bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anatomical characteristics of roots of citrus rootstocks that vary in specific root length
Authors: EISSENSTAT D. M. , ACHOR D. S. 
Published: March 2003

Among citrus rootstocks, higher specific root length (SRL, root length/d. wt) has been linked to several specific morphological and physiological traits, including smaller average root diameter, higher root hydraulic conductivity and higher rates of root proliferation. In this study, thickness of the outer tangential exodermal (hypodermal) wall and its suberin layer, number of passage cells, presence of epidermis, and stelar anatomy were examined and related to variation in root diameter of field roots of known maximum age. We also compared root morphology and anatomy of young roots in the field with those of potted rootstock seedlings in the glasshouse. Fibrous roots were measured separately from pioneer (framework) roots. Among the fibrous roots, only the first‐order (root links having a root tip) and second‐order (root links bearing first‐order roots) laterals were examined. Among first‐order field roots, larger root diameter was caused by larger rather than more numerous cells in the cortex. Root diameter of first‐order roots was positively correlated with both number of passage cells in the exodermis and thickness of the secondary walls of the exodermis in both field and potted plants.Exodermal walls were about 80% thicker in field‐ than pot‐grown roots. In the field, in more than 50% of the first‐order roots examined less than 30% of the root surface was still covered by epidermis, with few differences among rootstocks. In contrast, in roots of 19‐wk‐old glasshouse plants generally 70–100% of the epidermis was still intact. There was no evidence of secondary xylem development in second‐order fibrous roots in the field; in seedling, pot‐grown rootsystems, 75–97% of second‐order roots had formed secondary xylem despite their small diameter (<0.8 mm).It is argued that there can be suites of physiological, morphological and anatomical traits in roots that co‐vary with specific root length. Investigations of how root morphology and anatomy are linked to root function, moreover, need to recognize trait variability and the potentially important differences between field‐ and pot‐ grown (seedling) roots.
Air pollution: forest health and passive sampling
Authors: Chappelka Arthur H. 
Published: March 2003

32nd Annual Air Pollution Workshop Auburn University in Auburn, AL, USA, April 2000Air pollution has profound effects on agriculture, forests and natural ecosystems. The first Air Pollution Workshop was held over 30 years ago, and the most vital issues have always been highlighted within this forum. This year, forest health and passive sampling of air pollutants were two key areas of interest.
Longevity of mycorrhizal roots depends on branching order and nutrient availability
Authors: Majdi Hooshang , Damm Eva , Nylund Jan‐Erik 
Published: March 2003

Summary

The effects are reported of branching order and nitrogen fertilization on the longevity of mycorrhizal short roots at a Norway spruce (Picea abies) stand in south‐west Sweden.
A 4‐yr qualitative analysis was made, using minirhizotrons, of the emergence frequency and life span of individual mycorrhizal roots of three root orders (unbranched, main axes of branched and side branches of branched short roots, orders 1, 2 and 3, respectively).
Longevity of mycorrhizal roots varied with branching order and soil depth, being greatest in unbranched (order 1) roots and those at the greatest soil depth (40–85 cm). Nitrogen addition decreased the proportion of higher mycorrhizal root orders (a fivefold reduction in order 3 compared with controls), while increasing the median longevity. Seasonal effects were recorded; mycorrhizal roots produced in spring and summer remained unsuberized during the winter.
Mycorrhizal root longevity depends on the branching order of mycorrhizal roots and nitrogen addition decreases branching density while increasing longevity. The survival of mycorrhizal roots, which remain vital and unsuberized over winter, enhances water and nutrient efficiency of Norway spruce.
Direct inhibition of leaf dark respiration by elevated CO2 is minor in 12 grassland species
Authors: Tjoelker M. G. , Oleksyn J. , Lee T. D. , Reich P. B. 
Published: March 2003

