bluuebunny/crossref_metadata_2025 huggingface dataset:
Sugar and fructan accumulation during metabolic adjustment between respiration and fermentation under low oxygen conditions in wheat roots
Authors: Albrecht Gerd , Mustroph Angelika , Fox Theodore C.
Published: January 2004

In terms of gene expression and carbohydrate metabolism, the response of wheat seedlings to hypoxia is dramatically different from the anoxic response. Total carbohydrate content of roots increased 4‐fold during 6 days of hypoxia, with a 17‐fold increase in fructans. In contrast, anoxically treated roots depleted all soluble carbohydrates and died within 72 h. Gas exchange measurements (CO2 release vs. O2 uptake) demonstrate that hypoxia establishes a new balance between fermentation and aerobic respiration in the roots without altering the flux of carbon through glycolysis. Furthermore, the respiratory component of this new balance is 55% higher in roots that have been hypoxically pretreated compared to non‐hypoxically pretreated roots. The establishment of this new homeostasis under hypoxia involves the induction of glycolytic (aldolase and enolase) and fermentative enzymes (pyruvate decarboxylase, alcohol dehydrogenase, and lactate dehydrogenase). Enzyme induction is generally complete within 24 h with mRNA induction occurring primarily during Period I (0–6 h of hypoxia), and maximal enzymes activities attained during Period II (6–24 h of hypoxia). Accumulation rates of Suc, hexoses, and fructans also change during Periods I and II. By the start of Period III (24–144 h of hypoxia), the metabolic adjustments are complete and fructans are the major carbohydrate accumulated. In anoxia, the pattern of enzyme induction was dramatically different: aldolase was not induced and declined throughout the treatment. Alcohol dehydrogenase, pyruvate decarboxylase, and lactate dehydrogenase were induced as in hypoxia, but rapidly declined within 72 h of anoxia. Only enolase exhibited a similar expression pattern in both anoxia and hypoxia.
Promoter analysis and transcription profiling: Integration of genetic data enhances understanding of gene expression
Authors: Venter Mauritz , Botha Frederik C.
Published: January 2004

It is increasingly evident that transcription control might be conserved among organisms. For this reason, genome sequencing and gene expression profiling methods, which have yielded a plethora of data in different organisms, may be applied in species where genomic sequence is limited to mostly expression array and EST data. The identification of transcription factors and promoters associated with gene expression profiles and ESTs could therefore contribute to elucidate and predict complex regulatory events in plants.
Methyl jasmonate alters N partitioning, N reserves accumulation and induces gene expression of a 32‐kDa vegetative storage protein that possesses chitinase activity in Medicago sativa taproots
Authors: Meuriot Frédéric , Noquet Carine , Avice Jean‐Christophe , Volenec Jeffrey J. , Cunningham Suzanne M. , Sors Thomas G. , Caillot Sébastien , Ourry Alain
Published: January 2004

This study presents the effects of methyl jasmonate (MeJA) on growth, N uptake, N partitioning, and N storage in taproots of non‐nodulated alfalfa (cv. Lodi). When compared to untreated plants, addition of 100 µM MeJA to the nutrient solution for 14 days reduced total growth and modified biomass partitioning between shoots and roots in favour of taproots and lateral roots. MeJA decreased N uptake (after 7 days) and increased N partitioning towards roots after 14 days. This preferential N partitioning to roots was accompanied by increased N storage in taproots as soluble proteins. Compared to total soluble proteins, VSP accumulation occurred earlier (7 days), and was greater (2‐fold increase) in plants treated with 100 µM MeJA. Steady‐state transcript levels for two VSPs (32 and 57 kDa) also increased markedly (about 4‐fold) in roots of plants treated with 100 µM MeJA. This suggests that MeJA could act directly (transcriptional regulation) or indirectly (via the changes of N partitioning among alfalfa organs) on N storage as soluble proteins and in particular, VSPs. Because the deduced amino acid sequence of the 32 kDa VSP clone reveals high homology with Class III chitinases, we propose that the 32 kDa VSP may have a role in pathogen defense, in addition to its function as a storage protein.
Expression of nir, nor and nos denitrification genes from Bradyrhizobium japonicum in soybean root nodules
Authors: Mesa Socorno , Alché Juan de Dios , Bedmar Eulogio , Delgado Maria J.
Published: January 2004

Expression of Bradyrhizobium japonicum wild‐type strain USDA110 nirK, norC and nosZ denitrification genes in soybean root nodules was studied by in situ histochemical detection of β‐galactosidase activity. Similarly, PnirK‐lacZ, PnorC‐lacZ, and PnosZ‐lacZ fusions were also expressed in bacteroids isolated from root nodules. Levels of β‐galactosidase activity were similar in both bacteroids and nodule sections from plants that were solely N2‐dependent or grown in the presence of 4 mM KNO3. These findings suggest that oxygen, and not nitrate, is the main factor controlling expression of denitrification genes in soybean nodules. In plants not amended with nitrate, B. japonicum mutant strains GRK308, GRC131, and GRZ25, that were altered in the structural nirK, norC and nosZ genes, respectively, showed a wild‐type phenotype with regard to nodule number and nodule dry weight as well as plant dry weight and nitrogen content. In the presence of 4 mM KNO3, plants inoculated with either GRK308 or GRC131 showed less nodules, and lower plant dry weight and nitrogen content, relative to those of strains USDA110 and GRZ25. Taken together, the present results revealed that although not essential for nitrogen fixation, mutation of either the structural nirK or norC genes encoding respiratory nitrite reductase and nitric oxide reductase, respectively, confers B. japonicum reduced ability for nodulation in soybean plants grown with nitrate. Furthermore, because nodules formed by each the parental and mutant strains exhibited nitrogenase activity, it is possible that denitrification enzymes play a role in nodule formation rather than in nodule function.
Localization of arginine decarboxylase in tobacco plants
Authors: Bortolotti Cristina , Cordeiro Alexandra , Alcázar Rubén , Borrell Antoni , Culiañez‐Macià Francisco A. , Tiburcio Antonio F. , Altabella Teresa
Published: January 2004

