bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low‐temperature resistance in Polylepis tarapacana, a tree growing at the highest altitudes in the world
Authors: Rada F. , García‐Núñez C. , Boero C. , Gallardo M. , Hilal M. , González J. , Prado F. , Liberman‐Cruz M. , Azócar A. 
Published: March 2003

ABSTRACTThe Polylepis tarapacana forests found in Bolivia are unique with respect to their altitudinal distribution (4200–5200 m). Given the extreme environmental conditions that characterize these altitudes, this species has to rely on distinct mechanisms to survive stressful temperatures. The purpose of this study was to determine low‐temperature resistance mechanisms in P. tarapacana. Tissue was sampled for carbohydrate and proline contents and micro‐climatic measurements were made at two altitudes, 4300 and 4850 m, during both the dry cold and wet warm seasons. Supercooling capacity (−3 to −6 °C for the cold dry and −7 to −9 °C for the wet warm season) and injury temperatures (−18 to −23 °C for both seasons), determined in the laboratory, indicate that P. tarapacana is a frost‐tolerant species. On the other hand, an increase in supercooling capacity, as the result of significant increase in total soluble sugar and proline contents, occurs during the wet warm season as a consequence of higher metabolic activity. Hence, P. tarapacana, a frost‐tolerant species during the colder unfavourable season, is able to avoid freezing during the more favourable season when minimum night‐time temperatures are not as extreme.
Photosynthetic acclimation of plants to growth irradiance: the relative importance of specific leaf area and nitrogen partitioning in maximizing carbon gain
Authors: Evans J. R. , Poorter H. 
Published: March 2003

AbstractChanges in specific leaf area (SLA, projected leaf area per unit leaf dry mass) and nitrogen partitioning between proteins within leaves occur during the acclimation of plants to their growth irradiance. In this paper, the relative importance of both of these changes in maximizing carbon gain is quantified. Photosynthesis, SLA and nitrogen partitioning within leaves was determined from 10 dicotyledonous C3 species grown in photon irradiances of 200 and 1000 µmol m−2 s−1. Photosynthetic rate per unit leaf area measured under the growth irradiance was, on average, three times higher for high‐light‐grown plants than for those grown under low light, and two times higher when measured near light saturation. However, light‐saturated photosynthetic rate per unit leaf dry mass was unaltered by growth irradiance because low‐light plants had double the SLA. Nitrogen concentrations per unit leaf mass were constant between the two light treatments, but plants grown in low light partitioned a larger fraction of leaf nitrogen into light harvesting. Leaf absorptance was curvilinearly related to chlorophyll content and independent of SLA. Daily photosynthesis per unit leaf dry mass under low‐light conditions was much more responsive to changes in SLA than to nitrogen partitioning. Under high light, sensitivity to nitrogen partitioning increased, but changes in SLA were still more important.
Chilling‐induced Ca2+ overload enhances production of active oxygen species in maize (Zea mays L.) cultured cells: the effect of abscisic acid treatment
Authors: Chen W. P. , Li P. H. 
Published: March 2003

AbstractChilling (4 °C) induced a prolonged high level of intracellular Ca2+ (Ca2+ overload) and lipid peroxidation in maize (Zea mays L. cv Black Mexican Sweet) cultured cells. However, such Ca2+ overload and enhanced lipid peroxidation were not seen in abscisic acid (ABA)‐treated cells, which had an improved chilling tolerance. A Ca2+ ionophore, A23187, caused Ca2+ overload in both ABA‐treated maize cells and the untreated control, whereas an enhanced lipid peroxidation was detected only in the control. The high level of active oxygen species (AOS) in the control during chilling at 4 °C could be reduced by the presence of lanthanum (La3+), a Ca2+ channel blocker, in the medium. Moreover, both the A23187‐induced lipid peroxidation and AOS production in the control could be reduced by extracellular EGTA, a Ca2+ chelator. Laser‐scanning confocal microscopy revealed that mitochondria were one of the major AOS sources under chilling and during A23187 treatment. In vitro assays showed that superoxide production in isolated maize mitochondria was enhanced by the presence of Ca2+. Findings suggest that chilling‐induced Ca2+ influx in the control triggers a marked generation of AOS, which in turn results in the enhanced lipid peroxidation. The ability of ABA‐treated cells to avoid the chilling‐induced Ca2+ influx may serve as a mechanism that prevents the chilling‐induced oxidative stress and thus results in less chilling injury.
Stress‐related RNase PR‐10c is post‐translationally modified by glutathione in birch
Authors: Koistinen K. M. , Kokko H. I. , Hassinen V. H. , Tervahauta A. I. , Auriola S. , Kärenlampi S. O. 
Published: March 2003

