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1.
BMJ Open ; 13(11): e072150, 2023 11 27.
Article in English | MEDLINE | ID: mdl-38011964

ABSTRACT

INTRODUCTION: Attributing musculoskeletal (MSK) pain to normal and commonly occurring imaging findings, such as tendon, cartilage and spinal disc degeneration, has been shown to increase people's fear of movement, reduce their optimism about recovery and increase healthcare costs. Interventions seeking to reduce the negative effects of MSK imaging reporting have had little effect. To understand the ineffectiveness of these interventions, this study seeks to scope their behavioural targets, intended mechanisms of action and theoretical underpinnings. This information alongside known barriers to helpful reporting can enable researchers to refine or create new more targeted interventions. METHODS AND ANALYSIS: The scoping review will be conducted in accordance with the JBI methodology for scoping reviews and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Search terms will be devised by the research team. Searches of MEDLINE, EMBASE, CINAHL, AMED and PsycINFO from inception to current day will be performed. The review will include studies, which have developed or evaluated interventions targeting the reporting of MSK imaging. Studies targeting the diagnosis of serious causes of MSK pain will be excluded. Two independent authors will extract study participant data using predefined extraction templates and intervention details using the Template for Intervention Description and Replication checklist. Interventions will be coded and mapped to the technique, mechanism of action and behavioural target according to the Capability, Opportunity, Motivation-Behaviour (COM-B) model categories. Any explicit models or theories used to inform the selection of interventions will be extracted and coded. The study characteristics, behaviour change techniques identified, behavioural targets according to the COM-B and context specific theories within the studies will be presented in narrative and table form. ETHICS AND DISSEMINATION: The information from this review will be used to inform an intervention design process seeking to improve the communication of imaging results. The results will also be disseminated through a peer-reviewed publication, conference presentations and stakeholder events.


Subject(s)
Motivation , Musculoskeletal Pain , Humans , Research Design , Systematic Reviews as Topic , Review Literature as Topic
2.
Pain Rep ; 8(4): e1081, 2023.
Article in English | MEDLINE | ID: mdl-37293339

ABSTRACT

Introduction: The Tampa Scale of Kinesiophobia (TSK) is commonly used to assess fear of movement (FoM) in people with low back pain (LBP). However, the TSK does not provide a task-specific measure of FoM, whereas image-based or video-based methods may do so. Objectives: To compare the magnitude of FoM when assessed using 3 methods (TSK-11, image of lifting, video of lifting) in 3 groups of people: current LBP (LBP), recovered LBP (rLBP), and asymptomatic controls (control). Methods: Fifty-one participants completed the TSK-11 and rated their FoM when viewing images and videos depicting people lifting objects. Low back pain and rLBP participants also completed the Oswestry Disability Index (ODI). Linear mixed models were used to estimate the effects of methods (TSK-11, image, video) and group (control, LBP, rLBP). Linear regression models were used to assess associations between the methods on ODI after adjusting for group. Finally, a linear mixed model was used to understand the effects of method (image, video) and load (light, heavy) on fear. Results: In all groups, viewing images (P = 0.009) and videos (P = 0.038) elicited greater FoM than that captured by the TSK-11. Only the TSK-11 was significantly associated with the ODI (P < 0.001). Finally, there was a significant main effect of load on fear (P < 0.001). Conclusion: Fear of specific movements (eg, lifting) may be better measured using task-specific measures, such as images and videos, than by task-generic questionnaires, such as the TSK-11. Being more strongly associated with the ODI, the TSK-11 still plays an important role in understanding the impact of FoM on disability.