The lack of knowledge about the tissue and subcellular distribution of polyamines (PAs) and the enzymes involved in their metabolism remains one of the main obstacles in our understanding of the biological role of PAs in plants. Arginine decarboxylase (ADC; EC 4.1.1.9) is a key enzyme in polyamine biosynthesis in plants. We have characterized a cDNA coding for ADC from Nicotiana tabacum L. cv. Petit Havana SR1. The deduced ADC polypeptide had 721 amino acids and a molecular mass of 77 kDa. The ADC cDNA was overexpressed in Escherichia coli, and the ADC fusion protein obtained was used to produce polyclonal antibodies. Using immunological methods, we demonstrate the presence of the ADC protein in all plant organs analysed: flowers, seeds, stems, leaves and roots. Moreover, depending on the tissue, the protein is localized in two different subcellular compartments, the nucleus and the chloroplast. In photosynthetic tissues, ADC is located mainly in chloroplasts, whereas in non‐photosynthetic tissues the protein appears to be located in nuclei. The different compartmentation of ADC may be related to distinct functions of the protein in different cell types.
Control of chloroplast redox by the IMMUTANS terminal oxidase
Authors: Aluru Maneesha R. , Rodermel Steven R.
Published: January 2004

Variegation mutants offer excellent opportunities to study interactions between the nucleus‐cytoplasm, the chloroplast, and the mitochondrion. Variegation in the immutans (im) mutant of Arabidopsis is induced by a nuclear recessive gene and the extent of variegation can be modulated by light and temperature. Whereas the green sectors have morphologically normal chloroplasts, the white sectors are devoid of pigments and accumulate a colourless carotenoid, phytoene. The green sectors are hypothesized to arise from cells that have avoided irreversible photooxidative damage whereas the white sectors originate from cells that are photooxidized. Cloning of the IMMUTANS (IM) gene has revealed that IMMUTANS (IM) is a plastid homologue of the mitochondrial alternative oxidase. This finding suggested a model in which IM functions as a redox component of the phytoene desaturation pathway, which requires phytoene desaturase activity. Consistent with this idea, IM has quinol oxidase activity in vitro. Recent studies have revealed that IM plays a more global role in plastid metabolism. For example, it appears to be the elusive terminal oxidase of chlororespiration and also functions as a light stress protein.
Hyperhydricity in micropropagated carnation shoots: the role of oxidative stress
Authors: Saher Shady , Piqueras Abel , Hellin Eladio , Olmos Enrique
Published: January 2004

The physiology of hyperhydricity in relation to oxidative stress, mineral nutrients, antioxidant enzymes and ethylene has been studied in three micropropagated carnation cultivars under experimentally induced hyperhydricity. A marked increase in Fe content in comparison with normal tissues was observed in the hyperhydric tissues from the three cultivars. The levels of ethylene, solute leakage and malondialdehyde content were also significantly higher in the hyperhydric tissues. In relation to the time course of H2O2 production measured by fluorescence quenching, a similar trend could be observed for the three cultivars, with a clear increase in the generation of hydrogen peroxide in hyperhydric tissues. The activities of all the antioxidative enzymes studied, except lipoxygenase, were higher in the hyperhydric shoots. Phenylalanine ammonia‐lyase (PAL) showed a significant decrease in activity in the hyperhydric tissues in comparison with the controls for the three cultivars. Soluble guaiacol peroxidase had a strong increase in activity in hyperhydric shoots of the three cultivars. These results provide, for the first time, direct evidence of H2O2 generation in hyperhydric tissues, characterize the response of the antioxidant system to an oxidative stress during hyperhydricity in carnation leaves and point to the accumulation of toxic forms of oxygen as the inducer of some of the abnormalities observed.
Vessel differentiation in the pedicel of apple and the effects of auxin transport inhibition
Authors: Dražeta Lazar , Lang Alexander , Cappellini Chiara , Hall Alistair J. , Volz Richard K. , Jameson Paula E.
Published: January 2004

The growth dynamics of vessel formation and the effect of auxin transport inhibition on vessel differentiation were investigated in the pedicel of developing apple (Malus domestica Borkh.). Quantitative microscopic analysis showed that a majority of vessels were differentiated pre‐bloom with the commencement of pedicel extension but that the full conducting capacity of the xylem was attained shortly after bloom. The effect of a post‐bloom application of N‐(1‐Napthyl)phthalamic acid showed that an auxin‐like signal emanating from the young fruit not only stimulated vessel differentiation in the pedicel but also controlled fruit abscission and the development of the seed and fruit.
Seasonal and spatial variation of carbohydrates in mistletoes (Viscum album) and the xylem sap of its hosts (Populus × euamericana and Abies alba)
Authors: Escher Peter , Eiblmeier Monika , Hetzger Ilka , Rennenberg Heinz
Published: January 2004

