bluuebunny/crossref_metadata_2025 huggingface dataset:
Trends in immunosuppressive therapy: A report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS)
Authors: Benfield Mark R. , Stablein , Donald , Tejani Amir
Published: March 2003

Abstract: The North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) data registry has now compiled data for 11 years, and includes data on 6038 renal transplants in 5516 patients. With the availability of new data and immunosuppressive medications, trends in their usage continue to change. NAPRTCS data have previously demonstrated that increased doses of cyclosporin A (CsA) are associated with improved allograft outcomes, and there has been a steady increase in the dose of CsA given post‐transplantation. Transplants that occurred in 1987, 1989, 1991, and 1993 received a mean one‐year post‐transplant dose of 6.5, 7.0, 7.7, and 8.2 mg/kg/d, respectively. In the 1995 cohort, the dose decreased to 7.4 mg/kg/d. Since the introduction of Neoral®, its use has steadily increased. Of the 1997 cohort, 81% report Neoral® as the formulation of CsA used. The dose of CsA given, however, has not changed. At day 30 post‐transplant, the dose was 7.0 mg/kg/d for Sandimmune and 7.4 mg/kg/d for Neoral®. Finally, the outcome in black transplant patients is inferior to that of nonblack. Evaluation of CsA blood levels revealed that at 1 year post‐transplant, black patients consistently have CsA levels higher than nonblacks, and a lower percentage of black patients have a CsA level < 100 ng/mL. The percentage of patients using triple therapy (prednisone, azathioprine, and CsA) remained stable from 1987 to 1993 at 80–85%. However, in 1996 only 30% of patients were receiving triple therapy. This is probably due to the introduction of mycophenolate mofetil (MMF). Comparing the 1996–97 cohorts, there has been no significant change in the percentage of patients receiving prednisone (96.2% vs. 95.4%) or CsA (83.1% vs. 79.6%). However, during this time, the use of azathioprine has decreased from 50.0% to 35.8%, the use of tacrolimus has increased from 2.5% to 10.8%, and the use of MMF has increased from 6.5% to 35.8%.
Heart or heart–lung transplantation: Psychosocial outcome
Authors: Ikkos Esther Serrano‐ , Lask Bryan , Whitehead Bruce , Rees Phil , Graham Phillip
Published: March 2003

Abstract: The psychosocial outcome of 23 heart and 21 heart–lung transplant recipients, aged 5–17 yrs, was determined and compared with the psychosocial outcome of a group of 46 children and adolescents who underwent conventional cardiac surgery. Preoperatively, and 12 months post‐operatively, the patients’ physical health status, mental state (ICD‐9) and level of psychosocial functioning (GAF scale, DSM‐IIIR) were assessed. There was an improvement in physical health in all groups. Preoperatively, psychiatric disorder, including anxiety and phobic states, depression and adjustment reaction, was noted in 6/23 (26%) children assessed for heart transplantation, 6/21(28.5%) children assessed for heart–lung transplantation, and 12/46 (26%) children undergoing conventional cardiac surgery. The prevalence of psychiatric disorder remained in the transplant group but decreased in the non‐transplant comparison group (6.5%). Improvement in overall levels of psychosocial functioning were found in all groups, but over 40% of all the participants were still functioning below normal levels. In summary, children with end‐stage cardio‐respiratory disease benefit physically and psychologically from heart or heart–lung transplantation treatment but there is a need for systematic psychosocial support both before and after transplantation.
Cardiorespiratory functional assessment after pediatric heart transplantation
Authors: Pastore Enrica , Turchetta Attilio , Attias Leonello , Calzolari Armando , Giordano Ugo , Squitieri Cosimo , Parisi Francesco
Published: March 2003

Abstract: Limited data are available on the exercise capacity of young heart transplant recipients. The aim of this study was therefore to assess cardiorespiratory responses to exercise in this group of patients. Fourteen consecutive heart transplant recipients (six girls and eight boys, age‐range 5–15 yr) and 14 healthy matched controls underwent a Bruce treadmill test to determine: duration of test; resting and maximum heart rates; maximum systolic blood pressure; peak oxygen consumption (VO2 peak); and cardiac output. Duration of test and heart rate increase were then compared with: time since transplantation, rejections per year, and immunosuppressive drugs received. The recipients also underwent the following lung function tests: forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). When compared with healthy controls, transplant recipients had tachycardia at rest (126 ± 3.7 beats/min; p < 0.001); significantly reduced tolerance (9.3 ± 0.4 min; p < 0.001), a maximum heart rate of 169 ± 5.4 beats/min (p < 0.05); a cardiac output of 5.65 ± 0.6 L/min (p < 0.05); and a lower heart‐rate increase from rest to peak exercise (p < 0.001) but a similar VO2 peak. The heart‐rate increase correlated significantly with time post‐transplant (r = 0.55; p < 0.05), number of rejection episodes per year (r = − 0.63; p < 0.05), and number of immunosuppressive drugs (r = − 0.60; p < 0.05). The recipients had normal FVC and FEV1 values. After surgery, few heart transplant recipients undertake physical activity, possibly owing to over‐protective parents and teachers and to a lack of suitable supervised facilities. The authors stress the importance of a cardiorespiratory functional evaluation for assessment of health status and to encourage recipients, if possible, to undertake regular physical activity.
Successful renal transplant outcome after intravenous gamma‐globulin treatment of a highly sensitized pediatric recipient
Authors: Al‐Uzri Amira Y. , Seltz Barry , Yorgin Peter D. , Spier Catherine M. , Andreoni Kenneth
Published: March 2003

