bluuebunny/crossref_metadata_2025 huggingface dataset:
An unusual case of fatal pulmonary allograft rejection
Authors: Mogayzel Peter J. , Wise Barbara V. , Yang Stephen C. , Zachary Andrea A. , Colombani Paul M.
Published: March 2003

Abstract:This case report describes an atypical form of acute pulmonary allograft rejection that was refractory to conventional therapy. The rejection manifested primarily as interstitial lymphocytic infiltrates with little perivascular involvement. Despite aggressive therapy the patient died within 7 months of transplant. The timely recognition and treatment of unusual forms of allograft rejection is vital in the management of pulmonary transplant patients.
Visceral Kaposi's sarcoma with intracranial metastasis: A rare complication of renal transplantation
Authors: Bahat Elif , Akman Sema , Karpuzoglu Gulten , Aktan Sukru , Ucar Tanju , Arslan A. Gokhan , Nenonen Nancy , Guven Ayfer Gur , Karpuzoglu Tuncer
Published: March 2003

Abstract:The incidence of Kaposi's sarcoma (KS) has increased in solid organ transplantation recipients. This type of KS tends to be aggressive, involving lymph nodes, mucosa and visceral organs in about half of patients, sometimes in the absence of skin lesions. Brain involvement of KS has rarely been reported. A 16‐yr‐old Turkish boy underwent renal transplantation from his mother. The immunosuppressive regimen included prednisolone, cyclosporin A and azathioprine. Fourteen months later the azathioprine was changed to cyclophosphamide (3 mg/kg/day) because of the development of a nephrotic syndrome. After 12 weeks, the cyclophosphamide was changed to mycophenolate mofetil (MMF) to control the nephrotic syndrome. At this time his serum creatinine level rose to 2.1 mg/dL. Polyclonal or monoclonal antibodies were never given. Multiple intra‐abdominal lymphadenopathy was detected on abdominal tomography at the 32nd month after renal transplantation. Kaposi's sarcoma was diagnosed via laparotomy and biopsy. He had a generalized tonic and clonic seizure and contrast enhanced cranial tomography showed two intracranial masses which had an abundant vascular component which caused a mild shift. One of the masses was removed via a burr‐hole with the aim of diagnosis and treatment of the shift. A pathologic examination of the intracranial lesion was also reported as Kaposi's sarcoma. Herpes virus‐8 DNA was detected by PCR in the intracranial lesion.
Allogeneic bone marrow transplantation for infantile globoid‐cell leukodystrophy (Krabbe's disease)
Authors: Caniglia Maurizio , Rana Ippolita , Pinto Rita Maria , Fariello Giuseppe , Caruso Roberta , Angioni Adriano , Dionisi Vici Carlo , Sabetta Gaetano , De Rossi Giulio
Published: March 2003

Abstract: A 4‐month‐old‐girl affected by early expression of Krabbe's disease was treated with allogeneic bone marrow transplantation (BMT). The stem cell donor was her heterozygous HLA‐identical mother. The central nervous system (CNS) involvement at diagnosis was evident, but minimal. After BMT the child presented a severe hypotonia and an acute tetraventricular hydrocephalus; she died 180 days after the BMT with progressive severe neurologic deterioration. Leukocyte galactocerebrosidase (GALC) activity was present at donor levels 20 days after BMT. Full donor chimerism was evident 18 days after BMT. This report confirms that in early onset ‘Krabbe's syndrome' if the diagnosis is delayed after the birth, the progression of the neurologic deterioration is not reversed by BMT. It is to be demonstrated if a very early hemopoietic stem cell transplantation during the first weeks of life, could be appropriate and efficacious.
Renal transplant outcomes in adolescents: A report of the North American Pediatric Renal Transplant Cooperative Study
Authors: Smith Jodi M. , Ho P. L. (M.) , McDonald Ruth A.
Published: March 2003

Abstract: Recipient age at transplant is an important predictor of outcome. The age most commonly associated with increased risk is infancy. An important, but less recognized, age group at high risk is the adolescent. We analyzed the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) database to determine the patient and graft outcomes of adolescents (13–17 yr of age) compared with younger children. The adolescent age group had a similar percentage patient survival rate compared to that of the younger age groups, except for the infants (0–1 yr), who had a dramatic drop‐off in the early post‐transplant period. Regarding the long‐term graft survival for living donor recipients, adolescents had the poorest percentage graft survival compared to the other age groups, including the infants (p < 0.001). Among cadaver donor recipients, the adolescent group had a significantly poorer graft survival than the 2–5 yr and 6–12 yr age groups (p < 0.001). Although the infants had the poorest graft survival (p < 0.001), after the sharp drop‐off in the immediate post‐transplant period the slope of their graft‐survival curve was similar to that of the 13–17 yr age group. The percentage of late acute rejection episodes among the 6–12 yr (26.0%) and 13–17 yr (22.2%) age groups was significantly higher than in the younger age groups (p < 0.001). The adolescents had relatively poor rejection reversal outcomes compared to the other age groups, with fewer complete rejection reversals and a greater number of partial reversals (p < 0.001). The increased risk of graft loss, late acute rejection, and incomplete rejection reversal observed in the adolescent age group demands further investigation. Lack of compliance with immunosuppression regimens may be an important contributory factor. Strategies to address the unique concerns of this high‐risk population will be essential to improve outcomes.
Living‐related liver transplantation for biliary atresia associated with polysplenia syndrome
Authors: Hasegawa Toshimichi , Kimura Takuya , Sasaki Takashi , Okada Akira
Published: March 2003

