bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of high‐dose chemotherapy and stem cell rescue in the treatment of malignant brain tumors: A reappraisal
Authors: Finlay Jonathan L.
Published: March 2003

Abstract: The outcome for children with malignant brain tumors has improved modestly in recent years. Notable is the improved 5‐yr disease‐free survival for those children with ‘standard‐risk’ medulloblastoma and other primitive neuro‐ectodermal tumors (PNET) (i.e. tumors without neuraxis dissemination at presentation). For other children with newly diagnosed malignant brain tumors, especially in the absence of radical surgical resection, the outcome remains poor despite surgery, irradiation and conventional chemotherapy. Patients whose tumors recur despite initial therapy continue to experience a dismal outlook with these conventional strategies of treatment. In an attempt to improve the outlook for such brain tumor patients with poor prognoses, strategies utilizing high‐dose (potentially myeloablative) chemotherapy with autologous stem cell rescue have been developed. These studies, conducted initially in patients with recurrent tumors, were then extended to patients with newly diagnosed malignant gliomas and brain‐stem tumors, as well as to young children with various malignant brain tumors at diagnosis in an attempt to avoid irradiation to the brain. The results of several of these studies are summarized, updating information reviewed in an earlier summary in 1996, demonstrating durable disease‐free survival for a proportion of patients with recurrent malignant gliomas and medulloblastomas/PNET, as well as encouraging data in some of those patients with newly diagnosed brain tumors.
The use of advanced‐age donor hearts adversely affects survival in pediatric heart transplantation
Authors: Chin Clifford , Miller Joan , Robbins Robert , Reitz Bruce , Bernstein Daniel
Published: March 2003

Abstract: There is a limited supply of adequate donor hearts for cardiac transplantation. The safety of using advanced‐age donor hearts has been debated in adult transplantation but has not been studied previously in pediatric recipients. In this retrospective study, survival of 79 pediatric heart transplant recipients was reviewed. Pediatric recipient groups were stratified based on donor age (group 1 donor age > 40 yr, n = 5; group 2 donor age ≤ 40 yr, n = 74). Survival of 267 adolescent (ages 11–17) heart transplant recipients in the United Network for Organ Sharing (UNOS) database was also reviewed. Patients were likewise divided into two groups based on donor age (> 40 yr, n = 12; ≤ 40 yr, n = 255). Survival at one yr was 20% in group 1 vs. 78% in group 2 (p < 0.005). Cause of death in all group 1 patients was graft failure secondary to acute rejection. Analysis of risk of death was only significantly attributable to the age of the donor. The increased risk attributable to advanced donor age was also supported by the UNOS data. The UNOS one and two‐year Kaplan–Meier survival curves were significantly lower in adolescent patients who received donor hearts > 40 yr of age. One‐year survival was 58% (older donors) vs. 85% (younger donors, p < 0.005) and two‐year survival was 44% (older donors) vs. 79% (younger donors, p<0.005). Advanced‐age donor hearts should be contraindicated in pediatric transplantation with the exception of critically ill patients who may not be able to wait for a younger heart.
Hematopoietic stem‐cell transplantation using unrelated cord‐blood versus matched sibling marrow in pediatric bone marrow failure syndrome: One center’s experience
Authors: Shaw Peter H. , Haut Paul R. , Olszewski Marie , Kletzel Morris
Published: March 2003

Abstract: Hematopoietic stem‐cell transplantation (HSCT) is an effective mode of therapy in pediatrics for the treatment of both malignant and non‐malignant disorders. We compared the course of children transplanted with unrelated umbilical cord blood (UCB) to those transplanted with allogeneic sibling bone marrow (BM) for bone marrow failure syndromes. Thirteen patients with a median age of 6.3 years were transplanted for the following diseases between April 1992 and November 1997: myelodysplastic syndromes, aplastic anemia, Diamond–Blackfan anemia, myelofibrosis, paroxysmal nocturnal hemoglobinuria, osteopetrosis and dyskeratosis congenita. The stem cell source was BM in ten patients and UCB in three. We retrospectively examined the conditioning regimens, stem cell source and dose, days to engraftment, survival and complication rate to see whether there was a significant advantage in using one source over the other. The median time to an absolute neutrophil count > 500 per µL was 25 days for UCB patients and 16 days for BM patients. The median time to a platelet count > 20 000 per µL was 55 days for UCB patients and 22 days for BM patients. The 100‐day mortality was 66% in UCB patients and 20% in BM patients. The overall mortality rates were 66% and 40%, respectively. Three patients died prior to engraftment. Seven patients (54%) were still alive as of May 1999 with a median follow‐up of 1574 days post‐transplant. The patients transplanted with BM had faster engraftment and lower rates of graft‐versus‐host disease, 100‐day mortality and overall mortality. HLA‐matched sibling BM is preferred as a source but transplantation using unrelated UCB is still an option in treating pediatric bone marrow failure syndromes.
A comparison of microbiologic flora of the sinuses and airway among cystic fibrosis patients with maxillary antrostomies
Authors: Dosanjh A. , Lakhani S. , Elashoff D. , Chin C. , Hsu V. , Hilman B.
Published: March 2003

