bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secondary metabolites and nutrient concentrations in silver birch seedlings under five levels of daily UV‐B exposure and two relative nutrient addition rates
Authors: De La Rosa T. M. , Julkunen‐Tiitto R. , Lehto T. , Aphalo P. J. 
Published: March 2003

Summary

Changes in secondary metabolites in silver birch ( Betula pendula ) seedlings are presented in response to ultraviolet‐B radiation (UV‐B) and nutrient addition.
Concentrations of individual secondary metabolites and nutrients were measured in leaves of greenhouse‐grown silver birch seedlings exposed to five time‐integrated irradiances of biologically effective UV‐B (I BE
UV‐B ) and fertilized with two relative nutrient addition rates.
Several phenolics were not only induced by UV‐B, but their concentration was dependent on UV‐B daily time‐integrated irradiance. Relative nutrient addition rate also affected the concentration of phenolics but had little effect on the UV‐B daily time‐integrated irradiance‐responses. The mineral nutrient concentration of leaves was affected by nutrient addition but not by increasing I BE
UV‐B . Possible threshold‐exposures for the accumulation of secondary metabolites or nutrients were not detected.
UV‐B and relative nutrient addition rate have mainly an additive (rather than synergistic) effect in silver birch, and leaves respond to increasing UV‐B by synthesizing metabolites (e.g. flavonols), which are important UV‐B filters. This study reports the first UV‐B‐exposure‐response curves for individual secondary metabolites and nutrients in leaves of a woody tree species.
Can unidirectional influx be measured in higher plants? A mathematical approach using parameters from efflux analysis
Authors: Britto Dev T. , Kronzucker Herbert J. 
Published: March 2003

Summary

A comprehensive and pragmatic approach to the design of unidirectional ion transport experiments in plants is presented here, revising and simplifying classical models.
The kinetic constant for cytosolic ion exchange ( k
c ) is critical to the understanding of the interrelated flux processes occurring simultaneously at the cellular level. This constant is most effectively estimated using the compartmental analysis by efflux method, which, by providing values for additional kinetic parameters (i.e. unidirectional influx and efflux) can be used to determine the extent of distortion inherent in assessments of influx at, or close to, the steady state.
Focusing on the kinetics of nitrogen exchange, with tracer efflux experiments in barley ( Hordeum vulgare
) using
13NH4+, conducted under perturbation conditions, it was demonstrated that a transitional state was rapidly established following a concentration shift, characterized by a restoration of the preperturbational (steady‐state) kc value. It is concluded that a reasonably accurate estimate of unidirectional influx can be made when influx measurements are conducted subsequent to the establishment of this transitional state.
A mathematical treatment of unidirectional flux processes allows the exact determination of errors caused by ionic counterfluxes under steady‐state conditions.
Soil‐borne fungal pathogens: scaling‐up from hyphal to colony behaviour and the probability of disease transmission
Authors: Stacey A. J. , Truscott J. E. , Gilligan C. A. 
Published: March 2003

Summary

The transmission of many fungal soil‐borne plant pathogens is mediated by the growth of the fungal colony from an infectious to a susceptible host plant.
Here we develop a mechanistic, spatially‐explicit, mathematical model that allows us to scale from hyphal growth and branching, through colony growth to analyse and predict the transmission of infection. We derive approximate analytical solutions for colony behaviour. These are used to drive equations for the evolution of the pathozone dynamics which characterize the ability of pathogens to infect hosts from various distances in soil.
It is possible to scale up from hyphal behaviour to the scale of transmission of infection. We identify two key periods in pathozone dynamics: an initial period during which no transmission of infection occurs, followed by the advection of the pathozone profile away from the infectious host at an approximately constant rate.
The models enable the prediction of probability of transmission of infection from hyphal‐scale behaviour. However, a coherent theory scaling from hyphal dynamics through colony behaviour to properties of the whole epidemic awaits further theoretical and experimental work.
Analysis of gene expression in arbuscular mycorrhizas: new approaches and challenges
Authors: Franken P. , Requena N. 
Published: March 2003