Abstract:This report describes a 1‐yr‐old boy with biliary atresia (BA) and polysplenia syndrome (PS) who underwent successful living‐related liver transplantation (LTx). At the time of initial hepatic portoenterostomy, he was noticed to have a preduodenal portal vein (PV), non‐rotation of the intestine, and polysplenia. Because he did not achieve good bile excretion, he underwent a living‐related LTx (using a left lateral segment from his mother) at the age of 14 months. Evaluation of the vascular anatomy was made by angiography, magnetic resonance imaging (MRI), computerized tomography (CT), and Doppler ultrasound. The PV was stenotic from the confluence of the superior mesenteric vein (SMV) and splenic vein (SpV) to the hepatic hilum. The retrohepatic inferior vena cava (IVC) was deficient cranially to the renal vein and was connected to the azygous vein. The supra‐hepatic IVC was detected below the diaphragm and was connected to three hepatic veins. The common hepatic artery (HA) originated from the superior mesenteric artery. At LTx, the PV was dissected to the level of confluence of the SMV and the SpV, from which the venous graft was interposed using the donor's ovarian vein. Three hepatic veins were plastied into one orifice, which was anastomosed to the graft's hepatic vein under the diaphragm. The graft vascularity and function has been good for 1 yr after LTx. In the present case, sufficient pre‐LTx evaluation of vascular anomalies seemed to help performance of the successful LTx.
The effects of shading on kaempferol content and leaf characteristics of five soybean lines
Authors: Buttery B. R. , Gaynor J. D. , Buzzell R. I. , MacTavish D. C. , Armstrong R. J.
Published: March 2003

Previous work has shown that the presence of kaempferol triglucoside (K9) in soybean (Glycine max L. Merr.) leaves is associated with reduced numbers of stomata, especially on the upper surface. In the present test, shade was imposed on soybean plants as a means of altering the level of K9, and thus testing the relationship between quantities of K9 and stomatal density. Five lines of soybean that differ in their complement of flavonol glycosides were grown in the field unshaded and also with a 64 and 80% reduction in daylight intensity. Samples of the second, sixth and tenth trifoliate leaves were taken at 34, 53 and 77 days after planting. Shade reduced the quantities of flavonoids on a per leaf and a per unit area basis. Shade had no effect on stomatal density in lines containing K9, but reduced stomatal density in lines lacking K9. We envisage two opposing effects of shade on stomatal density: a direct effect in which shade reduces numbers, and an indirect effect in which a decrease in K9 content allows an increase in stomatal density. The net effect of shade on lines containing K9 appears to be the maintenance of a constant stomatal density. The quantity of K9 was highly correlated with stomatal density within all treatment combinations, and with all treatments combined.
Targeting of proteins into chloroplasts
Authors: Keegstra Kenneth , Bruce Barry , Hurley Melissa , Li Hsou‐min , Perry Sharyn
Published: March 2003

Most chloroplastic proteins are synthesized in the cytoplasm and are transported to their proper location as a posttranslational event. In the present paper we briefly review some aspects of this transport process. Because chloroplasts contain six different locations, one interesting aspect of protein targeting into chloroplasts that we consider is how precursor proteins are targeted to these various locations. One step shared by many proteins is transport across the envelope membranes. Although this process has been well studied, the components of the apparatus that mediate this transport step are mostly unidentified. Strategies to identify components of this transport apparatus are considered.
An endogenous growth inhibitor, 3‐hydroxy‐β‐ionone. III. Its longitudinal gradients in the first internode of Phaseolus vulgaris
Authors: Kato‐Noguchi Hisashi
Published: March 2003

Dark‐grown, 10‐day‐old bean seedlings (Phaseolus vulgaris L. cv. Morocco) were transferred to continuous light, and the resulting changes in growth rate and concentration of 3‐hydroxy‐β‐ionone, an endogenous growth inhibitor, were monitored. The growth rate of the first internodes of the seedlings decreased rapidly and leveled off 20 h after onset of light. This plateau value was about 25% of the growth rate of the non‐irradiated control. The concentration of 3‐hydroxy‐β‐ionone in the internodes of the irradiated seedlings increased rapidly and reached a plateau value after 16 h. This increased level of the inhibitor was about 5 times the level in the non‐irradiated control. The changes in the levels of the inhibitor in the internodes reflected the light‐induced growth inhibition of the internodes. The longitudinal distribution of the growth inhibitor along the first internodes of the seedlings was closely correlated with the light‐induced growth inhibition of the corresponding region of the internodes. The present results suggest that the endogenous growth inhibitor 3‐hydroxy‐β‐ionone may play an important role in the inhibition by light of internode growth of bean seedlings.
Meta‐topolin, an alternative to benzyladenine in tissue culture?
Authors: Werbrouck Stefaan P. O. , Strnad Miroslav , Van Onckelen Henry A. , Debergh Pierre C.
Published: March 2003

The metabolism and the in vitro effects of the cytokinin N6‐(3‐hydroxybenzyl)adenine (meta‐topolin, mT) were compared with those of N6‐benzyladenine (BA), N6‐benzyl‐9‐(2‐tetrahydropyranyl)adenine (BPA) and N6‐benzyladenine‐9‐riboside ([9R]BA) in micropropagated Spathiphyllum floribundum Schott cv. Petite. In vitro, BA, BPA and [9R]BA were mainly converted into the stable derivative N6‐benzyladenine‐9‐glucoside ([9G]BA), located at the basal part of the plant. N6‐(3‐O‐β‐D‐glucopyranosyl)benzyladenine‐9‐riboside {(OG)[9R]mT} was the main derivative of mT. This new cytokinin‐O‐glucoside, which was present in all plant parts, was metabolized much faster than [9G]BA during acclimatization. The effect of BA and mT on in vitro shoot and root production and post vitro rooting was compared. Only mT combined a good shoot production with in vitro root formation. The plants that developed on medium with 10 µM or more mT rooted better during acclimatization than those developed on medium with equimolar concentrations of BA.
Sensing environmental temperature change through imbalances between energy supply and energy consumption: Redox state of photosystem II
Authors: Huner N. P. A. , Maxwell D. P. , Gray G. R. , Savitch L. V. , Krol M. , Ivanov A. G. , Falk S.
Published: March 2003