Abstract: The placement of maxillary antrostomies among cystic fibrosis (CF) patients has been used as a treatment to allow localized antibiotic lavage of infected sinus passages. This procedure is increasingly recommended by lung transplantation centers as a prerequisite prior to accepting a CF patient as a candidate for transplantation. Our study attempts to define the degree of identity between sinus, endotracheal and sputum cultures from 35 patients. The samples (n = 137) were collected within two weeks of each other. An analysis of the microbiologic type, strain, and antibiotic resistance patterns was undertaken. Random‐ization analysis was performed and a p‐value of < 0.05 was considered significant. The results indicated a high degree of correlation between sinus–sputum pairs (n = 55) and endotracheal samples (p < 0.008). This study provides evidence that there is a potential for cross‐infection between sinus passages and the lower airway. The localized irrigation of CF sinus cavities post‐transplantation may be warranted in an attempt to reduce bacterial counts and potential direct infection of the allograft. However, it is unlikely that this will eliminate this risk because bacterial colonization continues and the CF trachea is another source of infection.
Cannulation of the aorta in organ donors with aortic and caval injuries at the time of procurement
Authors: Molmenti Ernesto P. , Molmenti Hebe , Marubashi Shigeru , Sanchez Edmund Q. , Gogel Brian , Goldstein Robert M. , Levy Marlon F. , Fasola Carlos G. , Gonwa Thomas A. , Klintmalm Goran B.
Published: March 2003

Abstract: Injuries sustained by major vessels during procurement pose a major threat to organ viability. Aortic and inferior vena cava lacerations produce rapid hemorrhage associated with hypoperfusion and ischemic damage. We describe a technique that will prevent such damage in the event of vascular mishaps.
Prediction of mortality and timing of referral for lung transplantation in cystic fibrosis patients
Authors: Augarten Arie , Akons Hannah , Aviram Micha , Bentur Lea , Blau Hannah , Picard Elie , Rivlin Joseph , Miller Mervyn S. , Katznelson Daniel , Szeinberg Amir , Shmilovich Haim , Paret Gideon , Laufer Joseph , Yahav Yaacov
Published: March 2003

Abstract: Lung transplantation (Tx) is an optional treatment for cystic fibrosis (CF) patients with end‐stage lung disease. The decision to place a patient on the Tx waiting list is frequently complex, difficult, and controversial. This study evaluated the current criteria for lung Tx and assessed additional parameters that may identify CF patients at high risk of death. Data were extracted from the medical records of 392 CF patients. Forty of these patients had a forced expiratory volume in 1 s (FEV1) less than 30% predicted, and nine of these 40 patients were transplanted. A comparison was performed between the survival of those transplanted (n = 9) and those not transplanted (n = 31), by means of Kaplan–Meier survival curves. The influence on survival of age, gender, nutritional status, sputum aspergillus, diabetes mellitus, recurrent hemoptysis, oxygen use, and the decline rate of FEV1, were investigated by means of univariate and multivariate analyses. The rate of decline of FEV1 was evaluated employing the linear regression model. CF patients with a FEV1 < 30% and who did not receive a lung transplant had survived longer than CF patients who did receive a lung transplant (median survival 7.33 vs. 3.49 yr, 5‐yr survival 73% vs. 29%). Two factors – rate of decline in FEV1 values and age < 15 yr – were found to influence the mortality rate, while the other parameters examined did not. Our results indicate that the current criterion of FEV1 < 30% predicted, alone is not sufficiently sensitive to predict the mortality rate in CF patients and time of referral for Tx, as many of these patients survive for long periods of time. Additional criteria to FEV1 < 30%, should include rapidly declining FEV1 values and age < 15 yr.
Reasons why some children receiving tacrolimus therapy require steroids more than 5 years post liver transplantation
Authors: Jain Ashok , Mazariegos George , Kashyap Randeep , Marsh Wallis , Khanna Ajay , Iurlano Kathy , Fung John , Reyes Jorge
Published: March 2003

Abstract: Tacrolimus is a potent immunosuppressive agent and has been used in liver transplantation (LTx) for nearly a decade. More than 70% of children can be maintained on tacrolimus monotherapy, without steroids, by the end of 1 yr post‐Tx. This freedom from steroids does not appear to change significantly in subsequent years. The use of steroids has obvious metabolic and cosmetic disadvantages, besides affecting linear growth in children. The present study identifies why some children still require steroid therapy after successful LTx. One hundred and sixty‐six consecutive pediatric patients who had undergone primary LTx between October 1989 and December 1992, were included in this study. Follow‐up ranged from 6 to 9 yr (mean 7.5 ± 0.8 yr). One hundred and forty‐one children were alive in November 1998 and these patients constituted the study group. Their current rate of prednisone use, reason for prednisone use, and prednisone dose were examined retrospectively. Of the 141 patients, 139 (98.5%) had stopped taking steroids at some time‐point after LTx. Thirteen patients (9%) were off immunosuppression altogether (group I), 97 were undergoing tacrolimus monotherapy (group II), and the remaining 31 were receiving therapy with steroids and tacrolimus (group III). The mean prednisone dose at the last follow‐up was 6.5 ± 4.9 mg/day (median 5.0 mg/day). In group III, two children were never weaned off steroids because of inadequate follow‐up (both lived outside the country), and the remaining 29 children completely stopped steroid therapy at some time‐point after LTx; however, prednisone was re‐introduced for clinically suspected or biopsy‐proven rejection in 24. Seven children in group III had completely stopped immunosuppressive therapy either as part of an immunosuppression reduction protocol (n = 3) or for suspected or proven post‐transplant lymphoproliferative disorder (PTLD) (n = 4). In eleven of the 18 children in group III, requirement of steroid for rejection was thought to be related, in part, to non‐compliance. In three children in group III, steroids were re‐introduced for renal dysfunction, and two of these patients subsequently received a kidney Tx. In one child with cerebral ischemia, steroids were used to reduce brain edema, and another child had features of auto‐immune hepatitis. Hence, almost all children can be weaned off steroids when tacrolimus is used as primary immunosuppresson after primary LTx. However, ≈ 22% of children may need re‐institution of steroids because of late acute rejection or renal dysfunction. The concomitant use of other non‐steroidal immunosuppressive agents with tacrolimus may further reduce the dose and rate of steroid use.
G protein β3 subunit 825T genotype is not associated with differing outcome in pediatric renal transplant recipients
Authors: Hocher Berthold , Pleschka Aiko , Yang Fang , Kraus Rolf , Neumayer Hans‐H. , Filler Guido
Published: March 2003