SummaryThis review summarizes the most recent results obtained using molecular biological techniques in the understanding of the arbuscular mycorrhizal symbiosis. On the plant side, cDNA libraries have been established from mycorrhizal RNA using several techniques, such as suppressive subtractive hybridization, and a large number of clones are being sequenced to obtain expressed sequence tags (ESTs). These ESTs can be transferred to solid supports (arrays) and hybridized with cDNA from different sources to obtain RNA accumulation profiles of genes expressed during the mycorrhizal symbiosis. On the fungal side, EST libraries are also being established, both using direct cloning and suppressive subtractive hybridization techniques. For both partners, the next steps are the detailed analysis of some relevant genes concerned with regulation and function, as well as the study of their role in the symbiosis. At the end of this review, we discuss how results about gene expression and functioning from molecular analyses can help in understanding the ecology of the symbiosis and the way in which it can be further exploited for application in plant production systems.
Stem respiration increases in CO2‐enriched sweetgum trees
Authors: Edwards Nelson T. , Tschaplinski Timothy J. , Norby Richard J. 
Published: March 2003

Summary

Stem respiration in trees results in substantial CO 2
release to the atmosphere. Stem respiration is an important component of the carbon budget of forest stands that could be perturbed by CO
2 enrichment of the atmosphere.
We measured stem respiration in a free‐air CO 2
enrichment (FACE) experiment in a 15‐yr‐old sweetgum (
Liquidambar styraciflua
) plantation. The trees were exposed to ambient or 1.4× ambient [CO
2
]. Stem respiration of 12 trees in ambient [CO
2
] and 12 trees in CO
2 ‐enriched plots was continuously monitored over a period of 1 year.
CO2 enrichment caused a 23% increase in annual growth respiration (Rg) and a 48% increase in maintenance respiration (Rm). During a 4‐d period when CO2 fumigation was turned off, both respiration and stem sucrose concentrations declined in the CO2‐enriched trees. Concentrations of other soluble sugars did not change.
We conclude that elevated [CO 2
] caused stem respiration to increase and that the increase was driven by increased substrate supply from leaves. We suggest that both
R
g
and
R
m rate responses may result from changes in growth rates and live to dead tissue ratios rather than from mechanistic alterations of the respiratory processes.
Anthocyanins in vegetative tissues: a proposed unified function in photoprotection
Authors: Steyn W. J. , Wand S. J. E. , Holcroft D. M. , Jacobs G. 
Published: March 2003

SummaryThe function of anthocyanins in green, vegetative tissues has always been a contentious issue. Here we evaluate their proposed photoprotective function since recent findings have shown that anthocyanins reduce photoinhibition and photobleaching of chlorophyll under light stress conditions. Anthocyanins generally accumulate in peripheral tissues exposed to high irradiance, although there are some exceptions (e.g. accumulation in abaxial leaf tissues and in obligatory shade plants) and accumulation is usually transient. Anthocyanin accumulation requires light and generally coincides with periods of high excitation pressure and increased potential for photo‐oxidative damage due to an imbalance between light capture, CO2 assimilation and carbohydrate utilization (e.g. greening of developing tissues, senescence and adverse environmental conditions). Light attenuation by anthocyanin may help to re‐establish this balance and so reduce the risk of photo‐oxidative damage. Although it has been suggested that anthocyanins may act as antioxidants, the association between anthocyanins and oxidative stress appears to relate to the ability of anthocyanins to reduce excitation pressure and, hence, the potential for oxidative damage. The various aspects of anthocyanin induction and pigmentation presented here are compatible with, and support, the proposed general role of anthocyanins as photoprotective light screens in vegetative tissues.
Consumers’ views of breast care services in Ireland
Authors: Kennedy P. , Murphy‐Lawless J. , Quin S. , Hickey E. 
Published: March 2003