Summary

•  Direct inhibition of dark respiration by elevated atmospheric concentrations of CO2 could alter the carbon balance of plants and ecosystems. The short‐term response of leaf dark respiration to elevated CO2 concentrations are reported here in 12 grass and forb species of a North American grassland community.
•  Specific respiration rates at 25°C and a range of measurement CO2 concentrations were determined for detached leaves of each species field‐grown in monoculture.
•  On average, respiration rates were 1.8% lower at 700 than at 360 µmol mol−1 CO2. Among species, responses ranged from a 6.4% inhibition to a 2.4% stimulation and were generally not statistically significant. Across a range of CO2 concentrations from 360 to 1300 µmol mol−1, respiration rates declined linearly and were 11% lower at 1300 than 360 µmol mol−1 CO2.
•  Direct inhibition of leaf respiration is small compared with other longer‐term, indirect effects of CO2 on carbon exchange. The direct effects of rising atmospheric CO2 concentrations on respiration rates should result in minimal effects on plant carbon exchange in grasslands.
MAP kinase signal transduction pathways in plants
Authors: Morris Peter C. 
Published: March 2003

SummaryThe mitogen‐activated protein kinase (MAP kinase) signal transduction cascades are routes through which eukaryotic cells deliver extracellular messages to the cytosol and nucleus. These signalling pathways direct cell division, cellular differentiation, metabolism, and both biotic and abiotic stress responses. In plants, MAP kinases and the upstream components of the cascades are represented by multigene families, organized into different pathways which are stimulated and interact in complex ways. Experimental strategies for the analysis of MAP kinase cascades include the yeast two‐hybrid system; using this approach in vitro interactions between specific MAP kinase cascade components have been analysed and putative plant cascades postulated. Transient transformation of protoplasts with epitope‐tagged kinases has allowed cascades to be tested in planta. There is clear evidence for the involvement of MAP kinases in plant cell division and in the regulation of auxin signalling. Biotic (pathogens and pathogen‐derived elicitors from fungi, bacteria and viruses) and abiotic stresses including wounding, mechanical stimulation, cold, drought and ozone can elicit defence responses in plants through MAP kinase pathways. There are data suggesting that ABA signalling utilizes a MAP kinase pathway, and probably ethylene and perhaps cytokinins do so also. The objective of this paper is to review this rapidly advancing field.

Contents

Summary
67

I.
Introduction
68

II.
Background
68

III.
MAP kinase targets and targeting specificity
69

IV.
Assays and inhibitors
70

V.
Two well characterized MAP kinase pathways, Hog1 and Sevenless
71

VI.
MAP kinases in plants
73

VII.
MAP kinases and cell division
76

VIII.
MAP kinases and plant hormones
76

IX.
MAP kinase and abiotic stress
78

X.
MAP kinase and biotic stress
80

XI.
Future perspectives for MAP kinase research in plants
83

Acknowledgements
84

References
84
Light‐dependent growth rate determines changes in the population of Planktothrix rubescens over the annual cycle in Lake Zürich, Switzerland
Authors: Walsby A. E. , Schanz F. 
Published: March 2003

Summary• Analyses were made to determine which changes in a Lake Zürich population of Planktothrix rubescens were dependent on light‐ and temperature‐dependent growth rates, and when growth was limited by the mixing depth.• Changes in vertical distribution of the cyanobacterium, determined weekly from August 1998 to September 1999, were related to growth increments calculated at 1‐h time and 1‐m depth intervals from values of irradiance, attenuance, temperature and biomass in the lake, using algorithms based on growth rates in culture.• Population biovolume varied annually from 1.2 to 120  cm3 m−2. During summer, modelled growth in the metalimnion matched the 50‐fold population increase. Modelled growth exceeded the observed increase when Planktothrix was mixed into the nutrient‐depleted epilimnion, suggesting nutrient limitation. The measured increase ceased when the mixed depth exceeded the critical depth for growth in autumn (Sverdrup’s principle). Light limitation explained the gradual decrease of the population in winter. The steep decline in spring had other causes.• Population changes were largely determined by interactions of light and depth distribution; decreases in nutrient loading have had little impact on Planktothrix growth in Lake Zürich.
Variations in ageing and meristematic activity in relation to flower‐bud and fruit excision in the Beta species complex
Authors: Hautekèete N.‐C. , Piquot Y. , Van Dijk H. 
Published: March 2003

