bluuebunny/crossref_metadata_2025 huggingface dataset:
A fourth ADP/ATP carrier isoform in man: identification, bacterial expression, functional characterization and tissue distribution
Authors: Dolce Vincenza , Scarcia Pasquale , Iacopetta Domenico , Palmieri Ferdinando
Published: December 2004

The mitochondrial ADP/ATP carriers (AACs) catalyze the exchange of cytosolic ADP for matrix ATP. We have identified and characterized a novel member of the AAC subfamily of mitochondrial metabolite transport proteins, termed AAC4. The AAC4 gene maps to human chromosome 4q28.1, and its product AAC4 is 66–68% identical to human AAC 1–3 and is localized to mitochondria. AAC4 transcripts are exclusively present in liver, testis and brain unlike those of AAC 1–3. Consistent with its belonging to the AAC subfamily, upon heterologous expression and reconstitution into liposomes AAC4 exchanges ADP for ATP by an electrogenic antiport mechanism with high specificity and high sensitivity to carboxyatractyloside and bongkrekic acid.
Evidence of underplating from seismic and gravity studies in the Mahanadi delta of eastern India and its tectonic significance
Authors: Behera Laxmidhar , Sain Kalachand , Reddy P. R.
Published: December 2004

We have imaged the crustal configuration of the Mahanadi delta of eastern India by modeling both wide‐angle seismic and Bouguer gravity data. This delta has undergone several stages of rifting, subsidence, sedimentation, and uplift. It is one of the important Gondwana sedimentary basins of India where widespread volcanic activity occurred during the Early Cretaceous along the rift zones. This volcanic activity corresponds to the breakup of greater India from east Gondwana (e.g., present Antarctica and Australia). We have derived a five‐layer crustal model with velocities of 6.0, 6.5, 6.0, 7.0, and 7.5 km/s having estimated densities of 2.7, 2.8, 2.65, 2.9, and 3.05 g/cm3, respectively. The velocity‐density relation along with heat flux and other geological/geochronological information indicates typical rift‐related evolution of the delta with a midcrustal low‐velocity (6.0 km/s) and low‐density (2.65 g/cm3) zone and a ∼10 km thick high‐velocity (7.5 km/s) and high‐density (3.05 g/cm3) layer at the base of the crust, presumably due to underplating. The Moho upwarping or crustal thinning in the rift zone and emplacement of thick, high‐velocity material at the base of the crust strongly suggests basaltic underplating probably due to the Kerguelen hot spot activity. These activities are synchronous with ∼117 Ma Rajmahal volcanism in northeast India and the Lambert graben in East Antarctica and are closely associated with the Gondwana breakup in the India‐Antarctica sector. The rifting stages are closely correlated with the sedimentation phases of the lower and upper Gondwana deposits in the Mahanadi delta, which evolved parallel to the Lambert graben in East Antarctica.
Limiting diameter of pancake ice
Authors: Shen Hayley H. , Ackley Stephen F. , Yuan Yong
Published: December 2004

Two mechanisms have been hypothesized to limit the diameter of pancake ice, one due to bending failure and the other due to tensile failure. We conducted two series of laboratory experiments to monitor pancake ice growth from an open water condition in indoor wave tanks. One used urea doped water and the other used salt water with concentration similar to ocean conditions. The final size of the pancakes and the wave conditions are reported here. The laboratory data suggest that in the growth stage, pancake ice floe diameter is limited by tensile failure, in contrast to the bending failure control of floe diameter in ice breakup by waves. The final diameter of the pancake floes is proportional to the wavelength. The proportionality is controlled by wave amplitude and freezing conditions. For wave amplitude A, the proportionality obtained from data agrees closely with the tensile failure theoretical prediction of 1/A0.5.
Strain rate and temperature dependence of Omori law scaling constants of AE data: Implications for earthquake foreshock‐aftershock sequences
Authors: Ojala Ira O. , Main Ian G. , Ngwenya Bryne T.
Published: December 2004

Little is known about the temperature and strain rate dependence of acoustic emission AE activity (AE). Hence, we carried out a preliminary series of flow‐through triaxial compression tests on porous sandstones at different temperatures and strain rates. The AE data exhibits clear foreshock and aftershock sequences with respect to the dynamic failure of the test specimen. Significant AE activity starts less than 5 min before sample failure irrespective of the strain rate. The increase in the AE event rate is steeper and the foreshock exponent p′ is smaller in the slow strain rate tests. It could be the reason why there are no easily recognisable foreshock sequences for most individual earthquakes. The aftershock decay parameter p is a linear function of test temperature as it has also been inferred for natural seismicity. The seismic b‐value decreases systematically with increasing deformation rate suggesting a greater proportion of small cracks in the slow strain rate tests. Hence, the AE activity is a function of both strain rate and temperature.
Dedolomitization and flow in fractures
Authors: Singurindy Olga , Berkowitz Brian
Published: December 2004

An experimental study was carried out to examine the evolution of flow patterns in both time and space under different flow regimes, caused by incongruent dissolution of fractured dolomite. Analysis of oscillatory behavior of the overall hydraulic conductivity was based on the fluid residence time, which influences strongly aragonite and calcite precipitation in fractured dolomite rocks. The results are in accordance with field observations.
Advancements of Global Navigation Satellite System radio occultation retrieval in the upper stratosphere for optimal climate monitoring utility
Authors: Gobiet A. , Kirchengast G.
Published: December 2004