A basic requirement of all photosynthetic organisms is a balance between overall energy supply through temperature‐independent photochemical reactions and energy consumption through the temperature‐dependent biochemical reactions of photosynthetic electron transport and contiguous metabolic pathways. Since the turnover of photosystem II (PSII) reaction centers is a limiting step in the conversion of light energy into ATP and NADPH, any energy imbalance may be sensed through modulation of the redox state of PSII. This can be estimated in vivo by chlorophyll a fluorescence as changes in the redox state of PSII, or photosystem II excitation pressure, which reflects changes in the redox poise of intersystem electron transport carriers. Through comparisons of photosynthetic adjustment, we show that growth at low temperature mimics growth at high light. We conclude that terrestrial plants, green algae and cyanobacteria do not respond to changes in growth temperature or growth irradiance per se, but rather, respond to changes in the redox state of intersystem electron transport as reflected by changes in PSII excitation pressure, We suggest that this chloroplastic redox sensing mechanism may be an important component for sensing abiotic stresses in general. Thus, in addition to its role in energy transduction, the chloroplast may also be considered a primary sensor of environmental change through a redox sensing/signalling mechanism that acts synergistically with other signal transduction pathways to elicit the appropriate molecular and physiological responses.
Using firefly luciferase to identify the transition from transient to stable expression in bombarded wheat scutellar tissue
Authors: Lonsdale David M. , Lindup Suzanne , Moisan Lisa J. , Harvey Alison J.
Published: March 2003

Transformation of wheat by the biolistic procedure is unpredictable and inefficient. To gain insight into the fate of transgenes introduced into wheat scutellar tissue by particle bombardment, the expression of the firefly luciferase gene was followed using low‐light video imaging. Luciferase expression can be detected as early as 40 to 50 min after bombardment. After 48 h, the levels of transient expression in individual scutella fall rapidly, becoming undetectable 10 to 20 days later. Luciferase activity was observed to recover in a small percentage of the material and it was from this material that transformed plants, stably expressing luciferase, were recovered. We concluded that the calluses which recover luciferase expression are stably transformed and we have termed the transition period between transient and stable expression the transformation boundary. The percentage of scutella displaying luciferase activity, as measured at 30 days post‐bombardment, was judged a realistic measure of the efficiency of the transformation procedure. The results of our experiments suggest that the selection and regeneration of plants were not major factors contributing to the poor transformation efficiencies associated with biolistic transformation. The results demonstrate that luciferase can be used to assess rapidly and quantify the efficiency of the transformation procedure without the need to produce transformed plants. This will allow different procedures to be rapidly assessed and compared and should provide valuable insight into the conditions required to improve the efficiency of DNA integration and stable expression in species recalcitrant to transformation.
Shade‐tolerance as a predictor of responses to elevated CO2 in trees
Authors: Kerstiens Gerhard
Published: March 2003

Evidence from 10 studies comparing angiosperm trees and 5 studies comparing conifers of differing shade‐tolerance was analysed. The number of intraphyletic comparisons in which the more shade‐tolerant species showed the greater relative increase of biomass in elevated CO2 was significantly higher than would be expected by chance alone. It is suggested that more shade‐tolerant species are inherently better disposed, in terms of plant architecture and partitioning of biomass and nitrogen, to utilise resources (light, water, nutrients) that are potentially limiting in elevated CO2 and that these traits are responsible for the interaction between shade‐tolerance and CO2 concentration. Compared with less shade‐tolerant angiosperm trees, more shade‐tolerant angiosperm species generally have a lower leaf area ratio in ambient CO2 and show a smaller relative reduction in elevated CO2. Furthermore, leaf nitrogen content is usually lower in more shade‐tolerant angiosperm species and tends to be more strongly reduced by elevated CO2 in those species. Within angiosperm trees, more shade‐tolerant species showed a stronger stimulation of net leaf photosynthetic rate in most experiments, but this trend was not significant.
Iron, sulfur, and chlorophyll deficiencies: A need for an integrative approach in plant physiology
Authors: Imsande John
Published: March 2003

Green plants deficient in nitrogen, sulfur, or iron develop a similar yellow coloration. In each case, the yellow coloration is accompanied by a lowered chlorophyll concentration. This review attempts to collate some of the biochemical information concerning these three seemingly diverse nutritive deficiencies and bares a need for a more integrative approach to plant physiology. The biochemical and biological roles of nitrogen, sulfur and iron in living systems are examined, with emphasis on sulfur and iron. Mechanistically, iron and/or sulfur are highly reactive components of many enzymes. Indeed, iron and sulfur sometimes form Fe2S2, Fe3S4, or Fe4S4 clusters which are very active electron transfer agents. Recently, iron‐sulfur clusters have been reported to serve as sensors of oxidative stress, to couple photosynthesis with several metabolic pathways, to participate in the reduction of sulfite and nitrite, and to participate in regulation of gene expression. Thus, there are several mechanisms by which a deficiency of nitrogen, sulfur, or iron could produce the same low‐chlorophyll, yellow phenotype in plants. Unless the interactions and coordination of the various pathways connected to chlorophyll synthesis are elucidated, it is unlikely that we will select the quickest and most direct path to plant improvement.
Yellowing and photosynthetic decline of barley primary leaves in response to atmospheric CO2 enrichment
Authors: Sicher Richard C.
Published: March 2003