3.
Eur J Pain ; 27(4): 459-475, 2023 04.
Article in English | MEDLINE | ID: mdl-36587243

ABSTRACT

BACKGROUND AND OBJECTIVES: Persistent nonspecific back pain is now established as a biopsychosocial phenomenon that can be meaningfully affected by individuals' cognitions, emotions, lifestyle factors and family and social relationships. Recent guidelines for the treatment of adolescents with persistent nonspecific back pain, as well as those for youth with mixed chronic pain, strongly recommend interdisciplinary care in which adolescents receive treatment for both mind and body. The objective of this scoping review was to examine the interventions evaluated in randomized trials for adolescents with persistent back pain to determine whether they correspond to these guidelines and to reveal future research priorities. DATABASES AND DATA TREATMENT: The review protocol was registered in March 2022. We followed the PRISMA guidelines for scoping reviews. Twelve electronic databases were searched for relevant study reports. Data were charted on study characteristics, participant characteristics and intervention details using the Template for Intervention Description and Replication (TIDieR) checklist. RESULTS: The search yielded 1952 records, of which eight reports representing seven randomized trials were eligible. The most common interventions were exercise therapy (n = 6) and back education (n = 4). Five studies employed multiple intervention components, but none was multidisciplinary. Studies primarily targeted posture or biomechanical factors. One study included an intervention addressing participants' fears and beliefs about pain. CONCLUSIONS: Randomized trials for adolescents with persistent back pain have primarily relied upon an outdated, biomechanical explanation of persisting pain. Future randomized trials should align with current treatment recommendations and measure outcomes across multiple biopsychosocial domains. SIGNIFICANCE: This scoping review describes in detail the interventions included in randomized trials for adolescents with persistent, nonspecific back pain. The review is important because it reveals discrepancies between those interventions and the interventions recommended for this population.


Subject(s)
Back Pain , Chronic Pain , Adolescent , Humans , Back Pain/psychology , Chronic Pain/therapy , Life Style , Outcome Assessment, Health Care , Randomized Controlled Trials as Topic
4.
Clin Epigenetics ; 10: 46, 2018.
Article in English | MEDLINE | ID: mdl-29636834

ABSTRACT

Background: Genetic variants within the fatty acid desaturase (FADS) gene cluster (human Chr11) are important regulators of long-chain (LC) polyunsaturated fatty acid (PUFA) biosynthesis in the liver and consequently have been associated with circulating LC-PUFA levels. More recently, epigenetic modifications such as DNA methylation, particularly within the FADS cluster, have been shown to affect LC-PUFA levels. Our lab previously demonstrated strong associations of allele-specific methylation (ASM) between a single nucleotide polymorphism (SNP) rs174537 and CpG sites across the FADS region in human liver tissues. Given that epigenetic signatures are tissue-specific, we aimed to evaluate the methylation status and ASM associations between rs174537 and DNA methylation obtained from human saliva, CD4+ cells and total leukocytes derived from whole blood. The goals were to (1) determine if DNA methylation from these peripheral samples would display similar ASM trends as previously observed in human liver tissues and (2) evaluate the associations between DNA methylation and circulating LC-PUFAs. Results: DNA methylation at six CpG sites spanning FADS1 and FADS2 promoter regions and a putative FADS enhancer region were determined in two Caucasian cohorts of healthy volunteers: leukocytes in cohort 1 (n = 89, median age = 43, 35% male) and saliva and CD4+ cells in cohort 2 (n = 32, median age = 41, 41% male). Significant ASM between rs174537 and DNA methylation at three CpG sites located in the FADS2 promoter region (i.e., chr11:61594865, chr11:61594876, chr11:61594907) and one CpG site in the putative enhancer region (chr11:61587979) were observed with leukocytes. In CD4+ cells, significant ASM was observed at CpG sites chr11:61594876 and chr11:61584894. Genotype at rs174537 was significantly associated with DNA methylation from leukocytes. Similar trends were observed with CD4+ cells, but not with saliva. DNA methylation from leukocytes and CD4+ cells also significantly correlated with circulating omega-6 LC-PUFAs. Conclusions: We observed significant ASM between rs174537 and DNA methylation at key regulatory regions in the FADS region from leukocyte and CD4+ cells. DNA methylation from leukocytes also correlated with circulating omega-6 LC-PUFAs. These results support the use of peripheral whole blood samples, with leukocytes showing the most promise for future nutrigenomic studies evaluating epigenetic modifications affecting LC-PUFA biosynthesis in humans.