Recent studies have identified a novel polymorphism (C825T) of the gene encoding the β3 subunit of heterotrimeric G proteins (GNB3), associated with enhanced activation of G proteins, which appears to be more common in hypertensive patients. The donor GNB3 825TT genotype was associated with reduced kidney allograft survival in adults. We examined (in 100 Caucasian pediatric renal transplant recipients) whether the GNB3 (C825T) polymorphism was associated with disease progression and outcome after renal transplantation. The slope of 1/creatinine was determined by linear regression analysis of a median of 12 points before and after renal transplantation, and the population was divided into two groups of equal size, before and after transplantation, according to the slope. The observed frequencies were 57 for the CC, 33 for the CT, and 10 for the TT haplotype. For comparison, 738 consecutive newborn babies with the same ethnic background were typed in the same hospital. Allele frequencies were statistically not significantly different (chi‐square test, p = 0.1327). When dividing the pediatric renal transplant recipients into two groups with regard to the slope of 1/creatinine, both before and after renal transplantation, the observed proportions were CC 26, CT 17, and TT 7 in the group with the poorer slope and CC 31, CT 16, and TT 3 in the group with the better slope before renal transplantation (not significant [NS], chi‐square test, p = 0.1777). The observed proportions after renal transplantation were CC 26, CT 16, and TT 8 in the group with the poorer slope and CC 31, CT 15, and TT 4 in the group with the better slope, respectively (NS, chi‐square test, p = 0.167). Allograft survival was not associated with the T allele. In conclusion, in a sizeable number of pediatric renal transplant recipients the GNB3 C825T polymorphism was found not to be a genetic risk factor for end‐stage kidney disease. In addition, kidney graft function and survival was also found not to be associated with a recipient GNB3 C825T polymorphism.
Costs and consequences of stem cell transplantation in children
Authors: Barr Ronald D.
Published: March 2003

Abstract:Economic evaluation is a comparison of the costs and consequences of alternative healthcare interventions. Consequences are best assessed as utilities; quality‐adjusted measures of effectiveness. Although few substantive data are available, it appears that hematopoietic stem cell transplantation is even more cost‐effective in children than in adults.
Effect of light on abscisic acid‐induced proline accumulation in leaves: comparison between barley and wheat
Authors: Pesci P.
Published: March 2003

Light enhanced the abscisic acid‐induced accumulation of proline in barley (Hordeum vulgare L. cv. Georgie) and wheat (Triticum durum L. cv. Valnova). In wheat ABA is ineffective in the dark. In both barley and wheat, the accumulation of proline in the light showed the same characteristics as those of the process that occurs in barley in the dark, namely a synergistic interaction between the hormone and K(Na)Cl, an enhancing effect of Cl− anion in excess over K+ cation in the incubation medium, and an inhibiting effect of D‐mannose and monensine. In wheat, furthermore, light is needed during treatment with ABA if proline is to accumulate. Light was effective in both wheat and barley during the second or accumulation phase of the hormonal process, whereas the events occurring in the first (or lag) phase did not require light. The results suggest that in wheat light induces a putative factor(s) involved in the proline accumulation pathway that is lost in the dark, whereas in barley it is present in the dark.
Comparison of physiological responses of guard cell protoplasts of Nicotiana glauca isolated from leaves collected before dawn or at midday
Authors: Dodge S. M. , Marsh P B. , Tallman G.
Published: March 2003

We observed that guard cell protoplasts isolated from leaves collected at midday from Nicotiana glauca Graham (tree tobacco) did not give the same physiological responses to light as those isolated from leaves collected in early morning. Based on that observation, we attempted to determine whether there were significant differences between the physiological responses of guard cell protoplasts isolated from leaves collected before dawn (with closed stomata) and those isolated from leaves collected at midday (with open stomata). We isolated guard cell protoplasts from leaves collected before dawn and at midday and compared (1) rates of red and blue light‐induced pH changes in weakly buffered media caused by changes in their metabolism, (2) their rates of oxygen consumption in darkness and oxygen evolution in light and (3) relative rates of decay of variable chlorophyll a fluorescence in their chloroplasts. Studies with the vital stain fluorescein diacetate failed to reveal any significant differences in the viabilities of protoplast preparations from leaves collected before dawn and at midday. Furthermore, protoplasts from leaves collected at these times swelled to similar extents in an osmotic medium containing 10 µM fusicoccin and 5 mM KCI. Nevertheless, rates of light‐induced pH changes, rates of oxygen consumption and evolution and rates of decay of variable chlorophyll a fluorescence were all lower in preparations of guard cell protoplasts from leaves collected at midday than in preparations from leaves collected before dawn. Initial volumes of guard cell protoplasts isolated from leaves collected at midday were 150% of those of guard cell protoplasts isolated from leaves collected before dawn. We suggest that the differences in responses of guard cell protoplasts isolated from leaves collected before dawn and at midday may be caused by (1) nonoptimal isolation conditions for guard cell protoplasts prepared from leaves collected at midday, (2) the lower surface‐to‐volume ratio of guard cell protoplasts isolated from leaves collected at midday or (3) diurnal and/or circadian regulation of guard cell metabolism over the course of a day.
Involvement of a high irradiance response in photoinhibition of white clover seed germination at low water potential
Authors: Niedźwiedź‐Siegień Irena , Lewak Stanisław
Published: March 2003

