involved in lignin monomer synthesis, while misregulation of several cell wall-related genes and other MYB transcription factors was specifically associated with PtMYB8-OE. Together, the results suggest that MYB1 and MYB8 may be part of a conserved transcriptional network involved in secondary cell wall deposition in conifers
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