AbstractOne Irish woman in 14 develops breast cancer. There are 1700 new cases each year. These rates compare poorly with EU figures. The government indicated in 1995 that it favoured rapid, comprehensive diagnostic facilities, using the triple assessment model of clinical care, to improve survival rates and to diminish the anxiety women experience about breast cancer. Implementation of this policy was delayed until 1999, when a plan for centres of excellence in breast care was conceived. To compliment this plan, the Department of Health and Children wanted consumer views on existing breast care services. The Women’s Health Council was asked by the Department of Health and Children, through the National Cancer Forum, to conduct research on women’s views and reactions as consumers of existing services for symptomatic breast disease. The research team was asked to document women’s views on: diagnostic services; counselling; additional treatment services such as surgery and radiotherapy. The methodology consisted of four strands: questionnaires and focus groups with consumers of breast care services; postal questionnaires to clinic staff and a literature review. Striking aspects were the long delays women experienced before obtaining a completed diagnosis; often chaotic clinic settings which added greatly to women’s shock and anxiety; the lack of support if they received a diagnosis of cancer; and problems relating to limited resources for cancer treatment, including radiotherapy. We explored women’s coping mechanisms and their experiences, in the context of the model of quality of care. Finally, we argue that a centre of excellence must develop a multidimensional model of breast disease care that incorporates the full range of psycho‐social dimensions for women, if it is to earn its claim to excellence.
Reduced‐fat foods: the shopper’s viewpoint
Authors: Hill D. S. , Knox B. , Hamilton J. , Parr H. , Stringer M. 
Published: March 2003

AbstractThe inclusion of reduced‐fat foods in the daily diet affords consumers the potential to reduce overall dietary fat. Nevertheless, despite an increased range of these food products throughout the market, there has remained a lack of widespread consumer acceptance. The aim of the study was therefore to understand why consumers choose or reject reduced‐fat foods. Ninety consumers were interviewed by means of a qualitative approach within food retail outlets in the United Kingdom. Thematic content analysis indicated that uptake or rejection of these products is influenced by health concerns, ‘goodness of fit’ with individual dietary health strategies, the preferences of different household members, perceived sensory properties and scepticism towards these products. The results imply a need to explore and innovate ‘natural’ fat substitutes and to improve the sensory quality of reduced‐fat products. Further research is required to determine how these foods are used within the household and incorporated within the overall diet. Policy must seek to restore consumer trust in reduced‐fat food products and the food supply generally.
The effects of the US Food Stamp Program on the dietary quality of parents and their teenagers and children1
Authors: Sapp Stephen G. 
Published: March 2003

AbstractAlthough previous research finds that participation in Food Stamp Programs increases the nutrient availability of low‐income households, examination of the dietary quality of parents, their teenagers (aged 13–18 years), and their children (aged 1–12 years) indicates that participation has no effect on dietary quality of any of these groups. Examination of data from the Continuing Survey of Food Intake by Individuals and Diet and Health Surveys, conducted in the USA, 1994–96, indicates that although transfer payments in the Food Stamp Program might improve quality of life in other areas by freeing income otherwise spent on food, the receipt of food assistance does not improve dietary quality. The findings show that children tend to eat healthier diets than their parents or teenage siblings. Implications are suggested regarding the use of transfer payments to improve the dietary quality of persons living in poverty.
Consumer complaints and redress: an important mechanism for protecting and empowering consumers1
Authors: Hogarth Jeanne M. , English Maureen P. 
Published: March 2003

AbstractThis paper explores a consumer complaint programme as a tool for empowering consumers, using the consumer complaint programme of a United States federal agency as a case study. After describing the structure and role of the Federal Reserve System (the central bank of the United States) in handling complaints, the paper follows a complaint through the System, looks at trends in complaints and provides a profile of consumers who complain. The paper concludes with information on the economic impact of complaint resolution and consumer satisfaction with third‐party complaint investigation.
Food, exercise and lifestyle: an initial teacher training perspective
Authors: Lakin Liz 
Published: March 2003

AbstractAll too often, we are told via the media that our children are overweight, under‐exercised and eating poor diets. This is disconcerting at the best of times but even more so when we, as a country, are reviewing our farming and food production practices. So what is our perception of food and how does this relate to the lives we lead? These questions were put to initial teacher‐trainees (ITT) at the University of Gloucestershire. They will be the teachers of tomorrow, playing a significant role in the development and lifestyles of our children. The answers received were varied; both encouraging and giving cause for concern. This paper describes an action research project based around the analysis of those answers in the light of current research into food and health. Throughout the paper, published research findings relating to school children's perception of food and nutrition are compared with the trainee teachers’ views. The comparison draws striking similarities. The implications of this point to the way we teach food and nutrition in schools and on our ITT programme at the University of Gloucestershire. Whilst praising the good practice that already exists, this paper recognises that there is a need to adequately equip trainee teachers, especially at primary level, to educate children towards a more holistic understanding of the food we eat and how it relates to the lifestyles we lead.
Consumer skills for all: a research study carried out for the General Consumer Council for Northern Ireland
Authors: Edwards Carol 
Published: March 2003