Seeds of white clover (Trifolium repens L., cv. Podkowa) were germinated at water potential ψ=−0.3 MPa in darkness, at 25°C. A short exposure to blue light (B) inhibited germination in a manner similar to that described earlier for red (R) and far‐red (FR) light (Niedźwiedź‐Siegień and Lewak 1989). No reversibility of B, R and FR effects was observed. Saturation irradiance and energy was the lowest for R and the highest for B. The reciprocity of irradiance versus time of exposure was observed only for non‐saturating irradiances of B, R and FR.
Inhibition of ethylene action prevents root penetration through compressed media in tomato (Lycopersicon esculentum) seedlings
Authors: Zacarias Lorenzo , Reid Michael S.
Published: March 2003

Tomato (Lycopersicon esculentum L. cv. Rutgers) seedlings germinated on 2% agar containing the inhibitor of ethylene action, silver thiosulfate (STS), failed to insert their radicles into the agar. The growing seedlings developed a corkscrew morphology because of their inability to develop a gravitropic axis. Treatment with STS increased root length, and decreased hypocotyl elongation. These effects were also observed in seedlings germinated in atmospheres containing 2 000 µl 1−1 2,5‐norbornadiene (NBD), another inhibitor of ethylene action. Neither of the inhibitors suppressed root penetration by seedlings grown on soft agar (0.5%). The altered pattern of growth appears to be due to restricted water uptake, since water application restored normal growth but not root penetration. Under low impedance, the rate of ethylene production was higher on STS‐ or NBD‐treated roots. Increasing the concentration of agar in the growing medium increased ethylene production in untreated roots, and reduced that of those treated with inhibitors. The inability of roots to penetrate impeding agar surfaces was also observed in seedlings of an ethylene‐resistant mutant (er) of Arabidopsis thaliana. These data indicate that ethylene plays a role in the response of roots to mechanical impedance, and that inhibition of their action impaired root insertion through compressed media. Possible mechanisms involved in these processes are discussed.
Thylakoid protein phosphorylation, state 1‐state 2 transitions, and photosystem stoichiometry adjustment: redox control at multiple levels of gene expression
Authors: Allen John F.
Published: March 2003

In photosynthesis in chloroplasts, control of thylakoid protein phosphorylation by redox state of inter‐photosystem electron carriers makes distribution of absorbed excitation energy between the two photosystems self‐regulating. During operation of this regulatory mechanism, reduction of plastoquinone activates a thylakoid protein kinase which phosphorylates the light‐harvesting complex LHC II, causing a change in protein recognition that results in redistribution of energy to photosystem I at the expense of photosystem II, thus tending to oxidise the reduced plastoquinone pool. These events correspond to the transition from light‐state 1 to light‐state 2. The reverse transition (to light‐state 1) is initiated by transient oxidation of plastoquinone, inactivation of the LHC II kinase, and return of dephosphorylated LHC II from photosystem I to photosystem II, supplying excitation energy to photosystem II and thereby reducing plastoquinone. State 1‐state 2 transitions therefore operate by means of redox control of reversible, post‐translational modification of pre‐existing proteins. A balance in the rates of light utilization by photosystem I and photosystem II can also be achieved, on longer time‐scales and between wider limits, by adjustment of the relative quantities, or stoichiometry, of photosystem I and photosystem II. Recent evidence suggests that adjustment of photosystem stoichiometry is also a response to perturbation of the redox state of inter‐photosystem electron carriers, and involves specific redox control of de novo protein synthesis, assembly, and breakdown. It is therefore suggested that the same redox sensor initiates these different adaptations by control of gene expression at different levels, according to the time‐scale and amplitude of the response. This integrated feedback control may serve to maintain redox homeostasis, and, as a result, quantum yield. Evidence for the components required by such systems is discussed.
Molecular genetics of sulfate assimilation in plants
Authors: Leustek Thomas
Published: March 2003

The sulfate assimilation pathway is the primary route by which higher plants obtain the sulfur necessary for growth. Sulfur is involved in a myriad of processes of central importance in metabolism. In the past few years much has been learned about this pathway and its regulation through analysis’of the genes encoding the enzymes and proteins that make up the sulfate assimilation pathway. The recent molecular genetic analysis builds on the biochemical and physiological groundwork of past studies. Further, gene analysis has provided the opportunity to compare directly the evolution of sulfate assimilation in plants and other organisms.,
Ultraviolet‐B responses of nuclear genes encoding light‐harvesting complex II proteins in pea (Pisum sativum) are altered by norflurazon‐ and photobleaching‐induced chloroplast changes
Authors: Liu Liansen , White Michael J.
Published: March 2003

