bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential effects of aluminium on osmotic potential and sugar accumulation in the root cells of Al‐resistant and Al‐sensitive wheat
Authors: Tabuchi Akira , Kikui Satoshi , Matsumoto Hideaki
Published: January 2004

The changes in osmotic potential and the concentration of osmotic solutes in the cell sap of the root tips exposed to Al were examined in two cultivars of wheat (Triticum aestivum) differing in Al resistance. Root elongation was less influenced by an 8‐h exposure to 20 μM or 50 μM Al in Al‐resistant cv. Atlas 66 than in Al‐sensitive cv. Scout 66. After Al treatment the osmotic potential of the root cells was decreased in Atlas 66 but increased in Scout 66 indicating that the Al treatment osmotically stimulated the driving force for water uptake in Atlas 66 but suppressed it in Scout 66. Al increased the concentration of soluble sugars, the major osmotic solute in the root cells in Atlas 66, but decreased it in Scout 66. Al at both low (5 μM) and high (50 μM) concentrations, also increased the concentration of soluble sugars in the Al‐resistant genotype ET8 but a high Al concentration decreased it in Al‐sensitive genotype ES8. Enzymatic analyses and thin‐layer chromatography revealed that soluble sugars in the root cells of both Atlas 66 and Scout 66 mainly consisted of monosaccharides such as glucose, fructose and a small amount of sucrose. These results suggest that the accumulation of soluble sugars in Al‐resistant wheat Atlas 66 keeps the osmotic potential in the root cells low and thus, enables the root cells to take up water and to elongate against the pressure produced by cell wall rigidification under Al stress.
Phytohormonal responses in enod40‐overexpressing plants of Medicago truncatula and rice
Authors: Dey Moul , Complainville Arnaud , Charon Celine , Torrizo Lina , Kondorosi Adam , Crespi Martin , Datta Swapan
Published: January 2004

Phytohormones are well‐known regulators of the symbiotic Rhizobium–legume association in the plant host. The enod40 nodulin gene is associated with the earliest phases of the nodule organogenesis programme in the legume host and modifying its expression resulted in perturbations of nodule development in Medicago truncatula. Therefore in our pursuit to mimic the initial signal transduction steps of legume nodulation in the alien physiological set‐up of a rice plant, we have expressed the Mtenod40 gene in rice. Molecular data confirm the stable integration, inheritance and transcription of the foreign gene in this non‐legume. We have compared the phytohormonal responses of Mtenod40‐overexpressing and control plants in a homologous legume background (M. truncatula) and in the non‐legume rice. An enod40‐mediated root growth response, induced by inhibition of ethylene biosynthesis, was observed in both plants. On the other hand, a significant differential effect of cytokinins was observed only in rice plants. This suggests that ethylene inhibits enod40 action both in legumes and non‐legumes and reinforces that some of the early signal transduction steps of the nodule developmental programme may function in rice.
Interaction of spermine with a signal transduction pathway involving phospholipase C, during the growth of Catharanthus roseus transformed roots
Authors: Echevarría‐Machado Ileana , Ku‐González Angela , Loyola‐Vargas Victor M. , Hernández‐Sotomayor S. M. Teresa
Published: January 2004

In Cantharanthus roseus transformed roots, the application of methylglyoxal bis(guanylhydrazone) (MGBG), an inhibitor of S‐adenosylmethionine decarboxylase (SAMDC; EC 4.1.1.50), inhibited the root growth in a dose‐dependent manner with a DL50 of about 300 µm. Spermidine and spermine (Spm) levels and SAMDC and phospholipase C (PLC; EC 3.1.4.3) activities were reduced in the presence of the inhibitor. The inhibition was reversed by the addition of Spm. Radioactivity from [14C]Spm was detected in an immunoprecipitated fraction with an antibody anti‐PLC‐δ. To our knowledge, this is the first direct evidence that demonstrates an interaction of Spm with the signal transduction cascade phosphoinositide‐Ca2+.
PII signalling in unicellular cyanobacteria: analysis of redox‐signals and energy charge
Authors: Forchhammer Karl , Irmler Angelika , Kloft Nicole , Ruppert Ulrike
Published: January 2004

This communication presents a short outline of the current knowledge on the molecular basis of PII signal transduction in unicellular cyanobacteria with respect to the perception of environmental stimuli. First, the general characteristics of the PII signalling system in unicellular cyanobacteria are presented, the hallmark of which is modification by serine‐phosphorylation, as compared to the paradigmatic PII signal transduction system in proteobacteria, which is based on tyrosyl‐uridylylation. Then, the focus is turned on the signals controlling PII phosphorylation state. Recently, the cellular phosphatase (termed PphA), which specifically dephosphorylates phosphorylated PII (PII‐P) was identified in Synechocystis sp. strain PCC 6803. With the availability of a PphA‐deficient mutant and the purified components for in vitro assay of PphA mediated PII‐P dephosphorylation, novel insights into the signals, to which PII‐P dephosphorylation responds, can be obtained. Here we present an investigation of the response of PII‐P dephosphorylation towards treatments that affect the redox‐balance of the cells. Furthermore, a possible role of varying ATP/ADP ratios on PII‐P dephosphorylation was examined. From these studies, together with previous investigations, we conclude that PII‐P dephosphorylation specifically responds to changes in the levels of central metabolites of carbon metabolism, in particular 2‐oxoglutarate.
Variation in nitrate uptake and assimilation between two ecotypes of Lotus japonicus and their recombinant inbred lines
Authors: Harrison Judith , Hirel Bertrand , Limami Anis M.
Published: January 2004