Global Navigation Satellite System–based radio occultation (RO) measurements promise to become a valuable observational basis for climate research, numerical weather prediction, and atmospheric process studies, thanks to their unique combination of global coverage, high accuracy and vertical resolution, and long‐term stability. Concerning the quality of the RO‐derived atmospheric profiles, performance simulation studies and first data analysis results from the current CHAMP satellite mission are encouraging but also reveal weaknesses of present RO retrieval chains at high altitudes (above 30 km). This study aims at providing, first, understanding of these weaknesses and, second, mitigation by an advanced retrieval scheme. We first evaluated present state‐of‐the‐art high‐altitude RO retrieval algorithms. We found clear superiority for using statistical optimization involving background information over using exponential extrapolation and a sensitivity of RO retrieval products to biases in background information calling for sensible bias mitigation. Exploiting these findings, an advanced high‐altitude retrieval scheme is presented, which focuses on minimizing residual retrieval biases in the upper stratosphere and thereby on optimizing the climate monitoring utility of retrieved profiles. Applied to a large ensemble of simulated occultation events, the advanced scheme proved to be effective. The scheme is currently under evaluation with real data from the CHAMP mission. It will then serve as part of a processing chain generating RO‐based global climatologies of refractivity, geopotential height, temperature, and humidity based on RO data from CHAMP, SAC‐C, GRACE and other future satellites carrying RO instruments.
A simulated soil moisture based drought analysis for the United States
Authors: Sheffield Justin , Goteti Gopi , Wen Fenghua , Wood Eric F.
Published: December 2004

Droughts have severe economic, environmental and social impacts. Timely determination of the current level of drought may aid the decision making process in reducing the impacts from drought. In this study, high‐resolution, land surface hydrology simulations using the Variable Infiltration Capacity (VIC) model are used to derive a hydrologically based drought index. Soil moisture data from a retrospective simulation from 1950 to 1999 over the continental United States are used to develop probability distributions of monthly average soil moisture, and the relative position of soil moisture fields within the historic distribution provides a measure of drought in relation to the long‐term behavior. The index is able to identify the major drought events during the latter part of the twentieth century and shows good agreement with the time series of U.S. drought from two Palmer Drought Severity Index (PDSI) data sets. On average, 30% of the United States experienced dry conditions (<10% soil moisture quantile) during 1950–1999, peaking at over 70% coverage at the height of the 1950s drought. Many dry events exhibit long‐term persistence, especially in the West, which is important in terms of the cumulative impacts. The physical basis of the model allows the index to take into account a number of processes, which contribute to the development of drought, such as snow accumulation and melt that other indices ignore or treat unsatisfactorily. Furthermore, the high spatial and temporal resolution of the simulations ensure that the drought index is able to allow for the effects of short‐term changes in meteorology as well as longer‐term climate variations, and resolve the high spatial variability in soil moisture and drought occurrence. The potential for implementing the analysis in an operational mode exists by using data from the near real‐time simulations within the North American Land Data Assimilation System (NLDAS).
Soluble E‐selectin and soluble ICAM‐1 levels as markers of the activity of atopic dermatitis in children
Authors: Wolkerstorfer Albert , Savelkoul Huub F. J. , De Waard van der Spek Flora B. , Neijens Herman J. , Meurs Tim van , Oranje Arnold P.
Published: December 2004

The expression of adhesion molecules is up‐regulated in the skin of atopic dermatitis (AD) patients, and the levels of the soluble adhesion molecules sE‐selectin and sICAM‐1 have been reported to reflect the endothelial activation in the skin of AD patients. The objective of the study was to investigate the relationship between symptom score and levels of sE‐selectin, sICAM‐1 and sVCAM‐1 before and after 2 weeks of treatment. Eighteen children with an exacerbation of AD were admitted and treated with corticosteroid dilutions under occlusive wet dressings (wet‐wrap treatment). Symptom score (objective SCORAD) and levels of sE‐selectin, sICAM‐1, and sVCAM‐1 were assessed before and after 2 weeks of treatment. A significant correlation between the objective SCORAD before treatment and the level of sE‐selectin (p < 0.05), but not the level of sICAM‐1 (p = 0.7) or sVCAM‐1 (p = 0.5) was observed. The treatment resulted in a high degree of remission, which was reflected by a significant decrease in the level of sICAM‐1 (p < 0.01), whereas there was only a trend in the level of sE‐selectin to decrease (p = 0.08). The level of sE‐selectin after 2 weeks of treatment still correlated significantly with the objective SCORAD before treatment (p < 0.005). Soluble E‐selectin is a relative objective marker for the severity of AD. SCORAD is a treatment‐sensitive symptom of AD, whereas E‐selectin may be a more stable underlying systemic representation of AD.
Mold‐specific immunoglobulin G antibodies in a child population
Authors: Korppi Matti , Laitinen Sirpa , Taskinen Taina , Reiman Marjut , Nevalainen Aino , Husman Tuula
Published: December 2004

