bluuebunny/crossref_metadata_2025 huggingface dataset:
The Childhood Origins of Asthma (COAST) study
Authors: Lemanske Robert F.
Published: March 2003

Although asthma is probably a heterogeneous disease or syndrome, three factors and/or events consistently emerge for their ability to significantly influence asthma inception in the first decade of life: immune response aberrations, which appear to be defined best by the concept of cytokine dysregulation; lower respiratory tract infections, in particular respiratory syncytial virus (RSV); and some form of gene–environment interaction that needs to occur at a critical time‐period in the development of the immune system or the lung. It remains to be firmly established, however, how any one or all of these factors, either independently or interactively, influence the development of childhood asthma. For example, cytokine dysregulation (T helper 1/T helper 2 imbalance) appears to track best epidemiologically with allergic diseases. As not everyone who undergoes allergic sensitization develops asthma, some other host–environment interaction must need to occur to target this chronic allergic inflammatory response to the lower airway. Some evidence suggests that this event might be an environmental insult in the form of a virus infection, particularly with RSV, which has a predilection for infecting, destroying, and/or in some way biologically altering lower airway epithelium. However, only a fraction of children develop recurrent wheezing following RSV infections, despite the fact that nearly all children have been infected at least once by 2 years of age. Thus, although RSV infections may have the potential of targeting the inflammatory response to the lower airway, they may only be able to do so during a vulnerable time‐period during development of the immune system or lung. This developmental component may further reflect important gene–environment interactions that regulate both short‐ and long‐term airway physiological alterations that manifest themselves clinically as childhood asthma. Efforts to determine and define the importance of these three factors to asthma pathogenesis are the focus and goal of the COAST (Childhood Origins of Asthma) project.
Acute childhood asthma in Finland:A retrospective review of hospital admissions from 1976 to 1995
Authors: Malmström K. , Korhonen K. , Kaila M. , Dunder T. , Nermes M. , Klaukka T. , Sarna S. , Juntunen‐Backman K.
Published: March 2003

The prevalence of childhood asthma has increased markedly in many Western societies during recent decades. We wanted to study whether the incidence and severity of childhood asthma in Finland had changed during the time‐period 1976–95. Hospital admission rates from 1976 to 1995 were obtained from the National Hospital Discharge Register and the individual intensive care unit (ICU) registers of the five university hospitals in Finland. The number and length of treatment periods for childhood asthma in all Finnish hospitals and at the ICUs of the five university hospitals were analyzed. The number of children receiving special reimbursement for asthma medication costs was obtained from the central register of the Social Insurance Institution. The data showed that during the time‐period investigated, hospital admissions as a result of asthma had increased by 2.8‐fold, but the mean length of hospital stay had more than halved (from 7.3 to 2.6 days). The increase in hospital admissions showed greatest significance in the 0–4‐year age‐group among both sexes (p < 0.001). In contrast, a significant reduction in hospital admissions was found among the 10–14‐year age‐group (p < 0.001). No discernible change in admission to ICUs was seen. During the same time‐period, the number of children receiving special reimbursement for asthma medication costs increased 7.5‐fold. Hence, a major increase has occured in the number of children diagnosed with asthma that has not been paralleled by a proportionate increase in the number of hospital admissions. While the prevalence of mild and moderate asthma has increased, the occurrence of severe asthma has remained essentially unchanged.
Ontogeny of T‐helper 1 and T‐helper 2 cytokine production in childhood
Authors: Smart Joanne M. , Kemp Andrew S.
Published: March 2003

Compared to adults, infants and young children demonstrate differences in their immune response, indicating that there is maturation or change over time and it is probable that this may be reflected in cytokine production. Cytokine responses have been demonstrated to be different in atopic and non‐atopic individuals. In this study, we examined T‐helper 1 (Th1) (interferon‐γ[IFN‐γ]) and T‐helper 2 (Th2) (interleukin [IL]‐4, IL‐5, and IL‐13) cytokine release from atopic and non‐atopic children in response to the staphylococcal superantigen, staphylococcal enterotoxin B (SEB). In non‐atopic and atopic children, IFN‐γ, IL‐4, and IL‐5 release was significantly related to age. Non‐atopic children younger than 2 years of age were found to have significantly reduced Th2 (IL‐4, IL‐5, and IL‐13) responses when compared with older, non‐atopic children. Atopic children had a reduced IFN‐γ response when compared with non‐atopics in early childhood; however, the decreased IFN‐γ response seen in early childhood did not persist after 10 years. These age‐related changes in cytokine production provide further support for the concept that cytokine deviations may determine the natural history of atopic disease during early childhood. In addition, the present study indicates the necessity of age‐matched controls when examining children for both Th1 (IFN‐γ) and Th2 (IL‐4) cytokine release.
Inhalation treatment: Errors in application and difficulties in acceptance of the devices are frequent in wheezy infants and young children
Authors: Marguet C. , Couderc L. , Le Roux P. , Jeannot E. , Lefay V. , Mallet E.
Published: March 2003