Abstract: Approximately 10% of patients on the renal transplant (Tx) cadaver waiting list have high (> 20%) panel‐reactive antibody (PRA) levels to human leukocyte antigens (HLA). Intravenous gamma‐globulin (IVIG) has been shown to reduce anti‐HLA cytotoxic antibody levels through an anti‐idiotypic antibody‐blocking effect. We report a successful renal Tx outcome in a 7‐yr‐old‐girl with high PRA levels owing to a failed renal Tx who experienced a significant reduction in PRA levels (from 96% to 0%) concomitant with IVIG therapy. IVIG was infused weekly (500 mg/kg/week) for 3 consecutive weeks every 12 weeks. Thirty‐four months after starting IVIG therapy, the PRA activity dropped to zero and IVIG was stopped. Then IVIG therapy was resumed after 8 months due to a rebound in PRA activity to 52%. Forty‐four months after starting IVIG therapy, the patient was cross‐matched with a cadaver donor who shared three antigens with the first living donor. The cross‐match was positive with the recipient's sera obtained prior to IVIG therapy and negative with the recipient's sera obtained post‐IVIG therapy. A successful cadaver renal Tx was performed using anti‐thymocyte globulin (ATGAM) induction therapy and a tacrolimus‐based immunosuppression protocol. IVIG was given (1 g/kg) prior to Tx and at day 4 post‐operatively. A single mild acute rejection episode occurred 10 days post‐transplantation that responded to pulse methylprednisolone therapy and an increase in the tacrolimus oral dose. We conclude that a prolonged course of IVIG infusions, without immunosuppressive medications or plasmapheresis, is likely to have been beneficial in modulating the immune response in this highly sensitized recipient. Randomized multicenter trials are required to define the role of IVIG in this specific population.
Human herpesvirus type 8 infections among solid organ transplant recipients
Authors: Allen Upton D.
Published: March 2003

Abstract: Human herpes virus 8 (HHV‐8) is known to be associated with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL) and a form of Castleman's disease. Recently, it has also been shown to be associated with acute bone marrow failure in transplant patients. While, the full spectrum of clinical manifestations due to HHV‐8 is yet to be defined in transplant recipients, it is known to cause post‐transplant KS as a result of primary as well as secondary infection. This review will discuss the possible role of HHV‐8 as a cause of disease in solid organ transplant recipients by focussing on important issues, including the biology of the virus, epidemiology, clinical manifestations, laboratory diagnosis and treatment, followed by a discussion of issues of relevance to the pediatric transplant recipient.
Hematopoietic and immune recovery after allogeneic peripheral blood stem cell transplantation and bone marrow transplantation in a pediatric population
Authors: Nagatoshi Yoshihisa , Kawano Yoshifumi , Watanabe Tsutomu , Abe Takanori , Okamoto Yasuhiro , Kuroda Yasuhiro , Takaue Yoichi , Okamura Jun
Published: March 2003

Abstract: To compare the hematopoietic and immune recoveries after allogeneic transplantation with different cell sources, we analyzed the recovery patterns of blood components after allogeneic peripheral blood stem cell transplantation (PBSCT) in comparison with that after allogeneic bone marrow transplantation (BMT) in a pediatric population. Sixteen patients received PBSCT, and 24 received BMT between January, 1995 and March, 2000. The patients had acute lymphoblastic leukemia (ALL; n = 22), acute myelogenous leukemia (AML; n = 8), myelodysplastic syndrome (MDS; n = 3), or other diseases (n = 7). The median ages of patients in the PBSCT and BMT groups were 9 yr and 6 yr, respectively. Cyclosporin A (CsA) plus methotrexate or methylprednisolone was used as a graft‐vs.‐host disease (GvHD) prophylaxis regimen in the PBSCT group, whereas CsA alone or methotrexate alone was used in the BMT group. Circulating lymphocyte numbers and subpopulations determined by flow cytometric analysis were used as markers of immune recovery. In the PBSCT group, the median number of harvested CD34+ cells was 7.25 (range: 1.3–27.6) × 106/kg of the recipient's body weight, while the median number of harvested nucleated cells was 4.7 (range: 3.7–10.5) × 108/kg. All of the patients were engrafted. Myeloid engraftment occurred sooner after PBSCT than after BMT (median number of days to achieve absolute neutrophil counts (ANC) > 0.5 × 109/L; 11 and 15, respectively; p < 0.0001) and similar results were found for platelet engraftment (median number of days to achieve a platelet count of > 20 × 109/L; 12 and 21, respectively; p = 0.004). On the other hand, after PBSCT the absolute numbers of total circulating lymphocytes and lymphocyte subpopulations were not significantly different from those after BMT. The incidence of acute GvHD after PBSCT was the same as that after BMT, while chronic GvHD developed more frequently after PBSCT than after BMT (p = 0.005). In a pediatric population, the indications for PBSCT and BMT should be based on these findings in addition to regard for the donor's safety.
Avascular necrosis of the femoral head following heart transplant in a child
Authors: Beals Rodney K. , Cobanoglu Adnan M. , Croy Thomas J.
Published: March 2003