The determination of immunoglobulin G (IgG) antibodies to molds has been used as an objective evidence of significant mold exposure. Until present, no data have been published on antibody responses to molds in healthy children living in normal housing conditions. The microbe‐specific IgG antibody concentrations of 21 molds and 3 actinobacteria were determined by enzyme‐linked immunosorbent assay (ELISA) in 103 1‐ to 6‐year‐old children (12.4% of the population of that age), and in 111 7‐ to 14‐year‐old school children (12.1%). The international standard sera were available, and the IgG concentrations of the test sera could be expressed in mg/l. On average, IgG concentrations increased in relation to age until the age of 6–7 years. At school age the increase still continued but more slowly. Actinobacteria were the only exceptions; all three tested strains Sreptomyces albus, S. griseus and S. halstedii resulted in rather high concentrations until 3 years of age. If the children lived in a farm, mold‐specific IgG concentrations increased at an earlier age than in other children. The results between farmers' children and other children differed significantly before school age for 20 of the 24 microbes tested, the four exceptions being the 3 actinobacteria and the mold Aspergillus versicolor. The reference values must be age related, and separate references are needed for farmers' children before school age.
Allergen‐induced cytokine secretion in atopic and non‐atopic asthmatic children
Authors: Böttcher Malin F. , Bjurström Jenny , Mai Xiao‐Mei , Nilsson Lennart , Jenmalm Maria C.
Published: December 2004

Atopic asthma is characterized by excessive T helper 2 (Th2)‐like immunity to allergens in the bronchial mucosa. The Th2‐cytokine interleukin (IL)‐4 induces IgE production, while the Th2‐cytokine IL‐5 promotes eosinophilic inflammation in the airways of asthmatics. Most asthmatics are atopic, but a subgroup is non‐atopic. We hypothesize that allergen‐induced Th2, particularly IL‐5, responses can be observed in peripheral blood in both atopic and non‐atopic asthmatic children but not in healthy control children. The aim of the present study was to determine IL‐4, IL‐5, IL‐9, IL‐10, IL‐13 and IFN‐γ secretion induced from peripheral blood mononuclear cells (PBMC) by a broad panel of inhalant allergens (timothy, cat, birch, dog and house dust mite) in asthmatic children with and without sensitization. The study included 13 atopic asthmatic, 5 non‐atopic asthmatic, and 12 non‐atopic non‐asthmatic children. PBMC were stimulated with allergens and cytokine production was measured with enzyme‐linked immunosorbent assay (ELISA). Higher levels of cat and dog antigen‐induced IL‐5 release were more commonly observed in both atopic and non‐atopic asthmatics than in controls. Children with atopic, but not non‐atopic, asthma produced higher levels of allergen‐induced IL‐4 and IL‐9 than controls. Non‐atopic asthmatics produced more IL‐10 than atopic asthmatics after cat stimulation. High levels of eosinophilia‐associated IL‐5 responses are induced by cat and dog allergen in both atopic and non‐atopic asthmatic children. The Th2 cytokines IL‐4 and IL‐9 were associated only with atopic asthma, probably due to their IgE‐inducing properties.
Epstein–Barr virus‐related post‐transplant lymphoproliferative disease in solid organ transplant recipients, 1988–97: A Canadian multi‐centre experience
Authors: Allen Upton , Hebert Diane , Moore Dorothy , Dror Yigal , Wasfy Samia ,   the Canadian PTLD Survey Group – 1998
Published: December 2004

Abstract: The aim of this work was to obtain information on the magnitude of the problem, disease characteristics, and clinical practices relating to post‐transplant lymphoproliferative disease (PTLD) in Canadian institutions. Adult and pediatric Canadian solid organ transplant groups were sent a questionnaire between July and October 1998. Analyzable data were obtained from 33 transplant groups. For the period 1988–97, 90 cases of PTLD were seen among 4283 solid organ transplant recipients. The incidence of PTLD varied from 0 to 14.6%, with the highest rates in children. Lymph nodes were the sites most frequently affected. Among the classifiable lesions, the majority were monoclonal. The lesions were of B‐cell origin in 42.2% and of T‐cell in 15.6%. The lesions were classified as monomorphic in 31.1%, polymorphic 18.9%, and hyperplastic in 1.1%. Tumors were reported as low grade in 26.7% and high grade in 10%. The majority of patients (71.1%) received reduced immunosuppression. Anti‐viral agents were used in 52.2%. Chemotherapy was used in 27.8%, while immune globulin was used in 22.2%. Surgical resection was used in 20.0%, radiotherapy in 14.4%, and interferon‐α therapy in 12.2%. The results showed that 48.9% of the patients had died, while 25.6% and 8.9% were regarded as having complete remission and partial remission, respectively. In conclusion, the incidence of PTLD varies widely across Canadian centres. Children are disproportionately affected and the mortality rate is high. Management practices vary significantly, and the need for information sharing was identified as one way of optimizing management.
Clinical approach to graft hepatic artery thrombosis following living related liver transplantation
Authors: Dalgic Aydin , Dalgic Buket , Demirogullari Billur , Ozbay Ferda , Latifoglu Osman , Ersoy Emin , Ahmet Mahli  , Ilgit Erhan , Ozdemir Hakan , Arac Mehmet , Akyol Gulen , Tatlicioglu Ertan
Published: December 2004

Abstract: Hepatic artery thrombosis (HAT) has an occurrence rate of 1.7–26% following living donor liver transplantation (LDLT) and is one of the most common reasons for graft loss and mortality in this population. There is a higher incidence of HAT in pediatric recipients. The aim of this case report is to discuss clinical approaches for the treatment of HAT occurring in the early post‐operative period after LDLT. An 11‐month‐old, 7.8‐kg female with cirrhosis secondary to biliary atresia underwent LDLT at Gazi University Hospital in Ankara. The graft was a left lateral segment from her father with a left hepatic artery (HA) of 2 mm diameter and a graft weight/recipient body weight ratio of 2.0%. After an uneventful early post‐operative period, HAT was diagnosed by Doppler ultrasonography (USG) on the fifth post‐operative day. Following angiographic evaluation, immediate exploration and reanastomosis was performed using an operation microscope. Post‐operatively, the HA was patented by Doppler USG and graft function returned to normal. Now, 42 months later, the patient continues to do well with normal graft function, using a regimen of tacrolimus monotherapy for immunosuppression. In countries which have very limited resources for urgent re‐transplantation, given their serious donor shortage, graft salvage may be the only option for patient survival when HAT occurs. In these circumstances, early diagnosis and immediate revascularization may be the only method for graft salvage. A daily routine of Doppler USG examination in the early post‐operative period may provide a method for the early diagnosis of HAT, before liver enzymes are elevated and hepatic necrosis has begun.
The effect of aprotinin on transfusion requirements in pediatric orthotopic liver transplantation
Authors: Rentoul Toni M. , Harrison Victor L. , Shun Albert
Published: December 2004