The recent availability of small‐volume spacers has facilitated the general use of inhaled treatment in infants. The purpose of this study was to evaluate any errors made by parents when using this new inhalation technique and the child's behavior during the inhalation. Ninety‐four young children (61% boys) under 5 years of age were enrolled in the study. Inhalation treatment was recommended either by a general practitioner or by a pediatrician. Data concerning treatment regimens, the ability of parents to use the spacer and metered‐dose inhalers (MDIs), and the acceptance of the devices, were collected by means of a demonstration and questionnaire. Unexpectedly, the doses, administration times, and duration of the treatments varied from one child to the next. No explanation or training in administering the treatment via the spacers was given to 12% and 47% of the parents, respectively. Fourteen per cent of parents did not shake the MDIs, 12% did not monitor the valves, and 22% allowed too short a time for inhalation. The lack of explanation increased the occurence of errors in manipulation of the devices. The procedure was judged to be easy to follow by 78% of the parents, but the face mask was accepted with difficulty by 22% of the children. Repeated crying during administration of the treatment was observed in 38% of the patients, particularly the youngest. Crying influenced the acceptance of the face mask, reduced parental compliance, and made the use of the devices more difficult. Errors altering the efficiency of inhalation treatment in infants are frequent. Most of these errors could be avoided by spending more time to inform the parents about correct usage. Furthermore, repeated crying during inhalation is common in young children and this problem should to be taken into consideration in the evaluation of treatment.
T lymphocytes in food allergy: Overview of an intricate network of circulating and  organ‐resident cells
Authors: Eigenmann Philippe A.
Published: March 2003

Although food hypersensitivity might be divided in IgE‐ and non‐IgE mediated food allergy, there is a large body of evidence implicating T lymphocytes overall in the pathogenesis of food allergy. Priming of naive T cells will occur mainly in Peyer's patches (PP), where surface receptors (l‐selectin, CCR7 and CXCR4) will help to initiate diapedesis of the cells to the submucosa. Various antigen‐presenting cells (e.g. dendritic cells, M cells) will present food antigen‐derived epitopes and initiate either non‐responsiveness, or a food‐mediated immune response. Food‐specific memory T cells express various surface receptors such as the α4β7‐integrin, or the cutaneous lymphocyte antigen. It is speculated, that they might also express specific chemokine receptors (CCR4, CCR7 or CCR9). Organ‐specific homing will be facilitated through the corresponding receptors (i.e. MAdCAM‐1 in the gut, VCAM‐1 or fibronectin in other mucosal organs, or E‐selectin in the skin). Locally secreted chemokines might help to attract T cells through their corresponding chemokine receptors. Finally, potential T‐cell directed therapeutic interventions (peptide‐derived immunotherapy, DNA vaccination, or strategies preventing T cells from trafficking to target organs) are discussed.
Serum immunoglobulin E, IgA, and IgG antibodies to different cow's milk proteins in children with cow's milk allergy: Association with prognosis and clinical manifestations
Authors: Hidvegi Edit , Cserhati Endre , Kereki Erzsebet , Savilahti Erkki , Arato Andras
Published: March 2003

Diverse pathogenic mechanisms elicit different clinical manifestations in cow's milk allergy (CMA). Our aim was to determine the concentration of serum immunoglobulin levels to different cow's milk proteins in patients with CMA and to determine how these values were related to clinical symptoms and prognosis. Fifty children (mean age 10.9 months, range: 1–34 months) with previously confirmed CMA were enrolled in this study. All had various clinical manifestations of CMA, including gastrointestinal, skin, and respiratory symptoms. At the diagnosis of CMA the serum total and the milk‐specific immunoglobulin (Ig)E values were measured by enzyme immunoassay and fluoroimmunoassay, respectively, while the relative levels of serum IgA and IgG antibodies against different cow's milk proteins were determined by a sensitive enzyme‐linked immunosorbent assay (ELISA). The results were compared to those of 30 non‐atopic age‐matched control children. On average, after 9.2 months (range 2–31 months) on a milk‐free diet, a repeated challenge was performed in 38 children. At the re‐challenge, 12 patients had clinical symptoms while the remaining 26 children were symptom‐free. The IgG antibody level to bovine serum albumin (BSA) was significantly lower in the patients than in the controls (median: 0.36 vs. 2.94, p < 0.01). There was a close correlation among all individual IgA and IgG antibodies to different cow's milk proteins. The anti‐α‐casein IgG level (of 2.10) in children with a positive reaction at the re‐challenge was significantly higher than in those with a negative reaction (0.89) (p < 0.05). The total IgE serum concentration was also significantly higher in those who had symptoms at the re‐challenge compared to those who did not have any reaction at this time (22.9 vs. 6.8 kU/l, geometric mean, p < 0.02). There was no association between the clinical manifestations and the IgG and IgA antibody levels to the cow's milk proteins studied, except for the anti‐BSA IgA level, which was higher in patients with gastrointestinal symptoms. The serum total IgE and anti‐α‐casein IgG levels could have prognostic values; their increase at the beginning of the disease may indicate the development of tolerance to cow's milk only at a later age and after a longer duration of CMA. However, as there is considerable overlap among the values observed in different groups of patients, there is a limitation of these tests for predicting the prognosis.
Effect of exclusive breast‐feeding and early solid food avoidance on the incidence of atopic dermatitis in high‐risk infants at 1 year of age
Authors: Schoetzau Angela , Filipiak‐Pittroff Birgit , Franke Käthe , Koletzko Sibylle , Von Berg Andrea , Gruebl Armin , Bauer Carl Peter , Berdel Dietrich , Reinhardt Dietrich , Wichmann H.‐Erich ,   for the GINI Study Group
Published: March 2003