In the present field study we analysed the seasonal pattern of carbohydrate composition and contents in the xylem sap of Viscum album and the xylem sap of a deciduous (Populus×euramericana) and a coniferous (Abies alba) host tree species. The results were compared with the soluble carbohydrate composition and contents of mistletoe tissues. On both hosts significant amounts of glucose, fructose, and sucrose were found in the xylem sap of Viscum throughout the seasons. The general seasonal pattern of sugar contents, i.e. high concentrations in spring and lower concentrations in other seasons on Populus, and intermediate concentrations throughout the year on Abies, largely reflected the xylem sap carbohydrate composition and contents of the respective host. These observations provide indirect evidence for carbohydrate flux from the xylem sap of the host into the mistletoe. However, in both hosts xylem sap seems to be deviated into the mistletoe without specific control of carbohydrate flux. Differences observed between the seasonal pattern of xylem sap carbohydrate concentrations in Viscum on Populus and Abies may originate from the different time of leaf development of these species. A clear‐cut seasonal pattern of soluble carbohydrates was not observed in the leaves of Viscum on both hosts. Still soluble carbohydrates seem to be reallocated from the senescing to the newly developed leaves of Viscum indicating that the seasonal requirement of carbohydrate for growth and development can only completely be met by carbohydrate acquisition from the host and their own photosynthesis.
Microarray analysis and redox control of gene expression in the cyanobacterium Synechocystis sp. PCC 6803
Authors: Singh Abhay K. , Li Hong , Sherman Louis A.
Published: January 2004

Expression profiles of Synechocystis sp. PCC 6803 genes in response to growth in iron‐deficient versus iron‐sufficient media and after 30 min treatment with H2O2 were determined using a full‐genome microarray. We used an anova model that accounted for slide and replicate (random) effects as well as dye (a fixed) effects to identify statistically significant, differentially expressed genes that changed by 1.25‐fold or greater during each of these experiments. We utilized this microarray data to identify gene clusters that were regulated under these stresses, because we are interested in cellular redox control and the way in which the cell responds to oxidative stresses. We are particularly interested in using differential expression to help determine the function of genes involved in redox control and cluster analysis aids this process. We concentrated on four gene clusters, two of which were similarly affected by both stresses, and two that were only differentially regulated by one of the stresses. We also analysed the regulatory genes that responded to these oxidative stresses and discussed the changes in transcription of the RNA polymerase sigma factors and the other regulatory proteins, many of which represent two‐component regulatory systems.
Mechanotransduction in root gravity sensing cells
Authors: Perbal Gérald , Lefranc Agnès , Jeune Bernard , Driss‐Ecole Dominique
Published: January 2004

The analysis of the dose–response curve of the gravitropic reaction of lentil seedling roots has shown that these organs are more sensitive when they have been grown in microgravity than when they have been grown on a 1 g centrifuge in space before gravistimulation. This difference of gravisensitivity is not due to the volume or the density of starch grains of statoliths, which are about the same in both conditions (1 g or microgravity). However, the distribution of statoliths within the statocyte may be responsible for this differential sensitivity, since the dispersion of these organelles is greater in microgravity than in 1 g. When lentil roots grown in microgravity or in 1 g are stimulated at 0.93 g for 22 min, the amyloplasts sediment following two different trajectories. They move from the proximal half of the statocytes toward the lower longitudinal wall in the microgravity grown sample and from the distal half toward the longitudinal wall in the 1 g grown sample. At the end of the stimulation, they reach a similar position within the statocytes. If the roots of both samples are left in microgravity for 3 h, the amyloplasts move toward the cell centre in a direction that makes an average angle of 40° with respect to the lower longitudinal wall. The actin filaments, which are responsible for this movement, may have an overall orientation of 40° with respect to this wall. Thus, when roots grown in microgravity are stimulated on the minicentrifuge the amyloplasts slide on the actin filaments, whereas they move perpendicular to them in 1 g grown roots. Our results suggest that greater sensitivity of seedling roots grown in microgravity should be due to greater dispersion of statoliths, to better contacts between statoliths and the actin network and to greater number of activated mechanoreceptors. One can hypothesize that stretch activated ion channels (SACs) located in the plasma membrane are responsible for the transduction of gravistimulus. These SACs may be connected together by elements of the cytoskeleton lining the plasma membrane and to the actin filaments. They could be stimulated by the action of statoliths on the actin network and/or on these elements of the cytoskeleton which link the mechanoreceptors (SACs).
Tissue‐specific expression and developmental regulation of cytochrome b561 genes in Arabidopsis thaliana and Raphanus sativus
Authors: Verelst Wim , Kapila Jyoti , De Almeida Engler Janice , Stone Julie M. , Caubergs Roland , Asard Han
Published: January 2004