Abstract: A case of avascular necrosis of the femoral head following heart transplantation in a 2‐year‐old child has been followed to skeletal maturity. Avascular necrosis is a well‐known complication following steroid use in childhood. There are no reported cases of avascular necrosis following heart transplant in childhood. Similar cases should be reported
Pediatric cardiac transplant: Results using a steroid‐free maintenance regimen
Authors: Leonard H. , Hornung T. , Parry G. , Dark J.H.
Published: March 2003

Abstract: We report on survival, rejection, lymphoma and renal function following cardiac transplant using a steroid‐free maintenance immunosuppressive regimen. We have performed 73 cardiac transplants in 71 children under 16 yr of age in the last 12 yr. There were eight perioperative and four late deaths giving actuarial survival of 88, 88, 85 and 70% at 1, 2, 5 and 10 yr, respectively. A total of 11 (15.3%) children had one episode of rejection (grade 3) in the first 6 months; one died and one was re‐transplanted because of rejection. There was only one episode of late rejection (8 yr post‐transplant) because of low drug levels in a patient with lymphoma and sepsis. This patient did not survive. Three other children (5.6%) also developed lymphoma and recovered but one died subsequently of graft failure. Four children have developed severe renal failure (glomerular filtration rate GFR <30 mL/min/m2). Two have not survived and one is expected to commence dialysis soon. The remainder have mild to moderate renal impairment. We report excellent survival and low rejection rates without use of long‐term steroids. However the doses of cyclosporin used have had a significant effect on renal function in many cases.
Adaptation of potassium translocation into the shoot of maize (Zea mays) to shoot demand: Evidence for xylem loading as a regulating step
Authors: Engels Christof , Marschner Horst
Published: March 2003

In order to manipulate the shoot demand for mineral nutrients per unit root weight, maize (Zea mays L.) seedlings were grown in nutrient solution with different temperatures in the root zone and at the shoot base. The aerial temperature was kept uniform at 24/20°C day/night. At a root zone temperature (RZT) of 24°C, shoot growth was reduced by decreasing the shoot base temperature (SBT) to 12°C; at a RZT of 12°C, shoot growth was increased by raising the SBT to 24°C. At both RZT root growth was not affected by the SBT. Thus, the shoot demand for nutrients per unit root was either increased by raising, or decreased by lowering the SBT. The net uptake rate of potassium (K), as determined from accumulation rates between sequential harvests, was not affected within the first 3 days after lowering the SBT, whereas net translocation rates of K into the shoot and translocation rates in the xylem exudate of decapitated plants were markedly reduced. Obviously, translocation of K into the shoot seems to be regulated independently from K uptake into the root cells. Translocation rates of K in the xylem exudate of decapitated plants were markedly reduced when the nutrient solution was replaced by CaCl2 solution during exudation. But, depending on the SBT before decapitation, significant differences remained in the translocation rates of K even when K uptake from the nutrient solution was prevented.

From the results it is suggested that xylem loading of K is regulated separately from K uptake from the external solution and that the adaptation of K translocation to shoot demand is coupled with an altered capacity of the root for xylem loading.
NMR imaging of roots: methods for reducing the soil signal and for obtaining a 3‐dimensional description of the roots
Authors: Southon Timothy E. , Jones Richard A.
Published: March 2003

Studies of root morphology or root architecture are limited by the problems of observing roots in soil. NMR imaging can preferentially detect the water in roots rather than soil and can therefore produce a map of the distribution of the water in roots, even though there is much more water in the soil than in the roots. The gradient echo imaging technique was shown to detect less signal from water in soil than the more usual spin‐echo technique, probably because the signal loss due to magnetic field inhomogeneities was not refocused in the gradient echo experiments. The gradient echo sequence produced images of a water‐filled capillary tube in soil and of the main roots of a 31‐day‐old oat plant, images which had better contrast than those from the spin‐echo sequence. The improvement was particularly noticeable in the wetter soils. The finer roots could only be observed in the driest of soil and with the spin‐echo sequence. Magnetic field inhomogeneities have a greater effect on thinner roots than on thicker ones, and because the initial signal from thin roots was so small, the additional signal loss due to magnetic field inhomogeneities made the fine roots undetectable with the gradient echo sequence. The problem of loss of perspective associated with projection images was overcome by taking a number of images with different projection planes. By comparing images, a set of (x, y, z) coordinates was obtained for the 4 main roots of a 31‐day‐old oat plant. Computer graphics methods made it possible to compare the digitised root coordinate data set with the original images, thereby confirming the accuracy of the digitised data.
Manipulation of xylem transport affects Zn and Mn transport into developing wheat grains of cultured ears
Authors: Pearson J. N. , Rengel Z. , Jenner C. F. , Graham R. D.
Published: March 2003

Zinc and manganese loading into developing wheat grain is little understood at present. The objective of this work was to investigate factors that may affect the rate of transport of Zn and Mn into developing wheat grain of cultured ears. Ears 18‐22 days post‐anthesis were cultured in solutions containing labelled Zn and Mn. The effect of additions of Cu, Fe, citrate, malate and EDTA to the culture solution was observed. The effect of humidity and awn removal as well as the sucrose status of the ears on Zn and Mn transport was also investigated. The effect of high concentration of Zn and Mn on [14C]‐sucrose transport was determined. High humidity almost completely blocked transport of Zn and Mn into the grain. Awn removal reduced the transport of Zn and Mn to the lemma but not the grain. When the ears were depleted of sucrose (by maintaining them in the dark prior to labelling) transport of Zn and Mn to the grain was reduced compared to ears cultured with sucrose. The presence of Cu reduced the loading of Zn into the grain. There was little effect of Cu on Mn transport or Fe on either Zn or Mn transport. High concentrations of Zn and Mn in the culture solution did not affect [14C]‐sucrose loading into the grain but loading of Zn and Mn was limited at high concentrations suggesting membrane saturation. This study demonstrates that sucrose status and humidity clearly influence the transport of Zn and Mn into the grain, and that other ions may influence Zn and Mn transport.
Functional analysis of the ver gene using antisense transgenic wheat
Authors: Chong Kang , Bao Shi‐lai , Xu Tao , Tan Ke‐hui , Liang Tie‐bing , Zeng Jun‐zhi , Huang Hua‐liang , Xu Ji , Xu Zhi‐hong
Published: March 2003