A large genetic variability was observed in the shoot NO3– content of recombinant inbred lines (RILs) of Lotus japonicus. To determine the cause of this variability, we have studied some aspects of nitrate uptake and assimilation in the two parental ecotypes (Gifu and Funakura) and four representatives of the RILs population differing both in their shoot biomass and shoot NO3– content. Higher shoot NO3–content was mainly due to an increase in the uptake of the ion regardless of the plant biomass production. The positive correlation observed between the shoot NO3– content and the steady state level of mRNA encoding high affinity NO3– transporters suggests that the higher NO3– influx is due to enhanced expression of the transporters. In contrast, neither the level of nitrate reductase mRNA, nor the potential enzyme activity in vivo in the different lines was correlated with the shoot NO3– content. This indicates that NO3– transport in Lotus is one of the main checkpoints controlling shoot NO3– accumulation. In addition, this study shows that at least in Lotus, it is possible, through breeding strategies, to lower the NO3– content without affecting biomass production.
Malate valves to balance cellular energy supply
Authors: Scheibe Renate
Published: January 2004

In green parts of the plant, during illumination ATP and NAD(P)H act as energy sources that are generated mainly in photosynthesis and respiration, whereas in darkness, glycolysis, respiration and the oxidative pentose‐phosphate pathway (OPP) generate the required energy forms. In non‐green parts, sugar oxidation in glycolysis, respiration and OPP are the only means of producing energy. For energy‐consuming reactions, the delivery of NADPH, NADH, reduced ferredoxin and ATP has to take place at the required rates and in the specific compartments, since the pool sizes of these energy carriers are rather limited and, in general, they are not directly transported across biomembranes. Indirect transport of reducing equivalents can be achieved by malateoxaloacetate shuttles, involving malate dehydrogenase (MDH) for the interconversion. Isoenzymes of MDH are present in each cellular compartment. Chloroplasts contain the redox‐controlled NADP‐MDH that is only active in the light. In addition, a plastid NAD‐MDH that is permanently active and is present in all plastid types has been found. Export of excess NAD(P)H through the malate valves will allow for the continued production of ATP (1) in photosynthesis, and (2) in oxidative phosphorylation. In the latter case, the coupled production of NADH is catalysed by the bispecific NAD(P)‐GAPDH (GapAB) in chloroplasts that is active with NAD even in darkness, or by the specific plastid NAD‐GAPDH (GapCp) in non‐green tissues. When plants are subjected to conditions such as high light, high CO2, NH4+ nutrition, cold stress, which require changed activities of the enzymes of the malate valves, changed expression levels of the MDH isoforms can be observed. In nodules, the induction of a nodule‐specific plastid NAD‐MDH indicates the changed requirements for energy supply during N2 fixation. Furthermore, the induction of glucose 6‐phosphate dehydrogenase isoforms by ammonium and of ferredoxin and ferredoxin‐NADP reductase by nitrate has been described. All these findings are in line with the assumption that a changed redox state caused by metabolic variability leads to the induction of enzymes involved in redox poise.
Gibberellin structure and function: biological activity and competitive inhibition of gibberellin 2‐ and 3‐oxidases
Authors: King Rod W. , Junttila Olavi , Mander Lewis N. , Beck Ellen J.
Published: January 2004

Some gibberellin (GA) analogues, especially with C‐16,17 modifications of GA5, can inhibit growth of plants apparently by acting as competitors with the endogenous substrate of GA biosynthetic enzymes. Here, we directly confirm the competitive action of GA derivatives but also show that some analogues may retain significant bioactivity. A recombinant 3‐oxidase from pea, which converts GA20 to bioactive GA1, was inhibited by GA5, and 16,17‐dihydro‐GA5 derivatives, especially if the C‐17 alkyl chain length was increased by up to three carbons or if the C‐13 hydroxyl was acetylated. Genetic confirmation that GA5 analogues target 3‐oxidases in vivo was provided by comparing the growth response of a WT (LE) pea with a 3‐oxidase mutant (le‐1). Two pea 2‐oxidases that inactivate bioactive GAs, were inhibited by GA1 and GA3 but were generally insensitive to GA5 analogues. α‐Amylase production by barley half‐seeds in response to GA analogues provided a method to study their action when effects on GA biosynthesis were excluded. This bioactivity assay showed that 16,17‐dihydro GA5 analogues have some inherent activity but mostly less than for GA5 (5–50‐fold), which in turn was 100‐fold less active than GA1 and GA3. However, although C‐17 alkyl derivatives with one or two added carbons showed little bioactivity and were purely 3‐oxidase inhibitors, adding a third carbon (the 17‐n‐propyl‐16,17‐dihydro GA5 analogue) restored bioactivity to that of GA5. Furthermore, this analogue has lost its capacity to inhibit stem elongation of Lolium temulentum (Mander et al., Phytochemistry 49:1509–1515, 1998a), although it strongly inhibits the 3‐oxidase. Thus, the effectiveness of a GA derivative as a growth retardant will reflect the balance between its bioactivity and its capacity to inhibit the terminal enzyme of GA biosynthesis. The weaker growth inhibition in dicots including pea (approximately 10%) than in monocots such as L. temulentum (>35%) is suggestive of taxonomic differences in the bioactivity of GAs and/or their effects on GA biosynthesis.
Dual induction rather than intermediate daylength response of flowering in Echinacea purpurea
Authors: Heide Ola M.
Published: January 2004