Abstract: The use of aprotinin to reduce blood loss by inhibiting fibrinolysis thereby decreasing transfusion requirements during orthotopic liver transplantation (OLT), is well‐documented in adults. We set out to test the hypothesis that the prophylactic use of aprotinin reduced blood product requirements during pediatric OLT.

A retrospective study was performed, reviewing data from 24 OLTs performed over a 4‐yr period. Six patients did not receive aprotinin (group 1), while 18 (group 2) received a weight‐based dose of aprotinin. Both groups were comparable with respect to demographics, baseline characteristics and surgical variables except for a significantly more prolonged activated partial thromboplastin time (APTT) in the aprotinin group (p = 0.015). Despite the fact that median values for transfused volumes of red blood cells (78.3 vs. 36.7 mL/kg) and fresh frozen plasma (51.9 vs. 23.7 mL/kg) were more than halved in the aprotinin group, there was no statistical difference demonstrated. The failure to reach statistical significance can probably be explained by the small number in group 1 and a high level of scatter. All patients in group 1 required intraoperative transfusion of RBC and fresh frozen plasma (FFP) while two patients in group 2 did not require RBC and seven received no FFP. There were four patients in group 1 and 17 in group 2 who did not receive platelets while five in group 1 and 12 in group 2 did not receive cryoprecipitate. The differences between the groups in avoidance of these blood products did not reach statistical significance. There was little difference between groups with respect to albumin and crystalloid requirements. No statistical difference was demonstrated in intraoperative hematologic profiles between the two groups except during the anhepatic phase of surgery when there was a statistically significant more prolonged prothrombin time (p = 0.04) and a greater international normalized ratio (p = 0.027) in group 2.
Hydraulic adjustment in jack pine and black spruce seedlings under controlled cycles of dehydration and rehydration
Authors: Blake Terence J. , Li Jiyue
Published: December 2004

Drought adjustments were compared in black spruce (Picea mariana[Mill] B.S.P), and jack pine (Pinus banksiana[Lamb.]) by subjecting seedlings to five cycles of dehydration and rehydration. A computer‐controlled root misting chamber system, supplied low (−1.5 MPa), moderate (−2.0 MPa), and severe (−2.5 MPa) dehydration, respectively, in cycles 1, 3 and 5. Although cell water relations failed to adjust to chronic dehydration, there was limited osmotic adjustment in black spruce (cycle 3), and water was re‐allocated from the apoplast to the symplast in jack pine (cycles 1 and 3). Dehydration postponement was more important than dehydration tolerance. Jack pine was better able to postpone dehydration than black spruce. Specific conductivity, the hydraulic conductivity per unit stem cross‐sectional area, was lower in jack pine and slower to decline during chronic dehydration. When specific conductivity was corrected for the greater leaf area in black spruce, the leaf‐specific conductivity did not differ in the two species. There was no increase in needle leakage in jack pine and stomata in jack pine seedlings reopened fully after rehydration. Black spruce was more of a ‘water spender’, and less water stress (−2.0 MPa, cycle 3) was required to lower specific conductivity, compared to jack pine (−2.5 MPa, cycle 5). Leakage from needle membranes increased in black spruce, and stomata failed to reopen after rewatering (cycles 3 and 5). A greater needle area, smaller root system, and a higher specific conductivity lowered the water stress threshold for cavitation in black spruce, which is confined to moister sites in the boreal forest. Jack pine had a larger root system, smaller needle area and lower specific conductivity than black spruce. Because of these static features, jack pine is more drought tolerant and it is often found on sites that are too hot and dry for black spruce.
Drought enhances maize chilling tolerance. II. Photosynthetic traits and protective mechanisms against oxidative stress
Authors: Aroca Ricardo , Irigoyen Juan José , Sánchez‐Díaz Manuel
Published: December 2004

In the present research we studied the photosynthetic traits and protective mechanisms against oxidative stress in two maize (Zea maysL.) genotypes differing in chilling sensitivity (Z7, tolerant and Penjalinan, sensitive) subjected to 5°C for 5 days, with or without pretreatment by drought. The drought pretreatment decreased the symptoms of chilling injury in Penjalinan plants estimated as necrotic leaf area and maximum quantum yield of photosystem II. Furthermore, drought pretreatment diminished the level of lipid peroxidation caused by chilling in Penjalinan plants. After one day of recovery from chilling the Z7 and drought‐pretreated Penjalinan plants showed higher net photosynthesis rates than the non‐drought‐pretreated Penjalinan plants, thereby decreasing the probability of generating reactive oxygen species. The greater net photosynthesis was correlated with the greater NADP‐malate dehydrogenase activity. No differences in either the de‐epoxidation state of the xanthophyll cycle or the antioxidant enzyme activities were found among the chilled groups of plants. However, a drastic decrease in ascorbate content was observed in chilled Penjalinan plants without drought pretreatment. As we found an increase of H2O2content after drought pretreatment, we suggest its involvement as a signal in the drought‐enhanced chilling tolerance of maize.
Metabolic adaptation to prolonged anoxia in leaves of American cranberry (Vaccinium macrocarpon)
Authors: Schlüter Urte , Crawford Robert M. M.
Published: December 2004