Ascorbate (Asc) is an essential molecule in many aspects of development and stress responses in plants and animals. Cytochromes b561 (cyts b561) are tightly coupled to Asc homeostasis. These proteins are found in mammalian tissues, where they are involved in the regeneration of Asc, serving the synthesis of catecholamine neurotransmitters, and in intestinal iron reduction. Plant genomes encode homologous membrane‐associated, Asc‐reducible cyts b561. The expression of these proteins in plants, however, has so far not been studied. We have now examined the expression of two Arabidopsis thaliana cyt b561‐encoding genes—Artb561‐1 and Artb561‐2—using relative‐quantitative RT‐PCR and in situ hybridization (ISH) techniques. The genes show overlapping and distinct tissue‐ and organ‐specific expression patterns. Transcripts of both genes are found in leaf epidermal cells, and expression seems to correlate with leaf maturation and cessation of cell elongation. Both genes are also expressed in the epidermal cell layer of stems and roots in the L1 layer of the shoot apex, in the vascular system of leaves, stems and roots, and in the root pericycle. In addition, Artb561‐1 is expressed in the root cap, whereas Artb561‐2 mRNA is found in the epidermis of lateral roots, in the root meristem, and in unfertilized ovules. These observations provide important information for the elucidation of the physiological function of cyts b561 in plants.
Growth and morphological responses to different UV wavebands in cucumber (Cucumis sativum) and other dicotyledonous seedlings
Authors: Shinkle James R. , Atkins Alaina K. , Humphrey Erin E. , Rodgers Christiana W. , Wheeler Shelley L. , Barnes Paul W.
Published: January 2004

We examined the influence of short‐term exposure of different UV wavebands on the fine‐scale kinetics of hypocotyl growth of dim red light‐grown cucumbers (Cucumis sativusL.) and other selected dicotyledonous seedlings to evaluate: (1) whether responses induced by UV‐B radiation (280–320 nm) are qualitatively different from those induced by UV‐A (320–400 nm) radiation, and (2) whether different wavebands within the UV‐B elicit different responses. Responses to brief (30 min) irradiations with 3 different UV wavebands all included transient inhibition of elongation during irradiation followed by wavelength specific responses. Irradiations with proportionally greater short wavelength UV‐B (37% of UV‐B between 280 and 300 nm) induced inhibition of hypocotyl elongation within 20 min of onset of irradiation, while UV‐B including only wavelengths longer than 290 nm (and only 8% of UV‐B between 290 and 300 nm) induced inhibition of hypocotyl elongation with a lag of 1–2 h. The response to short wavelength UV‐B was persistent for at least 24 h, while the response to long wavelength UV‐B lasted only 2–3 h. The UV‐A treatment induced reductions in elongation rates of approximately 6–9 h following exposure followed by a continued decline in rates for the following 15–18 h. Short wavelength UV‐B also induced positive phototropic curvature in both cucumber andArabidopsisseedlings, and this response was present in nph‐1 mutantArabidopsisseedlings defective in normal blue light phototropism. Reciprocity was not found for the response to short wavelength UV‐B. The short wavelength and long wavelength UV‐B responses differed in dose–response relationships and both short wavelength responses (phototropic curvature and elongation inhibition) increased sharply at wavelengths below 300 nm. These results indicate that different photosensory processes are involved in mediating growth and morphological responses to short wavelength UV‐B (280–300 nm), long wavelength UV‐B (essentially 300–320 nm) and UV‐A. The existence of two separate types of hypocotyl inhibition responses to UV‐B, with one that depends on the intensity of the light source, provides alternate interpretations to findings in other studies of UV‐B induced photomorphogenesis and may explain inconsistencies between action spectra for inhibition of stem growth.
Influence of ozone on ribonuclease activity in wheat (Triticum aestivum) leaves
Authors: Booker Fitzgerald L.
Published: January 2004

Ribonucleases (RNases) degrade RNA and exert a major influence on gene expression during development and in response to biotic and abiotic stresses. RNase activity typically increases in response to pathogen attack, wounding and phosphate (Pi) deficiency. Activity also increases during senescence and other programmed cell death processes. The air pollutant ozone (O3) often induces injury and accelerated senescence in many plants, but the biochemical mechanisms involved in these responses remain unclear. The objective of this study was to determine whether RNase activity and isozyme expression was stimulated in wheat (Triticum aestivum L.) flag leaves following treatment with O3. Plants were treated in open‐top chambers with charcoal‐filtered air (27 nmol O3 mol−1) (control) or non‐filtered air plus O3 (90 nmol O3 mol−1) (O3) from seedling to reproductive stage. After exposure for 56 days, RNase activity was 2.1 times higher in flag leaf tissues from an O3‐sensitive cultivar in the O3 treatment compared with the control, which generally coincided with foliar injury and lower soluble protein concentration, but not soluble leaf [Pi]. Soluble [Pi] in leaf tissue extracts from the O3 and control treatments was not significantly different. RNase activity gels indicated the presence of three major RNases and two nucleases, and their expression was enhanced by the O3 treatment. Isozymes stimulated in the O3 treatment were also stimulated in naturally senescent flag leaf tissues from plants in the control. However, soluble [Pi] in extracts from naturally senescent flag leaves was 50% lower than that found in green flag leaves in the control treatment. Thus, senescence‐like pathological responses induced by O3 were accompanied by increased RNase and nuclease activities that also were observed in naturally senescent leaves. However, [Pi] in the leaf tissue samples suggested that O3‐induced injury and accelerated senescence was atypical of normal senescence processes in that Pi export was not observed in O3‐treated plants.
14‐3‐3 proteins: regulation of signal‐induced events
Authors: Ferl Robert J.
Published: January 2004