Subject(s)
CD4-Positive T-Lymphocytes/chemistry , DNA Methylation , Fatty Acid Desaturases/genetics , Leukocytes/chemistry , Saliva/chemistry , Adult , Alleles , Chromosomes, Human, Pair 11/genetics , Delta-5 Fatty Acid Desaturase , Female , Healthy Volunteers , Humans , Male , Middle Aged , Organ Specificity , White People/genetics , Young Adult
5.
Plant Biotechnol J ; 14(1): 299-312, 2016 Jan.
Article in English | MEDLINE | ID: mdl-25923308

ABSTRACT

The utilization of high amounts of nitrate fertilizers for crop yield leads to nitrate pollution of ground and surface waters. In this study, we report the assimilation and utilization of nitrate luxuriant levels, 20 times more than the highest N fertilizer application in Europe, by transgenic poplars overexpressing a cytosolic glutamine synthetase (GS1). In comparison with the wild-type controls, transgenic plants grown under high N levels exhibited increased biomass (171.6%) and accumulated higher levels of proteins, chlorophylls and total sugars such as glucose, fructose and sucrose. These plants also exhibited greater nitrogen-use efficiency particularly in young leaves, suggesting that they are able to translocate most of the resources to the above-ground part of the plant to produce biomass. The transgenic poplar transcriptome was greatly affected in response to N availability with 1237 genes differentially regulated in high N, while only 632 genes were differentially expressed in untransformed plants. Many of these genes are essential in the adaptation and response against N excess and include those involved in photosynthesis, cell wall formation and phenylpropanoid biosynthesis. Cellulose production in the transgenic plants was fivefold higher than in control plants, indicating that transgenic poplars represent a potential feedstock for applications in bioenergy. In conclusion, our results show that GS transgenic poplars can be used not only for improving growth and biomass production but also as an important resource for potential phytoremediation of nitrate pollution.


Subject(s)
Biofuels , Nitrates/metabolism , Populus/metabolism , Trees/metabolism , Biodegradation, Environmental/drug effects , Biomass , Carbohydrate Metabolism/drug effects , Carbohydrate Metabolism/genetics , Carbon/metabolism , Chlorophyll/metabolism , Gene Expression Profiling , Gene Expression Regulation, Plant/drug effects , Glutamate-Ammonia Ligase/metabolism , Lignin/metabolism , Nitrogen/metabolism , Nitrogen/pharmacology , Phenotype , Plant Proteins/genetics , Plant Proteins/metabolism , Plants, Genetically Modified , Populus/drug effects , Populus/genetics , Populus/growth & development , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reproducibility of Results , Solubility , Transcriptome/genetics , Trees/drug effects , Trees/genetics , Trees/growth & development
6.
Plant Physiol Biochem ; 94: 181-90, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26113157

ABSTRACT

Transgenic hybrid poplars engineered to express ectopically the heterologous pine cytosolic GS1a display a number of significant pleiotropic phenotypes including enhanced growth, enhanced nitrogen use efficiency, and resistance to drought stress. The present study was undertaken in order to assess mechanisms whereby ectopic expression of pine GS1a in transgenic poplars results in enhanced agronomic phenotypes. Microarray analysis using the Agilent Populus whole genome array has allowed identification of genes differentially expressed between wild type (WT) and GS transgenics in four tissues (sink leaves, source leaves, stems, and roots) under three growth conditions (well-watered, drought, and recovery). Analysis revealed that differentially expressed genes in functional categories related to nitrogen metabolism show a trend of significant down-regulation in GS poplars compared to the WT, including genes encoding nitrate and nitrite reductases. The down-regulation of these genes was verified using qPCR, and downstream effects were further tested using NR activity assays. Results suggest that higher glutamine levels in GS transgenics regulate nitrate uptake and reduction. Transcript levels of nitrogen-related genes in leaves, including GS/GOGAT cycle enzymes, aspartate aminotransferase, GABA shunt enzymes, photorespiration enzymes, asparagine synthetase, phenylalanine ammonia lyase, isocitrate dehydrogenase, and PII, were also assessed using qPCR revealing significant differences between GS poplars and the WT. Moreover, metabolites related to these differentially expressed genes showed alterations in levels, including higher levels of GABA, hydroxyproline, and putrescine in the GS transgenic. These alterations in nitrogen homeostasis offer insights into mechanisms accounting for drought tolerance observed in GS poplars.