The indigenous North American Cranberry (Vaccinium macrocarpon), when cultivated in specially constructed cranberry bogs, is normally flooded in winter to prevent frost injury. This protection under ice can give rise to prolonged periods of anoxia, which depending on the state of the vines and environmental conditions, can cause severe oxygen‐deprivation injury. An experimental study of the tolerance of cranberry vines to controlled total anoxia reveals that mature dark‐green perennating leaves with high carbohydrate levels are able to survive prolonged periods of total oxygen‐deprivation while younger newly formed leaves are readily damaged. During the anoxic treatment the mature leaves exhibit a marked downregulation of metabolism. Carbohydrate consumption and energy metabolism stabilize at low levels soon after the switch from aerobic to anaerobic pathways. Pathways such as TCA cycle or photosynthesis, which are non‐operating during the anoxia treatment, are severely affected but still measurable after 28 days anoxia. In the post‐anoxic period the perennating leaves rapidly re‐establish their capacity for aerobic respiration and photosynthesis.
Identification of new aromatic cytokinins in Arabidopsis thaliana and Populus × canadensis leaves by LC‐(+)ESI‐MS and capillary liquid chromatography/frit–fast atom bombardment mass spectrometry
Authors: Tarkowská Danuše , Doležal Karel , Tarkowski Petr , Åstot Crister , Holub Jan , Fuksová Květoslava , Schmülling Thomas , Sandberg Göran , Strnad Miroslav
Published: December 2004

A search for naturally occurring aromatic cytokinins (ARCKs) in Arabidopsis thaliana plants and Populus × canadensis leaves led to the discovery of four new plant hormone substances: 6‐(2‐methoxybenzylamino)purine (ortho‐methoxytopolin, MeoT), 6‐(3‐methoxybenzylamino)purine (meta‐methoxytopolin, MemT) (Fig. 1) and their 9‐β‐D‐ribofuranosyl derivatives. These substances were identified by liquid chromatography electrospray ionization mass spectrometry [LC (+)ESI‐MS] and capillary‐liquid chromatography/frit‐fast atom bombardment–mass spectrometry [CapLC/frit‐FAB‐MS] after pre‐column derivatization. The chemical structures were subsequently confirmed by chemical synthesis. Because of lack of heavy labelled internal standards, the endogenous levels of methoxytopolins in A. thaliana plants, Populus × canadensis leaves and samples derived from cultures of Agrobacterium tumefaciens strain GV3101 were determined by enzyme‐linked immunosorbent assay (ELISA) of HPLC‐fractionated extracts. While the levels of MeoT, MemT and their ribosides in A. thaliana shoots and Populus × canadensis leaves were relatively low (approximately 0.25–10 pmol g−1 FW for MeoT and MemT, respectively), the A. tumefaciens strain produced up to 600 times more of the newly identified substances. Cytokinin activity of methoxytopolines was demonstrated in three bioassays testing their ability to stimulate tobacco callus growth, to delay chlorophyll degradation in excised wheat leaves, and to induce betacyanin synthesis in Amaranthus caudatus var. atropurpurea cotyledons. Notably, their anti‐senescing activity in the wheat leaf assay exceeded that of BAP and Z by almost 200%. Methoxytopolins are proposed to be new members of the biologically active aromatic cytokinin family, which might have specific physiological functions.

The structures of 6‐(2‐methoxybenzylamino)purine (ortho‐methoxytopolin, MeoT) and 6‐(3‐methoxybenzylamino)purine (meta‐methoxytopolin, MemT).

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Expression of subtilisin‐like serine proteases in Arabidopsis thaliana is cell‐specific and responds to jasmonic acid and heavy metals with developmental differences
Authors: Golldack Dortje , Vera Pablo , Dietz Karl‐Josef
Published: December 2004

The expression of two novel subtilisin‐like serine proteases At‐SLP2 and At‐SLP3 from Arabidopsis thaliana and the recently identified Arabidopsis subtilase ARA12 was analysed with respect to plant development, stress response and cell specificity. In juvenile plants the mRNAs of the subtilisin‐like proteases At‐SLP2, At‐SLP3 and ARA12 were detected with varying transcript levels in leaves but not in roots. In mature Arabidopsis plants transcripts were abundant in leaves, roots and flowers revealing developmental regulation of synthesis of subtilases. By in situ hybridization it was shown that the subtilisin‐like proteases were predominantly present in epidermal cells and in the vascular bundles, in the phloem and in developing xylem elements. In flowers additional signals were localized, for example, in pistils, ovules and anthers. In flowers and juvenile developing leaves, expression of the subtilisin‐like proteases increased following treatment with jasmonate and cadmium, respectively, suggesting that these proteases are responsive to stress and pathogen stimuli. The physiological relevance of these data in relation to plant morphogenesis and development is discussed.
Spiral growth and cell wall properties of the gibberellin‐treated first internodes in the seedlings of a wheat cultivar tolerant to deep‐sowing conditions
Authors: Chen Lei , Higashitani Atsushi , Suge Hiroshi , Takeda Kazuyoshi , Takahashi Hideyuki
Published: December 2004