The function of ver203, a gene related to vernalization in winter wheat, was investigated by expression of a complementary DNA as an antisense RNA in transgenic plants. A verc203:gus fusion‐expression plasmid was constructed in pBI221, which contains a CaMV (cauliflower mosaic virus) 35S‐promoter, a gus gene and a nos terminator. The construct was then introduced into the plant by the pollen‐tube pathway. The results showed that heading was strongly inhibited in 6 of 326 vernalized antisense transgenic winter wheat plants, until both the vernalized control winter wheat and sense transgenic plants ripened. The hybridization analysis of DNA, amplification of the insert DNA sequences with PCR, northern blot analysis with double‐ and single‐stranded probes, and detection of GUS activity by X‐gluc assay gave strong positive results. This suggests that the VER203 protein plays an important role in controlling heading and flower development in winter wheat.
CO2, light and temperature influence senescence and protein degradation in wheat leaf segments
Authors: Herrmann B. , Feller U.
Published: March 2003

Effects of environmental conditions influencing photosynthesis and photorespiration on senescence and net protein degradation were investigated in segments from the first leaf of young wheat (Triticum aestivum L. cv. Arina) plants. The segments were floated on H2O at 25, 30 or 35°C in continuous light (PAR: 50 or 150 µmol m−2 s−1) in ambient air and in CO2‐depleted air. Stromal enzymes, including phosphoglycolate phosphatase, glutamine synthetase, ferredoxin‐dependent glutamate synthase, phosphoribulokinase, and the peroxisomal enzyme, glycolate oxidase, were detected by SDS‐PAGE followed by immunoblotting with specific antibodies. In general, the net degradation of proteins and chlorophylls was delayed in CO2‐depleted air. However, little effect of CO2 on protein degradation was observed at 25°C under the lower level of irradiance. The senescence retardation by the removal of CO2 was most pronounced at 30°C and at the higher irradiance. The stromal enzymes declined in a coordinated manner. Immunoreactive fragments from the degraded polypeptides were in most cases not detectable. However, an insolubilized fragment of glycolate oxidase accumulated in vivo, especially at 25°C in the presence of CO2. Detection of this fragment was minimal after incubation at 30°C and completely absent on blots from segments kept at 35°C. In CO2‐depleted air, the fragment was only weakly detectable after incubation at 25°C. The results from these investigations indicate that environmental conditions that influence photosynthesis may interfere with senescence and protein catabolism in wheat leaves.
A comparative study on carbohydrate reserves and ethanolic fermentation in the roots of two wetland and non‐wetland species after commencement of hypoxia
Authors: Albrecht Gerd , Biemelt Sophia
Published: March 2003

The problem of availability of storage carbohydrates (fructans and starch) in oxygen‐deficient roots was investigated in wetland species (Senecio aquaticus Hill., Myosotis palustris[L.] L. Em. Rchb.) and compared with related non‐wetland species (Senecio jacobaea L., Myosotis arvensis[L.] Hill.) with respect to ethanolic fermentation (PDC activity, ethanol production).

In response to 24 h of hypoxic treatment, the pyruvate decarboxylase (PDC) activity in roots increased 4‐fold in M. arvensis and S. jacobaea, 2‐fold in S. aquaticus and only slightly in M. palustris. The rise in PDC activity was accompanied by an increase in ethanol content in the roots. The increase in ethanolic fermentation in roots of intact plants was associated with a slight increase in fructose and glucose and in a clear rise in sucrose content during the first 24‐48 h after commencement of the hypoxic treatment. Following 24 h of hypoxia, the content of fructans started to increase significantly for the duration of the experiment (9 days) in the four species. Since starch content changed only slightly during this period, the fructan:starch ratio increased under low energy availability. In the roots of flooding‐tolerant Senecio aquaticus, the ratio shifted most clearly from 2:1 in normoxia to 9:1 in hypoxia. For the roots of the two wetland species investigated, the results indicate a stronger accumulation of carbohydrates accompanied by a lower increase in PDC activity under root hypoxia, when compared with the related non‐wetland species respectively.
Sequence of drought response of maize seedlings in drying soil
Authors: Schmidhalter Urs , Evéquoz Michel , Camp Karl‐Heinz , Studer Christoph
Published: March 2003