The aim of this study was to assess the preventive effect of exclusive breast‐feeding and early solid food avoidance on atopic dermatitis (AD) in infancy. This study is part of a dietary clinical trial in a prospective cohort of healthy term newborns at risk of atopy. It was recommended to breast‐feed for at least 4 months and to avoid solid food in the same time‐period. Eight hundred and sixty‐five infants exclusively breast‐fed, and 256 infants partially or exclusively formula‐fed, were followed‐up until the end of the first year following birth. AD and sensitization to milk and egg were considered as study end‐points. The 1‐year incidence of AD was compared between the two study groups. Adjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated by multiple logistic regression. The incidence of AD was calculated in relation to age at introduction of solid food and amount of food given. In the breast‐fed group, the adjusted OR for AD was 0.47 (95% CI 0.30–0.74). The strongest risk factor was the occurrence of AD in the subject's core family. The risk of infants with AD to be sensitized to milk was four times higher, and to egg eight times higher, than in infants without AD. Age at first introduction of solid food and diversity of solid food showed no effect on AD incidence. We conclude that in infants at atopic risk, exclusive breast‐feeding for at least 4 months is effective in preventing AD in the first year of life.
Predictive factors for delayed graft function (DGF) and its impact on renal graft survival in children: A report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) *
Authors: Tejani Amir H. , Sullivan E. Kenneth , Alexander Steven R. , Fine Richard N. , Harmon William E. , Kohaut Edward C.
Published: March 2003

Abstract: We define delayed graft function (DGF) as the need for dialysis during the first post‐transplant week. We analyzed 5272 transplants, of which 2486 were of living donor (LD) and 2786 were of cadaver donor (CD) origin. Twelve per cent (620/5272) of all patients developed DGF. Donor specific rates were 5.6% for LD and 19.1% for CD patients. Factors predictive of DGF in CD patients were: African‐American race (25%), prolonged cold ischemia (24%), absence of T‐cell induction antibody therapy and absence of HLA‐DR matching. The relative risk (RR) for graft failure due to DGF was 6.02 (p < 0.001) in LD patients and 2.58 (p < 0.001) for CD recipients. Two‐year graft survival (GS) in LD patients without DGF was 89.6%, compared to 41.6% for those with DGF (p < 0.001); in CD patients it was 80.2% and 49.5%, respectively (p < 0.001). Censoring for primary non‐function, GS for LD patients with a functioning graft at 30 d post‐transplant and no DGF was 91.5%, compared to 70.1% for those with DGF (p < 0.001); GS for CD patients was 83.8% and 68.7%, respectively (p < 0.001). However, when patients whose grafts had failed during the first year were censored no differences in GS were noted between patients with and without DGF for either LD or CD recipients. To determine whether DGF acts as an independent risk factor for graft failure, patients were segregated into four groups: rejection with DGF; rejection without DGF; DGF without rejection; and no DGF, no rejection. When these groups were compared DGF emerged as an independent risk factor for graft failure. This large study reviewing pediatric renal transplantation over 10 yr clearly delineates the role of DGF as a major risk factor for graft failure.
Neoral monitoring 2 hours post‐dose and the pediatric transplant patient
Authors: Dunn Stephen P.
Published: March 2003

Abstract: Cyclosporin A therapy has evolved greatly over the past 25 years of clinical experience. Sophisticated studies of CsA pharmacokinetics and pharmacodynamics have led to a better understanding of the relationship between dose response and biological effect. It has become apparent that achieving target drug exposure is necessary for optimal clinical outcomes. Monitoring dose response has become a key aspect of immunosuppressive management. This review presents the information available supporting cyclosporin drug concentration drawn two hours post dose (C‐2) in children who have been transplanted as the best single indicator of CsA exposure. Further studies evaluating the clinical benefit of achieving C‐2 targets in children are indicated.
Calcium‐dependent protein kinase in maize and sorghum induced by polyethylene glycol
Authors: Pestenácz Anikó , Erdei László
Published: March 2003

Several environmental and hormonal stresses activate signal transduction in plants. Various enzymes are involved in these mechanisms. Studying one of these enzymes, we found osmotically‐induced, calcium‐dependent protein kinases (CDPKs), and hypothesized a connection between osmotic and hormonal signals. CDPKs were investigated in cultivars of relatively drought‐tolerant maize (Zea mays L.) and drought‐tolerant sorghum (Sorghum bicolor L.). Plants were grown hydroponically for 11 days and treated with abscisic acid (ABA, 0.1 μM) starting from day 5, and with polyethylene glycol 6000 starting from day 8 at 0, 100 and 200 mOsm concentrations. As a function of time, treatments lasted for 0, 15, 30, 60, 120 min and 72 h. For the determination of CDPK activity, the 25000 g supernatant of shoots and roots were used for SDS‐PAGE and autoradiography. An increased CDPK activity was found after 1 h of osmotic stress in sorghum roots and Only low levels of phosphorylation could be measured in maize. Little or no activities were detected in the shoots. The Ca2+‐dependent phosphorylation appeared as 49‐ and 52‐kDa bands. Calmodulin (CaM) added in vitro did not change the enzyme activity but inhibition by a CaM antagonist, trifluoroacetic acid, was significant. We also found that pretreatment with ABA reverted the stress‐induced changes in sorghum roots. We concluded that this CDPK is involved in the early steps of the signal transduction pathway, and is connected with ABA‐induced mechanisms.
Alterations in the antioxidative system of suspension‐cultured soybean cells (Glycine max) induced by oxidative stress
Authors: Knörzer Oliver C. , Burner Jörg , Boger Peter
Published: March 2003