Summary• Removal of developing fruits delays ageing in many annual plant species. This has long been seen as evidence that ageing is caused by resource depletion due to fruit development. Excision experiments can be interpreted from both evolutionary‐ecology and resource‐allocation viewpoints. Iteroparous (reproducing repeatedly) and annual plants may show different responses to excision. Furthermore, under the resource‐depletion hypothesis, the more precocious the excision of reproductive organs, the greater the effect on allocation patterns.• A controlled‐conditions experiment was set up involving six life cycles (from long‐lived iteroparous to annual taxa of wild beets, Beta spp.) under three treatments of excision of reproductive‐parts (buds, fruits and control).• Treatment effect was similar in semelparous and iteroparous beets, although effect on reproduction was more obvious in iteroparous ones. Flower‐bud removal tended to induce resource allocation in new reproductive meristems, whatever the life cycle, without any effect on ageing in semelparous beets and probably none on survival in most iteroparous plants. Fruit removal had no effect.• These results and the occurrence of between‐accessions variation are discussed in terms of the ecological significance of optimal allocation strategies.
Using radiocarbon to determine the mycorrhizal status of fungi
Authors: Hobbie Erik A. , Weber Nancy S. , Trappe James M. , Van Klinken Gert J. 
Published: March 2003

Summary

Measurements of 13
C in fungal sporocarps are useful in assessing mycorrhizal or saprotrophic status. Because
14
C measurements can indicate the age of fungal carbon (C) and mycorrhizal fungi depend closely on recent photosynthate,
14 C may provide additional insight into possible mycorrhizal status.
Sporocarps, needles, and litter from Woods Creek, OR, USA together with archived sporocarps were measured for 14 C content by accelerator mass spectrometry.
Known mycorrhizal fungi resembled current‐year needles ( Amanita
,
Cantharellus
and
Gomphidius
) or atmospheric CO
2
(
Tuber
) in
14
C and indicated an average age of 0–2 yr for incorporated C, whereas saprotrophic genera (
Pleurocybella
,
Lepiota
and
Hypholoma
) were composed of C at least 10 yr old. Of genera tentatively considered mycorrhizal from previous work with
13
C, only
Otidia
and
Sowerbyella
appeared mycorrhizal from
14
C measurements, whereas
Aleuria
,
Clavulina
,
Paurocotylis
and
Ramaria (sensu lato ) consisted of older carbon and were presumably saprotrophic.
14
C clearly separated known mycorrhizal or saprotrophic fungi and indicated
13
C measurements should be interpreted cautiously on species of unknown status.
14
C results for needles and mycorrhizal fungi suggested that C sources other than atmospheric CO
2
may contribute small amounts of C. Possible sources include storage of carbohydrates and amino acids, organic nitrogen uptake, and incorporation of soil‐respired CO
2 by anaplerotic or photosynthetic pathways.
The influence of socio‐economic status on salt consumption in Northern Ireland
Authors: Purdy Joanna , Armstrong Gillian , McIlveen Heather 
Published: March 2003

AbstractThe long‐established association between high salt consumption and hypertension has led to calls for a reduction in salt intake. There is particular concern for the health status of Northern Irish consumers, who already have among the highest rates of coronary heart disease and stroke in the United Kingdom. With these concerns in mind, it is essential to establish the sources and patterns of salt consumption from discretionary and processed food sources before a reduction can be achieved. This study investigated differences in salt consumption patterns among consumers of varying socio‐economic status. Research consisted of a consumer questionnaire (n= 360) distributed within Northern Ireland. The results of the study revealed high discretionary salt usage and frequent consumption of processed foods among consumers of lower socio‐economic status. General observations from the questionnaire would suggest a need for improved health education for consumers in this group. The objective of health promotion should be to encourage a reduction in table and cooking salt usage and, in particular, in the consumption of highly salted processed foods. Enhanced product labelling is also encouraged to increase consumer awareness of current salt levels in food and of the availability of low‐salt foods. In addition, the results of this study advocate further development activity in the production of product formulations with low‐salt status.
Healthy eating in the school environment – a holistic approach*
Authors: Burke Linda 
Published: March 2003