The Hong Mang Mai wheat cultivar is tolerant to deep‐sowing conditions because it has an elongated first internode that is sensitive to gibberellin (GA3). The cells in the GA‐treated first internodes were approximately 4.2 mm long, twice as long as the untreated Hong Mang Mai first internode cells. The elongation of the first internode of Hong Mang Mai, particularly when treated with GA3, was accompanied by remarkable spiral growth. In contrast, the first internodes of the GA‐insensitive cultivar Norin 10 did not exhibit GA3‐induced elongation or spiral growth. The walls of the first internode cells of GA3‐treated Hong Mang Mai seedlings showed increased extensibility and higher (1→3), (1→4)‐β‐d‐glucanase activity, autolysis and glucan contents than the cell walls of untreated Hong Mang Mai first internodes. The changes in the cell wall extensibility due to GA3 treatment correlated strongly with the GA3‐induced changes in cell wall glucan content, autolysis, and glucanase activity. GA3‐treated Hong Mang Mai seedlings showed elevated expression of Glucanase EI gene in the first internode compared to GA3‐treated Norin 10. Thus, GA aids first internode elongation in Hong Mang Mai by enhancing glucan turnover and thus increasing cell wall loosening. The spiral growth of the first internode also helps the plant elongate against soil resistance, thereby promoting the deep‐sowing tolerance of this cultivar.
Age‐dependence of the antioxidative system in tobacco with enhanced glutathione reductase activity or senescence‐induced production of cytokinins
Authors: Dertinger Ulrike , Schaz Ulrike , Schulze Ernst‐Detlef
Published: December 2004

Tobacco leaves of plants with enhanced glutathione reductase activity (GR46‐27, Nicotiana tabacum L. cv. Samsun) or with autoregulated senescence‐induced production of cytokinins (PSAG12‐IPT, N. tabacum L. cv. Wisconsin) were studied during the course of leaf development and senescence by measuring photosynthesis, chlorophyll and protein content, the antioxidants ascorbate, glutathione and α‐tocopherol as well as the antioxidative enzymes ascorbate peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2) and superoxide dismutase (SOD, EC 1.15.1.1). The photosynthetic rate, as well as the chlorophyll and protein content, dropped with increasing leaf age after having reached a maximum at the end of the exponential growth phase. The concentrations of the water‐soluble antioxidants ascorbate and glutathione fell continuously with age, whereas the concentration of the lipophilic α‐tocopherol increased. The activities of the antioxidative enzymes APX, GR and SOD reached their maximum at the beginning of leaf development, but were reduced in senescing leaves. The age‐dependent course of the measured leaf parameters in GR46‐27 leaves was similar to the one in wild‐type leaves, with the exception of an overall enhanced GR activity. In contrast, in old leaves of PSAG12‐IPT plants, which possess a much higher life span, the chlorophyll and protein content, the photosynthetic rate, the antioxidant concentrations of ascorbate and glutathione as well as the activities of the antioxidative enzymes were higher than in wild‐type leaves. The results show that the capacity of the antioxidative system to scavenge radicals is sufficiently balanced with the plant metabolism, and its decline with increasing age is not the cause, but a consequence of senescence and ageing in plants.
Diurnal and seasonal variations in the photosynthetic performance and water relations of two co‐occurring Mediterranean shrubs, Erica multiflora and Globularia alypum
Authors: Llorens Laura , Peñuelas Josep , Filella Iolanda
Published: December 2004

Diurnal and seasonal fluctuations in the photosynthetic performance and water relations of two co‐occurring Mediterranean shrubs, Erica multiflora and Globularia alypum were monitored throughout two consecutive years at Garraf Natural Park in north‐east Spain. Leaf gas exchange rates, chlorophyll fluorescence and shoot water potentials were measured once each season. Leaf nitrogen and carbon concentrations, leaf δ13C and δ15N and specific leaf area (SLA) were also measured once a year (August) on well developed mature leaves. Globularia alypum experienced seasonal fluctuations in their water potential, with the lowest values recorded in summer, whereas E. multiflora did not show significant differences in water potential among seasons. Moreover, lower water potentials were found in G. alypum than in E. multiflora throughout the entire study, suggesting that the latter behaved as a drought‐avoiding species, whereas the former tolerated lower water potentials. In both species, maximum leaf gas exchange rates were observed in autumn and secondarily in spring; in contrast, photosynthetic and transpiration rates reached absolute minima in summer. The stronger fluctuations in water potential and leaf gas exchange rates found in G. alypum compared to E. multiflora, suggest that G. alypum is, sensu Levitt (1980), a water spender, whereas E. multiflora is a water conservative. This hypothesis is further supported by a higher integrated water‐use efficiency (higher δ13C values) and a higher degree of sclerophylly (lower SLA) in E. multiflora in comparison with G. alypum. Globularia alypum showed higher leaf gas exchange rates and higher predawn potential photochemical efficiency (Fv/Fm) than E. multiflora during most of the study. In spring and autumn, predawn Fv/Fm values were within the optimal range, whereas chronic photoinhibition in summer and winter was detected in both species. However, whereas both species could maintain positive photosynthetic rates in winter, frequent negative values were found in summer, suggesting higher levels of stress during the drought period. These results together with the high correlations that were found between the net photosynthetic rates and several parameters of water availability (accumulated rainfall, soil moisture or midday water potential) provided further evidence of the key role of water availability in the regulation of the photosynthetic rates in these Mediterranean species. Warmer and drier conditions in future decades, as a consequence of climate change, may alter the present, slight competitive advantage of G. alypum and the fitness of both shrub species within semi‐arid Mediterranean environments.
Germination strategy of Striga hermonthica involves regulation of ethylene biosynthesis
Authors: Sugimoto Yukihiro , Ali Abdelbagi Mukhtar , Yabuta Sumiyo , Kinoshita Hiromi , Inanaga Shinobu , Itai Akihiro
Published: December 2004