The role of functional and intact chloroplasts in mediating the ultraviolet‐B (UV‐B, 290–320 nm) regulation of two nuclear genes encoding light‐harvesting complex II proteins in pea (Pisum sativum L. cv. Extra Early Alaska) was studied. Plants with chloroplasts lacking or containing carotenoids and functional photosystem II were obtained by growth under dim red light (0.2 µmol m−2 s−1) in the presence or absence of norflurazon (NF), an inhibitor of carotenoid biosynthesis. The NF‐treatment resulted in an increase in AB80 (lhcb1*2) mRNA but no substantial change in Cab‐8 (lhcb1*4) mRNA, indicating that the mRNA accumulations for AB80 and Cab‐8 were differently correlated with the presence and absence of carotenoids. The mRNA levels for both Cab‐8 and AB80 in the NF‐treated plants were reduced to the same extent by partially photobleaching the chloroplasts with 3 h of higher intensity white light (W, 110 µmol m−2 s−1), suggesting that chloroplast integrity was equally important for transcript accumulation of both genes. The mRNAs of both Cab‐8 and AB80 in non‐NF‐treated control plants were decreased by UV‐B irradiation, with the level of AB80 mRNA reduced to a greater extent. The UV‐B‐induced mRNA reduction of both genes was inhibited by NF. The difference between the UV‐B responses of the two genes was unaffected by NF, but was abolished by photobleaching the NF‐treated plants prior to the UV‐B irradiation. Therefore, the presence of carotenoids enhanced rather than prevented the UV‐B down‐regulation, and the difference in UV‐B responses of the two genes may be dependent on chloroplast integrity.
Gravitropism and development of wild‐type and starch‐deficient mutants of Arabidopsis during spaceflight
Authors: Kiss John Z. , Katembe W. Jira , Edelmann Richard E.
Published: March 2003

The “starch‐statolith” hypothesis has been used by plant physiologists to explain the gravity perception mechanism in higher plants. In order to help resolve some of the controversy associated with ground‐based research that has supported this theory, we performed a spaceflight experiment during the January 1997 mission of the Space Shuttle STS‐81. Seedlings of wild‐type (WT) Arabidopsis, two reduced‐starch strains, and a starchless mutant were grown in microgravity and then given a gravity stimulus on a centrifuge. In terms of development in space, germination was greater than 90% for seeds in microgravity, and flight seedlings were smaller (60% in total length) compared to control plants grown on the ground and to control plants on a rotating clinostat. Seedlings grown in space had two structural features that distinguished them from the controls: a greater density of root hairs and an anomalous hypocotyl hook structure. However, the slower growth and morphological changes observed in the flight seedlings may be due to the effects of ethylene present in the spacecraft. Nevertheless, during the flight, hypocotyls of WT seedlings responded to a unilateral 60‐min stimulus provided by a 1‐g centrifuge while those of the starch‐deficient strains did not. Thus, the strain with the greatest amount of starch responded to the stimulus given in‐flight, and, therefore, these data support the starch‐statolith model for gravity sensing.
Endogenous gibberellin A1 levels control thermoperiodic stem elongation in Pisum sativum
Authors: Grindal Grete , Ernstsen Arild , Reid James B. , Junttila Olavi , Lindgård Bente , Moe Roar
Published: March 2003

Gibberellin (GA) is believed to be involved in thermoperiodic stem elongation. With this in mind, we studied the correlation between gibberellin A1 (GA1) levels and stem elongation affected by alternating day (DT) and night temperature (NT) in 5 genotypes of Pisum sativum differing in their degree of dwarfism. The endogenous GA content in the tissue of two of the genotypes was determined by combined gas chromatography and mass spectrometry. The wild genotype developed 40 to 50% shorter stems and internodes under a low DT and high NT combination (negative difference [DIF] between DT and NT, DT/NT 15.5/21.5 or 14/24°C) than under the opposite regime of high DT and low NT (positive DIF, DT/NT 22.5/16.5 or 24/14°C). The GA biosynthetic mutants ls and le, and the auxin and brassinosteroid mutant lkb responded in a similar way, but not as strongly as the wild type. The stem length of the GA‐insensitive slender mutant (la crys) was reduced by only 8% under negative compared to positive DIF. In the wild type endogenous GA levels decreased by 60% from positive to negative DIF in the upper part of the stem. Further, there was a corresponding decrease in the levels of precursors to GA1, i.e. GA53, GA44, GA19 and GA20, while 2β‐hydroxylated GA20 and GA1, GA29 and GA8, respectively, were unaffected by DIF. A similar increase in the ratios of GA29 to GA20 and GA8 to GA1 from positive to negative DIF was seen in the stem tissue of the le mutant as in the wild type. The temperature regimes affected the levels of GA1 and its precursors in combined leaf and petiole samples and in the shoot tip in a similar manner as in the stem tissue. However, the different temperature regimes did not affect the ratio of GA8/GA1 in the shoot tip. The results indicate that altered stem elongation of the pea plants in response to diurnal temperature alternations may be mediated by changes in endogenous levels of GA1. The GA1 levels may be controlled by an effect of DIF on both biosynthetic and inactivation steps.
β‐1,3‐Glucanases in wheat and resistance to the Russian wheat aphid
Authors: Van Der Westhuizen A. J. , Qian X.‐M. , Botha A.‐M.
Published: March 2003