Echinacea purpurea cv. Bravado and Magnus have been reported to be intermediate daylength plants (IDP) which flower in response to photoperiods between 13 and 16 h. The present experiments with E. purpurea cv. Bravado show that E. purpurea is actually a dual induction short‐long‐day plant which flowers promptly and consistently when grown in short day (SD) followed by long day (LD) conditions, but not with the reverse sequence of photoperiods. The flowering response increased with increasing duration of both the SD and the LD treatments. A minimum of 4 weeks of SD followed by 12 LD was required for complete flowering. No flowering occurred in continuous SD or LD, whereas a high proportion of plants flowered in continuous 14‐h daylength. However, flowering was more variable in intermediate daylength than after transition from SD to LD. Furthermore, photoperiods between 13 and 16 h could satisfy both the primary SD induction and the secondary LD induction requirements. As a number of dual induction plants, both short‐long‐day and long‐short‐day plants, have such an overlapping window of effective photoperiods that can trigger both the SD and LD responses, the rationale for maintaining IDP as a separate and genuine flowering response group is seriously challenged.
Adaptation of the photosynthetic electron transport chain in cyanobacteria to iron deficiency: The function of IdiA and IsiA
Authors: Michel Klaus‐Peter , Pistorius Elfriede K.
Published: January 2004

In this review we give an overview on the adaptational responses of photosystem (PS) II and PSI in cyanobacteria to iron starvation, mainly summarizing our results with the mesophilic Synechococcus elongatus PCC 7942. We also discuss this process with respect to the strong interrelationship between iron limitation and oxidative stress that exists in cyanobacteria as oxygenic photosynthetic organisms. The adaptation of the multiprotein complexes PSII and PSI to iron starvation is a sequential process, which is characterized by the enhanced expression of two major iron‐regulated proteins, IdiA (iron deficiency induced protein A) and IsiA (iron stress induced protein A). Our results suggest that IdiA protects the acceptor side of PSII against oxidative stress under conditions of mild iron limitation in a currently unclear way, whereas prolonged iron deficiency leads to the synthesis of a chlorophyll a antenna around PSI‐trimers consisting of IsiA molecules. The physiological consequences of these alterations under prolonged iron starvation, as shown by acridine yellow fluorescence measurements, are a reduction of linear electron transport activity through PSII and an increase of cyclic electron flow around PSI as well as an increase in respiratory activity. IdiA and IsiA expression are mediated by two distinct helix‐turn‐helix transcriptional regulators of the Crp/Fnr family. IdiB positively regulates expression of idiA under iron starvation, and Fur represses transcription of isiA under iron‐sufficient conditions. Although both transcriptional regulators seem to operate independently of each other, our results indicate that a cross‐talk between the signal transduction pathways exists. Moreover, IdiA as well as IsiA expression are affected by hydrogen peroxide. We suggest that due to the interdependence of iron limitation and the formation of reactive oxygen species, peroxide stress might be the superior trigger that leads to expression of these proteins under iron starvation. The modifications of PSII and PSI under iron starvation influence the redox state of redox‐sensitive components of the electron transport chain, and thus the activity of metabolic pathways being regulated in dependence of the redox state of these components.
Induction of high affinity phosphate transporter in the duckweed Spirodela oligorrhiza
Authors: Hase Akira , Nishikoori Miwa , Okuyama Hidetoshi
Published: January 2004

Duckweed plants (Spirodela oligorrhiza) grown under phosphate (Pi)‐deficient conditions (– P plants) exhibited more than 50‐fold higher Pi uptake activity than plants grown under Pi‐sufficient conditions (+ P plants). The Pi uptake activity of – P plants measured using 32Pi was significantly inhibited by carbonylcyanide m‐chlorophenylhydrazone, indicating that Pi uptake is energized by the electrochemical proton gradient across the plasma membrane (PM). When Pi uptake was examined at various concentrations of Pi, more active uptake of Pi was observed in – P plants than in + P plants, irrespective of the Pi concentrations. An immunoblot analysis of the PM proteins using antiserum against the conserved sequence of the high‐affinity Pi transporter recognized the occurrence and large accumulation of a novel protein band at 48 kDa in – P plants. The protein was almost completely extracted with chloroform‐methanol (2:1, v/v), but only a trace amount of the protein was detected in + P plants. Immunohistochemical studies of plant roots using the same antiserum demonstrated a large accumulation of high‐affinity Pi transporters at the outermost cortical cells of – P plants, but not of + P plants. When an immunoblot analysis of PM proteins was performed using antiserum against the PM H+‐ATPase, a positive band of about 96 kDa was detected in both plants with a similar signal intensity. Furthermore, ATP‐hydrolytic and ATP‐dependent H+‐transporting activities of PM H+‐ATPase in – P plants were not higher than those in + P plants. However, kinetic analyses showed that the PM H+‐ATPase in – P plants had a lower Km value and a higher coupling efficiency between ATP hydrolysis and H+ pumping than the corresponding values in + P plants. These results suggest that the significant stimulation of Pi uptake in – P plants may be due mainly to the induction and accumulation of the high‐affinity Pi transporter in the PM, and that the electrochemical proton gradient across the PM may be generated by the high‐ATP‐affinity and energy‐efficient H+ pump in – P plants. This would facilitate the acquisition of Pi in S. oligorrhiza under Pi‐depleted conditions.
Composition and desiccation‐induced alterations of the cell wall in the resurrection plant Craterostigma wilmsii
Authors: Vicré Maïté , Lerouxel Olivier , Farrant Jill , Lerouge Patrice , Driouich Azeddine
Published: January 2004