AbstractThe General Consumer Council for Northern Ireland (GCCNI) is one of the four Consumer Councils operating within the United Kingdom (the others are the Welsh, the Scottish and the National Consumer Council, which covers England and links with the other Consumer Councils). The GCCNI has a long standing interest in consumer education, and has produced a quantity of well‐regarded consumer education material aimed at both schools and adults over recent years. It has also organised regular consumer education events for schools and conferences on this subject., However, the GCCNI is aware that many people in Northern Ireland suffer difficulties in relation to consumer issues and is looking for a clear policy on dealing with those difficulties. They contracted researchers at Queen's University, Belfast to investigate the extent of the problem, with the aim of identifying the key aspects of a new consumer education and skills development strategy and the gaps and deficiencies in current provision that need to be addressed. While the GCCNI acknowledges that these problems are not exclusive to Northern Ireland, and that the nature of the problems is relatively well‐known, they felt that conditions in Northern Ireland were unique and deserving of a specific and targeted solution. Policy and decision makers in other countries will find the Northern Ireland experience of interest, both from the way in which the problem was approached and the solution which evolved.
Bone morphogenetic proteins (BMP6 and BMP7) enhance the protective effect of neurotrophins on cultured septal cholinergic neurons during hypoglycemia
Authors: Nonner Doris , Barrett Ellen F. , Kaplan Paul , Barrett John N. 
Published: March 2003

The effects of two bone morphogenetic proteins (BMP6, BMP7), alone and in combination with neurotrophins, were tested on cultures of embryonic day 15 rat septum. A week‐long exposure to BMP6 or BMP7 in the optimal concentration range of 2–5 n m increased the activity of choline acetyltransferase (ChAT) by 1.6–2‐fold, in both septal and combined septal−hippocampal cultures. The increase in ChAT activity reached significance after 4 days and continued to increase over an 11‐day exposure. Under control culture conditions neither BMP significantly altered the number of cholinergic neurons, and BMP effects on ChAT activity were less than linearly additive with those of nerve growth factor. The effects of BMPs and BMP + neurotrophin combinations were also assayed under two stress conditions: low‐density culture and hypoglycemia. In low‐density cultures BMPs and BMP + neurotrophin combinations preserved ChAT activity more effectively than neurotrophins alone. During 24 h hypoglycemic stress, BMPs alone did not preserve ChAT activity, but BMP + neurotrophin combinations preserved ChAT activity much more effectively than neurotrophins alone. These results demonstrate that BMP6 and BMP7 enhance ChAT activity under control and low‐density stress conditions, and that during a hypoglycemic stress their trophic effect requires and complements that exerted by neurotrophins.
[3H](2S,4R)‐4‐Methylglutamate: a novel ligand for the characterization of glutamate transporters
Authors: Apricó Karina , Beart Philip M. , Lawrence Andrew J. , Crawford Duncan , O'Shea Ross D. 
Published: March 2003

