bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Transcriptional Cascade Regulating Expression of Heat Stress Proteins during Seed Development ofArabidopsis
Authors: Kotak Sachin , Vierling Elizabeth , Bäumlein Helmut , Koskull-Döring Pascal von 
Published: January 2007

AbstractWithin the Arabidopsis thaliana family of 21 heat stress transcription factors (Hsfs), HsfA9 is exclusively expressed in late stages of seed development. Here, we present evidence that developmental expression of HsfA9 is regulated by the seed-specific transcription factor ABSCISIC ACID–INSENSITIVE3 (ABI3). Intriguingly, ABI3 knockout lines lack detectable levels of HsfA9 transcript and protein, and further ectopic expression of ABI3 conferred the ability to accumulate HsfA9 in response to abscisic acid in transgenic plantlets. Consequently, the most abundant heat stress proteins (Hsps) in seeds (Hsp17.4-CI, Hsp17.7-CII, and Hsp101) were not detectable in the ABI3 knockout lines, but their expression could be detected in plants ectopically expressing HsfA9 in vegetative tissues. Furthermore, this seed-specific transcription factor cascade was reconstructed in transient β-glucuronidase reporter assays in mesophyll protoplasts by showing that ABI3 could activate the HsfA9 promoter, whereas HsfA9 in turn was shown to be a potent activator on the promoters of Hsp genes. Thus, our study establishes a genetic framework in which HsfA9 operates as a specialized Hsf for the developmental expression of Hsp genes during seed maturation.
Repression of Flowering inArabidopsisRequires Activation ofFLOWERING LOCUS CExpression by the Histone Variant H2A.Z
Authors: Deal Roger B. , Topp Christopher N. , McKinney Elizabeth C. , Meagher Richard B. 
Published: January 2007

AbstractThe histone variant H2A.Z has been implicated in numerous chromatin-mediated processes, including transcriptional activation, euchromatin maintenance, and heterochromatin formation. In yeast and humans, H2A.Z is deposited into chromatin by a conserved protein complex known as SWR1 and SRCAP, respectively. Here, we show that mutations in the Arabidopsis thaliana homologs of two components of this complex, ACTIN-RELATED PROTEIN6 (ARP6) and PHOTOPERIOD-INDEPENDENT EARLY FLOWERING1 (PIE1), produce similar developmental phenotypes and result in the misregulation of a common set of genes. Using H2A.Z-specific antibodies, we demonstrate that ARP6 and PIE1 are required for the deposition of H2A.Z at multiple loci, including the FLOWERING LOCUS C (FLC) gene, a central repressor of the transition to flowering. Loss of H2A.Z from chromatin in arp6 and pie1 mutants results in reduced FLC expression and premature flowering, indicating that this histone variant is required for high-level expression of FLC. In addition to defining a novel mechanism for the regulation of FLC expression, these results support the existence of a SWR1-like complex in Arabidopsis and show that H2A.Z can potentiate transcriptional activation in plants. The finding that H2A.Z remains associated with chromatin throughout mitosis suggests that it may serve an epigenetic memory function by marking active genes and poising silenced genes for reactivation.
The influence of below‐ground herbivory and defoliation of a legume on nitrogen transfer to neighbouring plants
Authors: AYRES E. , DROMPH K. M. , COOK R. , OSTLE N. , BARDGETT R. D. 
Published: January 2007