Resurrection plants have the unique capacity to revive from an air‐dried state. In order to tolerate desiccation they have to overcome a number of stresses, mechanical stress being one. In leaves of the Craterostigma species, an extensive shrinkage occurs during drying as well as a considerable cell wall folding. Our previous microscopically analysis using immunocytochemistry on the resurrection plant Craterostigma wilmsii, has shown an increase in labelling of xyloglucan and unesterified pectins in the cell wall during drying. In this study, we have undertaken a biochemical approach to separate, quantify and characterize major cell wall polysaccharides in fully hydrated and dry leaves of C. wilmsii. Our results show that the overall cell wall composition of C. wilmsii leaves was similar to that of other dicotyledonous plants with respect to the pectin content. However, the structure of the hemicellulosic polysaccharide xyloglucan was characterized to be XXGG‐type. The data also demonstrate marked changes in the hemicellulosic wall fraction from dry plants compared to hydrated ones. The most conspicuous change was a decrease in glucose content in the hemicellulosic fraction of dry plants. In addition, xyloglucan from the cell wall of dry leaves was relatively more substituted with galactose than in hydrated walls. Together these findings show that dehydration induces significant alteration of polysaccharide content and structure in the cell wall of C. wilmsii, which in turn might be involved in the modulation of the mechanical properties of the wall during dehydration.
Tomato LeAGP‐1 is a plasma membrane‐bound, glycosylphosphatidylinositol‐anchored arabinogalactan‐protein
Authors: Sun Wenxian , Zhao Zhan Dong , Hare Michael C. , Kieliszewski Marcia J. , Showalter Allan M.
Published: January 2004

Arabinogalactan‐proteins (AGPs) are a class of highly glycosylated, hydroxyproline‐rich glycoproteins that function in plant growth and development. Tomato LeAGP‐1 represents a major AGP expressed in cultured cells and plants. Based on cDNA and amino acid sequence analyses along with carbohydrate and other biochemical analyses, tomato LeAGP‐1 is hypothesized to be a classical AGP localized to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor. Here, this hypothesis was tested and supported with the following experiments. First, tomato (Lycopersicon esculentum, cv. UC82B) cotyledon protoplasts were isolated following cell wall digestion with cellulase and pectinase, and LeAGP‐1 was immunolocalized to the plasma membrane with a LeAGP‐1 antibody. Second, LeAGP‐1 was shown to be a major AGP component in plasma membrane vesicles from tomato cv. Bonnie Best suspension‐cultured cells by Western blot analysis with the LeAGP‐1 antibody. Third, fluorescence microscopy of plasmolysed, transgenic tobacco (Nicotiana tabacum BY‐2) suspension‐cultured cells expressing a green fluorescent protein (GFP)‐LeAGP‐1 fusion product demonstrated localization to the plasma membrane and Hechtian threads. Fourth, the GFP‐LeAGP‐1 fusion protein was present in plasma membrane preparations from these transgenic tobacco cells by Western blot analysis with a GFP antibody. Fifth, GFP‐LeAGP‐1 secreted into the culture media contained ethanolamine, presumably attached to the C‐terminal amino acid residue, consistent with its processing and release from the plasma membrane. Thus, these data support the hypothesis that LeAGP‐1 is localized to the plasma membrane via a GPI anchor and suggest possible roles for LeAGP‐1 in cellular signalling and matrix remodelling.
New insights towards the function of glutamate dehydrogenase revealed during source‐sink transition of tobacco (Nicotiana tabacum) plants grown under different nitrogen regimes
Authors: Tercé‐Laforgue Thérèse , Mäck Gisela , Hirel Bertrand
Published: January 2004

The metabolic, biochemical and molecular events occurring in the different leaf stages along the main axis of tobacco (Nicotiana tabacum) plants grown either on a nitrogen‐rich medium, on a medium containing ammonium as sole nitrogen source or on a nitrogen‐depleted medium, are presented. This study shows that the highest induction of cytosolic glutamine synthetase (GS1) protein and transcript occurs when nitrogen remobilization is maximal as the result of nitrogen starvation, whereas both glutamate dehydrogenase (GDH) transcript and activity remain at a very low level. In contrast, GDH is highly induced when plants are grown on ammonium as sole nitrogen source, a physiological situation during which leaf protein nitrogen remobilization is limited. It is therefore concluded that GDH does not play a direct role during the process of nitrogen remobilization but is rather induced following a built up of ammonium provided externally or released as the result of protein hydrolysis during natural leaf senescence.
Fluridone and norflurazon, carotenoid‐biosynthesis inhibitors, promote seed conditioning and germination of the holoparasite Orobanche minor
Authors: Chae Sang Heon , Yoneyama Koichi , Takeuchi Yasutomo , Joel Daniel M.
Published: January 2004