The objectives of this study were the changes of antioxidative key enzyme activities under stress conditions induced by a peroxidizing herbicide using photoheterotrophi‐cally grown, suspension‐cultured soybean celts (Glycine max L.). Within two days, 50 to 500 nM oxyfluorfen. a p‐nitrodiphenyl ether herbicide, caused up to 100% inhibition of growth, while simultaneously, the chlorophyll was 25% to completely bleached. The major cellular antioxidants ascorbate and glutathione showed different responses. Under stress conditions with more than 250 nM oxyfluorfen, the cellular ascorbate‐ concentration was halved, whereas dehydroascorbate remained roughly constant. The glutathione content (approximately one‐fifth of that of ascorbate in untreated control cells) increased nearly 3‐fold in the presence of 250 nM oxyfluorfen. Under this condition, oxidized glutathione was 5 times above the control level. The specific activities of selected enzymes participating in cellular defence, namely ascor‐bate peroxidase, glutathione reductase, rnonodehydroascorbate reductase. peroxidase and catalase increased by 40 to 70% with oxyfluorfen concentrations between 50 and 500 nM, while dehydroascorbate reductase showed a significant decrease. Glutathione transferase activity even increased 6‐fold under oxyfluorfen stress.
Far‐red light inhibits growth but promotes carotenoid accumulation in the green microalga Dunaliella bardawil
Authors: Sánchez‐Saavedra M. P. , Jiménez C. , Figueroa F. L.
Published: March 2003

It has been demonstrated that far‐red light reduces growth of marine phytoplankton and that light quality controls growth and photosynthetic metabolism in algae. The green halotolerant microalga, Dunaliella bardawil, accumulates high amounts of β‐carotene (up to 10% of its dry weight) under conditions of high light or nutrient limitation. The influence of increasing irradiance and of far‐red light in D. bardawil was studied. Continuous irradiance was provided by white fluorescent lamps alone (WL) or supplemented with far‐red Linestra lamps (WL+FR). For both types of light, cultures were acclimatized at increasing irradiances (50‐300 µmol m−2 s−1), and cell density, photosynthetic activity and pigment content were determined. Cell density increased with the photon irradiance, and was higher in WL than in WL+FR under the same irradiance, but the reverse occurred in respect of cell volume. Growth rate was higher under WL+FR. Far‐red light induced faster growth but reduced the maximal cell density of the cultures. Chlorophyll a concentration was higher in white light, but total carotenoid content increased dramatically in both far‐red light treatments (about 50% on a per cell basis) and with the increase of irradiance. Our results show that far‐red light has a significant influence on growth and photosynthesis of D. bardawil, inducing a decrease in cell density, photosynthetic activity and chlorophyll concentration, and an increase in growth rate, cell volume and carotenoid content.
Influence of nitrogen deficiency on senescence and the amounts of RNA and proteins in wheat leaves
Authors: Crafts‐Brandner Steven J. , Hölzer Regina , Feller Urs
Published: March 2003

Senescence‐associated coordination in amounts of enzymes localized in different cellular compartments were determined in attached leaves of young wheat (Triticum aestivum L. cv. Arina) plants. Senescence was initiated at the time of full leaf elongation based on declines in total RNA and soluble protein. Removal of N from the growth medium just at the time of full leaf elongation enhanced the rate of senescence. Sustained declines in the amount of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39), and a marked decrease in the rbcS transcripts, just after full leaf elongation indicated that Rubisco synthesis/degradation was very sensitive to the onset of senescence. Rubisco activase amount also declined during senescence but the proportion of rca transcript relative to the total poly A RNA pool increased 3‐fold during senescence. Thus, continued synthesis of activase may be required to maintain functional Rubisco throughout senescence. N stress led to declines in the amount of proteins located in the chloroplast, the peroxisome and the cytosol. Transcripts of the Clp protease subunits also declined in response to N stress, indicating that Clp is not a senescence‐specific protease. In contrast to the other proteins, mitochondrial NADH‐glutamate dehydrogenase (EC 1.4.1.2) was relatively stable during senescence and was not affected by N stress. During natural senescence with adequate plant nitrate supply the amount of nitrite reductase (EC 1.7.7.1) increased, and those of glutamine synthetase (EC 1.4.7.1) and glutamate synthase (EC 6.3.1.2) were stable. These results indicated that N assimilatory capacity can continue or even increase during senescence if the substrate supply is maintained. Differential stabilities of proteins, even within the same cellular compartment, indicate that proteolytic activity during senescence must be highly regulated.
Stimulatory effects of sodium and calcium hypochlorite, pre‐chilling and cytokinins on the germination of Cypripedium macranthos seed in vitro
Authors: Miyoshi Kazumitsu , Mii Masahiro
Published: March 2003