Ethylene involvement in germination of Striga hermonthica (Del.) Benth., an important root parasitic weed on poaceous crops, was investigated at the physiological and molecular levels. Seeds, conditioned at 30°C for 14 days, were treated with ethylene, ethephon or 1‐aminocyclopropane‐1‐carboxylic acid (ACC). Ethylene consistently induced low germination. Ethephon and ACC effectively stimulated germination at concentrations of 0.01 and 1 mM, respectively. In contrast to ethylene, both ethephon and ACC acted in a concentration‐dependent manner. Germination induced by the synthetic strigolactone GR24 was inhibited by aminoethoxyvinylglycine (AVG) and 1‐methylcyclopropene. ACC reversed the inhibition caused by AVG. When seeds were treated with GR24 in sealed vials, ethylene concentration in headspace gas increased prior to the onset of germination. Total RNA extracted from germinating seeds 12 h after GR24 treatment was used for PCR‐based amplification of cDNA fragments encoding the ACC synthase‐ and oxidase‐active site domains. Two distinct cDNA fragments encoding ACC synthase (SHACS1 and SHACS2) and one encoding ACC oxidase (SHACO1) were cloned and sequenced. Southern analysis suggested that each of the cloned genes was present as a single copy in the genome of S. hermonthica. Northern analyses showed that SHACS1 exhibited a temporal change in expression peaking at 10 h after GR24 treatment, which coincided with a steady increase in ethylene concentration. SHACS2 was expressed at a low level with a similar trend. SHACO1 exhibited a temporal change in expression peaking at 15 days during conditioning, when seed response to GR24 was maximal. In summary, expression of ACC synthase and ACC oxidase genes was found to be responsive to a germination stimulant and to conditioning, respectively. The implications of these findings with respect to germination of S. hermonthica under field conditions are discussed.
Cloning and characterization of barley long chain acyl‐CoA oxidase and its possible regulation by glucose
Authors: Grossi Maria , Giuntini Pietro , Mazzucotelli Elisabetta , Crosatti Cristina , Pistelli Laura , De Bellis Luigi , Alpi Amedeo , Stanca A. Michele , Cattivelli Luigi
Published: December 2004

A barley (Hordeum vulgare L.) full‐length clone coding for long chain acyl‐CoA oxidase (ACX), key enzyme of β‐oxidation, was isolated by cDNA library screening and 5′‐rapid amplification of cDNA ends. The cDNA encodes for a polypeptide of 667 amino acids, with a molecular mass of 74.5 kDa. The amino acid sequence, beside an extensive similarity with other plant and mammalian ACXs, showed a PTS1 peroxisomal targeting signal at the C terminus and a conserved FAD‐binding domain. The gene was over‐expressed in E. coli and the fusion protein was shown to possess long chain acyl‐CoA oxidase activity. Polyclonal antibodies were raised against a large fragment of the protein encoded by the barley putative ACX gene. Northern and Western analysis demonstrated that a basal level of long chain ACX is always present along the barley life cycle, while a higher level of expression is typical of actively growing tissues such as germinating embryos, ovary before anthesis, developing embryos, shoots and roots apexes. In vitro germination experiments with glucose and glucose analogues provided evidence about the involvement of a glucose‐deriving signal in the positive modulation of ACX expression. This result highlights the role of ACX, not only during oil reserve mobilization, but also in plant growth and metabolism.
Seasonal and spatial variation of reduced sulphur compounds in mistletoes (Viscum album) and the xylem sap of its hosts (Populus × euramericana and Abies alba)
Authors: Escher Peter , Eiblmeier Monika , Hetzger Ilka , Rennenberg Heinz
Published: December 2004

In the present field study with adult trees inhabited by Viscum album, the question was addressed as to whether European mistletoes are able to remove reduced sulphur from the xylem sap of its hosts. For this purpose the reduced sulphur composition and content of the xylem sap of Viscum album and the corresponding hosts Populus × euramericana and Abies alba were analysed. The xylem sap of Viscum was enriched in reduced sulphur compared to the hosts but still reflected the higher reduced sulphur content of Populus compared to Abies. Despite similar xylem sap composition of the hosts with glutathione as the dominating thiol, Viscum on Populus contained predominantly cysteine, Viscum on Abies predominantly glutathione in its xylem sap. These findings suggest selective and different removal of reduced sulphur from these hosts. Still the amount of reduced sulphur removed was too small to result in changes of the concentration of thiols in the xylem sap of the hosts that are statistically significant, probably due to the high variability encountered under field conditions. Despite the differences in the reduced sulphur composition and contents of the xylem sap between Viscum on Populus and Viscum on Abies, total thiol content as well as thiol composition of Viscum leaves on the two hosts were similar throughout the seasons. The seasonal pattern in the thiol composition and contents of Viscum leaves showed high levels in spring and autumn and low levels in summer. The significance of these seasonal changes is discussed.
Cellular and subcellular localization of the lignin biosynthetic enzymes caffeic acid‐O‐methyltransferase, cinnamyl alcohol dehydrogenase and cinnamoyl‐coenzyme A reductase in two monocots, sugarcane and maize
Authors: Ruelland Eric , Campalans Anna , Selman‐Housein Guillermo , Puigdomènech Pere , Rigau Joan
Published: December 2004