The field of signal transduction has experienced a significant paradigm shift as a result of an increased understanding of the roles of 14‐3‐3 proteins. There are many cases where signal‐induced phosphorylation itself may cause a change in protein function. This simple modification is, in fact, the primary basis of signal transduction events in many systems. There are a large and growing number of cases, however, where simple phosphorylation is not enough to effect a change in protein function. In these cases, the 14‐3‐3 proteins can be required to complete the change in function. Therefore signal transduction can be either the relatively simple process where phosphorylation alters target activity, or it can be a more complex, multistep process with the 14‐3‐3 proteins playing the major role of bringing the signal transduction event to completion. This makes 14‐3‐3‐modulated signal transduction a more complicated process with additional avenues for regulation and variety. Adding further complexity to the process is the fact that 14‐3‐3 proteins are present as multigene families in most organisms (Aitken et al. Trends Biochem Sci 17: 498–501, 1992; Ferl Annu Rev Plant Physiol Plant Molecular Biology 47: 49–73, 1996), with each member of the family being differentially expressed in various tissues and with potentially differential affinity for various target proteins. This review focuses on the 14‐3‐3 family of Arabidopsis as a model for further developing understanding of the roles of the 14‐3‐3 proteins as modulators of signal transduction events in plants. The primary approaches to these questions are not unlike the approaches that would be used in the functional dissection of any multigene family, but the interpretation of these data will have wide implications since the 14‐3‐3 s physically interact with other protein families.
Arsenic uptake, translocation and speciation in pho1 and pho2 mutants of Arabidopsis thaliana
Authors: Quaghebeur Mieke , Rengel Zed
Published: January 2004

Arsenate [As (V)] is taken up by phosphate [P (V)] transporters in the plasma membrane of roots cells, but the translocation of As from roots to shoots is not well understood. Two mutants of Arabidopsis thaliana (L.) [(pho1, P deficient) and (pho2, P accumulator)], with defects in the regulation and translocation of P (V) from roots to shoots, were therefore used in this study to investigate uptake, translocation and speciation of As in roots and shoots of plants grown in soil or nutrient solution. The shoots of the pho2 mutant contained higher P concentrations, but similar or slightly higher As concentrations, in comparison with the wild type. In the pho1 mutant, the P concentration in the shoots was lower, and the As concentration was higher, in comparison with the wild type. Both pho2 and the wild type contained mainly As (III) in roots and shoot (67–90% of total As). Arsenic was likely to be translocated by a different pathway to P (V) in the pho2 and pho1 mutants. Therefore, it is suggested that As (III) is the main As species translocated from roots to shoots in Arabidopsis thaliana.
Isolation of a dehydrin cDNA from orange and grapefruit citrus fruit that is specifically induced by the combination of heat followed by chilling temperatures
Authors: Porat Ron , Pasentsis Konstantinos , Rozentzvieg Dafna , Gerasopoulos Dimitrios , Falara Vasiliki , Samach Alon , Lurie Susan , Kanellis Angelos K.
Published: January 2004

Dehydrins (DHNs; late embryogenesis abundant D‐11) are a family of plant proteins induced in response to environmental stresses such as water stress, salinity and freezing or which occur during the late stages of embryogenesis. Previously, it was reported that citrus contains a small gene family encoding a unique class of dehydrins that differs from most other plant dehydrins in various respects, such as having an unusual K‐segment similar to that of gymnosperms. In the present study, we identified by cDNA differential display analysis a ‘Navel’ orange 202‐bp polymerase chain reaction (PCR) fragment, which encoded the typical plant angiosperm‐type K‐segment consensus sequence, and of which the expression was down‐regulated by exposure to low oxygen levels. The full‐length cDNA sequence of the orange DHN, designated csDHN (for Citrus sinensis DHN), was further isolated by 5′‐and 3′‐RACE; it had a total length of 933 bp and encoded a predicted polypeptide of 235 amino acids. In addition, the same 202‐bp ‘Navel’ dehydrin PCR fragment was used to screen a ‘Star Ruby’ grapefruit flavedo cDNA library, and its full‐length grapefruit homologue, designated cpDHN (for C. paradisi DHN) was isolated and found to have a total length of 1024 bp and to encode a predicted polypeptide of 234 amino acids. The defined orange and grapefruit DHN proteins were completely identical in the 196 amino acids of their N‐terminus but differed in their C‐terminus region. Overall, the csDHN and cpDHN proteins share 84% identity and contain the conserved dehydrin serine cluster (S‐segment) and a putative nuclear localization signal, but csDHN has one conserved dehydrin K‐segment consensus sequence, whereas cpDHN contains two dehydrin K‐segments. Both csDHN and cpDHN represent single copy genes, in ‘Navel’ orange and ‘Star Ruby’ grapefruit genomes, respectively. We found that the cpDHN gene was consistently expressed in the fruit peel tissue at harvest, but that its message levels dramatically decreased during storage at either ambient or low temperatures. However, a pre‐storage hot water treatment, given to enhance fruit‐chilling tolerance, increased cpDHN mRNA levels during the first 3 weeks of cold storage at 2°C, and enabled the message levels to be retained for up to a further 8 weeks of cold storage at 2°C. The hot water treatment by itself had no inductive effect on cpDHN gene expression when the fruits were held at non‐chilling temperatures. Other stresses applied to the fruit, such as wounding, UV irradiation, water stress, low oxygen and exposure to the stress hormone ethylene decreased DHN mRNA levels, whereas abscisic acid had no effect at all.
Low‐temperature‐induced transmembrane potential changes in mesophyll cells of Arabidopsis thaliana, Helianthus annuus and Vicia faba
Authors: Krol Elzbieta , Dziubińska Halina , Trebacz Kazimierz
Published: January 2004