The photosynthetic response of barley (Hordeum vulgare L. cv. Brant) primary leaves was studied as a function of chlorosis induced by CO2 enrichment. Leaf yellowing, measured as changes of chlorophyll a and b, was more extensive in controlled environments at elevated (680 ± 17 µl l−1) than at ambient (380 ± 21 µl l−1) CO2. Stomatal conductance of primary leaves was decreased by growth in elevated CO2 between 11 and 18 days after sowing (DAS) when measured at both 380 and 680 µl l−1 CO2. Internal leaf CO2 concentration (Ci) was also lower for elevated‐ compared to ambient‐CO2‐grown primary leaves between 11 and 14 DAS. Results suggest that non‐stomatal factors were responsible for the decreased photosynthetic rates of elevated‐ compared to ambient‐CO2‐grown primary leaves 18 DAS. Various photochemical measurements, including quantum absorptance (α), minimal (F0), maximal (Fm), and variable (Fv) chlorophyll fluorescence, as well as the Fv/Fm ratio, were significantly decreased 18 DAS in the elevated‐ compared to ambient‐CO2 treatment. Photochemical (qP) and nonphotochemical (qN) chlorophyll fluorescence quenching coefficients of 18‐day‐old primary leaves did not differ between CO2 treatments. Photosynthetic electron transport rates of photosystem II were slightly lower for elevated‐ compared to ambient‐CO2‐grown primary leaves 18 DAS. Concentrations of α‐amino N (i.e. free amino acids) in barley primary leaves were increased by CO2 enrichment 10 DAS, but subsequently, α‐amino N decreased in association with photosynthetic decline. Total acid protease activity was greater in elevated‐ than in ambient‐CO2‐grown leaves 18 DAS. The above findings suggest that photoinhibition and premature senescence were factors in the CO2‐dependent yellowing of barley primary leaves.
Characteristics of Fe‐deficiency‐induced acidification in subterranean clover
Authors: Wei L. C. , Loeppert R. H. , Ocumpaugh W. R
Published: March 2003

Iron‐deficiency‐induced acidification is one of the important reactions of plant Fe‐deficiency‐stress response, but the overall understanding of this reaction is limited. The characteristics of Fe‐deficiency‐induced acidification of subterranean clover (subclover) (Trifolium brachycalycinum Katzn. and Morley cv. Koala) were studied in this paper. Plants were grown hydroponically under ‐Fe conditions, and Fe‐deficiency‐induced acidification was determined using pH‐stat, back‐titration and chemical equilibrium procedures. Fe‐deficiency‐induced acidification was undetectable during the first day after Fe‐deficiency stress initiation, but the maximum acidification rate was attained by the second day, when plants exhibited visual chlorosis symptoms. The acidification rate was relatively constant with increasing Fe‐deficiency chlorosis, suggesting that a critical level of Fe deficiency was needed to trigger acidification, but that once the acidification process was initiated, the intensity of acidification was independent of severity of Fe deficiency. Net H+‐release (PR) rate determined using a chemical equilibrium method and net acidity release (AR) rate determined using a back‐titration method were practically identical, indicating that Fe‐deficiency‐induced acidification involved almost entirely the release of free H+, not organic acid. In the assay temperature range of 5 to 35°C, PR rate was highest at about 20°C. Net acidity release rate was almost totally inhibited at pH values ≤4.5 and increased with increasing assay pH up to pH 9. The pH effect occurred within 30 min of incubation initiation, implying that the effect of pH is probably on the activity of H+ transport through the plasma membrane, not on the quantity of responsible protein(s). Cations were required in the incubation solution for Fe‐deficiency‐induced acidification. Divalent cations in the assay solution resulted in a higher AR rate than monovalent cations, and essential cations resulted in a higher AR rate than non‐essential cations, indicating that the relative effectiveness of cations is related to the efficiency of their absorption by plant roots. These results are discussed in relation to their practical significance and the mechanisms of Fe‐deficiency‐induced acidification.
Sucrose‐cleaving enzymes and carbohydrate pools in Lilium longiflorum floral organs
Authors: Ranwala Anil P. , Miller William B.
Published: March 2003

The activities of soluble invertase (EC 3.2.1.26), cell wall invertase (EC 3.2.1.26) and sucrose synthase (EC 2.4.1.13) were determined in Easter lily (Lilium longiflorum Thunb. cv. Nellie White) floral organs during flower development. These enzyme activities were correlated with dry weight gains and carbohydrate pools to investigate the importance of their expression in maintaining sink strength of floral organs. In the early stages of flower bud development, anthers exhibited the highest rates of dry weight gain and activity of sucrolytic enzymes. Once anther growth was completed, the dry weight gain of tepal, filament, stigma and style increased with a concomitant increase in hexose concentrations and invertase activity. Although all three enzymes capable of catalyzing sucrose cleavage were present in every flower organ of L. longiflorum, soluble invertase was the predominant enzyme in all flower organs except stigma where cell wall invertase dominated. Soluble invertase activity was highly correlated with dry weight gain in most of the flower organs.
Changes in photosystem II function during senescence of wheat leaves
Authors: Lu Congming , Zhang Jianhua
Published: March 2003