Leaf elongation in monocotyledonous plants is sensitive to drought. To better understand the sequence of events in plants subjected to soil drying, leaf elongation and transpiration of maize seedlings (Zea mays L.) of 4 cultivars were monitored continuously and the diurnal courses of the root and leaf water relations were determined. Results from this study indicate the following sequence of drought response: Leaf elongation decreased before changes in the leaf water relations of non‐growing zones of leaf blades were detected and before transpiration decreased. Reductions in leaf elongation preceded changes in the root water potential (ψw). Root ψw was not a very sensitive indicator of soil dryness, whereas the root osmotic potential (ψs) and root turgor (ψp) were more sensitive indicators. The earliest events observed in drying soil were a significant increase in the largest root diameter class (1 720 to 1 960 gm) and a decrease in leaf elongation (P= 0.08) 2 days after withholding water. Significant increases in root length were observed 2 days later. Soil drying increased the number of fine roots with diameters of <240 µm. Slight increases in soil strength did not affect leaf elongation in the drying soil.
Enzymatic degradation of polar lipids in Vigna unguiculata leaves and influence of drought stress
Authors: Sahsah Y. , Campos P. , Gareil M. , Zuily‐Fodil Y. , Pham‐Thi A. T.
Published: March 2003

14C‐labelled polar lipids (monogalactosyl‐diacylglycerol [MGDG], digalactosyl‐diacylglycerol [DGDG], phosphatidylcholine [PC] and phosphatidylglycerol [PG]), purified from Vigna unguiculata leaves, were used as substrates to study the lipolytic activities of Vigna unguiculata leaf extracts. Analysis of the radioactive degradation products revealed the presence of at least three enzyme activities contributing to the hydrolysis of the four main leaf membrane lipids: Lipolytic acyl hydrolase (LAH) activities responsible for the deacylation of galactolipids and phospholipids, phospholipase D (PLD, EC 3.1.4.4) activity which gives rise to phosphatidic acid, and as suggested by the presence of diacylglycerols in minor quantities after phospholipid hydrolysis, phosphatidate phosphohydrolase (PAP, EC 3.1.3.4) and/or phospholipase C (PLC, EC 3.1.4.3.) activity. Under the conditions described in the present paper, the presence of phospholipase A (PLA1, EC 3.1.1.3 and PLA2, EC 3.1.1.4) activities remains hypothetical, due to the absence of lysophospholipids. LAH and PLD were partially soluble and partially associated with the membranes. When Vigna unguiculata plants were submitted to drought, the enzymatic degradation of galactolipids and phospholipids increased. The stimulation of lipolytic activities was greater in the drought‐sensitive cultivar of Vigna unguiculata (cv. 1183) than in the drought‐tolerant (cv. EPACE‐1) one. In cv. 1183, MGDG‐ and DGDG‐LAH activities in the membrane fractions were dramatically stimulated at a rather moderate water deficit (−0.75 MPa). A sharp increase in membrane phospholipolytic activities was also observed at mild drought stress (−1.2 MPa). In contrast, in cv. EPACE‐1, the stimulation of lipolytic activities was less drastic and occurred at lower leaf water potentials (below −1.2 MPa for galactolipases, and below −1.4 MPa for phospholipases). Our results confirm the presence in leaves of higher plants of a very active LAH acting on galactolipids, whereas PLD is the main enzyme responsible for the degradation of phospholipids, particularly when plants are submitted to drought stress. The differences in stimulation of lipolytic activities between the two Vigna cultivars was in accordance with the different levels of membrane lipid degradation shown previously and could explain their different capacity to sustain drought.
Stromal and thylakoid‐bound ascorbate peroxidases in NaCl‐treated wheat
Authors: Meneguzzo Sandra , Sgherri Cristina L.M. , Navari‐Izzo Flavia , Izzo Riccardo
Published: March 2003

Salinity is one of the most widespread causes of plant growth inhibition and reduction of agricultural productivity. Activated oxygen species seem to be implicated in the injury mechanism induced by salt. In our work, the effect of NaCl was studied in chloroplasts from seedlings of two cultivars of Triticum durum Desf., differently sensitive to drought and to heavy metals (cv. Ofanto more tolerant than cv. Adamello). The seedlings were grown for 9 days in Hoagland's no. 2 solution, to which increasing concentrations of NaCl (0, 50 and 100 mM) were added. The results indicate an involvement of activated oxygen species in the mechanism of cellular toxicity of NaCl and the capability of the seedlings to induce their antioxidant defences. In chloroplasts of both cultivars, NaCl treatment induced a significant increase in ascorbate, even if cv. Ofanto showed the higher response. Ascorbate peroxidases appear to behave differently in the two cultivars in response to NaCl‐induced oxidative stress of chloroplasts. In seedlings of Adamello treated with 50 mM NaCl, a sudden increase in thylakoid‐bound ascorbate peroxidase (tAPX) activity and a decrease in that of stromal ascorbate peroxidase (sAPX) occurred. Differently, in Ofanto, a slight increase of both sAPX and tAPX was induced by NaCl. In both cultivars, three well‐resolved bands of sAPX were found. In chloroplasts of both cultivars, monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) behaved similarly, even if in Adamello a greater decrease of DHAR was shown. The experimental evidence suggested a more marked effect of NaCl stress on Adamello as compared with Ofanto.
Grain yield, carbon isotope discrimination, mineral and silicon content in durum wheat under different precipitation regimes
Authors: Merah O. , Deléens E. , Monneveux P.
Published: March 2003