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko) is one of the most destructive insect pests of cereals world‐wide. Although resistant cultivars have been bred, the biochemical mechanism of resistance is unknown. The aim of this work was to gain information on the mechanism of resistance which could contribute to more directed breeding of resistant cultivars in the future. The effect of RWA infestation on the inter‐ and intracellular β‐1,3‐glucanase activities was studied in different resistant wheat (Triticum aestivum L.) cultivars containing the Dn‐1 gene for RWA resistance and corresponding near‐isogenic susceptible cultivars. The activity was determined spectrophotometrically by measuring the release of glucose from laminarin. Infestation differentially induced the intra‐ and intercellular activities to much higher levels in resistant than susceptible cultivars within 48 h. According to immunological studies induced enzyme activities were due to increased protein levels. The intracellular β‐1,3‐glucanase contained about 8% exo‐activity. The exo‐activity made an insignificant contribution to the intercellular activity. The genetic background into which the resistance gene was bred did affect the level of activity that corresponded to the resistance performance. Seven apoplastic isoforms of β‐1,3‐glucanase, varying from acidic to basic, were resolved by isoelectric focusing. All isoenzymes were equally induced and no specific one could be linked to resistance or susceptibility. The RWA induced β‐1,3‐glucanase activity in resistant cultivars closely resembles defence responses during pathogenesis and seems to be part of a general defence response like the hypersensitive reaction (HR), which confers resistance to the RWA. This knowledge might be helpful in future to identify genes for RWA resistance. The increased β‐1,3‐glucanase activity after RWA infestation might serve as an additional measure to biochemically trace resistance in crosses during breeding.
Effect of elevated CO2 on carbon partitioning and exudate release from Plantago lanceolata seedlings
Authors: Hodge Angela , Millard Peter
Published: March 2003

Plantago lanceolata L. seedlings were grown in sand microcosm units over a 43‐day experimental period under two CO2 regimes (800 or 400 µmol mol−1) to investigate the effect of elevated atmospheric CO2 concentration on carbon partitioning and exudate release. Total organic carbon (TOC) content of the collected exudate material was measured throughout the experimental period. After 42 days growth the seedlings were labelled with [14C]‐CO2 and the fate of the label within the plant and its release by the roots monitored. Elevated CO2 significantly (P ≤ 0.001) enhanced shoot, root and total dry matter production although the R:S ratio was unaltered, suggesting no alteration in gross carbon partitioning. The cumulative release of TOC (in mg C) over 0‐42 days was unaltered by CO2 treatment however, when expressed as a percentage of net assimilated C, ambient‐grown plants released a significantly (P≤ 0.001) higher percentage from their roots compared to elevated CO2‐grown plants (i.e. 8 vs 3%). The distribution of 14C‐label was markedly altered by CO2 treatment with significantly (P≤ 0.001) greater per cent label partitioned to the roots under elevated CO2. This indicates increased partitioning of recent assimilate below‐ground under elevated CO2 treatment although there was no significant difference in the percentage of 14C‐label released by the roots. Comparison of plant C budgets based on 14C‐pulse‐chase methodology and TOC measurements is discussed.
Molecular physiology of glutamine and glutamate biosynthesis in developing seedlings of conifers
Authors: Cánovas Francisco M. , Cantón Francisco R. , García‐Gutiérrez Angel , Gallardo Fernando , Crespillo Remedios
Published: March 2003

Nitrogen is a limiting factor in tree growth and development. The incorporation of ammonium ions in carbon skeletons is catalyzed by the sequential action of the enzymes glutamine synthetase (GS) and glutamate synthase (GOGAT). Most studies on nitrogen‐assimilating enzymes have been reported for annual crop plants. Knowledge of these enzymes in woody plants is much more limited, particularly at the molecular level. Here, we review current available information on glutamine/glutamate biosynthesis and chloroplast development in conifers.
H+/PPi stoichiometry of a membrane‐bound pyrophosphatase of plant mitochondria
Authors: Zancani Marco , Casolo Valentino , Vianello Angelo , Macrí Francesco
Published: March 2003

The H+/PPi stoichiometry of the mitochondrial H+‐PPiase from pea (Pisum sativum L.) stem was determined by two kinetic approaches, and compared with the H+/substrate stoichiometries of the mitochondrial H+‐ATPase, and the vacuolar H+‐PPiase and H+‐ATPase. Using sub‐mitochondrial particles or preparations enriched in vacuolar membranes, the rates of substrate‐dependent H+‐transport were evaluated: by a mathematical model, describing the time‐course of H+‐gradient (ΔpH) formation; or by determining the rate of H+‐leakage following H+‐pumping inhibition by EDTA at the steady‐state ΔpH. When the H+‐transport rates were divided by those of PPi or ATP hydrolysis, measured under identical conditions, apparent stoichiometries of ca 2 were determined for the mitochondrial H+‐PPiase and H+‐ATPase, and for the vacuolar H+‐ATPase. The stoichiometry of the vacuolar H+‐PPiase was found to be ca 1. From these results, it is suggested that the mitochondrial H+‐PPiase may, in theory, function as a primary H+‐pump poised towards synthesis of PPi and, therefore, acting in parallel with the main H+‐ATPase.
Elongation factor 1α (EF‐1α) transcript levels are developmentally and environmentally regulated in apple plants
Authors: Watillon Bernard , Kettmann Richard , Boxus Philippe , Burny Arsène
Published: March 2003