Fluridone and norflurazon, two carotenoid‐biosynthesis inhibitors, shortened the conditioning period required by seeds of Orobanche minor in order to respond to the germination stimulant strigol. Neither fluridone nor norflurazon alone induced seed germination of O. minor, they promoted strigol‐induced germination. In addition, these compounds restored the conditioning and germination of seeds at a supraoptimal temperature (30°C) as well as in the light. Gibberellic acid (GA3) showed similar promotive and protective effects on the conditioning and germination of O. minor seeds. Although fluridone and norflurazon are known to prevent abscisic acid (ABA)‐biosynthesis, and stresses such as supraoptimal temperatures have been reported to induce ABA accumulation in plants, the amount of ABA in the seeds or that released from the seeds into the conditioning media was not affected by the fluridone treatment and by exposure to the supraoptimal temperature. These results indicate that the promotive and protective effects of fluridone and norflurazon on the conditioning and germination of O. minor seeds would be attributed to other perturbations rather than the inhibition of ABA‐biosynthesis.
Sequence of morphological and physiological events during natural ageing and senescence of a castor bean leaf: sieve tube occlusion and carbohydrate back‐up precede chlorophyll degradation
Authors: Jongebloed Udo , Szederkényi Judit , Hartig Katja , Schobert Christian , Komor Ewald
Published: January 2004

The development of castor bean (Ricinus communis L. var. sanguineus) leaves from bud break to abscission was studied to determine whether senescence of phloem precedes or follows chlorophyll degradation in the course of natural ageing of leaves. The castor bean leaf blade took 20 days for full expansion and its average life span was 60 days. From the day of full expansion on it suffered a substantial loss in N, a small loss in C, K and P and a gain in Ca, Mg and S. The content of soluble sugars increased with time, paralleled by a decrease of photosynthetic activity. Starch accumulated shortly before chlorophyll breakdown. The amino acid level in the leaves decreased steadily together with nitrate reductase and glutamine synthetase activity. Reactive oxygen species increased and oxidation‐protecting compounds decreased during the life span of the leaves. Shortly after full leaf expansion an increasing number of sieve plates showed strong callose depositions when visualized by aniline blue method. At day 40 only half of the sieve tubes appeared functional. Chlorophyll breakdown followed these processes with a time lag of approximately 10 days. The sieve tube sap of ageing leaves had the same sucrose concentrations as young leaves, whereas amino acid concentrations decreased. High levels of reduced ascorbic acid and glutathione together with increasing levels of glutaredoxin indicated oxidative strain during senescence. We speculate that the gradual increase of reactive oxygen species during ageing together with the import of calcium ions lead to the stimulation of callose synthesis in plasmodesmata and sieve plates with the consequence of inhibition of phloem transport leading to carbohydrate back‐up in the leaf blade. The latter may finally induce chlorophyll breakdown and, at the end, leaf abscission at the petiole base. Thus phloem blockage would precede and may be causal for chlorophyll degradation in leaf senescence.
Redox regulation: an introduction
Authors: Dietz Karl‐Josef , Scheibe Renate
Published: January 2004

The redox‐state is a critical determinate of cell function, and any major imbalances can cause severe damage or death. The cellular redox status therefore needs to be sensed and modulated before such imbalances occur. Various redox‐active components are involved in these processes, including thioredoxins, glutaredoxins and other thiol/disulphide‐containing proteins. The cellular reactions for cytoprotection and for signalling are integrated with physiological redox‐reactions in photosynthesis, assimilation and respiration. They also determine the developmental fate of the cell and finally decide on proliferation or cell death. An international workshop on redox regulation, organized by the research initiative FOR 387 of the Deutsche Forschungsgemeinschaft, was held in Bielefeld, Germany in 2002. A selection of articles originating from the meeting is printed in this issue of Physiologia Plantarum.
Mechanisms of vasomotor rhinitis
Authors: Garay R.
Published: January 2004

Nonallergic non‐infectious perennial rhinitis (NANIPER) is a heterogeneous disorder comprising several pathophysiological entities. The etiology of some of these disorders (e.g. drug‐induced rhinitis, nonallergic rhinitis with eosinophilia syndrome [NARES], occupational rhinitis, hormonal rhinitis, emotion‐induced rhinitis, physical/chemical irritant‐induced rhinitis) is well established. In contrast, the aetiology of idiopathic forms of rhinitis (also known as vasomotor rhinitis) is largely unknown. Mechanistic studies have suggested that non‐IgE‐mediated inflammatory and/or neurogenic processes may be involved. There is evidence that localized inflammation is the underlying cause of symptoms in drug‐induced rhinitis and NARES, since eosinophilia is an important pathophysiological component in these conditions. In contrast, neurogenic reflex mechanisms initiated by environmental factors appear to be involved in idiopathic rhinitis. It has been suggested that there may be an imbalance of the sympathetic and parasympathetic nervous systems, with parasympathetic hyper‐activity and sympathetic hypo‐activity resulting in nasal congestion and rhinorrhoea. Indirect evidence suggests that C‐fibres may also play an important role in the pathophysiology of idiopathic rhinitis.
Primary exclusions: are they rising?
Authors: Pavey Sue , Visser John
Published: January 2004