Twenty‐one durum wheat genotypes originating from different geographic areas were grown during 3 successive years. The trials were characterised by different precipitation regimes. Carbon isotope discrimination (Δ), carbon content (CC) and ash content (ma) were assessed in the flag leaf during anthesis, then in the kernel at full maturity. Differences between the 3 years, due to water availability, were noted for Δ, ma, CC and yield. Genotypic differences were also noted within each year for all the traits studied. Some genotypes from the Middle East exhibited higher flag leaf and kernel Δ than those originating from the West of the Mediterranean basin. The kernel Δ was strongly correlated with grain yield (GY). The leaf Δ correlated with GY only under strong water limitation and with biomass production (BP) in favourable water conditions. For the flag leaf, Δ was correlated with ma and with CC. Silicon content was then assessed in the flag leaf and in the kernel on a subset of 10 genotypes differing in their Δ values. Strong positive correlations were noted between silicon content and Δ and ma for the flag leaf. However, no clear relationship was found between silicon content and GY. The results obtained in this study confirm the validity of kernel Δ as a predictive criterion for GY under water stress and suggest the possible use of kernel ma as an alternative criterion to select genotypes with higher water stress tolerance.
Light regulation of gibberellin A1 content and expression of genes coding for GA 20‐oxidase and GA 3β‐hydroxylase in etiolated pea seedlings
Authors: Gil Joan , García‐Martinez José L.
Published: March 2003

White light (WL) inhibited the stem elongation of etiolated pea (Pisum sativum L.) seedlings and the inhibition was partially reversed by the application of gibberellin A1 (GA1), the active GA in shoot growth. The amount of GA1 in the apical shoot was reduced to about 25% after 2 h of WL, and to a trace level after 4 h. The effect of light on GA1 content was reversed when the plants were transferred again to the dark after 6 h of WL. The effect of light on the expression of GA 20‐oxidase and GA 3β‐hydroxylase genes, coding for the last steps of GA1 biosynthesis, was also investigated. Contrary to expectations, the amounts of GA 20‐oxidase and GA 3β‐hydroxylase transcripts increased in the entire apical shoot of WL‐irradiated seedlings, and this increase was negated in seedlings treated with GA1 before WL irradiation, probably as a result of negative feed‐back regulation. The effect of WL on GA 20‐oxidase transcripts was mainly localized in the apex (hook) whereas the effect on GA 3β‐hydroxylase transcripts was mainly localized in the subapical tissues. Red and far‐red light also enhanced the GA 20‐oxidase transcript level, but not that of GA 3β‐hydroxylase, suggesting that different photoreceptors are involved in the regulation of these genes by WL. The results presented indicate that the inhibition of stem elongation by light is due, at least partially, to a decrease of GA1 content by a still unknown mechanism. The increase of GA8 upon WL irradiation raises the possibility that an inactivation activity may be involved in the control of the content of GA1 by light.
Soluble sugar content of white spruce (Picea glauca) seeds during and after germination
Authors: Downie Bruce , Bewley J. Derek
Published: March 2003

In white spruce (Picea glauca [Moench.] Voss.) seeds, the raffinose family oligosaccharides (RFOs) provide carbon reserves for the early stages of germination prior to radicle protrusion. Some seedlots contain seeds that are dormant, failing to complete germination under optimal conditions. Since dormancy may be imposed through a metabolic block in reserve mobilization, the goal of this project was to identify any impediment to RFO mobilization in dormant relative to nondormant seeds. Desiccated seeds contain primarily, and in order of abundance on a molar basis, sucrose and the first 3 members of the RFOs, raffinose, stachyose and verbascose. Upon radicle protrusion at 25°C, the contents of RFOs decreased to low amounts in all seed parts, regardless of prior dormancy status and sucrose was metabolized to glucose and fructose, which increased in seed parts. During moist chilling at 4°C, RFO content initially decreased before stabilizing and then increasing. In seeds that did not complete germination, the synthesis of RFOs at 4°C favored verbascose, so that at the end of 14 (nondormant) or 35 (dormant) weeks, verbascose contents in megagametophytes exceeded the amount initially present in the desiccated seed. This was also true in the embryos of the dormant seedlot. In seed parts from both seedlots after months of moist chilling, stachyose amounts exceeded raffinose amounts. Upon radicle protrusion at 4°C, RFO contents decreased to amounts most similar to those present in seeds that completed germination at 25°C. Hence, the RFOs are utilized as a source of energy, regardless of the temperature at which white spruce seeds complete germination. Based on the similarity of sugar contents in seed parts between dormant and nondormant seeds that did not complete germination, differences in sugar metabolism are probably not the basis of dormancy in white spruce seeds.
Intraplastidial lipid trafficking: Regulation of galactolipid release from isolated chloroplast envelope
Authors: Räntfors Mats , Evertsson Ivar , Kjellberg J. Magnus , Stina Sandelius Anna
Published: March 2003