Subject(s)
Glutamate-Ammonia Ligase/biosynthesis , Nitrogen/metabolism , Pinus/genetics , Plant Proteins/biosynthesis , Plants, Genetically Modified/enzymology , Populus/enzymology , Stress, Physiological , Glutamate-Ammonia Ligase/genetics , Pinus/enzymology , Plant Proteins/genetics , Plants, Genetically Modified/genetics , Populus/genetics
7.
PLoS One ; 8(2): e56421, 2013.
Article in English | MEDLINE | ID: mdl-23451045

ABSTRACT

BACKGROUND: Glutamine synthetase (GS) plays a central role in plant nitrogen assimilation, a process intimately linked to soil water availability. We previously showed that hybrid poplar (Populus tremula X alba, INRA 717-1B4) expressing ectopically a pine cytosolic glutamine synthetase gene (GS1a) display enhanced tolerance to drought. Preliminary transcriptome profiling revealed that during drought, members of the superoxide dismutase (SOD) family were reciprocally regulated in GS poplar when compared with the wild-type control, in all tissues examined. SOD was the only gene family found to exhibit such patterns. RESULTS: In silico analysis of the Populus genome identified 12 SOD genes and two genes encoding copper chaperones for SOD (CCSs). The poplar SODs form three phylogenetic clusters in accordance with their distinct metal co-factor requirements and gene structure. Nearly all poplar SODs and CCSs are present in duplicate derived from whole genome duplication, in sharp contrast to their predominantly single-copy Arabidopsis orthologs. Drought stress triggered plant-wide down-regulation of the plastidic copper SODs (CSDs), with concomitant up-regulation of plastidic iron SODs (FSDs) in GS poplar relative to the wild type; this was confirmed at the activity level. We also found evidence for coordinated down-regulation of other copper proteins, including plastidic CCSs and polyphenol oxidases, in GS poplar under drought conditions. CONCLUSIONS: Both gene duplication and expression divergence have contributed to the expansion and transcriptional diversity of the Populus SOD/CCS families. Coordinated down-regulation of major copper proteins in drought-tolerant GS poplars supports the copper cofactor economy model where copper supply is preferentially allocated for plastocyanins to sustain photosynthesis during drought. Our results also extend previous findings on the compensatory regulation between chloroplastic CSDs and FSDs, and suggest that this copper-mediated mechanism represents a common response to oxidative stress and other genetic manipulations, as in GS poplars, that affect photosynthesis.


Subject(s)
Droughts , Glutamate-Ammonia Ligase/metabolism , Plant Proteins/metabolism , Populus/enzymology , Superoxide Dismutase/metabolism , Gene Expression Regulation, Plant , Glutamate-Ammonia Ligase/genetics , Plant Proteins/genetics , Superoxide Dismutase/genetics
8.
Plant Biotechnol J ; 10(7): 883-9, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22672155

ABSTRACT

Hybrid poplar (Populus tremula X P. alba) genetically engineered to express the pine cytosolic glutamine synthetase gene (GS1a) has been previously shown to display desirable field performance characteristics, including enhancements in growth and nitrogen use efficiency. Analysis of wood samples from a 3-year-old field trial of three independently transformed GS1a transgenic hybrid poplar lines revealed that, when compared with wild-type controls, ectopic expression of GS1a resulted in alterations in wood properties and wood chemistry. Included were significant enhancements in wood fibre length, wood density, microfibre angle, per cent syringyl lignin and elevated concentrations of wood sugars, specifically glucose, galactose, mannose and xylose. Total extractive content and acid-insoluble lignin were significantly reduced in wood of GS1a transgenics when compared with wild-type trees. Together, these cell wall characteristics resulted in improved wood pulping attributes, including improved lignin solubilization with no concurrent decrease in yield. Trees with increased GS1a expression have improved characteristics for pulp and paper production and hold potential as a feedstock for biofuels production.


Subject(s)
Glutamate-Ammonia Ligase/metabolism , Populus/enzymology , Populus/growth & development , Wood/chemistry , Cell Wall/metabolism , Crosses, Genetic , Glutamate-Ammonia Ligase/genetics , Hybridization, Genetic , Lignin/metabolism , Plants, Genetically Modified , Populus/genetics
9.
BMC Plant Biol ; 11: 119, 2011 Aug 25.
Article in English | MEDLINE | ID: mdl-21867507