Cinnamoyl‐coenzyme A reductase (CCR, EC 1.2.1.44), cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195) and caffeic O‐methyl transferase (COMT, EC 2.1.1.68) are three enzymes of the biosynthetic pathway of lignin. This pathway has been mostly studied in dicots but is less well known in monocots. We report the histochemical localization of these enzymes in maize (Zea mays L.) and sugarcane (Saccharum officinarum L.). Antibodies directed against maize COMT and sugarcane CAD and CCR were generated. Western experiments were performed with the 3 antibodies, and immunolocalization experiments were performed with anti‐CAD and anti‐COMT antibodies. The three enzymes were present in actively lignifying tissues, such as maize roots and mesocotyls, and sugarcane roots and stems. At the cellular level, CAD and COMT were mainly found in xylem. No major differences could be seen in the distribution patterns of both enzymes, except that CAD was detected in the endodermis, while COMT was not. At a subcellular level, the three enzymes appeared to be mainly cytosolic.
CND41, a chloroplast nucleoid protein that regulates plastid development, causes reduced gibberellin content and dwarfism in tobacco
Authors: Nakano Takeshi , Nagata Noriko , Kimura Takuma , Sekimoto Masayo , Kawaide Hiroshi , Murakami Shinya , Kaneko Yasuko , Matsushima Hisashi , Kamiya Yuji , Sato Fumihiko , Yoshida Shigeo
Published: December 2004

CND41, a DNA binding protein of chloroplast nucleoids, may function as a negative regulator of chloroplast gene expression. The reduction of CND41 in an antisense transformant accelerated plastid development in shoot apex cells and early young leaves, and caused a dwarf phenotype and altered leaf morphology. Plant height and leaf shape could be restored almost to those of the wild type by application of gibberellins (GAs), clearly indicating that a reduction in GA content was a prime cause of the dwarf phenotype in CND41 antisense transformants. The transformants had reduced endogenous levels of active gibberellin (GA1), a biologically active GA, compared to those of wild‐type plants. Possible relationships between chloroplast development affected by CND41 function and GA biosynthesis are discussed.
Influence of seasonal time constraints on growth and development of common frog tadpoles: a photoperiod experiment
Authors: Laurila Anssi , Pakkasmaa Susanna , Merilä Juha
Published: December 2004

Organisms living in seasonal environments are often limited by the time available to complete their development. Especially individuals in northern populations may face severe time constraints in their need of completing development before the end of the growth season. Larval amphibians have been widely used in studies of phenotypic plasticity. However, their responses to changes in photoperiod, the main seasonal cue in many organisms, are unknown. In a laboratory experiment, we studied whether common frog (Rana temporaria) tadpoles originating from two populations (separated latitudinally by 1600 km) adjust their growth and development according to the progress of the season by using photoperiodic cues, and whether these responses are temperature dependent. We hypothesised that if frogs use photoperiod as a cue, they should increase growth and development rates as a response to photoperiodic treatments mimicking progressing season. Although our predictions were not verified in either of the populations, photoperiod manipulations had effects on larval life history in both populations. When exposed to progressing season treatments and high temperature, tadpoles from the southern population ceased feeding, which led to delayed metamorphosis and increased mortality. In the northern population, age at metamorphosis was unaffected by the photoperiod treatments, but growth rate until metamorphosis and metamorphic size were slightly larger in the treatments with shorter (increasing or decreasing) day length. Irrespective of photoperiod treatments, growth and development rates, size at metamorphosis and food consumption were higher in the northern as compared to the southern population. These results indicate that in contrast to several insect species, the critical life history decisions in amphibian larvae may not be strongly influenced by photoperiodic cues, but different populations seem to differ in this respect. However, the strong temperature×photoperiod interactions in several traits in the southern population suggest that the role of photoperiodic cues may be affected by other environmental factors, although the ecological significance of these differences remains unclear.
Synchrony in brown trout, Salmo trutta, population dynamics: a ‘Moran effect’ on early‐life stages
Authors: Cattanéo Franck , Hugueny Bernard , Lamouroux Nicolas
Published: December 2004

Synchrony among populations (i.e. spatial covariation in temporal fluctuations of population size or growth rate) is a common feature to many animals. Both large‐scale autocorrelated climatic factors (the ‘Moran effect’) and dispersal between populations are candidates to explain synchrony, although their relative influence is difficult to assess. Only a few investigations have reported patterns of synchrony among freshwater populations, and even fewer directly related these patterns to an environmental variable. In the present study, we analysed the spatio‐temporal patterns of fluctuation of 57 brown trout populations widespread across France, each sampled continuously during 5 years. We compared the respective influence of connectivity and stream distance within basins (i.e. that potentially allow a basin‐scale dispersal) and environmental factors (hydrological and air temperature variables, available for 37 sites) on the synchrony of brown trout cohort densities (0+, 1+ and adults). A series of Mantel tests revealed that the degree of synchrony was not related to connectivity or stream distance between sites, suggesting no effect of dispersal at the basin‐scale. The degree of synchrony among sites for the 0+ fish was significantly related to the degree of hydrological synchrony (based on high flows during the emergence period). For all three age classes, the synchrony in the temperature patterns did not explain synchrony in trout dynamics. Our results allow us to discuss the respective influence of dispersal and climatic factors on the spatio‐temporal patterns of trout dynamics at the basin scale.