A method is described for cell‐free studies of lipid release from isolated chloroplast envelope. The isolated membrane fraction incorporated radiolabeled galactose into galactolipids, predominantly monogalactosyldiacylglycerol, prior to immobilization of the membrane vesicles onto strips of nitrocellulose. The strips with immobilized membrane were individually incubated with various co‐factors and the incubations were terminated by removing the strips. Radioactivity was determined for the strips with immobilized membrane as well as for the material released during the assay. The release of galactolipids from immobilized chloroplast envelope was time‐ and temperature dependent, required stroma protein(s) and was further stimulated by hydrolysable ATP, GTP and ≤50 μM acyl‐CoAs, of which 16:1‐CoA was the most stimulative. To investigate whether guanine nucleotide‐binding proteins could be involved, stroma and envelope were independently or together incubated with [α‐32P]GTP or [Γ‐32P]GTP. Stroma and envelope proteins were phosphorylated and the envelope fraction contained GMP/GDP binding proteins as well. When the fractions were co‐incubated, the patterns of protein phosphorylation and guanine nucleotide binding was different compared to the additive effects of the separate fractions, suggesting that guanine nucleotides may have roles in galactolipid release in addition to providing energy. The results point to several similarities between the regulation of galactolipid release from isolated chloroplast envelope and the regulation of vesicular trafficking among animal and yeast cytosolic membranes, although other mechanisms for lipid release cannot, at this stage, be ruled out.
Response of antioxidative enzymes to plum pox virus in two apricot cultivars
Authors: Hernández J. A. , Talavera J. M. , Martínez‐Gómez P. , Dicenta F. , Sevilla F.
Published: March 2003

Recent evidence has indicated that activated oxygen species (AOS) may function as molecular signals in the induction of defence genes.  In the present work, the response of antioxidative enzymes to the plum pox virus (PPV) was examined in two apricot (Prunus armeniaca L.) cultivars, which behaved differently against PPV infection. In the inoculated resistant cultivar (Goldrich), a decrease in catalase (CAT) as well as an increase in total superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities were observed. Ascorbate peroxidase (APX), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) did not change significantly in relation to non‐inoculated (control) plants. In the susceptible cultivar (Real Fino), inoculation with PPV brought about a decrease in CAT, SOD and GR, whereas a rise in APX, MDHAR and DHAR activities was found in comparison to non‐inoculated (control) plants.  Apricot leaves contain only CuZn‐SOD isozymes, which responded differently to PPV depending on the cultivar. Goldrich leaves contained 6 SODs and both SOD 1 and SOD 2 increased in the inoculated plants. In leaves from Real Fino, 5 SODs were detected and only SOD 5 was increased in inoculated plants.  The different behaviour of SODs (H2O2‐generating enzymes) and APX (an H2O2‐remover enzyme) in both cultivars suggests an important role for H2O2 in the response to PPV of the resistant cultivar, in which no change in APX activity was observed. This result also points to further studies in order to determine if an alternative H2O2‐scavenging mechanism takes place in the resistant apricot cultivar exposed to PPV. On the other hand, the ability of the inoculated resistant cultivar to induce SOD 1 and SOD 2 as well as the important increase of DHAR seems to suggest a relationship between these activities and resistance to PPV.  This is the first report about the effect of PPV infection on the antioxidative enzymes of apricot plants. It opens the way for the further studies, which are necessary for a better understanding of the role of antioxidative processes in viral infection by PPV in apricot plants.
Production of clover broomrape seed germination stimulants by red clover root requires nitrate but is inhibited by phosphate and ammonium
Authors: Yoneyama Koichi , Takeuchi Yasutomo , Yokota Takao
Published: March 2003

The effect of nutrients (nitrate, ammonium, urea, phosphate and potassium) on the production and/or exudation of germination stimulants for clover broomrape (Orobanche minor Sm.), a root holoparasite, by its host red clover (Trifolium pratense L.) was examined using hydroponically grown material. Potassium (K2SO4) concentrations up to 100 mg l–1 (based on K) did not affect the production of germination stimulants by red clover while, in contrast, phosphate (NaH2PO4) was highly inhibitory even at concentrations as low as 1 mg l–1 (based on P). Nitrate (NaNO3) markedly promoted stimulant production in a dose‐dependent manner from 2 to 50 mg l–1 (based on N). Ammonium [(NH4)2SO4] had no effect at 2 mg l–1 (based on N) but was inhibitory at higher concentrations. Ammonium is known to be a seed germination inhibitor of root parasites, indicating that ammonium has a dual inhibitory action. Urea had no effect at 2 mg l–1 (based on N) but was promotive at higher concentrations. These results provide a basis for the inhibitory effects of nitrogen fertilizer on infection by root parasitic weeds, broomrapes and witchweeds, and explain why these parasites prevail in areas where there is lower phosphorus availability in soils.
Early detection of graft incompatibility in apricot (Prunus armeniaca) using in vitro techniques
Authors: Errea Pilar , Garay Lilibeth , Marín Juan Antonio
Published: March 2003

Graft compatibility has been studied in vitro using callus tissues of apricot (Prunus armeniaca) and different Prunus rootstocks to form scion/rootstock combinations with different degrees of graft compatibility. In these species, incompatibility is manifested by a breakdown of the trees at the union area that can occur some years after grafting. Here, the possibility of obtaining an early detection method to determine graft incompatibility is explored by callus fusion in vitro. The adhesion of the two callus partners, the development of the cells at the contact surface (cell arrangement, intensity of cell‐wall staining), and the presence of lipid and phenolic compounds have been studied during the first 3 weeks after grafting in both compatible and incompatible combinations. Differences were observed at the second and the third week of callus co‐culture in most of the characters determined, although these differences were present as early as the first week in the case of phenolic compounds. The behaviour of the grafts grown in vitro was correlated to that of the same combinations in the field, suggesting that callus fusion in vitro could be a possible and reliable method for an early detection of graft incompatibility in different Prunus combinations.
The nitrogen‐induced recovery of α‐zein gene expression in in vitro cultured opaque2 maize endosperms depends on the genetic background
Authors: Locatelli Franca , Manzocchi Lucia A. , Viotti Angelo , Genga Annamaria
Published: March 2003