Cypripedium macranthos is a wild orchid that is becoming endangered. Efficient methods for its propagation from seed, which is indispensable for conservation, production and breeding, have not been reported. The effects of sodium and calcium hypochlorite, pre‐chilling and cytokinins on the germination of seeds of Cypripedium macranthos Swartz were examined. The duration of treatment with a solution of hypochlorite prior to sowing was one of the critical factors that affected germination. Approximately 70% of seeds that had been treated with either a solution of NaClO that contained 0.5% available chlorine for 60 min or with one of Ca(ClO)2 with 3.2% available chlorine for 7 h, germinated after 3 months of culture at 20°C, subsequent to 2 months chilling at 4°C. Chilling seeds at 4°C prior to culture at 20°C was another factor that stimulated germination. Even chilling for 2 weeks had a promotive effect on germination, and chilling for 2 months enhanced it most effectively: the frequency of germination was 67% after 3 months of culture at 20°C. However, the promotive effects of chilling on germination were reduced by holding seeds at 20°C for 3 and 6 weeks prior to chilling treatment. Germination of 58‐70% was achieved by the addition of 1 µM cytokinin to the medium, while the frequency was only 17% in cytokinin‐free medium. We report a reproducible and efficient method for enhancing seed germination of C. macranthos, which involves treatment with hypochlorite prior to sowing, and the combination of chilling at 4°C prior to germination and exposure to a cytokinin.
Water‐stress‐induced heat tolerance in geranium leaf tissues: A possible linkage through stress proteins?
Authors: Arora Rajeev , Pitchay Dharmalingam S. , Bearce Bradford C.
Published: March 2003

Evidence is accumulating in favor of a linkage at the cellular level between various abiotic stresses. We conducted a study to evaluate the effect of water stress on the heat tolerance of zonal geraniums, Pelargonium×hortorum cv. Evening Glow. Water stress was imposed by withholding irrigation until pots reached 30% (by weight) of well‐watered controls, and by maintaining the pot weight by additions of water for another 7 days. Leaf xylem water potential (XWP, MPa), relative water content (RWC. %), and heat‐stress tolerance (HST; LT50, defined as the temperature causing half‐maximal % injury based on electrolyte leakage) were measured in control, stressed, and recovered plants. Proteins were extracted from the leaves following the above treatments, and SDS‐PAGE and immunoblotting were performed by using standard procedures. Immunoblots were probed with antibodies to dehydrin and 70‐kDa heat shock cognate (HSC70) proteins. Data indicate that XWP and RWC, respectively, were −0.378 MPa and 92.3% for control plants and −0.804 MPa and 78.6% for stressed plants. Water‐stressed plants exhibited a significant increase in HST compared to control (LT50 of 55°C vs 51°C). Water‐stress‐induced HST was not due to heat acclimation (leaf warming in stressed plants). Data also indicate that water‐stress treatment did not increase freezing tolerance of geranium leaves. Increased HST was associated with the accumulation of several heat‐stable, dehydrin proteins (25–60 kDa), and both cytosolic and ER luminal (BiP) HSC70 proteins. Leaf XWP, RWC, and HST reversed to control levels concomitant with the disappearance/reduction of dehydrins and HSC70 proteins in water‐stress‐relieved plants. The possibility of a cellular linkage between water stress and heat‐stress tolerance is discussed.
DNA methylation levels and ethylene production in senescent, suspension‐cultured pear fruit cells: Implications for epigenetic control?
Authors: Romani Roger J.
Published: March 2003

Auxin‐deprived, senescent, suspension‐cultured pear (Pyrus communis cv. Passe Crassane) fruit cells that can be stimulated to produce ethylene were employed in the search for a possible interdependence between DNA methylation levels and ethylene production. Neither short‐term stimulation of ethylene production by CuCl2, nor longer‐term stimulation by auxin, nor the inhibition of ethylene biosynthesis had a significant effect on the cellular level of DNA methylation. However, short‐term exposure to S‐adenosylhomocysteine enhanced cellular ethylene production and long‐term exposure to azacytidine resulted in the reduction of both DNA methylation levels and stress‐induced ethylene production. These and other correlative findings, or lack thereof, are discussed in the context of ethylene physiology, DNA methylation/demethylation, and epigenetic control.
Environmental control of flowering time in Antirrhinum majus
Authors: Cremer F. , Havelange A. , Saedler H. , Huijser P.
Published: March 2003

The effect of different environmental conditions on flowering time and the number of leaves produced before the first flower is formed has been investigated in Antirrhinum majus L. The effect of light quality has been tested by decreasing the red/far‐red ratio, generally resulting in a reduced flowering time and leaf number. Furthermore, it could be shown that photoperiod, temperature and light intensity are inversely correlated with flowering time and leaf number. However, lowering the temperature from 15 to 12°C resulted in a reduction of flowering time. This observation shows that Antirrhinum can be vernalised.

Using defined combinations of the four environmental factors we have been able to reduce flowering time to only 42 days or to delay flowering for at least 2 years. The results obtained allow an optimisation of the screening conditions for identifying flowering time mutants in Antirrhinum.
Factors regulating ethylene biosynthesis in etiolated Arabidopsis thaliana seedlings
Authors: Woeste Keith E. , Vogel John P. , Kieber Joseph J.
Published: March 2003

We examined the effect on etiolated Arabidopsis thaliana seedlings of a wide variety of factors that are known to induce ethylene in other plant tissues. Auxin, cytokinin, brassinosteroid and cupric ion were found to highly elevate ethylene production in these seedlings, but several other signaling compounds, as well as wounding and mechanical stimulation, had little or no effect. A mutant that disrupts the ACS5 gene (cin5) was partially defective in the induction of ethylene in the presence of brassinosteroids, suggesting a role for this isoform in mediating this response. Cytokinin displayed a synergistic interaction with both brassinosteroid and auxin, while the other interactions tested were essentially additive. Auxin and cytokinin have been shown to act synergistically to elevate ethylene biosynthesis in many other plant tissues. We show that the synergism between cytokinin and auxin in Arabidopsis is due to an enhancement of the effects of auxin, but not by increased elevation of ACS4 mRNA levels. These results suggest that cytokinin acts post‐transcriptionally to increase ACS4 function, which, coupled with the observation that auxin elevates ACS4 mRNA levels, accounts for the synergistic interaction.
Relationships between lipid peroxidation and anoxia tolerance in a range of species during post‐anoxic reaeration
Authors: Blokhina Olga B. , Fagerstedt Kurt V. , Chirkova Tamara V.
Published: March 2003