Glass microelectrodes were inserted into mesophyll cells of intact leaves from higher plants: Arabidopsis thaliana, Helianthus annuus and Vicia faba var minor, and transient membrane potential changes were recorded in response to a sudden temperature drop. The cold‐induced potential changes were unaffected by an anion channel inhibitor (anthracene‐9‐carboxylic acid) and potassium channel inhibitor (tetraethyl ammonium ion). Verapamil, a calcium channel inhibitor, caused significant suppression of the cold‐induced potential changes. In the presence of calmoduline antagonists (trifluoperazine and N‐6‐aminohexyl‐5‐chloro‐1‐naphtalenesulphonamide), their amplitudes decreased and their durations were prolonged. Neomycin, which suppresses phospholipase C, also caused substantial inhibition of the amplitudes of the cold‐induced potential changes. It is concluded that cold‐evoked membrane potential changes are due to calcium influxes from both the apoplast and internal stores.
Thermal dependence of enzyme function and inhibition; implications for, herbicide efficacy and tolerance
Authors: Mahan James R. , Dotray Peter A. , Light Ginger G.
Published: January 2004

Environmental temperature is a critical factor in the lives of almost all organisms. Plants experience periods of thermal stress related to seasonal patterns of temperature and periodic water deficits. Within the range of non‐lethal temperatures, there are a number of thermal effects on metabolism that are a result of the thermal dependence of enzymes. The thermal dependence of enzyme kinetic parameters was used to predict that the efficacy of the herbicide pyrithiobac on Palmer amaranth would be reduced at temperatures outside a 20–34°C thermal application range. This prediction is validated in a controlled environment study described in this paper. Palmer amaranth was grown for 16 days in growth chambers with 34/18°C day/night temperature regime. Pyrithiobac was applied to plants at 18, 27 or 40°C. After 1 h at the application temperatures the plants were returned to the 34/18°C regime for 14 days and post‐application biomass accumulation (efficacy) was determined. Dry weight accumulation, as a percentage of untreated controls, was 25, 2.5 and 70% for 18, 27 and 40°C application temperatures. Pyrithiobac efficacy was highest for the application within the thermal application range and significantly reduced at temperatures above and below. The validation of the earlier prediction suggests that temperature‐related kinetic limitations on herbicide efficacy may also occur in plants with bioengineered herbicide resistance based on herbicide metabolism. The theoretical aspects of such thermal limitations on herbicide resistance mechanisms are discussed.
The antioxidant status of photosynthesizing leaves under nutrient deficiency: redox regulation, gene expression and antioxidant activity in Arabidopsis thaliana
Authors: Kandlbinder Andrea , Finkemeier Iris , Wormuth Dennis , Hanitzsch Miriam , Dietz Karl‐Josef
Published: January 2004

Redox signals provide important information on plant metabolism during development and in dependence on environmental parameters and trigger compensatory responses and antioxidant defence. The aim of the study was to characterize the redox and antioxidant status of photosynthesizing leaves under N, P and S deficiency on a comparative basis. Therefore, redox signals, indicators of the cellular redox environment and parameters of antioxidant defence were determined and related to general growth parameters, namely (1) transcript levels of all chloroplast encoded genes; (2) ascorbate and glutathione; (3) activities of catalase (CAT) and ascorbate peroxidase (APX); and (4) transcript amounts of eight peroxiredoxins, three catalases and three ascorbate peroxidases. The results reveal distinct patterns of redox responses dependent on the type of nutrient deficiency. (1) Nitrogen deprivation caused up‐regulation of psbA, psbC, petA, petG and clpP transcripts, down‐regulation of psbG, psbK and ndhA, a five‐fold increase in ascorbic acid, a severe drop in CAT and APX activities, although cat1 mRNA levels were increased in young and old leaves. (2) With the exception of psbA and psaJ transcripts, P‐starvation induced a general trend to decreased mRNA abundance of plastome genes; ascorbate and glutathione levels were increased, as was the activity of APX and CAT. In accordance with that result, transcripts of all cat genes and stromal apx, as well as prxIIC, prxIID, were elevated under P deprivation. (3) Sulphur depletion increased transcripts of petA, petB, petD, petG, ndhJ and rpo‐genes. mRNAs of psbG, psbK, atpA, atpB, atpE and atpF were decreased. Glutathione levels dropped to less than 25% of control, in parallel activities of APX were stimulated in young leaves. Transcripts of many antioxidant enzymes were unaltered or decreased, only cat2 mRNA was increased. It is concluded that N‐, P‐ and S‐nutrient deprivation trigger distinct redox changes and induce oxidative stress with a rather defined pattern in the context of nutrient‐specific alterations in metabolism.
Persistent rhinitis – allergic or nonallergic?
Authors: Bachert C.
Published: January 2004