Summary

Both foliar and root herbivory can alter the exudation of carbon from plant roots, which in turn can affect nitrogen availability in the soil. However, few studies have investigated the effects of herbivory on N fluxes from roots, which can directly increase N availability in the soil and uptake by neighbouring plants. Moreover, the combined effects of foliar and root herbivory on N fluxes remains unexplored.
We subjected the legume white clover (Trifolium repens L.) to defoliation (through clipping) and root herbivory (by an obligate root‐feeding nematode, Heterodera trifolii Goggart) to examine how these stresses individually, and simultaneously, affected the transfer of T. repens‐derived N to neighbouring perennial ryegrass (Lolium perenne L.) plants using 15N stable‐isotope techniques. We also examined the effects of defoliation and root herbivory on the size of the soil microbial community and the growth response of L. perenne.
Neither defoliation nor root herbivory negatively affected T. repens biomass. On the contrary, defoliation increased root biomass (34%) and total shoot production by T. repens (100%). Furthermore, defoliation resulted in a fivefold increase in T. repens‐derived 15N recovered in L. perenne roots, and increased the size of the soil microbial biomass (77%). In contrast, root herbivory by H. trifolii slightly reduced 15N transfer from T. repens to L. perenne when T. repens root 15N concentration was included as a covariate, and root herbivory did not affect microbial biomass. Growth of L. perenne was not affected by any of the treatments.
Our findings demonstrate that defoliation of a common grassland legume can substantially increase the transfer of its N to neighbouring plants by directly affecting below‐ground N fluxes. These finding require further examination under field conditions but, given the prevalence of N‐limitation of plant productivity in terrestrial ecosystems, increased transfer of N from legumes to non‐N‐fixing species could alter competitive interactions, with implications for plant community structure.
Directly observed therapy and tuberculosis: how can a systematic review of qualitative research contribute to improving services? A qualitative meta‐synthesis
Authors: Noyes Jane , Popay Jennie 
Published: January 2007

Abstract Title. Directly observed therapy and tuberculosis: how can a systematic review of qualitative research contribute to improving services? A qualitative meta‐synthesis Aim.  This paper reports the findings from a qualitative meta‐synthesis concerning people with, or at risk of, tuberculosis, service providers and policymakers and their experiences and perceptions of tuberculosis and treatment.Background.  Directly observed therapy is part of a package of interventions to improve tuberculosis treatment and adherence. A Cochrane systematic review of trials showed an absence of evidence for or against directly observed therapy compared with people treating themselves.Method.  Qualitative systematic review methods were used to search, screen, appraise and extract data thematic analysis was used to synthesize data from 1990 to 2002, and an update of literature to December 2005. Two questions were addressed: ‘What does qualitative research tell us about the facilitators and barriers to accessing and complying with tuberculosis treatment?’ and ‘What does qualitative research tell us about the diverse results and effect sizes of the randomized controlled trials included in the Cochrane review?’ Findings help explain the diverse trial results in a Cochrane systematic review of directly observed therapy and tuberculosis and consider implications for research, policy and practice.Findings.  Five themes emerged from the 1990 to 2002 synthesis: socio‐economic circumstances, material resources and individual agency; explanatory models and knowledge systems in relation to tuberculosis and its treatment; the experience of stigma and public discourses around tuberculosis; sanctions, incentives and support, and the social organization and social relationships of care. Two additional themes emerged from the 2005 update.Conclusion.  The qualitative meta‐synthesis improved the relevance and scope of the Cochrane review of trials. The findings make a major contribution to the development of theory concerning global WHO‐branded disease control and the practicality of local delivery to people.
Temporal trends in the incidence of HIV infection in antenatal clinic attendees in Addis Ababa, Ethiopia, 1995–2003
Authors: Wolday D. , Meles H. , Hailu E. , Messele T. , Mengistu Y. , Fekadu M. , Parekh B. S. , Wuhib T. 
Published: January 2007

AbstractBackground.  The HIV incidence data are relevant in depicting the current dynamics and trend of the epidemic. Using a new laboratory method for HIV‐1 incidence, we aimed at estimating a 10‐year trend in HIV‐1 incidence in Addis Ababa, Ethiopia.Methods.  We determined the temporal trends in HIV incidence based on a total of 7744 serum specimens from pregnant women who attended antenatal clinics in Addis Ababa between 1995 and 2003. HIV incidence was determined by IgG‐capture HIV‐1 BED incidence enzyme immunoassay following a validation using a well‐characterized panel of serial serum specimens from subtype C‐infected seroconverters.Findings.  Of the 1350 HIV+ specimens tested as part of the annual sentinel survey between 1995 and 2003, a total of 1332 (98.7%) were tested by BED HIV‐1 incidence assay. The incidence rate of HIV‐1 infection declined significantly from 7.7% (95% CI, 3.9–11.5%) in 1995 to 2.0% (95% CI, 0.7–3.3%) in 2003. Although there was a trend, amongst the age group of 15–29 years, in age‐specific decline in incidence, it was not statistically significant. No change in HIV incidence rate was observed for the group aged above 30 years.Interpretation.  A corresponding decline in the incidence of HIV infection was observed with the decline in the prevalence of HIV infection between 1995 and 2003 in Addis Ababa City. Whether the declines were because of changes in sexual behaviours or other reasons needs to be explored. The BED HIV‐1 incidence assay provides a valuable tool in obtaining information on recent HIV‐1 infection.
Is susceptibility to severe infection in low‐income countries inherited or acquired?
Authors: Aaby P. 
Published: January 2007