The effect of nitrogen nutrition on the accumulation of seed storage proteins has been studied in vitro by cultivating on agar media maize (Zea mays L.) endosperm explants from seeds at 10 days after pollination. The experiments were performed on various genetic backgrounds bearing different opaque2 (o2) mutant alleles and on the corresponding wild‐type lines. In the seed of the o2 genotypes the high molecular weight α‐zein polypeptides (zHs), whose transcription is Opaque2 (O2) regulated, are absent or extremely reduced. The endosperms were incubated on basal agar medium with amino acid supply. In these growth conditions, fresh and dry weights increased in both wild‐type and o2 endosperms, irrespective of the genetic background. In 4 out of the 5 o2 mutant genotypes analysed we detected an accumulation of the zHs similar to the corresponding wild‐type explants or seeds. However, in one of these mutants, Mo17o2R, the addition of amino acids to the culture media had no effect on the zH accumulation. We showed that the Mo17o2R behaviour is not due to a negative regulation but to the absence of putative transcription factor(s) able to regulate the zH transcription occurring in the other o2 mutants.
Developmental expression of the mitochondrial pyruvate dehydrogenase complex in pea (Pisum sativum) seedlings
Authors: Luethy Michael H. , Gemel Joanna , Johnston Mark L. , Mooney Brian P. , Miernyk Jan A. , Randall Douglas D.
Published: March 2003

In order to better understand control of the mitochondrial pyruvate dehydrogenase complex (PDC), total catalytic activity was determined during development of the primary leaves of pea (Pisum sativum L.) seedlings, as well as in each leaf pair of 21‐day‐old plants. Activity of the PDC in clarified homogenates was highest in the youngest organs and then dropped dramatically as the leaves matured and became photosynthetically competent. As leaves began to senesce, total PDC activity dropped to zero. Steady‐state mRNA levels were determined using E1 and E3 cDNA probes. The overall pattern of transcript abundance matched the pattern observed for total PDC activity; transcript levels for E1α and E1β approached zero during senescence. Levels of the E1α, E1β, E2 and E3 subunits of the PDC were analyzed in the same samples, using specific antibodies. Quantitation of the immunoblotting results throughout this developmental series showed a pattern in parallel with that of catalytic activity and mRNA levels, although the relative changes in subunit protein levels were not as extreme as the changes in activity. The exception to the global pattern was that of the E3 subunit: lipoamide dehydrogenase. Expression of this enzyme was highest in mature, fully expanded leaves, which were active in photosynthesis and photorespiration, reflecting the additional role of E3 as a component of glycine decarboxylase.
Acetaldehyde emission by the leaves of trees – correlation with physiological and environmental parameters
Authors: Kreuzwieser Jürgen , Harren Frans J. M. , Laarhoven Lucas J. J. , Boamfa Iulia , Te Lintel‐Hekkert Sacco , Scheerer Ursula , Hüglin Carmen , Rennenberg Heinz
Published: March 2003

The leaves of trees emit significant amounts of acetaldehyde which is synthesized there by the oxidation of ethanol. In the present study, we examined plant internal and environmental factors controlling the emission of acetaldehyde by the leaves of young poplar (Populus tremula×P. alba) trees. The enzymes possibly involved in the oxidation of ethanol in the leaves of trees are catalase (CAT; EC 1.11.1.6) and alcohol dehydrogenase (ADH; EC 1.1.1.1), both expressed constitutively in the leaves of poplars. Inhibition of ADH in excised leaves caused a significant decrease of acetaldehyde emission accompanied by an increased ethanol emission. Since inhibition of CAT by aminotriazole did not affect acetaldehyde and ethanol emission, it is concluded that the oxidation of ethanol in the leaves is mediated by ADH rather than by CAT. Further studies indicated that aldehyde dehydrogenase (ALDH; EC 1.2.1.5) seems to be responsible for the oxidation of acetaldehyde. The present results demonstrate that acetaldehyde emission is clearly dependent on its production in the leaves as controlled by the delivery of ethanol to the leaves via the transpiration stream. Environmental factors that control stomatal conductance seem to be of less importance for acetaldehyde emission by the leaves.
Regulation of genes encoding β‐d‐glucan glucohydrolases in barley (Hordeum vulgare)
Authors: Harvey Andrew J. , Hrmova Maria , Fincher Geoffrey B.
Published: March 2003

Expression patterns of barley β‐d‐glucan glucohydrolase genes were monitored using cDNAs encoding isoenzymes ExoI and ExoII. The cDNAs were isolated from 5‐day‐old seedling libraries. The enzymes are encoded by a small gene family, in which marked differences in codon usage are evident. The cDNAs can be used as specific probes for two subfamilies of β‐d‐glucan glucohydrolase genes. Genes of both subfamilies are transcribed in the scutellum of germinated grain, in elongating coleoptiles, and in young roots and leaves. Low levels of mRNA for the isoenzyme ExoI gene subfamily could be detected in aleurone layers of germinated grain. Most of the β‐d‐glucan glucohydrolase activity can be extracted from tissues with dilute aqueous buffers. Enzyme activity is highest in young leaves and elongating coleoptiles, but is not well‐correlated with mRNA levels. The expression patterns are consistent with proposed roles for β‐glucan glucohydrolases in the turnover or modification of cell‐wall (1→3,1→4)‐β‐d‐glucans in elongating coleoptiles and in young vegetative tissues.