AbstractThe curriculum that pupils are taught within the classroom environment can either be reinforced or weakened by what goes on in the rest of the school environment. The study focused on pupils aged 11–12 years, to establish if healthy eating theory was put into practice in the school environment. The research encompassed three areas within the school: the pupils who are the recipients of the theory; the teacher who teaches them the importance of food and cooking skills; and the providers of food within the school environment. Three different post‐primary schools located within the Coleraine area of Northern Ireland were used.
An evaluation of consumer participation in hospital breast services
Authors: Innes L. , Bowen L. , Bruce N. , Scott L. , Williams P. 
Published: March 2003

AbstractCommunity expectations and research demonstrate that consumers play an important role in shaping services for women with breast cancer. Consumer contribution has been mandated recently in Victoria, Australia, to ensure the inclusion of consumer involvement in the planning and decision‐making processes within health organizations. As part of the redevelopment of breast services in Victoria, Southern Health has been funded to plan local improvements to care co‐ordination for women diagnosed with breast cancer in the southern metropolitan area of Melbourne. The establishment of effective consumer participation in breast services is an integral aspect of this project and a range of initiatives has been undertaken to achieve meaningful consumer involvement including the appointment of a consumer advisor; appointment of staff with extensive knowledge in women's health and community development to the project; establishment of a consumer reference group; and plans made to improve the receptivity of health service systems to consumer input. A preliminary evaluation of this ongoing project has indicated that a productive role for consumers in service practice review and policy and planning activities has been established and some change and engagement of staff has occurred. There is still work to be done to promote the involvement of a wider range of health professionals and to increase the level of trust between consumers and staff.
Protein kinase C regulation of dopamine transporter initiated by nicotinic receptor activation in slices of rat prefrontal cortex
Authors: Drew Allison E. , Werling Linda L. 
Published: March 2003

We previously reported that activation of nicotinic receptors causes an enhancement in amphetamine‐stimulated release of dopamine via its transporter from slices of prefrontal cortex, but no such enhancement of release from slices of nucleus accumbens or striatum. The nicotinic receptors mediating the enhancement most likely contain α4 and β2 subunits based upon pharmacological characterization. In this study, we sought to characterize the second messenger systems associated with the nicotine‐mediated response. Sodium channel involvement was confirmed by the observation that tetrodotoxin blocked nicotine‐mediated enhancement, whereas veratridine or elevated K+mimicked the enhancement seen with nicotine. Inclusion of EGTA blocked nicotine‐mediated enhancement, suggesting that, even though no exogenous Ca2+was added, endogenous stores were required for the enhancement. The enhancement by nicotine was also abolished by the L‐type voltage‐dependent calcium channel (VDCC) antagonist nitrendipine, but not by the N‐type VDCC antagonist ω‐conotoxin GVIA. Finally, inhibition of protein kinase C also abolished the nicotine‐mediated enhancement of amphetamine‐stimulated dopamine release, whereas inhibitors of Ca2+/calmodulin kinase II did not. These findings establish that nicotine can exert selective effects on dopamine transporter activity in prefrontal cortex, an area involved in cognition and learning.
The relationship between the aggregational state of the amyloid‐β peptides and free radical generation by the peptides
Authors: Monji Akira , Utsumi Hideo , Ueda Tadashi , Imoto Taiji , Yoshida Ichiro , Hashioka Sadayuki , Tashiro Ken‐ichiro , Tashiro Nobutada 
Published: March 2003

In the present study, we investigated whether or not the amyloid‐β protein (Aβ) peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of Aβ and Aβ‐induced cytotoxicity. The present results demonstrated a four‐line spectrum in the presence of both Aβ40 and Aβ42 with Ntert‐butyl‐α‐phenylnitrone (PBN), but not in the presence of PBN alone in phosphate‐buffered saline (PBS). The fact that the four‐line spectrum obtained for the Aβ/PBN in PBS was completely abolished in the presence of the iron‐chelating agent Desferal demonstrated the observed four‐line spectrum to be iron‐dependent. The present study also revealed that either Aβ40 or Aβ42 with PBN in phosphate buffer (PB) did not produce any definite four‐line spectrum. Both a thioflavine‐T (Th‐T) fluorometric assay and circular dichroism (CD) spectroscopy showed the amyloid fibril formation of Aβ in PBS to be much higher than that of Aβ in PB. Moreover, Aβ‐induced cytotoxicity assays showed Aβ incubated in PBS to be more cytotoxic than that incubated in PB. These results thus suggest that Aβ‐associated free radical generation is strongly influenced by the aggregational state of the peptides.
Regulation of MARCKS and MARCKS‐related protein expression in BV‐2 microglial cells in response to lipopolysaccharide
Authors: Sunohara Janet R. , Ridgway Neale D. , Cook Harold W. , Byers David M. 
Published: March 2003