Analyses of chlorophyll fluorescence were undertaken to investigate the alterations in photosystem II (PSII) function during senescence of wheat (Triticum aestivum L. cv. Shannong 229) leaves. Senescence resulted in a decrease in the apparent quantum yield of photosynthesis and the maximal CO2 assimilation capacity. Analyses of fluorescence quenching under steady‐state photosynthesis showed that senescence also resulted in a significant decrease in the efficiency of excitation energy capture by open PSII reaction centers (F'v/F'm) but only a slight decrease in the maximum efficiency of PSII photochemistry (F'v/F'm). At the same time, a significant increase in non‐photochemical quenching (qN) and a considerable decrease in photochemical quenching (qP) were observed in senescing leaves. Rapid fluorescence induction kinetics indicated a decrease in the rate of QA reduction and an increase in the proportion of QB‐non‐reducing PSII reaction during senescence. The decrease in both F'v/F'm and qP explained the decrease in the actual quantum yield of PSII electron transport ((φPSII). We suggest that the modifications in PSII function, which led to the down‐regulation of photosynthetic electron transport, would be in concert with the lower demand for ATP and NADPH in the Calvin cycle which is often inhibited in senescing leaves.
Interactive effects of ozone and low UV‐B radiation on antioxidants in spruce (Picea abies) and pine (Pinus sylvestris) needles
Authors: Baumbusch Lars O. , Eiblmeier Monika , Schnitzler Jörg‐Peter , Heller Werner , Sandermann, Jr Heinrich , Polle Andrea
Published: March 2003

To study the role of low UV‐B radiation in modulating the response of antioxidants to ozone, 4‐year‐old pine (Pinus sylvestris L.) and spruce (Picea abies L.) seedlings potted in natural soil, were exposed in phytochambers to fluctuating ozone concentrations between 9 and 113 nl 1−1 according to field data recorded at Mt Wank (1175 m above sea level, Bavaria, Germany) and two‐times ambient O3 levels. UV‐B radiation was either added at a biologically effective level of ca 1.2 kJ m−2 day−1 , which is close to that found in March at Mt Wank, or was excluded by filters (<0.08 kJ m−2 day−1). After one growth phase current‐year needles were collected and analysed for antioxidative enzyme activities (superoxide dismutase, SOD, EC 1.15.1.1; catalase, CAT, EC 1.11.1.6; guaiacol peroxidase, POD, EC 1.11.1.7) and soluble antioxidants (ascorbate, glutathione). CAT, POD, ascorbate and glutathione, but not SOD, were increased in needles of both species in response to twice ambient O3 levels. UV‐B radiation in the presence of ambient O3 caused an increase in total SOD activity in spruce but had no effects on antioxidants in pine. Twice ambient O3 levels together with low UV‐B radiation counteracted the O3‐induced increases in ascorbate and CAT in pine but not in spruce. Under these conditions spruce needles showed the highest antioxidative protection and revealed no indication of lipid peroxidation. Pine needles exposed to UV‐B and elevated O3 levels showed elevated lipid peroxidation and a 5‐fold increase in dehydroascorbate, suggesting that this species was less protected and suffered higher oxidative stress than spruce.
The role of mitochondrial electron transport during photosynthetic induction. A study with barley (Hordeum vulgare) protoplasts incubated with rotenone and oligomycin
Authors: Igamberdiev Abir U. , Hurry Vaughan , Krömer Silke , Gardeström Per
Published: March 2003

Mitochondrial contribution to photosynthetic metabolism during photosynthetic induction was investigated in protoplasts from barley leaves (Hordeum vulgare L. cv. Gunilla, Svalöf) by using an inhibitor of mitochondrial Complex I (rotenone) and an inhibitor of the mitochondrial ATPase (oligomycin). Both inhibitors increased the lag phase of photosynthetic induction after the transition of protoplasts from darkness to light. This effect was not observed with broken protoplasts or isolated chloroplasts. Using the method of rapid fractionation of protoplasts it was shown that the delay in photosynthetic induction was accompanied by a decrease in ATP/ADP ratios of the cytosol and mitochondria, whereas the ratio in chloroplasts was not affected. A delay in activation of chloroplastidic NADP‐dependent malate dehydrogenase (EC 1.1.1.82) was observed in the presence of either inhibitor. A delay was also observed in the rise of photochemical quenching of chlorophyll fluorescence in the presence of rotenone or oligomycin during photosynthetic induction. The results indicate that during the transition from dark to light the mitochondrial electron transport chain and its Complex I participate in the reoxidation of excessive redox equivalents from photosynthetic electron transport.
Low soil temperatures induce water deficits in olive (Olea europaea) trees
Authors: Pavel E. W. , Fereres E.
Published: March 2003