Abstract.From a low‐income country perspective, we need to emphasize factors which affect acquired susceptibility to severe infection. Such factors may lend themselves to modification by public health interventions. The present paper reviews the experience with understanding the causes of severe measles infection and the impact of health interventions in Guinea‐Bissau over a 28‐year period. In the 1970s, acquired susceptibility because of malnutrition was considered to be the main cause of high mortality. However, we found no association between nutritional status and subsequent risk of dying of measles. Instead, crowding and intensity of exposure were the main determinants of severe measles. Factors related to transmission have been substantiated for measles, chickenpox, whooping cough and polio. We found measles vaccination to be associated with a major reduction in mortality, particularly for girls. This suggested that measles vaccine has a beneficial nontargeted immune stimulatory effect. The importance of nontargeted effects was clearly documented when World Health Organization introduced a new high‐titre measles vaccine (HTMV). HTMV was fully protective but associated with twofold higher mortality for girls. Bacille Calmette Guérin (BCG), diphtheria–tetanus–pertussis (DTP) and oral polio vaccine (OPV) have also shown nontargeted effects, the effect being beneficial for BCG and OPV but negative for DTP. Both beneficial and negative effects are strongest for girls. There are many acquired factors, which affect susceptibility to infection in ways which have not been explored by medical science. They may have a major impact on child survival in low‐income countries.
Mechanisms of exercise‐induced ST‐segment depression in patients without typical angina pectoris
Authors: Sundkvist G. M. G. , Hjemdahl P. , Kahan T. , Melcher A. 
Published: January 2007

Abstract.Objective.  To evaluate if exercise‐induced ST‐segment depression without typical angina pectoris is related to increases in sympatho‐adrenal activity or β‐adrenoceptor sensitivity.Patients.  Thirteen patients (four men) aged 35–62 years with ST‐segment depression during exercise but atypical symptoms and normal myocardial scintigraphy, and 13 matched controls.Design and interventions.  Patients and controls were compared regarding responses with: (i) exercise testing without treatment, (ii) exercise testing following β‐adrenoceptor blockade by propranolol (0.15 mg kg−1 i.v.), (iii) incremental adrenaline infusions (0.1, 0.2, 0.4 and 0.8 nmol kg−1 min−1) and (iv) adrenaline infusions during α‐adrenoceptor blockade by phentolamine (0.5 mg min−1).Main outcome measures.  ST‐segment depression and tissue Doppler parameters reflecting contractility.Results.  Exercise lowered the ST‐segment by 2.44 mm without and 0.87 mm with β‐adrenoceptor blockade (P < 0.001 for difference) amongst patients, but not amongst controls. Maximal heart rate was slightly higher amongst patients (P < 0.05), despite similar loads and plasma catecholamine responses to exercise in the two groups; this difference disappeared after β‐adrenoceptor blockade with propranolol. ST‐segment depression during adrenaline infusion was greater in patients compared with controls (P < 0.01) despite similar increases in heart rate. α‐Blockade enhanced the ST‐segment depression (P < 0.001) and heart rate (P < 0.001) responses to adrenaline infusion more markedly amongst patients. Tissue Doppler imaging showed similar contractility and diastolic relaxation responses of patients and controls to adrenaline, but early diastolic movements did not increase amongst patients after phentolamine (P < 0.01).Conclusions.  Exercise‐induced ST‐segment depression in patients with a low likelihood of ischaemic heart disease is related to increased β‐adrenergic sensitivity regarding chronotropic and electrophysiological, but not inotropic responses.
Intracoronary enalaprilat during angioplasty for acute myocardial infarction: alleviation of postischaemic neurohumoral and inflammatory stress?
Authors: Schaefer U. , Kurz T. , Bonnemeier H. , Dendorfer A. , Hartmann F. , Schunkert H. , Richardt G. 
Published: January 2007