Reducing the number of pupils excluded from school has formed part of the Government's strategy for school improvement in recent years. The study reported here was conducted within an inner‐city LEA. In their article, Sue Pavey, research in special education, and John Visser, senior fellow lecturer in special education, both of whom work in the School of Education at the University of Birmingham, question the veracity of collected data on exclusions relating to the primary sector. Furthermore, they suggest that findings from their study indicate that exclusions are considered ineffective for the pupils concerned and are seen as a last resort by primary headteachers. More effective strategies for meeting the pupils' needs, argue Sue Pavey and John Visser, lie within enhanced, in‐school support services and multi‐agency approaches. The authors conclude that statistics on exclusion do not give a representative picture of real levels of exclusion in the LEA. This situation adversely affects strategic planning and the distribution of resources. In concluding their article, Sue Pavey and John Visser propose that resources should be spent on developing alternative strategies to exclusion and methods of identifying children at risk of disaffection.
Participation in transition review meetings: a case study of young people with learning disabilities leaving a special school
Authors: Carnaby Steven , Lewis Patricia , Martin Di , Naylor John , Stewart David
Published: January 2004

Transition into adulthood has been identified as a critical period in the lives of young people with learning disabilities, with national guidance and legislation emphasising the role of participation and inclusion as central to the transition process. In this article, Steven Carnaby, a clinical psychologist working with adults with learning disabilities in London and a lecturer in learning disability at the Tizard Centre, University of Kent; Patricia Lewis, head of the sixth form and SENCo; Di Martin, senior teacher and former SENCo; John Naylor, deputy head of the sixth form and head of arts; David Stewart OBE, headteacher, all from the Shepherd School, Nottingham, report the outcomes of a small‐scale case study exploring these issues. The project ran for four years and, in Phase 1, evaluated the ways in which students with learning disabilities were involved in their transition review meetings as they entered their final year at school. This first phase found that many students were excluded from meaningful discussion in their planning meetings, highlighting students with more severe disabilities as being more vulnerable to exclusion. After a series of recommendations were made for improving practice in terms of inclusion and participation, Phase 2 of the study assessed ways in which practice in these areas had improved. The school had developed more individualised ways of working using person‐centred techniques to enhance meaning for students. At the close of this article, the authors summarise these improvements and propose further strategies for enhancing the participation process.
Zimmermann–Laband syndrome with bilateral developmental cataract – a new association?
Authors: Shah N. , Gupta Y. K. , Ghose S.
Published: January 2004

An unusual case of Zimmermann–Laband syndrome in a young male child with an unreported association of bilateral developmental cataract is presented. The pathognomonic triad of gingival fibromatosis, aplastic or hypoplastic distal phalanges with absent nails, and enlargement of soft tissues of the face were obvious, besides the known moderate learning disability and mild hearing loss. The case is discussed in the light of relevant literature. To the best of our knowledge, this is the first report of early developmental cataracts in association with the Zimmermann–Laband syndrome. Besides detection and timely recognition of the syndrome to allow adequate dental care, ophthalmic screening at periodic intervals is merited to improve the overall quality of life for these patients.
Variations in expression of oral–facial–digital syndrome (type I): report of two cases
Authors: Driva T. , Franklin D. , Crawford P. J. M.
Published: January 2004

Two case reports are presented, both clearly demonstrating the diagnosis of oral–facial–digital syndrome, type I, but widely different in the expression of the condition. The first patient showed only mild expression of the syndrome. On examination at the age of 4 years there were no obvious extra oral signs, intraoral findings included the presence of supernumeraries in the primary dentition, spacing in two areas and the presence of an extra frenum. The second can be considered as a more severe case. This patient had many of the typical manifestations, including frontal bossing, a degree of zygomatic hypoplasia and clinodactyly. Orally, the most striking finding was a bilateral cleft palate which had not been diagnosed prior to examination at the age of 6 years. Other findings included multiple frena and a bifid tongue.
Caries prevalence and severity in urban Fijian school children
Authors: Jamieson L. M. , Thomson W. M. , Mcgee R.
Published: January 2004

Objectives.  To determine the prevalence and severity of dental caries in a sample of urban Fijian school children.

Design.  Cross‐sectional.

Sample and methods.  Children aged between 6 and 8 years who attended one of four primary schools in different localities of Suva completed self‐report questionnaires and were examined for dental caries.

Results.  A total of 704 children (response rate = 72·4%) returned questionnaires and were examined dentally. The prevalence of dental caries in the primary dentition was 87·6% and in the permanent dentition, 46·7%. The mean dfs and mean DFS were 8·43 (SD 7·82) and 2·38 (SD 1·37), respectively. High caries prevalence and severity were associated with infrequent brushing, snacking on sugar‐containing foods, having seen a dentist before, and having last visited a dentist because of pain.

Conclusions.  The caries prevalence of the sample was comparable with findings from a national oral health survey conducted in 1985/86, but the caries severity was greater. As in other developing countries, this may be due to an increased availability of refined sugar products without a concurrent rise in oral health awareness. The study findings contribute to the overall picture of Fijian school children's dental health.
Surviving male with incontinentia pigmenti: a case report
Authors: Cho S. Y. , Lee C. K. , Drummond B. K.
Published: January 2004

Summary.  Incontinentia pigmenti, or Block–Sulzberger Syndrome, is an X‐linked dominant disorder with characteristic skin, hair, eye and tooth abnormalities. It is classically considered a male‐lethal disorder with recurrent miscarriages of male foetuses. A few cases of surviving males with incontinentia pigmenti have been reported in the medical literature. This article reports the medical and dental findings of a boy diagnosed with incontinentia pigmenti.
Detection of a highly toxic clone of Actinobacillus actinomycetemcomitans (JP2) in a Moroccan immigrant family with multiple cases of localized aggressive periodontitis
Authors: Haubek D. , Westergaard J.
Published: January 2004