Olive trees are often subjected to low temperatures during winter. To quantify the effects of low temperatures on the water relations of olive trees, we studied the responses to low soil temperatures on winter days of variable evaporative demand (ET0) in 1‐year‐old potted olive (Oleo europaea L. cv. Picual) trees in 1996 and 1997. Low night (2.5 and 5.2°C) but ambient day soil temperatures (above 10°C) did not affect stomatal conductance (gs), leaf (Ψleaf) and stem (Ψstem) water potentials. Soil temperature levels inducing water stress in olive trees were determined for winter days with ET0 typical for southern Spain (ET0= 1.5 ± 0.3 mm day−1). Leaf and stem water potential decreased and root hydraulic resistance (rroot) increased when trees were exposed to night and day soil temperatures below 10°C. Stomatal conductance was not affected at soil temperatures between 6.4 and 10°C, but decreased at temperatures below 6.4°C. The soil temperature levels affecting the water uptake of olive trees remained relatively constant over the range of ET0 of 1‐2 mm day−1 during winter and early spring months. However, the soil temperature influencing gs appeared to be more variable and was affected by ET0. Olive tree recovery from low soil temperature stress depended on stress duration and severity and interacted with ET0. Recovery of ψ started already during the stress period, probably induced by stomatal closure and high rroot, thus allowing tree rehydration overnight. Root hydraulic resistance contributed the major part of whole‐tree hydraulic resistance in response to cold stress, accounting for 76 and 89% at 6.4 and 4.6°C, respectively; which indicates that rroot is the primary control of the water status in olive trees under low temperatures.
Thylakoid‐bound and stromal antioxidative enzymes in wheat treated with excess copper
Authors: Navari‐Izzo Flavia , Quartacci Mike F. , Pinzino Calogero , Vecchia Francesca Dalla , Sgherri Cristina L. M.
Published: March 2003

Copper is a catalyst in the formation of reactive free radicals and its toxicity may be due, at least in part, to oxidative damage. The response of thylakoid‐bound and stromal antioxidative enzymes against the generation of superoxide radical was investigated in seedlings of wheat (Triticum durum L. cv. Adamello) grown in hydroponic culture for 10 days and subjected to 10 and 50 µM copper treatments. Electron spin resonance of roots evidenced a spectrum of copper, the intensity of which increased with the treatment, whereas the carbon‐centered free radical spectrum detected in the control leaves was not seen anymore in the treated samples. As well as thylakoids, photosystem II (PSII) particles were able to produce the superoxide radical. Increased superoxide production both by thylakoids and PSII was observed in the sample treated with 50 µM Cu. Induction of thylakoid‐bound and stromal antioxidative enzymes, with the exception of dehydroascorbate reductase, was also detected in leaves treated with the highest copper concentration. No Mn‐superoxide dismutase (SOD, EC 1.15.1.1) was detected in thylakoids of wheat. Both stromal and thylakoid‐bound SOD were CuZn‐SOD with 16.2‐kDa subunits. Both western blotting and immuno‐electron microscopy showed that the SOD subunit was recognized by a polyclonal antibody against glyoxisomal CuZn‐SOD from watermelon cotyledon. In the stroma of wheat, ascorbate peroxidase showed at least three well‐resolved bands differently induced by copper treatments.
Activated oxygen‐mediated metabolic functions of leaf peroxisomes
Authors: Del Río Luis A. , Sandalio Luisa M. , Corpas Francisco J. , López‐Huertas Eduardo , Palma José M. , Pastori Gabriela M.
Published: March 2003

Peroxisomes are subcellular organelles with an essentially oxidative type of metabolism. The presence in these organelles of superoxide dismutases and the generation of superoxide radicals (O2•−) was first demonstrated in plant tissues and in recent years different experimental evidence has suggested the existence of cellular functions related to activated oxygen species. Some of these functions are analyzed in this work.

In purified intact peroxisomes from pea (Pisum sativum L.) leaves, xanthine oxidase and urate oxidase were found to be present. The occurrence and the level of the metabolites xanthine, hypoxanthine, uric acid, and allantoin were studied in extracts of pea leaf peroxisomes by HPLC. Xanthine, uric acid, and allantoin were detected in peroxisomes. These results suggest a cellular role for leaf peroxisomes in the catabolism of purines.

In peroxisomal membranes, 3 polypeptides (PMPs) with molecular masses of 18, 29 and 32 kDa, respectively, have been shown to generate superoxide radicals. These PMPs were purified from pea leaf peroxisomal membranes and characterized. While the 18‐ and 32‐kDa PMPs use NADH as electron donor for O2•− production, the 29‐kDa PMP was clearly dependent on NADPH.

Very recently, the occurrence in pea leaf peroxisomes of all the enzymes of the ascorbate‐glutathione cycle has been demonstrated. NADPH is required for the glutathione reductase activity of the cycle and this implies the reduction of NADP+ to NADPH. This recycling function could be carried out by the NADP‐dependent glucose‐6‐phosphate dehydrogenase (G6PDH), 6‐phosphogluconate dehydrogenase (6PGDH), and isocitrate dehydrogenase (ICDH). These 3 dehydrogenases have been demonstrated to be present in the matrix of pea leaf peroxisomes.

The catabolism of purines, the superoxide‐generating PMPs, the ascorbate‐glutathione cycle, and the dehydrogenase‐mediated recycling of NADPH, are activated oxygen roles of leaf peroxisomes that add to other functions previously known for peroxisomes from eukaryotic cells.
Zeaxanthin and non‐photochemical quenching in sun and shade leaves of C3 and C4 plants
Authors: Brugnoli Enrico , Scartazza Andrea , De Tullio Mario Carmelo , Monteverdi Maria Cristina , Lauteri Marco , Augusti Angela
Published: March 2003