Abstract.Aims.  Reperfusion after myocardial ischaemia is associated with a distinct ischaemia/reperfusion injury. Since ACE‐inhibition, beyond its influence on cardiac angiotensin II formation and kinin metabolism, has been shown to be cardioprotective by decreasing leucocyte adhesion and endothelin‐1 (ET‐1) release, we investigated the effects of intracoronary (i.c.) enalaprilat during primary angioplasty in acute myocardial infarction.Methods and Results.  Twenty‐two patients were randomized to receive i.c. enalaprilat (50 μg) or placebo immediately after reopening of the infarct‐related artery (IRA). Plasma concentrations of soluble L‐selectin, P‐selectin, intercellular adhesion molecule‐1 (sICAM‐1), vascular cell adhesion molecule‐1 (sVCAM‐1), ET‐1 and nitric oxide metabolite concentrations (NO(x)) were measured in pulmonary arterial blood. Coronary blood flow was assessed using corrected thrombolysis in myocardial infarction (TIMI) frame counts (CTFC). During reperfusion, there was a significant increase in sL‐selectin, sP‐selectin and ET‐1 in the placebo group, which was greatly diminished by enalaprilat. Levels of sVCAM‐1 and sICAM‐1 were not affected in either group. CTFC in the placebo group remained higher than normal in both the IRA and nonculprit vessels, whereas myocardial blood flow improved with enalaprilat.Conclusion.  Enalaprilat as adjunct to primary angioplasty might be a protective approach to prevent leucocyte adhesion and the release of ET‐1, thereby improving coronary blood flow.
Interleukin‐1α stimulation in monocytes by periodontal bacteria: antagonistic effects of Porphyromonas gingivalis
Authors: Bostanci N. , Allaker R. , Johansson U. , Rangarajan M. , Curtis M. A. , Hughes F. J. , McKay I. J. 
Published: January 2007

Periodontal pathogenic bacteria are associated with elevated levels of interleukin‐1α (IL‐1α) but it is unclear if all species can induce cytokine production equally. Porphyromonas gingivalis may be able antagonize IL‐1α induced by other species through the activity of its proteases or lipopolysaccharide (LPS). Monomac‐6 cells and primary human monocytes were treated with culture supernatants from Porphyromonas gingivalis, Fusobacterium nucleatum, Campylobacter rectus, Actinobacillus actinomycetemcomitans, Prevotella intermedius, Veillonella atypical and Prevotella nigrescens. IL‐1α protein levels were measured after 6 h of incubation. In addition, monocytes were co‐stimulated with supernatants from P. gingivalis and other bacteria. The role of P. gingivalis proteases was tested using Arg‐X and Lys‐X mutant strains. The role of LPS was investigated using purified P. gingivalis LPS and polymixin depletion. All species tested induced significant IL‐1α production, but P. gingivalis was the weakest. Co‐stimulation of monocytes with P. gingivalis antagonized the ability of other bacterial species to induce IL‐1α production. This effect was at its greatest with C. rectus (resulting in a 70% reduction). Gingipain mutant strains and chemical inhibition of protease activity did not reduce antagonistic activity. However, 100 ng/ml of P. gingivalis LPS can reproduce the antagonistic activity of P. gingivalis culture supernatants. Periodontitis‐associated bacterial species stimulate IL‐1α production by monocytes. P. gingivalis can antagonize this effect, and its LPS appears to be the crucial component. This study highlights the importance of mixed infections in the pathogenesis of periodontal disease because reduction of pro‐inflammatory cytokine levels may impair the ability of the host to tackle infection.
Impaired hippocampal plasticity and errors in cognitive performance in mice with maladaptive AChE splice site selection
Authors: Farchi Noa , Shoham Shai , Hochner Binyamin , Soreq Hermona 
Published: January 2007