Summary.  The JP2 clone of Actinobacillus actinomycetemcomitans, a high‐leukotoxin‐producing strain, characterized by a 530‐basepair (bp) deletion in the promoter region of the leukotoxin gene operon and mainly found among individuals with African origin, is associated with localized aggressive periodontitis. The objective of the study was to examine the occurrence of periodontal disease in a Moroccan immigrant family living in Denmark in which the oldest son (14 year) was referred and treated for localized aggressive periodontitis. Further, the potential occurrence of the JP2 clone of A. actinomycetemcomitans in the family was examined. Here we present the clinical, radiographic, and microbiological findings from the family. Clinical and radiographic examination of the other family members revealed that 3 of 5 younger siblings had localized aggressive periodontitis, one had gingivitis and the mother had chronic periodontitis. Despite scaling followed by intensive maintenance therapy several family members, including the sibling with gingivitis, had further attachment loss at the 1‐year examination. The JP2 clone of A. actinomycetemcomitans was isolated from subgingival plaque samples from 4 children with periodontitis. In contrast, it was not detected in plaque from the oldest boy, who had been treated for localized aggressive periodontitis by surgery combined with antibiotic therapy. The 4 children with periodontitis and colonized with the JP2 clone were treated by scaling and antibiotic administration. One month later the JP2 clone could still be detected in plaque samples. In conclusion, it is confirmed that members of immigrant families with African origin are potential carriers of the JP2 clone and that those families often have multiple family members with localized aggressive periodontitis. It is proposed that those families are given periodontal examination frequently to benefit from early diagnosis and treatment of the disease.
Propofol intravenous conscious sedation for anxious children in a specialist paediatric dentistry unit
Authors: Hosey M. T. , Makin A. , Jones R. M. , Gilchrist F. , Carruthers M.
Published: January 2004

Objectives.  To report on both the use and dosage of propofol, as a new intravenous (IV) conscious sedative agent, for anxious children referred to a specialist paediatric dentistry service.

Setting.  Paediatric Dentistry Unit, Glasgow Dental Hospital and School.

Sample.  Thirty‐four children, 25 females and 9 males, mean age 12 years 10 months, with a mean weight of 54·6 kg (range 30–110 kg).

Methods.  Report from 34 patients receiving intravenous sedation for the first time in respect of weight dose and amount of treatment completed.

Results.  Thirty‐two children successfully accepted operative dental care on their first visit, they received a mean total dose of 146·25 mg of propofol (range 10 mg to 356 mg); in relation to body weight, the mean was 2·5 mg/kg (range 0·2–5·4 mg/kg). The treatment that they received included fissure sealants, amalgam and adhesive restorations, root canal therapy and single and multiple extractions. Their sedation and recovery were uneventful.

Conclusions.  Sub‐anaesthetic doses of propofol used for IV conscious sedation infusion facilitated operative dental treatment in anxious children.
A new HLA‐B44 allele (B*44020102S) with a splicing mutation leading to a complete deletion of exon 5
Authors: Dubois V. , Tiercy J.M. , Labonne M.P. , Dormoy A. , Gebuhrer L.
Published: January 2004

Abstract:  Using a combination of serology and polymerase chain reaction with sequence‐specific primer (PCR‐SSP), we have identified in a volunteer bone marrow donor a new HLA class I antigen within the B44 serotype. This human leukocyte antigen (HLA)‐B44 variant was typed as ‘blank’ by microlymphocytotoxicity, whereas the B*44020101 allele was identified by PCR‐SSP. A family study confirmed the Mendelian segregation of this blank antigen identified on one of the maternal haplotype transmitted to her child. The DNA sequence of B*44new, now referred to as B*44020102S, performed from the promoter region to the 3′ untranslated region revealed a single nucleotide difference (A/G) compared to B*44020101 at the end of intron 4 in the acceptor‐splicing site. This mutation leads to an incorrect splicing characterized by the deletion of exon 5 that encodes the transmembrane domain of the HLA antigen. Indeed, full‐length complementary DNA sequencing revealed a complete absence of exon 5. Fluorescence‐activated cell sorter analysis confirmed the absence of expression of HLA‐B44 on the cell surface in the donor, compared to the HLA‐B44 positive control. The isoelectric focusing analysis failed to reveal the presence of an HLA‐B44 antigen in the donor, showing that no normal HLA‐B*44020101 allele was synthesized. The new B*440201010102S allele is a soluble form of B44 without any detectable cell‐surface expression. It can thus be considered as a soluble antigen, a form apparently inactive and unfit for antigen presentation.
Differential up‐regulation of HLA‐DM, invariant chain, and CD83 on myeloid and plasmacytoid dendritic cells from peripheral blood
Authors: Gómez J. , Borràs F.E. , Singh R. , Rajananthanan P. , English N. , Knight S.C. , Navarrete C.V.
Published: January 2004