A cDNA fragment corresponding to an elongation factor lα subunit (EF‐lα) messenger was amplified and used to isolate a corresponding full‐length copy from an apple (Malus domestica[L.] Borkh) cv. McIntosh ‘Wijcik’ cDNA library. Genomic Southern blot analysis using this probe confirmed that the EF‐1α factor is encoded by a multigenic family in apple. Northern blot analysis of corresponding transcript levels in apple tree organs at various developmental stages revealed that very young leaves contain higher levels of EF‐1α mRNA than older leaves, although significant levels could be detected in all organs tested. In response to wounding, a transient decrease in EF‐1α mRNA levels was observed in apple plantlets, followed by a slight increase. A 24‐h incubation at low temperature (5°C) induced a significant decrease in corresponding transcript abundance. In contrast, when dark‐grown, etiolated, apple plantlets were transferred to light conditions and analyzed with the same probe, few modifications in EF‐1α transcript abundance were detected.
Dual effect of ADP on the activity of the plasma membrane H+‐ATPase of red beet
Authors: Papini Roberto , De Michelis Maria Ida
Published: March 2003

The effect of ADP on the activity of the plasma membrane (PM) H+‐ATPase of red beet (Beta vulgaris L.) parenchyma discs was evaluated by analyzing the effect of increasing concentrations of ADP on the kinetics of the reaction. When the PM H+‐ATPase activity was assayed at pH 6.3, ADP behaved as a simple competitive inhibitor. When the activity was assayed at pH 7.1, ADP not only increased the apparent Km for MgATP but also decreased the Vmax of the reaction. When the C‐terminal domain of the PM H+‐ATPase was cleaved by controlled trypsin treatment or displaced by addition of lysophosphatidylcholine, only the competitive component of inhibition by ADP of the activity assayed at pH 7.1 was evident. The results are discussed in relation to the physiological relevance of the activation of the PM H+‐ATPase by displacement of the autoinhibitory C‐terminal domain.
Inflorescence commitment and subsequent development differ in their responses to temperature and photoperiod in Osteospermum jucundum
Authors: Adams Steven R. , Pearson Simon , Hadley Paul
Published: March 2003

Although Osteospermum is a species which is known to require a period of chilling to induce flowering, the precise form of the relationships between temperature and photoperiod on the phases of flowering has not been quantified. This study aimed to investigate the effects of temperature and photoperiod on time to inflorescence commitment and on the rate of subsequent floral development in Osteospermum jucundum cv. Zulu. To assess how temperature and photoperiod affected the number of days needed for inflorescence commitment, plants were transferred from a range of photothermal environments to a non‐inductive environment. The effect of temperature and photoperiod on subsequent inflorescence development was examined by transferring plants with initiated inflorescences to a range of photothermal environments. Inflorescence commitment occurred first in plants grown at a low average diurnal temperature (10.6°C), but no evidence was found to suggest that photoperiod affected the duration of this phase. Once initiated, high temperatures and long days hastened inflorescence development. The rate of progress to flowering from initiation increased linearly with photoperiod and temperature (up to an optimum of 23.5°C).
Increased expression of two cDNAs encoding metallothionein‐like proteins during growth of Cicer arietinum epicotyls
Authors: Muñoz Francisco J. , Ullán Ricardo V. , Labrador Emilia , Dopico Berta
Published: March 2003

The present study was undertaken to identify and characterize clones whose expression increase during Cicer arietinum epicotyl growth. Two cDNAs encoding two different plant metallothionein (MT)‐like proteins have been isolated from a cDNA library from epicotyls of Cicer arietinum L. cv. Castellana. The CanMT‐1 deduced protein appears to have the typical structure of type 1 MT where all Cys residues are in Cys‐X‐Cys motifs, while the CanMT‐2 has the typical structure of type 2 MT having Cys‐Cys and Cys‐X‐X‐Cys motifs within the N‐terminal domain. Both chickpea CanMTs are up‐regulated during epicotyl growth, showing increased expression in mature tissues, mostly CanMT‐1, which is undetectable in young epicotyls. Accordingly, stem of chickpea plants displayed the highest level of CanMT‐1 expression in the basal internode, with reduced growth, decreasing towards the apex. Osmotic stress by PEG, which inhibited growth, and ABA treatment induced the expression of MT‐like genes, which points to a relationship between chickpea MTs and ABA‐mediated stress response. Unlike CanMT‐2, CanMT‐1 is induced in chickpea epicotyls by cadmium indicating a different function for both clones. We conclude that these MT‐like proteins, in particular CanMT‐1, are regulated by the developmental stage and may participate in cell maturation process.
Purification and characterisation of a novel papain inhibitor from common bean (Phaseolus vulgaris) seed
Authors: Santino Angelo , Gallo Antonia , Leone Antonella , Poltronieri Palmiro , Zacheo Giuseppe
Published: March 2003

A proteinaceous inhibitor of papain was purified to apparent homogeneity from mature seeds of common bean (Phaseolus vulgaris L.). After four chromatographic steps, the papain inhibitor was purified 219‐fold with 12% recovery. On the basis of papain inhibitory activity, cystatins have been estimated to account for about 0.1% of the total protein content of mature common bean seeds. The purified protein, as other plant cystatins, is an acidic protein, heat stable and insensitive to reducing agents. Its molecular mass is about 37 kDa as judged by size exclusion chromatography and SDS‐PAGE. Moreover it is immunologically related to oryzacystatins, since it is recognised by a specific oryzacystatin I antiserum. Based on its biochemical properties the papain inhibitor described here belongs to the phytocystatin family. Papain inhibitory assays carried out during seed development showed that bean cystatin is active since early maturation stages. Our results suggest that, in common bean seed, cysteine proteinase inhibitors are important during seed development with a putative role in the control and regulation of endogenous thiol protease activity.
Plasma membrane H+‐ATPase in the root apex: Evidence for strong expression in xylem parenchyma and asymmetric localization within cortical and epidermal cells
Authors: Jahn Thomas , Baluska Frantisek , Michalke Wolfgang , Harper Jeffrey F. , Volkmann Dieter
Published: March 2003