ABSTRACT

BACKGROUND: Glutamine synthetase (GS; EC: 6.3.1.2, L-glutamate: ammonia ligase ADP-forming) is a key enzyme in ammonium assimilation and metabolism of higher plants. The current work was undertaken to develop a more comprehensive understanding of molecular and biochemical features of GS gene family in poplar, and to characterize the developmental regulation of GS expression in various tissues and at various times during the poplar perennial growth. RESULTS: The GS gene family consists of 8 different genes exhibiting all structural and regulatory elements consistent with their roles as functional genes. Our results indicate that the family members are organized in 4 groups of duplicated genes, 3 of which code for cytosolic GS isoforms (GS1) and 1 which codes for the choroplastic GS isoform (GS2). Our analysis shows that Populus trichocarpa is the first plant species in which it was observed the complete GS family duplicated. Detailed expression analyses have revealed specific spatial and seasonal patterns of GS expression in poplar. These data provide insights into the metabolic function of GS isoforms in poplar and pave the way for future functional studies. CONCLUSIONS: Our data suggest that GS duplicates could have been retained in order to increase the amount of enzyme in a particular cell type. This possibility could contribute to the homeostasis of nitrogen metabolism in functions associated to changes in glutamine-derived metabolic products. The presence of duplicated GS genes in poplar could also contribute to diversification of the enzymatic properties for a particular GS isoform through the assembly of GS polypeptides into homo oligomeric and/or hetero oligomeric holoenzymes in specific cell types.


Subject(s)
Glutamate-Ammonia Ligase/genetics , Multigene Family , Populus/enzymology , Comparative Genomic Hybridization , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Plant , Genes, Duplicate , Isoenzymes/genetics , Phylogeny , Populus/genetics , Populus/growth & development , Seasons
10.
J Exp Bot ; 62(13): 4423-31, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21642235

ABSTRACT

The initial reaction in the pathway leading to the production of indole-3-acetic acid (IAA) in plants is the reaction between chorismate and glutamine to produce anthranilate, catalysed by the enzyme anthranilate synthase (ASA; EC 4.1.3.27). Compared with non-transgenic controls, leaves of transgenic poplar with ectopic expression of the pine cytosolic glutamine synthetase (GS1a; EC 6.3.1.2) produced significantly greater glutamine and significantly enhanced ASA α-subunit (ASA1) transcript and protein (approximately 130% and 120% higher than in the untransformed controls, respectively). Similarly, tobacco leaves fed with 30 mM glutamine and 2 mM chorismate showed enhanced ASA1 transcript and protein (175% and 90% higher than controls, respectively). Furthermore, free IAA was significantly elevated both in leaves of GS1a transgenic poplar and in tobacco leaves fed with 30 mM glutamine and 2 mM chorismate. These results indicated that enhanced cellular glutamine may account for the enhanced growth in GS transgenic poplars through the regulation of auxin biosynthesis.


Subject(s)
Anthranilate Synthase/genetics , Glutamate-Ammonia Ligase/metabolism , Glutamine/metabolism , Indoleacetic Acids/metabolism , Pinus/enzymology , Plant Leaves/enzymology , Populus/growth & development , Anthranilate Synthase/metabolism , Chorismic Acid/metabolism , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Plant/drug effects , Glutamate-Ammonia Ligase/genetics , Glutamine/pharmacology , Immunoblotting , Pinus/drug effects , Plant Leaves/drug effects , Plant Leaves/genetics , Plants, Genetically Modified , Populus/drug effects , Populus/enzymology , Populus/genetics , Protein Subunits/genetics , Protein Subunits/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Nicotiana/drug effects , Nicotiana/metabolism
11.
J Sports Sci ; 27(7): 753-8, 2009 May.
Article in English | MEDLINE | ID: mdl-19437182

ABSTRACT

Pedometers have been identified as a tool for health professionals to promote physical activity. This study, which aimed to evaluate the effectiveness of wearing a pedometer on general practitioners' attitudes to promoting physical activity, was a pragmatic, multi-centred, randomized controlled trial within a primary care trust in England. The participants were 102 general practitioners (GPs). Eighty-five (48 males, 37 females) of the GPs completed pre and post questionnaires, 43 of whom were in the intervention group. Statistical analysis revealed no significant changes between the control and intervention groups for attitude to engage in physical activity (t(83) = 1.13, CI -0.362 to 0.099) or attitude to promote physical activity in their patients (t(83) = 1.7, CI -0.593 to 0.045). A higher volume of walking was significantly correlated with a more positive attitude to engage in physical activity (r = 0.58, P < 0.01) but not with a more positive attitude to promoting physical activity. Wearing a pedometer had no significant effect on GPs' attitudes to engaging in physical activity or promoting physical activity in their patients.