AbstractThe PR‐10c (previously termed as Bet v 1‐Sc3) protein of birch belongs to the family of intracellular pathogenesis‐related proteins. The high‐performance liquid chromatography electrospray ionization ion trap mass spectrometry (HPLC‐ESI‐MS) analysis of PR‐10c‐His fusion protein, produced in Escherichia coli, revealed three major peaks and masses. Enzymatic digestions and HPLC‐ESI‐MS and matrix assisted laser desorption/ionization – time of flight mass spectrometry (MALDI‐TOF‐MS) analyses of each fraction indicated that PR‐10c‐His protein is post‐translationally modified by carbamylation and S‐glutathiolation. Carbamylation was localized into the N‐terminal end of PR‐10c‐His and does not represent a biologically significant modification. The possible nuclease activity of PR‐10c was analysed with S‐glutathiolated and reduced fractions of PR‐10c‐His fusion protein. Both forms of PR‐10c‐His as well as the dimeric form of the protein possess RNase activity which is capable of digesting different RNA substrates. None of the fractions showed activity against single‐ or double‐stranded DNA. The MALDI‐TOF‐MS analysis of PR‐10c polypeptide extracted from zinc‐exposed birch roots showed that the protein is post‐translationally modified by glutathione (γ‐Glu‐Cys‐Gly) also in vivo. The S‐glutathiolated cysteine residue of PR‐10c is not conserved among Bet v 1 homologous proteins and is also unique in the PR‐10 family. As far as we know this is the first observation of S‐glutathiolation in plants, or any post‐translational modification in the PR‐10 family of proteins.
How does photorespiration modulate leaf amino acid contents? A dual approach through modelling and metabolite analysis
Authors: Novitskaya L. , Trevanion S. J. , Driscoll S. , Foyer C. H. , Noctor G. 
Published: March 2003

AbstractThe aim of this work was to establish the quantitative impact of photorespiration on leaf amino acid contents. Attached leaves of wheat and potato were incubated for 30–40 min under defined conditions in which net CO2uptake (A) was manipulated by irradiance, ambient CO2or ambient O2. The incubated portion of the leaf was sampled by a rapid‐quench method and photorespiratory flux (vo) was modelled from the measured rate of net CO2uptake. In both wheat and potato, the ratio between glycine and serine showed a strong positive correlation withvo. Aspartate and alanine correlated negatively withvobut glutamate and glutamine showed less clear relationships. In potato, glutamate and glutamine did not correlate clearly with eitherAorvo. In wheat, glutamine showed a general increase withAbut no relationship withvo, whereas 2‐oxoglutarate contents correlated positively withvoand negatively withA. As a result, glutamine : glutamate and glutamine : 2‐oxoglutarate increased with net CO2uptake in wheat, observations that are attributed primarily to imperfect and variable coupling between the supply of NH3in primary nitrogen assimilation and the associated delivery of 2‐oxoglutarate to the chloroplast. A simple theoretical analysis is used to illustrate the potentially marked impact of primary nitrogen assimilation on leaf glutamine, even against a background of high rates of photorespiratory ammonia recycling.
The effect of growth irradiance on leaf anatomy and photosynthesis in Acer species differing in light demand
Authors: Hanba Y. T. , Kogami H. , Terashima I. 
Published: March 2003