Peroxidation was studied in anoxically treated plant tissues and quantified as conjugated dienes/trienes in the total lipid fraction and as the production of thiobarbituric acid reactive substances (TBARS). Oxidative stress caused by re‐exposure of plants to oxygen led to an increase of conjugated diene/triene formation in rhizomes of Irisgermanica and roots of wheat (Triticum aestivum L.) and oats (Avena sativa L.), and after a long anoxic exposure (45 days) in the rhizomes of the very anoxia tolerant Iris pseudacorus. Second derivative (SD) spectrophotometry of the UV spectrum of lipid extracts confirmed the formation of dienes. However, determination of TBARS in Iris spp. showed no lipid peroxidation in the anoxia tolerant I. pseudacorus. In the rhizomes of the anoxia intolerant I. germanica, elevated levels of TBARS correlated positively with conjugated diene/triene formation. The results suggest that anoxic stress may induce qualitative changes in membrane lipids, as indicated by lipid peroxidation after restoration of aerobic conditions. The rate of lipid peroxidation correlated negatively with anoxic stress tolerance.
Effects of hyper‐osmotic stress on K+ fluxes, H+ extrusion, transmembrane electric potential difference and comparison with the effects of fusicoccin
Authors: Zingarelli Luisa , Teresa Marrè Maria , Massardi Ferdinando , Lado Piera
Published: March 2003

The stimulation of H+ extrusion by hyper‐osmotic stress (0.2–0.3 M mannitol) in cultured cells of Arabidopsis thaliana (L.) Heynh. was shown to be associated with an inhibition of Cl− efflux, whereas hypo‐osmotic stress, inhibiting H+ extrusion, early and strongly stimulated Cl− efflux. In this paper, we investigate the contribution of other factors [K+ transport and transmembrane electric potential difference (Em)] to the hyper‐osmotic‐induced activation of the plasma membrane (PM) H+‐ATPase. The effects of mannitol (MA) on K+ transport and on Em were compared with those of fusicoccin (FC) since the modes of action of osmotica and of the toxin in stimulating H+‐ATPase activity seem to differ at least in some steps. The changes in H+ extrusion induced by hyper‐ or hypo‐osmotic stress were opposite and could be reversed by the application of the respective opposite stress. The effect of MA on H+ extrusion was dependent on the presence of K+ (or Rb+) similarly to that of FC, while Na+ and Li+, which also stimulated the FC effect, were ineffective on that of MA. The MA effect was independent of the anions (Cl−, SO42−, NO3−) accompanying K+. K+ net uptake and K+ influx were stimulated by both MA and FC. Tetraethylammonium (TEA+) and Cs+ inhibited both MA‐ and FC‐induced H+ extrusion, suggesting the involvement of K+ channels. MA (0.2 M) induced a strong hyperpolarization of Em both in the absence and in the presence of K+. The hyperpolarizing effect of MA was also found when the cells were already hyperpolarized by FC, and was rapidly reversed by removing the osmoticum from the medium. In the presence of the lipophilic cation tributylbenzylammonium (TBBA+), MA was no longer able to stimulate H+ extrusion, while FC still stimulated it. In cells pretreated with TBBA+, which strongly depolarized Em, the subsequent addition of FC repolarized it, while the hyperpolarizing effect of MA was lacking. On the contrary, in cells pretreated with Erythrosine B (EB), Em was strongly depolarized and the following addition of FC did not hyperpolarize it, while the hyperpolarizing effect of MA was still observed. These results suggest that the mechanism of MA in activating H+ extrusion and K+ uptake is different from that of FC. The rise in net K+ uptake seems to be driven by the activation of some hyperpolarizing system that does not seem to depend on a direct activation of PM H+‐ATPase, but rather on the inhibition of Cl− efflux induced by hyper‐osmotic stress.
Carbon balance of a whole tomato plant and the contribution of source leaves to sink growth using the CO2 steady‐state feeding method
Authors: Shishido Yoshihiro , Kumakura Hiroshi , Nishizawa Takashi
Published: March 2003

To clarify the entire carbon balance of a young tomato plant and the contribution of each leaf to sink growth, the carbon balance of each leaf was quantitatively measured using the CO2 steady‐state feeding method to quantitatively measure the photosynthesis, translocation, distribution and respiration of newly fixed C. The entire carbon balance of the whole plant was calculated by adding the data of each leaf. The total amount of carbon fixed by all source leaves was 70.2 mg. Of this amount, in a 24‐h period, 29% was accumulated in the sinks, 28% remained in the source leaves and 42% was respired. Of the total amount of carbon accumulated in the sinks, the proportion accumulated in the shoot apex, stem and roots were 27, 40 and 29%, respectively. The third and fourth leaves contributed about 30–40% of the total growth of the main sinks. The distribution pattern of each leaf to the shoot apex of the plant was greatest in the first leaf and decreased with decreasing leaf age, whereas it showed an opposite trend in the roots.
The effect of mechanical impedance on root growth in pea (Pisum sativum). II. Cell expansion and wall rheology during recovery
Authors: Croser Clare , Bengough A. Glyn , Pritchard Jeremy
Published: March 2003