Subject(s)
Attitude of Health Personnel , Health Promotion , Physicians, Family/psychology , Sports Equipment , Walking , England , Female , Health Behavior , Humans , Male
12.
Phytochemistry ; 69(2): 382-9, 2008 Jan.
Article in English | MEDLINE | ID: mdl-17888468

ABSTRACT

Glutamine synthetase (GS) is the main enzyme involved in ammonia assimilation in plants and is the target of phosphinothricin (PPT), an herbicide commonly used for weed control in agriculture. As a result of the inhibition of GS, PPT also blocks photorespiration, resulting in the depletion of leaf amino acid pools leading to the plant death. Hybrid transgenic poplar (Populus tremula x P. alba INRA clone 7171-B4) overexpressing cytosolic GS is characterized by enhanced vegetative growth [Gallardo, F., Fu, J., Cantón, F.R., García-Gutiérrez, A., Cánovas, F.M., Kirby, E.G., 1999. Expression of a conifer glutamine synthetase gene in transgenic poplar. Planta 210, 19-26; Fu, J., Sampalo, R., Gallardo, F., Cánovas, F.M., Kirby, E.G., 2003. Assembly of a cytosolic pine glutamine synthetase holoenzyme in leaves of transgenic poplar leads to enhanced vegetative growth in young plants. Plant Cell Environ. 26, 411-418; Jing, Z.P., Gallardo, F., Pascual, M.B., Sampalo, R., Romero, J., Torres de Navarra, A., Cánovas, F.M., 2004. Improved growth in a field trial of transgenic hybrid poplar overexpressing glutamine synthetase. New Phytol. 164, 137-145], increased photosynthetic and photorespiratory capacities [El-Khatib, R.T., Hamerlynck, E.P., Gallardo, F., Kirby, E.G., 2004. Transgenic poplar characterized by ectopic expression of a pine cytosolic glutamine synthetase gene exhibits enhanced tolerance to water stress. Tree Physiol. 24, 729-736], enhanced tolerance to water stress (El-Khatib et al., 2004), and enhanced nitrogen use efficiency [Man, H.-M., Boriel, R., El-Khatib, R.T., Kirby, E.G., 2005. Characterization of transgenic poplar with ectopic expression of pine cytosolic glutamine synthetase under conditions of varying nitrogen availability. New Phytol. 167, 31-39]. In vitro plantlets of GS transgenic poplar exhibited enhanced resistance to PPT when compared with non-transgenic controls. After 30 days exposure to PPT at an equivalent dose of 275 g ha(-1), growth of GS transgenic poplar plantlets was 5-fold greater than controls. The response of young leaves to PPT treatment depends on physiological state as indicated by GS and Rubisco (LSU) levels. Young leaves from control plants, typically in a low differentiation state, respond to the herbicide showing up-regulation of GS and LSU. In contrast, young leaves from transgenic lines, with higher initial GS and LSU levels compared to control, display up-regulation of NADP(+)-isocitrate dehydrogenase. Differences between control and GS transgenics in their response to PPT are discussed in relation to their differences in photosynthetic and photorespiratory capacities (El-Khatib et al., 2004).


Subject(s)
Aminobutyrates/pharmacology , Cytosol/drug effects , Cytosol/enzymology , Gene Expression Regulation, Enzymologic , Populus/enzymology , Gene Expression Regulation, Plant , Glutamate-Ammonia Ligase , Plant Leaves/enzymology , Plant Leaves/genetics , Plants, Genetically Modified , Populus/drug effects , Populus/genetics , Populus/growth & development , Seedlings/drug effects , Seedlings/enzymology , Seedlings/genetics
13.
New Phytol ; 167(1): 31-9, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15948827

ABSTRACT

The present study addresses the hypothesis that enhanced expression of glutamine synthetase (GS) in transgenic poplar, characterized by the ectopic expression of pine cytosolic GS, results in an enhanced efficiency of nitrogen (N) assimilation and enhanced growth. Transgenic and control poplar were supplied with low and high N levels and the role of ectopic expression of the pine GS in growth and N assimilation was assessed by using amino acid analysis, (15)N enrichment, biochemical analyses, and growth measurements. While leaves of transgenic poplar contained 85% less (P < 0.01) free ammonium than leaves of nontransgenic control plants, leaves of transgenics showed increases in the levels of free glutamine and total free amino acids. Transgenic poplar lines also displayed significant increases in growth parameters when compared with controls grown under both low (0.3 mm) and high (10 mm) nitrate conditions. Furthermore, (15)N-enrichment experiments showed that 27% more (P < 0.05) (15)N was incorporated into structural compounds in transgenic lines than in nontransgenic controls. Using the methods described here, we present direct evidence for increased N assimilation efficiency and growth in GS transgenic lines.