The cell and subcellular localization of plasma membrane P‐type H+‐ATPase in root apices from Zea mays L. (maize) seedlings was investigated by immunofluorescence microscopy. H+‐ATPase was highly abundant in cells of epidermal and endodermal tissues as well as in phloem companion cells. Strong immunodecoration was also observed in a subset of xylem parenchyma cells forming a connection between the endodermis and metaxylem. Evidence that these cells are equipped for active membrane transport raises the potential that they play a special role in xylem loading. Significant amounts of H+‐ATPase were also observed in outer cortical cells. Progressively less H+‐ATPase was seen in cortical cells further away from the root‐soil interface. The H+‐ATPase was asymmetrically localized within both epidermal and outer cortical cells, with higher levels detected on cell surfaces closest to the root‐soil interface. This asymmetric localization of H+‐ATPase is consistent with the hypothesis that transport systems for uptake of nutrients from the soil are selectively targeted to cell surfaces most exposed to nutrients.
Diurnal changes in allocation and partitioning of recently assimilated carbon in loblolly pine seedlings
Authors: Kuehny Jeff S. , Topa Mary A.
Published: March 2003

We examined diurnal fluctuations in acquisition and partitioning of recently assimilated 14CO2, and in subsequent allocation and partitioning to roots of loblolly pine (Pinus taeda L.) seedlings. Nonmycorrhizal seedlings were grown under optimal nutrient conditions in continuously flowin solution culture. Shoots of 15‐week‐old loblolly pine seedlings were labeled with 14CO2 for 30 min at four separate labeling times: 1000, 1200, 1400 and 1600 h. Six whole plant harvests were conducted during a 48 h chase period, i.e. 0, 4, 8 12, 24 and 48 h after the end of the labeling and evacuation periods. Although assimilation of 14CO2 was constant between 1000 and 1400 h, there were significant differences in partitioning of 14C‐labeled assimilate in needles of all age classes. The highest percentage of recently assimilated 14CO2 in the ethanol‐soluble fraction of photosynthesizing tissue was observed near the beginning and end of the photoperiod. Partitioning of 14C in the ethanol‐soluble fraction declined between the 1000 and 1400 h labeling eriods, and was accompanied by an increase in partitioning of recently assimilated 14CO2 toward starch and a decrease in respiratory losses. These data suggest that most of the 14CO2 assimilated at 1000 h was used to support shoot metabolic activities and possibly restore soluble sugar reserves. Peak starch accumulation in needles during the 1400 h labeling period, concomitant with minimal respiratory loss, indicated that photosynthate production exceeded demand and export out of source leaves. A possible feedback regulation of photosynthesis by starch and/or sugar accumulation may be responsible for the observed decline in assimilation of 14CO2 during the 1600 h labeling period. Net accumulation of recently assimilated 14CO2 in roots was correlated with assimilation rate of 14CO2, but independent of partitioning of recently assimilated carbon in photosynthetic tissue. However, the percentage of total seedling 14C allocated to roots was essentially the same throughout the 48 h chase, regardless of time of labeling and assimilation rate. The data suggest a strong diurnal regulation of starch and soluble sugars synthesized from recently assimilated carbon in needles of loblolly pine seedlings that was independent of assimilation rate. Allocation and transport of recently assimilated carbon to roots of loblolly pine seedlings were not subject to short‐term fluctuations in supply and demand.
Xylem‐to‐phloem transfer of boron in broccoli and lupin during early reproductive growth
Authors: Shelp Barry J. , Kitheka Alice M. , Vanderpool Richard A. , Van Cauwenberghe Owen R. , Spiers Graeme A.
Published: March 2003

The aim of this study was to test the hypothesis that newly‐acquired boron (B) undergoes rapid xylem‐to‐phloem transfer in plants with restricted mobility. Analysis of the element accumulation and water usage by shoots of intact broccoli (Brassica oleracea var. italica Plenck cv. Commander) and lupin (Lupinus albus L. cv. Ultra) plants provided with a non‐deficient supply of B, revealed that the concentration of various mineral elements (K, P, Mg, Ca, B, Fe, Zn, Mo, Cu, Mn) in xylem sap of intact plants ranged from 0.3 µM to 3.5 mM, with B being present at 2.9‐3.5 µM. For each element assayed, the concentration was higher in phloem exudate (1.6 µM to 91 mM) than in xylem sap; B was present at about 0.4 mM. Intact broccoli and lupin plants or detached transpiring broccoli shoots were supplied simultaneously with enriched 10B, strontium (a xylem marker) and rubidium (a xylem/phloem marker) during early reproductive growth. The contents of these three compounds were determined in foliage and florets or fruits as a function of time (i.e. up to 12 h and 4 days for broccoli and lupin plants, respectively), and the content in florets or fruits was expressed as a percent of the total recovered. In general, the percent recovery of both 10B and rubidium in florets or fruits was similar and markedly greater than that for strontium, even at the earliest harvest times (within 2 h for broccoli and 1 day for lupin). The data indicate that in plants with restricted B mobility, B is supplied to sink tissues in the phloem, and the extent of B xylem‐to‐phloem transfer is closely determined by current uptake.