Although rhinitis has been classified as being either allergic, noninfectious, or ‘‘other forms’’ (nonallergic noninfectious), these categories lack strict classification criteria and often overlap. The term ‘‘nonallergic noninfectious rhinitis’’ is commonly applied to a diagnosis of any nasal condition, in which the symptoms are similar to those seen in allergic rhinitis but an allergic aetiology has been excluded. This group comprises several subgroups with ill‐defined pathomechanisms, and includes idiopathic rhinitis, irritative‐toxic (occupational) rhinitis, hormonal rhinitis, drug‐induced rhinitis, and other forms (non‐allergic rhinitis with eosinophilia syndrome [NARES], rhinitis due to physical and chemical factors, food‐induced rhinitis, emotion‐induced rhinitis, atrophic rhinitis). Unlike allergic rhinitis, there are no specific diagnostic tests and diagnosis is primarily based on a history of reaction to specific irritant‐toxic triggering agents (either general or occupational), drugs, infections, and hormonal status, coupled with exclusion of allergic rhinitis and other forms of non‐allergic rhinitis by skin prick testing. Accordingly, from a clinical standpoint NARES, irritative‐toxic, hormonal, drug‐induced and idiopathic rhinitis are possibly the least difficult forms of nonallergic rhinitis to diagnose.
Treatment of nonallergic perennial rhinitis
Authors: Ciprandi G.
Published: January 2004

Nonallergic perennial rhinitis (also commonly referred to as vasomotor rhinitis) is a chronic non‐IgE‐mediated condition that is characterized by symptoms which are similar to those seen in allergic rhinitis, but which persist for over nine months each year. Although treatment of vasomotor rhinitis involves the use of either intranasal corticosteroids or antihistamines, the corticosteroids are generally not effective in treatment of all the symptoms of vasomotor rhinitis and have generally been shown to be effective in patients with eosinophilia. With the exception of azelastine, the only topical antihistamine to be approved by the FDA for the treatment of nonallergic rhinitis, the antihistamines have also produced inconsistent results. While clinical studies of azelastine have demonstrated that this drug is highly efficacious in the treatment of all the symptoms of vasomotor rhinitis, mechanistic studies have demonstrated that azelastine has potent anti‐inflammatory effects (in particular attenuation of the expression and synthesis of pro‐inflammatory cytokines, leukotrienes, and cell adhesion molecules), which are likely to contribute to its clinical efficacy. Furthermore, pharamacokinetic studies have suggested that since azelastine has a more rapid onset of action, compared to most other antihistamines and intranasal corticosteroids, then azelastine nasal spray may be considered as primary therapy for patients with symptoms of both allergic and/or vasomotor (nonallergic perennial) rhinitis.
Productive pedagogies and the challenge of inclusion
Authors: Allan Julie
Published: January 2004

Julie Allan is Professor of Education at the Institute of Education, University of Stirling, where she also directs the Participation, Inclusion and Equity Research Network. In this article, she explores the challenges involved in achieving an inclusive education system. Her argument draws on recommendations from two separate studies, undertaken in Queensland, Australia and Scotland, which are attempting to shape inclusion policy and practice. The Queensland School Reform Longitudinal Study identified a set of productive pedagogies in which issues of social justice, equity and inclusion are foregrounded. The Scottish Parliamentary Inquiry into special needs, to which Professor Allan was adviser, recommended a number of changes aimed at establishing an inclusive education system for all pupils. Comparisons of the two sets of recommendations, which formed the basis of a series of workshops with teachers, school leaders and administrators within Education Queensland, have prompted two major questions which are addressed in this paper: what gets in the way of inclusive practice and what will it take to be inclusive? Julie Allan's responses to these questions take account of the ways in which we think about ‘special education’ teacher training and professional development; and educational policies and practices. She represents a fascinating set of ‘double‐edged responsibilities’ that will challenge practitioners, policy makers and teacher educators to refocus and reframe their thinking about special educational needs and inclusion.
The inclusion of learners with barriers to learning and development into ordinary school settings: a challenge for Uganda
Authors: Kristensen Kirsten , Omagor‐Loican Martin , Onen Negris
Published: January 2004

Colleagues in developing countries are required to meet a range of challenges when implementing educationally inclusive policies and practices. In this article, Kirsten Kristensen, clinical phychologist and senior consultant in special needs education and development; Martin Omagor‐Loican, commissioner for special needs education, careers guidance and counselling; and Negris Onen, principal education officer in the Ministry of Education and Sports in Uganda, describe work focused on addressing the needs of all learners, including those who experience barriers to learning and development, in ordinary, mainstream school settings. The authors draw upon a study of current attitudes, perceptions and knowledge about trends towards inclusion in Uganda. The findings indicate progress in the introduction and implementation of inclusive policies; improved professional development opportunities for staff concerned with special education at all levels; and relatively positive attitudes towards inclusion. The study also raises concerns, however, about the ways in which the education system is structured and managed in a country where class sizes are enormous and resources are few. The authors make a number of key recommendations for developing mechanisms, structures and capacity in support of inclusion at all levels and report positive and encouraging recent developments.
Count us in: the role of schools and colleges in meeting the mental health needs of young people with learning disabilities
Authors: Carpenter Barry , Morgan Hazel
Published: January 2004

In December 2002, the Foundation for People with Learning Disabilities' Committee of Inquiry into the mental health needs of young people with learning disabilities produced its report.