Subject(s)
Glutamate-Ammonia Ligase/metabolism , Nitrogen/metabolism , Populus/genetics , Populus/metabolism , Amino Acids/metabolism , Glutamate-Ammonia Ligase/genetics , Pinus/enzymology , Plant Leaves/metabolism , Plants, Genetically Modified
14.
Tree Physiol ; 24(7): 729-36, 2004 Jul.
Article in English | MEDLINE | ID: mdl-15123444

ABSTRACT

Physiological responses to water stress in hybrid poplar (INRA 7171-B4, Populus tremula L. x P. alba L.) lines transformed to overexpress a pine cytosolic glutamine synthetase (GS1) gene were compared with those of non-transgenic plants. Before, during and after a drought treatment, net photosynthetic rates (Anet) were higher in transgenic than in non-transgenic plants. Stomatal conductance (gs) was higher in transgenic than in non-transgenic plants before, but not after exposure to drought. Before drought treatment, a sudden reduction in photosynthetic photon flux caused a greater burst of CO2 efflux in transgenic than non-transgenic plants, indicating greater photorespiratory activity. Drought caused greater reductions in photochemical quenching, photosystem II (PSII) antennae transfer efficiency (Fv'/Fm') and light-adapted PSII yield (PhiPSII) in non-transgenic than in transgenic plants, especially at low irradiances. Antennae-based thermal dissipation was higher in transgenic plants than in non-transgenic plants both during the imposition of drought and 1 or 3 days after the relief of drought. Under severe water stress and subsequently, transgenic plants maintained a higher expression of glutamine synthetase, glutamate synthase and Rubisco and higher concentrations of chlorophyll and glycine than non-transgenic plants. These findings indicate that overexpression of pine cytosolic GS1 enhanced sustained photosynthetic electron transport capacity during severe stomatal limitation. The data also suggest that ectopic expression of cytosolic GS increases photorespiratory activity, and that this serves as a protective sink for electrons from photosynthetic reaction centers.


Subject(s)
Glutamate-Ammonia Ligase/genetics , Populus/physiology , Trees/physiology , Chlorophyll/physiology , Dehydration , Gene Expression Regulation, Enzymologic/genetics , Photosynthesis/physiology , Plant Transpiration/physiology , Plants, Genetically Modified/enzymology , Plants, Genetically Modified/physiology , Populus/enzymology , Populus/genetics , Trees/enzymology , Trees/genetics
15.
J Learn Disabil ; 35(5): 425-35, 447, 2002.
Article in English | MEDLINE | ID: mdl-15490539

ABSTRACT

Conventional methods of differentiating reading disability (RD) caused by deficits in decoding skills or comprehension from poor reading performance caused by inconsistent attention associated with attention-deficit/hyperactivity disorder (ADHD) have produced equivocal results. This study presents a model of differential diagnosis of attentional problems and RD that differs from these conventional approaches. The new diagnostic procedure uses intraindividual differences seen in the performance of at-risk learners on tasks related to reading that vary in their sensitivity to the sustained attention required for successful performance. The hypothesis is that children with inconsistent attention would perform more poorly on tests that require sustained attention, such as listening comprehension, than on tests that are more tolerant of inattention, such as reading comprehension. Such differences would not be seen in the test scores of children who have only RD, because their performance is determined more by the difficulty level of the reading tests than by the degree of sensitivity of the task to attention. The validity of this new model was evaluated by determining the capability of the differences seen in the scores of tests that differ in their sensitivity to sustained attention to predict the degree of inconsistency in sustained attention as measured by a continuous performance test. The data obtained from 39 children who are at risk for RD suggest that this is a viable model.


Subject(s)
Attention Deficit Disorder with Hyperactivity/complications , Attention Deficit Disorder with Hyperactivity/psychology , Dyslexia/diagnosis , Models, Psychological , Reading , Child , Diagnosis, Differential , Female , Humans , Male , Risk Factors , Task Performance and Analysis
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