The aim of the present work was to determine the factors limiting growth in mechanically impeded roots. Pea roots were grown in compressed and uncompressed sand cores, and then removed and transferred to hydroponics. Root elongation was slowed in impeded sand cores and did not recover to the unimpeded rates until 60 h after transfer to the hydroponics system. Root diameter was greater in impeded roots, and only after 36 h in hydroponics was new root tissue produced of the same diameter as the unimpeded controls. The turgor pressure of the growing cells was measured with a turgor probe and was the same in both treatments. The slower elongation rate of the previously impeded roots was, therefore, the result of axial tightening of the cell walls. Cell length profiles suggested that axial cell wall tightening persisted in the unrestricted hydroponics system. Production of new cells in unrestricted conditions was required before root elongation returned to the unimpeded state. Osmotic potential was decreased by approximately 0.2 MPa in previously impeded roots compared with the unimpeded ones. This corresponds to a decrease in water potential of 0.2 MPa. These data are discussed in relation to regulation of cell extension, solute unloading and the penetration of compacted soils by roots.
Temperature response and photoinhibition investigated by chlorophyll fluorescence measurements for four distinct species of dipterocarp trees
Authors: Kitao Mitsutoshi , Lei Thomas T. , Koike Takayoshi , Tobita Hiroyuki , Maruyama Yutaka , Matsumoto Yoosuke , Ang Lai‐Hoe
Published: March 2003

The effects of strong light in combination with elevated temperatures on the photosynthetic system were examined in 4 dipterocarp tree species with ecologically different habitats. The 4 dipterocarp tree species were: Shorea platyclados originated from upper dipterocarp forests, Shorea parvifolia– lowland and hill dipterocarp forests, Shorea assamica– lowland dipterocarp forests, and Dipterocarpus oblongifolius– riparian fringes. S. platyclados and D. oblongifolius have higher growth and survival rates in open sites than S. parvifolia and S. assamica. Tolerance of high temperature among the species was assessed by determining the critical temperatures (Tc) at which the minimal fluorescence (Fo) began to rise sharply. This was measured by exposing plants to an increasing temperature of about 1°C min−1. The intrinsic thermotolerance of the thylakoid membrane appears to be the highest for D. oblongifolius (Tc=46.4°C), intermediate for S. platyclados (45.7°C), and lowest for S. parvifolia and S. assamica (45.2 and 45.3°C, respectively). The temperature‐dependent efficiency of PSII electron transport (ΔF/F′m), photochemical quenching (qP), and the efficiency of light capture of open PSII (F′v/F′m) were measured at the photosynthetic steady state at least 10 min after the light exposure (180 μmol m−2 s−1 PFD). Stable temperature responses of ΔF/F′m and qP were observed in S. platyclados and D. oblongifolius, while those in S. parvifolia and S. assamica were more temperature‐dependent and severely affected at 45°C. Little difference was observed in temperature‐dependent F′v/F′m among species. Photoinhibitory light exposure (1600 μmol m−2 s−1 PFD) for 2 h at 40°C had little effect on the recovery kinetics from photoinhibition of S. platyclados and D. oblongifolius compared with those at 35°C. In contrast, the recovery from photoinhibition was retarded in S. parvifolia and S. assamica. These findings suggest that even at 40°C, a temperature below Tc, an exposure to strong light exacerbated photoinhibition in S. parvifolia and S. assamica corresponding to the closure of PSII reaction centers, as indicated by the decrease in qP at this temperature. Thus, S. platyclados and D. oblongifolius, which occur at uplands and riparian fringes with frequent disturbances, are suggested to have higher photosynthetic tolerance to elevated temperatures contributing to a circumvention of photoinhibition.
Pectin methylesterase modulates aluminium sensitivity in Zea mays and Solanum tuberosum
Authors: Schmohl Nicole , Pilling Jens , Fisahn Joachim , Horst Walter J.
Published: March 2003

Cell suspension cultures of Zeamays L. were adapted to grow under conditions of NaCl stress, which increased the cell‐wall pectin content of these cells by 31% compared with unadapted cells (controls). Both cultures were treated for 5 or 10 min with pectin methylesterase (PME) and afterwards incubated in the presence of Al for 2 h. The different capabilities of the cells to synthesise callose due to pre‐treatment were taken into account by calculating relative Al‐induced callose induction (digitonin=100%). Only in salt‐adapted cells with a degree of methylation of cell‐wall pectin (DM) decreasing from 34% (control) to 13%, did PME treatment enhance total and BaCl2‐non‐exchangeable Al contents and Al sensitivity as indicated by increased callose formation. In a further step, a wider variation in DM was achieved by subculturing the NaCl‐adapted cells for up to 3 weeks without NaCl supply and adapting them to the cellulose‐synthesis inhibitor 2,6‐dichlorbenzonitrile (DCB). This reduced DM to 26%, while short‐term treatment with pectolyase resulted in the lowest DM (12%). After the 2 h Al treatment, there was a close negative relationship between DM and relative callose formation of Al contents, with the exception of pectolyase‐treated cells. In addition, intact plants of Solanumtuberosum L. genotypes were characterised for their Al sensitivity in hydroponics using root elongation, Al‐induced callose formation and Al contents of root tips as parameters. Based on all three parameters, the transgenic potato mutant overexpressing PME proved to be more Al‐sensitive than the wild type, the Al‐resistant and even the Al‐sensitive potato cultivar. Especially in the root tips (1 cm), Al treatment (2 h, 50 μM) increased the activity of PME more in the Al‐sensitive than in the Al‐resistant genotypes. The presented data emphasise the importance of the DM of the pectin matrix and the activity of PME for the expression of Al toxicity and Al resistance.
Enhancement of salt tolerance in soybean with NaCl pretreatment
Authors: Umezawa Taishi , Shimizu Katsuyoshi , Kato Morio , Ueda Takao
Published: March 2003