Barry Carpenter, Chief Executive at Sunfield and Chair of the committee, and Hazel Morgan, head of the Foundation for People with Learning Disabilities, take this opportunity to share some insights into the workings of the committee and summarise the key findings. The committee drew evidence from a range of sources, but placed the voices and experiences of young people with learning disabilities at the centre of their proceedings. The committee's findings and recommendations were wide ranging and will have far‐reaching implications, but there are immediate messages that schools and colleges should hear. It is upon these messages, taking account of pastoral provision, the curriculum, transition and inter‐agency work, that Barry Carpenter and Hazel Morgan focus in this article.
IQEA and special schools
Authors: Beresford John , Stokes Hilary , Morris John
Published: January 2004

Projects focused on Improving the Quality of Education for All (IQEA) have been running for ten years. The Nottinghamshire special schools IQEA project is the first to draw schools exclusively from the special education sector. In this article, John Beresford, IQEA's research officer; Hilary Stokes, co‐ordinator of the Nottinghamshire special schools IQEA project; and John Morris, secondary inspector and IQEA co‐ordinator for Nottinghamshire LEA, briefly outline the philosophy in which IQEA is grounded. They discuss the particular challenges encountered in a special schools project and illustrate responses by providing a case study of one school's engagement in the project. The article concludes with a tentative assessment of the benefits that participation in the project has brought to the special schools and units involved.
The effectiveness of teaching strategies for students with dyslexia based on their preferred learning styles
Authors: Exley Sioned
Published: January 2004

Sioned Exley is the SENCo at Guilsborough School, a comprehensive school with 1,300 students in rural Northamptonshire. She undertook the research reported in this paper while working towards her MA at De Montfort University. The study reported here looked at whether teaching to the preferred learning styles of students with dylexia can improve their performance and attainment. Sioned Exley worked with a sample of seven students, four boys and three girls, in Years 7 and 8 in her school. Using both qualitative and quantitative methods, she indicates that five of the seven students made significant progress in both spelling and number work. All the students, in interviews, reported improved feelings about and attitudes towards their school work. While acknowledging that this is a small‐scale study, Sioned Exley draws some positive conclusions.
Understanding the implementation of software process improvement innovations in software organizations
Authors: Kautz Karlheinz , Nielsen Peter Axel
Published: January 2004

Abstract.  The development of software is a complex task frequently resulting in unfinished projects, project overruns and system failures. Software process improvement (SPI) approaches have been promoted as a promising remedy for this situation. The organizational implementation of such approaches is a crucial issue and attempts to introduce SPI into software organizations often fail. This paper presents a framework to understand, and subsequently successfully perform, the implementation of SPI innovations in software organizations. The framework consists of three perspectives on innovation: an individualist, a structuralist and an interactive process perspective. Applied to SPI, they emphasize different aspects of implementing SPI innovations. While the first focuses on leadership, champions and change agents, the second focuses on organization size, departmental and task differentiation and complexity, and the third perspective views the contents of the innovation, the social context and process of the implementation as related in an interactive process. We demonstrate the framework's applicability through two cases. We show that the three perspectives supplement each other and together provide a deeper understanding of the implementation process. Such understanding is crucial for the successful uptake of SPI approaches in software organizations.
Using regression splines to assess the impact of information technology investments on productivity in the health care industry
Authors: Ko Myung , Osei‐Bryson Kweku‐Muata
Published: January 2004

Abstract. This paper explores the impact of information technology (IT) investments on productivity using a new technique, multivariate adaptive regression splines (MARS). We believe that it provides additional insights on the nature of the impact of IT investments on productivity. The results from our study are compared with findings from a previous study that has also used the same data set. While the results of a previous study indicate that IT investments have a positive but uniform impact  on  productivity,  our  study  suggests  that  the  impact  of  IT  on  productivity  is not uniform but is contingent on other complementary factors. Our findings describe that the complementary relationship exists between IT and non‐IT related investments. Thus, improved organizational productivity cannot be expected from investment in IT alone but only together with non‐IT investments. Our findings also point out that further investment may not necessarily bring on higher organizational productivity.
Strategic orientation and performance of internet‐based businesses
Authors: Grover Varun , Saeed Khawaja A.
Published: January 2004

Abstract. Many of the pure internet‐based businesses that proliferated over the past 5 years have encountered serious problems as their lofty valuations have plunged. Industry observers have attributed this phenomenon to a variety of factors, generally framed in terms of poor conceptualization or implementation of the ‘business model’. This study explores an often‐used concept in strategic management called ‘strategic orientation’ and applies it to internet‐based businesses. Based on an analysis of over 100 public businesses, firms that cluster together with similar strategic orientation are observed. These strategic groups are then analysed for performance differences. The results are discussed with the intent of learning from the dot‐burn effects as we evolve to the next generation of internet‐based business.