Abstract:  Two main dendritic cell (DC) subsets have been described in peripheral blood, the myeloid subset or DC1 that is characterized by the presence of CD11c and the plasmacytoid subset or DC2 negative for this marker. The two subsets may perform different functions and have been defined as immunogenic (the myeloid subset) or tolerogenic (the plasmacytoid subset). The expression of human leukocyte antigen (HLA)‐DM molecules, which act as peptide editors in the antigen presentation process, was studied in freshly isolated plasmacytoid and myeloid DCs from peripheral blood. The expression of the invariant chain (Ii), the major histocompatibility complex class II (MHC‐II) : class II‐associated Ii peptide (CLIP) complex, and CD83 was also investigated. The results showed that intracellular expression of HLA‐DM and the Ii was significantly higher in the plasmacytoid than in the myeloid DC subset. In contrast, a higher fraction of cell expressing MHC‐II : CLIP complex was found in the myeloid than in the plasmacytoid DC subpopulation. CD83 was not detected in any of these two subsets. Following culture of these cells with interleukin‐3 (IL‐3), tumor necrosis factor‐α (TNFα) and/or heat shock protein‐70 (HSP‐70), the expression of intracellular HLA‐DM was up‐regulated in the myeloid DCs to levels similar to those found in the plasmacytoid DCs, whilst the Ii was down‐regulated in the plasmacytoid subset to similar levels to those expressed in the myeloid DCs. In addition, CD83 was up‐regulated in the myeloid (CD11c+) but not in the plasmacytoid (CD11c–) DCs. The expression pattern of these antigen‐processing molecules could be related to the immaturity and function attributed to these DC subsets.
The reagent database at dbMHC
Authors: Helmberg W. , Dunivin R. , Feolo M.
Published: January 2004

Abstract:  The reagent database dbMHC was built by the National Center for Biotechnology Information (NCBI) as an open resource for registration and characterization of HLA DNA‐typing kits and reagents. Each reagent is uniquely identified as sequence‐specific oligonucleotide (SSO) or primer (SSP), SSO mix, or SSP mix. Computerized prediction of allele reactivities, based on annealing stringency, is performed on all submissions to the reagent database. User‐specified allele reactivities may be added or deleted independently of the prediction algorithm. Updates of allele reactivities are performed in synchronization with the IMGT/HLA database, in order to account for newly discovered alleles. Probe and primer sequences aligned to allelic sequences can be displayed at any time. Reagents registered in the reagent database are grouped in typing kits. Each kit or kit batch is uniquely identified. Group‐specific amplification of alleles can be specified for an entire kit or for sections of each kit. Kits designed to test multiple loci are supported. Kits can be entered and updated via the web or submitted as batches in extensible markup language (XML) format. A tool for online interpretation of typing results is available. Both the reagent database and the typing kit database have been designed to facilitate the exchange of HLA typing based on raw typing data using the unique identifiers of kits or individual reagents. In addition, batch‐wise reinterpretation of previous typing data can be performed either using the NCBI web site or by locally using downloaded allele‐reactivity lists. Reinterpretation by the NCBI requires submission of raw typing data in XML format.
The structural basis of T‐cell allorecognition
Authors: Whitelegg A. , Barber L.D.
Published: January 2004

Abstract:  Foreign allogeneic major histocompatibility complex (MHC) class I and class II molecules elicit an exceptionally vigorous T‐cell response. A small component of the alloresponse comprises CD4+ T cells that recognize allogeneic MHC indirectly after processing into peptide fragments that are bound and presented by self‐MHC class II. The majority of alloreactive T cells directly recognize intact allogeneic MHC molecules expressed on foreign cells. Some alloreactive T‐cell interactions with allogeneic MHC molecules are indifferent to the bound peptide, but evidence suggests that most show specificity to peptide. The vigor and diversity of the direct alloreactive T‐cell response can therefore be explained by summation of numerous responses to each of the peptides in the novel set bound by allogeneic MHC molecules. Structural studies definitively show that the overall mechanism of T‐cell receptor (TCR) recognition of self‐MHC and allogeneic MHC molecules is similar. Many alloreactive T cells recognize several different combinations of MHC and bound peptide that do not necessarily possess structural homology. Flexibility within the TCR structure allows adaptation to the different contact surfaces. Crossreactivity seems to be an intrinsic property of the TCR required, because a single TCR must possess the ability to interact with both self‐MHC during positive selection and at least one combination of foreign antigenic peptide presented by self‐MHC. Recognition of allogeneic MHC molecules is an inadvertent consequence of the need for TCR crossreactivity.
Overexpression of glutathione reductase in Brassica juncea: Effects on cadmium accumulation and tolerance
Authors: Pilon‐Smits Elizabeth A. H. , Zhu, Yong Liang , Sears Tobin , Terry Norman
Published: January 2004

To determine the importance of glutathione reductase (GR, EC 1.6.4.2) for heavy metal accumulation and tolerance, a bacterial GR was expressed in Indian mustard (Brassica juncea L.), targeted to the cytosol or the plastids. GR activity in the cytosolic transgenics (cytGR) was about two times higher compared to wild‐type plants; in the plastidic transgenics (cpGR) the activity was up to 50 times higher. When treated with 100 μM CdSO4, cytGR plants did not differ from wild type in cadmium tolerance or accumulation. CpGR plants, however, showed enhanced cadmium tolerance at the chloroplast level: in contrast to wild‐type plants they showed no chlorosis, and their chlorophyll fluorescence parameters Fv/Fm and photochemical quenching were higher. Cadmium tolerance at the whole‐plant level (plant growth) was not affected. The lower cadmium stress experienced by the cpGR chloroplasts may be the result of reduced cadmium uptake and/or translocation: cadmium levels in shoots of cpGR plants were half as high as those in wild‐type shoots. These differences in cadmium tolerance and accumulation may result from increased root glutathione levels, which were up to two times higher in cpGR plants than in the wild type.