The relationships between non‐radiative energy dissipation and the carotenoid content, especially the xanthophyll cycle components, were studied in sun and shade leaves of several plants possessing C3 (Hedera helix and Laurus nobilis) or C4 (Zea mays and Sorghum bicolor) photosynthetic pathways. Sun‐shade acclimation caused marked changes in the organisation and function of photosynthetic apparatus, including significant variation in carotenoid content and composition. The contents of zanthophyll cycle pigments were higher in sun than in shade leaves in all species, but this difference was considerably greater in C3 than in C4 plants. The proportion of photoconvertible violaxanthin, that is the amount of violaxanthin (V) which can actually be de‐epoxidised to zeaxanthin, was much greater in sun than in shade leaves. The amount of photoconvertible V was always linearly dependent on the chlorophyll a/b ratio, although the slope of the relationship varied especially between C3 and C4 species. The leaf zeaxanthin and antheraxanthin contents were correlated with non‐radiative energy dissipation in all species under different light environments. These relationships were curvilinear and variable between sun and shade leaves and between C3 and C4 species. Hence, the dissipation of excess energy does not appear to be univocally dependent on zeaxanthin content and other photoprotective mechanisms may be involved under high irradiance stress. Such mechanisms appear largely variable between C3 and C4 species according to their photosynthetic characteristics.
Chlorophyll catabolism and gene expression in the peel of ripening banana fruits
Authors: Drury Rosybel , Hörtensteiner Stefan , Donnison Iain , Bird Colin R. , Seymour Graham B.
Published: March 2003

The biochemical and molecular basis of chlorophyll (Chl) catabolism in bananas was investigated during ripening at 20°C and at an elevated temperature (35°C) where degreening is inhibited. Biochemical analysis showed that Chl breakdown products could be isolated from fruit ripened at both temperatures. The coloured breakdown products, chlorophyllide and pheophorbide, were not detected at any stage of ripening in the two treatments; however, a non‐fluorescent Chl catabolite accumulated to a higher concentration at 20 than at 35°C. To investigate the ripening‐related gene expression associated with these changes, a cDNA library was generated from the peel of fruit ripened at 20°C. Differential screening of this library produced 20 non‐redundant families of clones including those encoding enzymes involved in ethylene biosynthesis, respiration, starch metabolism, cell wall degradation and other metabolic events. The expression of these genes was followed by northern analysis in fruit ripened at 20 and 35°C.
β‐1,3‐Glucanase isoenzymes and genes in resistant and susceptible pepper (Capsicum annuum) cultivars infected with Phytophthora capsici
Authors: Egea Catalina , Dickinson Matthew J. , Candela Milagros , Candela M. Emilia
Published: March 2003

Infection of pepper (Capsicum annuum) plants with Phytophthora capsici led to the accumulation of β‐1,3‐glucanases in the stem tissues soon after inoculation. After the appearance of the symptoms on the pepper stems, β‐1,3‐glucanase accumulation became much more pronounced in the resistant (Smith‐5 [S‐5]) than in the susceptible (Yolo Wonder [YW]) cultivar. β‐1,3‐Glucanase activity was also detected in the control stems (uninoculated) but only in the resistant cultivar. The direct detection of β‐1,3‐glucanase on polyacrylamide gels revealed a basic isoenzyme (Rf 0.18) in the intracellular fraction (INTRA‐F), which may be associated with the expression of resistance to P. capsici since its activity was detected only in the resistant cultivar. The fact that other basic isoenzymes (Rf 0.70 and 0.61 from the INTRA‐F and Rf 0.57 from the intercellular fraction) and one acidic isoenzyme (Rf 0.70 from the intercellular fraction) were detected in both cultivars suggests that these play a less important role in the development of resistance although they appeared earlier and at greater intensity in the resistant cultivar than in the susceptible one. Using degenerate primers and reverse‐transcriptase polymerase chain reaction (RT‐PCR), β‐1,3‐glucanase product of approximately 500 bp was obtained and cloned from cv. S‐5 total RNA. This was used as a probe on northern blots of RNA extracted from both cultivars at specific times after infection. One transcript, size 2.0 kb, was detected in both cultivars, and accumulated very close to the inoculation site between 1 and 3 days after inoculation, but to a greater extent in the resistant cultivar (S‐5) than in the susceptible cultivar (YW). These data suggest that an early and rapid accumulation of β‐1,3‐glucanase transcript is associated with the defence reaction that develops in pepper stems infected with P. capsici.
Effects of mechanical wounding, current application and heat treatment on chlorophyll fluorescence and pigment composition in tomato plants
Authors: Herde Oliver , Peña‐Cortés Hugo , Fuss Heidi , Willmitzer Lothar , Fisahn Joachim
Published: March 2003

Chlorophyll fluorescence quenching parameters and pigment content of wild‐type tomato plants (Lycopersicon esculentum Mill. cv. Moneymaker) were analyzed upon mechanical wounding, current application and heat treatment. Upon all stimuli the non‐photochemical quenching increased significantly in local and systemic tissue. Vice versa, the photochemical quenching decreased. Total chlorophyll content remained almost constant, zeaxanthin content increased 5–6‐fold, antheraxanthin content rose also, violaxanthin and neoxanthin on the other hand decreased significantly. These data indicate a similarity of processes on the level of photosynthesis and pigment composition that are induced by light‐stress and those induced by mechanical wounding, current application and heat treatment, which all lead to an inhibition of photosynthesis.
Hormonal cross‐talk regulates the Arabidopsis thaliana 1‐aminocyclopropane‐1‐carboxylate synthase gene 1 in a developmental and tissue‐dependent manner
Authors: Rodrigues‐Pousada Renato , Van Caeneghem Wim , Chauvaux Nancy , Van Onckelen Harry , Van Montagu Marc , Van Der Straeten Dominique
Published: March 2003