AbstractVariation in light demand is a major factor in determining the growth and survival of trees in a forest. There is strong relation between the light‐demand and the effect of growth irradiance on leaf morphology and photosynthesis in three Acer species: A. rufinerve (light‐demanding), A. mono (intermediate) and A. palmatum (shade‐tolerant). The increase in mesophyll thickness and surface area of chloroplasts facing the intercellular airspaces (Sc) with growth irradiance was highest in A. rufinerve. Although the increase in light‐saturated photosynthesis (Amax) was similar among the species, the increase in water use efficiency (WUE) was much higher in A. rufinerve than that in the other species, indicating that the response to water limitation plays an important role in leaf photosynthetic acclimation to high light in A. rufinerve. The low CO2 partial pressure at the carboxylation site (Cc) in A. rufinerve (130 µmol mol−1) at high irradiance was caused by low stomatal and internal conductance to CO2 diffusion, which minimized the increase in Amax in A. rufinerve despite its high Rubisco content. Under shade conditions, interspecific differences in leaf features were relatively small. Thus, difference in light demand related to leaf acclimation to high light rather than that to low light in the Acer species.
Contrasted responses to carbohydrate limitation in tomato fruit at two stages of development
Authors: BALDET P. , DEVAUX C. , CHEVALIER C. , BROUQUISSE R. , JUST D. , RAYMOND P. 
Published: March 2003

AbstractThe metabolic consequences of long‐term carbohydrate depletion have been well documented in many sink organs but not extensively in fruit. Therefore, in the present study the response to sugar limitation in tomato fruit (Lycopersicon esculentum Mill.) was investigated at two developmental stages; during the cell division and cell expansion phases. First, the response in excised fruit cultured in vitro was characterized. Sugar depletion caused an arrest of growth and an exhaustion of carbon reserves. The proteins that were degraded and the nitrogen released was transiently stored as asparagine and glutamine in both developmental stages and also as γ ‐aminobutyric acid (GABA) in expanding fruit. Fruit at the cell division stage appeared to be more sensitive to sugar limitation. The response to sugar depletion was then characterized in fruit from plants submitted to extended darkness. In planta, the effects of sugar‐limitation were similar to those described in vitro but much more attenuated, especially in expanding fruit, which still accumulated dry matter. The expression of cell cycle genes, sugar‐ and nitrogen‐related genes was reduced by darkness. Only asparagine synthetase gene expression was induced in both dark‐treated fruit. Together the present data revealed that the effects of the carbon limitation are more pronounced in the youngest fruits as it is probably controlled by the relative sink strength of the fruit.
The case for cytosolic NO3– heterostasis: a critique of a recently proposed model
Authors: BRITTO D. T. , KRONZUCKER H. J. 
Published: March 2003

ABSTRACTA model recently proposed by Siddiqi & Glass (Plant, Cell, and Environment 25, 1211–1217, 2002) attempts to reconcile discrepancies in the measurement of cytosolic nitrate concentrations ([NO3–]cyt) in plant root cells, specifically between low (∼ 4 mm) homeostatic values reported in studies using ion‐specific microelectrodes on the one hand, and wide fluctuations in [NO3–]cyt reported in other studies, especially those using compartmental analysis by tracer efflux (CATE). Although Siddiqi & Glass concede that cytosolic NO3– homeostasis, as determined by microelectrodes, is at odds with certain experimental observations, they nevertheless promote a model that takes microelectrode readings at face value, and assert that the variations seen using CATE methodology are artefacts attributable to contributions from substantial, rapidly exchanging, and highly variable NO3– pools putatively residing in organelles such as plastids and the endoplasmic reticulum. We show here that such a model is not tenable, drawing upon experimental evidence from previous studies, and from a more comprehensive model that examines the characteristics and consequences of subcompartmented cytoplasmic exchange in root cells.
Retracted: Enhanced Inhibition of Tumour Growth and Metastasis, and Induction of Antitumour Immunity by IL‐2‐IgG2b Fusion Protein
Authors: Budagian V. , Nanni P. , Lollini P. L. , Musiani P. , Carlo E. DI , Bulanova E. , Paus R. , Bulfone‐Paus S. 
Published: March 2003