Myristoylated alanine‐rich C kinase substrate (MARCKS) and MARCKS‐related protein (MRP) have been implicated in membrane‐cytoskeletal events underlying cell adhesion, migration, secretion, and phagocytosis. In BV‐2 microglial cells, lipopolysaccharide (LPS) elicited a dose‐dependent increase in mRNA of both MRP (sixfold) and MARCKS (threefold) with corresponding increases in [3H]myristoylated and immunoreactive protein levels. LPS also produced significant increases in protein kinase C (PKC)‐β twofold and PKC‐ε (1.5‐fold). Pro‐inflammatory cytokines produced by activated microglia (IL‐1β, IL‐6, TNF‐α) did not mimic LPS effects on MARCKS or MRP expression when added individually or in combination. LPS and IFN‐γ produced a synergistic induction of iNOS but not MARCKS or MRP. Induction of MARCKS and MRP by LPS was completely blocked by inhibitors of NF‐κB (PDTC) and protein tyrosine kinases (herbimycin A), partially blocked by the p38 kinase inhibitor SB203580, and unaffected by the MEK inhibitor PD98059. LPS induction of iNOS was considerably more sensitive to all these inhibitors. The Src kinase inhibitor PP2 had no effect, while the closely related inhibitor PP1 actually increased LPS induction of MARCKS and MRP. Our results suggest that MARCKS and MRP may play an important role in LPS‐activated microglia, but are not part of the neuroinflammatory response produced by cytokines.
Antidepressant drug treatments induce glial cell line‐derived neurotrophic factor (GDNF) synthesis and release in rat C6 glioblastoma cells
Authors: Hisaoka Kazue , Nishida Akira , Koda Tetsuzo , Miyata Masahiko , Zensho Hidenobu , Morinobu Shigeru , Ohta Mitsuhiro , Yamawaki Shigeto 
Published: March 2003

Modulation of neurotrophic factors to protect neurons from damage is proposed as a novel mechanism for the action of antidepressants. However, the effect of antidepressants on modulation of glial cell line‐derived neurotrophic factor (GDNF), which has potent and widespread effects, remains unknown. Here, we demonstrated that long‐term use of antidepressant treatment significantly increased GDNF mRNA expression and GDNF release in time‐ and concentration‐dependent manners in rat C6 glioblastoma cells. Amitriptyline treatment also increased GDNF mRNA expression in rat astrocytes. GDNF release continued for 24 h following withdrawal of amitriptyline. Furthermore, following treatment with antidepressants belonging to several different classes (amitriptyline, clomipramine, mianserin, fluoxetine and paroxetine) significantly increased GDNF release, but which did not occur after treatment with non‐antidepressant psychotropic drugs (haloperidol, diazepam and diphenhydramine). Amitriptyline‐induced GDNF release was inhibited by U0126 (10 µm), a mitogen‐activated protein kinase (MAPK)‐extracellular signal‐related kinase (ERK) kinase (MEK) inhibitor, but was not inhibited by H‐89 (1 µm), a protein kinase A inhibitor, calphostin C (100 nm), a protein kinase C inhibitor and PD 169316 (10 µm), a p38 mitogen‐activated protein kinase inhibitor. These results suggested that amitriptyline‐induced GDNF synthesis and release occurred at the transcriptional level, and may be regulated by MEK/MAPK signalling. The enhanced and prolonged induction of GDNF by antidepressants could promote neuronal survival, and protect neurons from the damaging effects of stress. This may contribute to explain therapeutic action of antidepressants and suggest new strategies of pharmacological intervention.