AbstractNeuronal splice site selection events control multiple brain functions. Here, we report their involvement in stress‐modulated hippocampal plasticity and errors of cognitive performance. Under stress, alternative splicing changes priority from synaptic acetylcholinesterase (AChE‐S) to the normally rare, soluble and monomeric AChE‐R variant, which facilitates hippocampal long‐term potentiation (LTP) and intensifies fear‐motivated learning. To explore the adaptive value of changes in AChE splicing, we compared hippocampal plasticity and errors of executive function in TgS and TgR transgenic mice overexpressing AChE‐S or AChE‐R, respectively. Hippocampal slices from TgS and TgR mice presented delayed and facilitated transition to LTP maintenance, respectively, compared with strain‐matched FVB/N controls. TgS slices further showed failed recruitment of both the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate and N‐methyl‐d‐aspartate components of LTP, refractory response to cholinergic enhancement and suppressed protein kinase C (PKC) levels. Stable LTP could, however, be rescued by phorbol ester priming, attributing the TgS deficits to disrupted signal transduction. In serial maze tests, TgS mice displayed more errors of conflict and executive function than did FVB/N controls, reflecting maladaptive performance under chronic AChE‐S overexpression. In contrast, TgR mice displayed enhanced serial maze performance, suggesting that chronic AChE‐R overexpression facilitates adaptive reactions. Our findings are compatible with the notion that changes in the alternative splicing of AChE pre‐mRNA and consequent alterations in PKC signalling are causally involved in modulating hippocampal plasticity and cognitive performance.
Hibernation model of tau phosphorylation in hamsters: selective vulnerability of cholinergic basal forebrain neurons – implications for Alzheimer's disease
Authors: Härtig Wolfgang , Stieler Jens , Boerema Ate S. , Wolf Jennifer , Schmidt Udo , Weißfuß Jana , Bullmann Torsten , Strijkstra Arjen M. , Arendt Thomas 
Published: January 2007

AbstractNeurofibrillar tangles made up of ‘paired helical filaments’ (PHFs) consisting of hyperphosphorylated microtubule‐associated protein tau are major hallmarks of Alzheimer's disease (AD). Tangle formation selectively affects certain neuronal types and systematically progresses throughout numerous brain areas, which reflects a hierarchy of neuronal vulnerability and provides the basis for the neuropathological staging of disease severity. Mechanisms underlying this selective neuronal vulnerability are unknown. We showed previously that reversible PHF‐like phosphorylation of tau occurs during obligate hibernation. Here we extend these findings to facultative hibernators such as Syrian hamsters (Mesocricetus auratus) forced into hibernation. In this model, we showed in the basal forebrain projection system that cholinergic neurons are selectively affected by PHF‐like phosphorylated tau, while γ‐aminobutyric acid (GABA)ergic neurons are largely spared, which shows strong parallels to the situation in AD. Formation of PHF‐tau in these neurons apparently does not affect their function as pacemaker for terminating hibernation. We conclude that although formation of PHF‐like phosphorylated tau in the mammalian brain follows a certain hierarchy, affecting some neurons more frequently than others, it is not necessarily associated with impaired neuronal function and viability. This indicates a more general link between PHF‐like phosphorylation of tau and the adaptation of neurons under conditions of a ‘vita minima’.
Optical imaging of temporal integration in human auditory cortex
Authors: Sable Jeffrey J. , Low Kathy A. , Whalen Christopher J. , Maclin Edward L. , Fabiani Monica , Gratton Gabriele 
Published: January 2007

AbstractBehavioral and physiological studies have indicated the existence of a temporal window of auditory integration (TWI), within which similar sounds are perceptually grouped. The current study exploits the combined temporal and spatial resolution of fast optical imaging (the event‐related optical signal, EROS) to show that brain activity elicited by sounds within and outside the TWI differs in location and latency. In a previous event‐related brain potential (ERP) study [Sable, Gratton, and Fabiani (2003) European Journal of Neuroscience, 17, 2492–2496], we found that the mismatch negativity (MMN; a brain response to acoustic irregularities) elicited by deviations in stimulus onset asynchronies (SOAs) had a unique shape when the deviant SOA was within the TWI. In the present study, we extended these ERP results using EROS. Participants heard trains of five tones. The first four tones had SOAs of 96, 192, 288 or 384 ms. The SOA of the fourth and fifth tones was either the same (standard) or one of the other three (deviant) SOAs. With a deviant SOA of 96 ms, the cortical response was approximately 2 cm anterior to responses to longer SOA deviants, and was followed by a later response that was absent in the other conditions. Similarly to the electrical MMN, the optical mismatch response amplitudes were proportional to the magnitude of interval deviance. These results, in combination with our previous findings, indicate that the temporal integration of sounds is reflected in cortical mismatch responses that differ from the typical response to interval deviance.