The Arabidopsis thaliana (L.) Heynh. 1‐aminocyclopropane‐1‐carboxylate synthase gene 1 (AT‐ACS1) was found to be developmentally regulated with pronounced activity in immature tissues. The effect of different hormones on this expression pattern was studied by using a transgenic line carrying the β‐glucuronidase (GUS) gene under control of the AT‐ACS1 promoter. In addition, the level of mRNA for AT‐ACS1 was assayed in different ethylene and auxin‐insensitive backgrounds, as well as in an auxin homeostasis mutant by using competitive reverse transcriptase polymerase chain reaction (RT‐PCR). The results support the existence of a hormonal cross‐talk involving auxin, cytokinin, and ethylene in the regulation of AT‐ACS1. These hormonal controls act in a developmental and tissue‐dependent manner.
Flavodoxin accumulation contributes to enhanced cyclic electron flow around photosystem I in salt‐stressed cells of Synechocystis sp. strain PCC 6803
Authors: Hagemann Martin , Jeanjean Robert , Fulda Sabine , Havaux Michel , Joset Francoise , Erdmann Norbert
Published: March 2003

The salt‐regulated accumulation of flavodoxin encoded by the isiB gene and its possible function were investigated in the cyanobacterium Synechocystis sp. strain PCC 6803. In Northern blot experiments, a slight increase of the isiB‐specific mRNA was observed in salt‐shocked and salt‐acclimated cells. High levels of flavodoxin protein were detected in cells acclimated to 342 mM NaCl. In order to analyze the function of flavodoxin in cyanobacterial salt acclimation, an insertion null mutant of isiB was constructed. It was possible to adapt this mutant to raised salt concentrations and, as expected, to low iron contents. Salt‐acclimated cells of wild type (WT) Synechocystis display increased activity of photosystem I (PSI), primarily used for increased cyclic electron transport capacity (Jeanjean et al. 1993, Plant Cell Physiol 34: 1073–1079). In salt‐acclimated cells of the flavodoxin null mutant, the level of cyclic electron flow was lower than in wild type cells. It was concluded that flavodoxin plays a role as an alternative electron carrier, used for cyclic electron flow in salt‐treated Synechocystis cells.
Role of hydrogen peroxide and different classes of antioxidants in the regulation of catalase and glutathione S‐transferase gene expression in maize (Zea mays L.)
Authors: Polidoros Alexios N. , Scandalios John G.
Published: March 2003

The role of hydrogen peroxide (H2O2) and various antioxidants in the regulation of expression of the three Cat and Gst1 genes of maize (Zea mays L.) has been investigated. Low concentrations of H2O2 appeared to inhibit Cat1, Cat3, and Gst1 gene expression, while higher doses strongly induced these genes. Time course experiments indicated that high concentrations of H2O2 induced Cat1, Cat2, and Gst1 gene expression to higher levels, and in less time, than lower H2O2 concentrations. Induction of Cat3 was superimposed on the circadian regulation of the gene. These results demonstrate a direct signaling action of H2O2 in the regulation of antioxidant gene responses in maize.The effects of the antioxidant compounds N‐acetylcysteine, pyrrolidine dithiocarbamate, hydroquinone, and the electrophile antioxidant responsive element (ARE)‐inducer β‐naphthoflavone were quite different and specific for each gene/compound/concentration combination examined. The response of each gene to each antioxidant compound tested was unique, suggesting that the ability of these compounds to affect expression of the maize Cat and Gst1 genes may not be the result of a common (antioxidant) mode of action. A putative regulatory ARE motif involved in the regulation of antioxidant and oxidative stress gene responses in mammalian systems is present in the promoter of all three maize catalase genes and we tested its ability to interact with nuclear extracts prepared from 10 days post‐imbibition senescing scutella. Protein‐DNA interactions in the ARE motif and the U2 snRNA homologous regions of the Cat1 promoter were observed, suggesting that ARE may play a role in the high induction of Cat1 in a tissue which, due to senescence, is under oxidative stress.
A comparison of Zn, Mn, Cd, and Ca transport mechanisms in oat root tonoplast vesicles
Authors: Gonzalez Alonso , Koren'Kov Victor , Wagner George J.
Published: March 2003

Oat root tonoplast vesicles were used to determine if tonoplast transport of the divalent cations Zn and Mn occurs via an antiport mechanism, like that described for Ca and Cd. Also, inhibitors reported to affect Ca transport were tested for their effects on Cd versus Ca transport and tonoplast ATPase activity. The ability of Ca, Cd, Zn, and Mn to alter the proton gradient was monitored using both the fluorescent probe acridine orange and C‐methylamine accumulation. After the proton gradient was established in MgATP‐energized vesicles, addition of Ca, Cd, and Zn to the reaction restored the fluorescence of acridine orange, indicating dissipation of the proton gradient. Fluorescence recovery was linearly correlated with metal concentration and followed the order Ca>Cd≧Zn. Addition of Mn did not restore the fluorescence of acridine orange. All four ions released C‐methylamine from MgATP‐energized vesicles in an ion‐concentration‐dependent manner, and with relative initial rates in the order of Ca>Cd>Zn>Mn. The observed ion‐concentration‐dependent release of protons from sealed vesicles suggests that Zn and Mn, like Ca and Cd, can be antiported into the plant vacuole. In an effort to assess whether Ca and Cd use the same carrier, we tested the effects of verapamil, Do‐Tea‐Br, nifedipine, ruthenium red, and LaCl2 on Ca versus Cd transport, and also on MgATPase activity. These compounds are shown to alter Ca transport in plants. Although some of the inhibitors had a negative effect on MgMAPase activity, the decrease in this activity did not account for the decrease in Ca or Cd transport observed in any case. Particularly verapamil had a much greater effect on Ca transport than Cd transport activity while not inhibiting ATPase substantially. Data presented provide evidence for Zn and Mn antiport activity in oat root tonoplast and show differences in responses of Ca and Cd antiport activities to several transport inhibitors.