Acclimation response to salt stress in soybean (Glycine max [L.] Merr. cv. Lee) was found in this study. Soybean seedlings were exposed to 0, 34 and 68 mM NaCl for 23 days (pretreatment), thereafter plants were exposed to 0, 68 and 137 mM NaCl until maturity (main treatment). There was no effect of pretreatment on growth, but at 137 mM NaCl, Na+ concentration in leaves of the plants pretreated with 34 mM NaCl was lower than that of plants pretreated with 0 and 68 mM NaCl. Furthermore, the survival rate under 137 mM NaCl improved with the 34 mM NaCl pretreatment. Therefore, it is possible that soybean can acclimate to salt stress by its increased survival rate, without showing any improvement in growth. The regulation of Na+ or Cl− concentration in leaves could be one of the possible factors involved in salt acclimation of soybean.
Asparagine and ureide accumulation in nodules and shoots as feedback inhibitors of N2 fixation in soybean
Authors: Vadez V. , Sinclair T. R. , Serraj R.
Published: March 2003

Inhibition of N2 fixation under water deficits has been hypothesized to result from N feedback within the plant involving ureides and/or asparagine (Asn). This study was undertaken to investigate ureide and Asn accumulation in shoots and nodules in response to treatments inhibiting nodule activity (acetylene reduction assay, ARA) such as Asn, ureide, or polyethylene glycol application to the nutrient solution of plants, boric acid on leaves, and imposition of a water deficit. ARA inhibition and nodule concentration of Asn and ureide were correlated to the ureide treatment applied (3–15 mM applied in the nutrient solution). Supplying Asn (3–9 mM applied in the nutrient solution) also induced an increase in nodule Asn and ureide concentration, which was associated with ARA inhibition. Spraying boric acid on leaves also inhibited ARA in parallel to an increase in shoot ureide and nodule Asn concentration while nodule ureide remained unchanged. By contrast, polyethylene glycol (PEG) inhibited ARA in parallel to an increase in nodule Asn and ureide concentration while shoot ureide was unchanged. The decline in ARA in response to water deficit was associated with an increase in nodule ureide, Asn and aspartate (Asp), although the increases in Asn and Asp were less than for ureides. Altogether, the results of these experiments indicated that Asn cannot be the only compound involved in the feedback inhibition of ARA. Instead ureide and Asn are probably both involved, either directly by accumulation of products that fail to be exported, or by feedback from the shoot due to an N‐compound supply that exceeds shoot requirements.
A hot water treatment induces resistance to Penicillium digitatum and promotes the accumulation of heat shock and pathogenesis‐related proteins in grapefruit flavedo
Authors: Pavoncello David , Lurie Susan , Droby Samir , Porat Ron
Published: March 2003

A new postharvest hot water brushing (HWB) treatment, which sprays hot water on fruit as they move along a belt of brush‐rollers, induced resistance against green mould decay caused by Penicillium digitatum (Pers. Fr.) Sacc in ‘Star Ruby’ grapefruit. The HWB treatment (62°C for 20 s) was most effective in inducing disease resistance when the fruit were inoculated after 1 and 3 days, but was less effective when the fruit were inoculated on the same day or 7 days later. The HWB treatment induced the accumulation of a 105‐kDa protein that cross‐reacted with an antibody raised against a bovine heat shock protein 70 (HSP70) and 18‐ and 21‐kDa proteins that cross‐reacted with pea HSP18 and HSP21 antibodies. The accumulation of a grapefruit 17‐kDa protein that cross‐reacted with a pea HSP17 antibody was not affected by the HWB treatment. HWB also induced the accumulation of 21‐, 22‐ and 25‐kDa proteins that cross‐reacted with citrus and tobacco chitinase antibodies and 38‐, 42‐ and 43‐kDa proteins that cross‐reacted with citrus and tobacco β‐1,3‐glucanase antibodies. The induction of the 105‐, 18‐ and 21‐kDa HSPs by the HWB treatment indicates that it was sufficient to provide a heat stress and, thus, was able to induce biochemical changes in the fruit peel tissue. Nevertheless, the accumulation of these HSPs was probably not related to the induction of fruit resistance against P. digitatum, since their accumulation could not be induced neither by direct inoculation with the pathogen nor following exposure to other treatments, such as UV irradiation, which also induce disease resistance. On the other hand, the increases in the accumulation of the 21‐, 22‐ and 25‐kDa chitinase proteins and of the 38‐ and 43‐kDa β‐1,3‐glucanases proteins, which were observed 1 and 3 days after the HWB treatment when the fruit appeared to be more resistant to P. digitatum, may be part of the complex fruit disease resistance mechanisms induced by the heat treatment.