[3H](2S,4R)‐4‐Methylglutamate ([3H]4MG), used previously as a ligand for low‐affinity kainate receptors, was employed to establish a binding assay for glutamate transporters (GluTs), as 4MG has also been shown to have affinity for the glial GluTs, GLT1 and GLAST. In rat brain membrane homogenates in the presence of Na+ ions at 4°C, specific binding of [3H]4MG was rapid and saturable (t1/2 ≈ 15 min), representing > 90% of total binding. Dissociation of [3H]4MG occurred in a biphasic manner, however, saturation studies and Scatchard analysis indicated a single site of binding (nH = 0.85) and a Kd of 6.2 ± 0.8 µm with a Bmax of 111.8 ± 23.8 pmol/mg protein. Specific binding of [3H]4MG was Na+‐dependent and inhibited by K+ and HCO3−. Pharmacological inhibition with compounds acting at GluTs revealed that Glu, d‐ and l‐aspartate, l‐serine‐O‐sulfate and ltrans‐pyrrolidine‐2,4‐dicarboxylate fully displaced specific binding. Drugs having preferential affinity for GLT1, kainate, dihydrokainate and lthreo‐3‐methylglutamate, all inhibited ≈ 40% of specific binding. The inhibition pattern of l‐serine‐O‐sulfate in the presence of a saturating concentration of dihydrokainate was suggestive of [3H]4MG also labelling GLAST. 6‐Cyano‐7‐nitroquinoxaline, a kainate receptor antagonist, and a range of Glu receptor agonists and antagonists failed to significantly inhibit [3H]4MG binding. The pharmacological profile of binding of [3H]4MG resembled that found for [3H]d‐aspartate, a ligand specific for GluTs, reinforcing the hypothesis that [3H]4MG was labelling GluTs in this assay. Together, these data illustrate the development of an efficient, economic binding assay that is suitable for the characterization of different subtypes of GluTs.
Cerebrin prohormone processing, distribution and action in Aplysia californica
Authors: Li L. , Floyd P. D. , Rubakhin S. S. , Romanova E. V. , Jing J. , Alexeeva V. Y. , Dembrow N. C. , Weiss K. R. , Vilim F. S. , Sweedler J. V. 
Published: March 2003

The isolation, characterization, and bioactivity in the feeding circuitry of a novel neuropeptide in the Aplysia californica central nervous system are reported. The 17‐residue amidated peptide, NGGTADALYNLPDLEKIamide, has been termed cerebrin due to its primary location in the cerebral ganglion. Liquid chromatographic purification guided by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry allowed the isolation of the peptide with purity adequate for Edman sequencing. The cerebrin cDNA has been characterized and encodes an 86 amino acid prohormone that predicts cerebrin and one additional peptide. Mapping using in situ hybridization and immunocytochemistry showed that cerebrin containing neuronal somata are localized almost exclusively in the cerebral ganglion, mostly in the F‐ and C‐clusters. Both immunostaining and mass spectrometry demonstrated the presence of cerebrin in the neurohemal region of the upper labial nerve. In addition, immunoreactive processes were detected in the neuropil of all of the ganglia, including the buccal ganglia, and in some interganglionic connectives, including the cerebral‐buccal connective. This suggests that cerebrin may also function as a local signaling molecule. Cerebrin has a profound effect on the feeding motor pattern elicited by the command‐like neuron CBI‐2, dramatically shortening the duration of the radula protraction in a concentration‐dependent manner, mimicking the motor‐pattern alterations observed in food induced arousal states. These findings suggest that cerebrin may contribute to food‐induced arousal in the animal. Cerebrin‐like immunoreactivity is also present in Lymnaea stagnalis suggesting that cerebrin‐like peptides may be widespread throughout gastropoda.
Basic fibroblast growth factor: a potential inhibitor of glutamine synthetase expression in injured neural tissue
Authors: Kruchkova Yelena , Ben‐Dror Iris , Herschkovitz Avia , David Magda , Yayon Avner , Vardimon Lily 
Published: March 2003

Basic fibroblast growth factor (bFGF) was recently shown to promote the survival of neural cells and tissues, raising hopes for its therapeutic potential in degenerative disorders of the CNS. Here we examine the effect of bFGF on the expression of glutamine synthetase, a key enzyme in the detoxification of the neurotransmitter glutamate. Expression of this enzyme is regulated by systemic glucocorticoids and, in chick neural retina tissue, is restricted to Müller glial cells. We report that exogenous supply of bFGF to retinal explants inhibits hormonal induction of glutamine synthetase expression. This inhibition appears to be mediated by the c‐Jun protein which accumulated, in response to bFGF, exclusively in Müller glial cells. Ischemic conditions, which reportedly stimulate the release of endogenous bFGF, also led to an increase in c‐Jun protein and a decline in glutamine synthetase expression. This decline could be competitively prevented by a soluble fibroblast growth factor receptor but not by a soluble epidermal growth factor receptor. The finding that endogenous release of bFGF or its exogenous supply down‐regulates glutamine synthetase expression suggests that in addition to its reported neuroprotective effect, bFGF may exacerbate glutamate mediated neurotoxicity through direct down‐regulation of glutamine synthetase.