Budagian V, Nanni P, Lollini PL, Musiani P, Di Carlo E, Bulanova E, Paus R, Bulfone‐Paus S. Enhanced Inhibition of Tumour Growth and Metastasis, and Induction of Antitumour Immunity by IL‐2‐IgG2b Fusion Protein. Scand J Immunol 2002;55:484–492Cytokine‐immunoglobulin (Ig)‐fusion proteins have attracted increasing interest as antitumour agents. Here, we have investigated the antimetastatic and antitumour responses elicited in vivo by mammary adenocarcinoma cells (TS/A) engineered to secrete interleukin (IL)‐2‐IgG fusion proteins. TS/A cells were transfected with DNA coding for IL‐2‐IgG2b, IgG2b or IL‐2, and injected subcutaneously into syngeneic mice. Animals injected with TS/A‐IL‐2 or TS/A‐IL‐2‐IgG2b both efficiently rejected tumours, whereas treatment with parental cells or TS/A‐IgG2b was lethal. Interestingly, only mice vaccinated with IL‐2‐IgG2b fusion protein‐secreting cells showed a long‐lasting protective immunity against a later challenge with parental tumour cells. Moreover, the metastatic potential of TS/A‐IL‐2‐IgG2b‐transfected cells was dramatically decreased compared with TS/A‐IL‐2‐cells, with a virtual absence of lung metastases after intravenous injection. Adenocarcinomas secreting IL‐2‐IgG2b exhibited a more prominent, early and persistent infiltration of CD4+, CD8+ and natural killer (NK) cells than TS/A‐IL‐2 cells. Therefore, upon transfection into adenocarcinoma cells, the IgG2b part of IL‐2 fusion protein exerts intriguing added antitumour properties over IL‐2 alone, thus contributing to a long‐lasting tumour immunity, probably by the recruitment of specific immune effector cells. These findings suggest a promising new oncotherapeutic strategy for poorly immunogenic tumours: vaccination with tumour cells engineered to secrete IL‐2‐IgG2b fusion protein.
Deep‐sea volcaniclastic sedimentary systems: an example from La Fournaise volcano, Réunion Island, Indian Ocean
Authors: Ollier  , Cochonat  , Lénat  , Labazuy  
Published: March 2003

A volcaniclastic sedimentary fan extending to water depths of 4000 m is characterized using gravity cores, camera surveys, high‐resolution sonar images, seismic records and bathymetry from the submarine portion of La Fournaise volcano, Réunion Island, a basaltic shield volcano in the SW Indian Ocean.Three main areas are identified from the study: (1) the proximal fan extending from 500 m water depth down to 2000 m water depth; (2) the outer fan extending from 2000 m water depth down to 3600 m water depth; (3) the basin extending beyond 3600 m water depth. Within these three main areas, seven distinct submarine environments are defined: the proximal fan is characterized by volcanic basement outcrops, sedimentary slides, deep‐water deltas, debris‐avalanche deposits, and eroded floor in the valley outlets; the outer fan is characterized by a discontinuous fine‐grained sedimentary cover overlying coarse‐grained turbidites or undifferentiated volcanic basement; the basin is characterized by hemipelagic muds and fine‐grained turbidites interbedded with sandy and gravelly turbidite lobes.The evolution of the deep‐sea volcaniclastic fan is strongly influenced by sector collapses, such as the one which occurred 0·0042 Ma ago. This collapse produced a minimum of 6 km3 of debris‐avalanche deposit in the proximal area. The feeding regime of the deep‐sea fan is ‘alluvial dominated’ before the occurrence of any sector collapse and ‘lava‐dominated’ after the occurrence of a sector collapse.The main deep‐water lava‐fed delta is prograding among the blocks of the debris‐avalanche deposits as a result of turbidity flows occurring on the delta slope. These turbidity flows are triggered routinely by wave‐action, earthquakes and accumulation of new volcanic debris on top of the deltas.Both turbidity currents triggered on the deep‐water delta slope, and those triggered by debris avalanche reworked volcaniclastic material as far as 100 km from the shore line.
Palaeoenvironmental significance of rounded pyrite in siliciclastic sequences of the Late Archaean Witwatersrand Basin: oxygen‐deficient atmosphere or hydrothermal alteration?
Authors: England Gavin L. , Rasmussen Birger , Krapez Bryan , Groves David I. 
Published: March 2003

AbstractPetrographic and sulphur isotope studies support the long‐held contention that rounded grains of pyrite in siliciclastic sequences of the Late Archaean Witwatersrand Supergroup originated as placer grains. The grains are concentrated at sites where detrital heavy minerals are abundant within quartz‐pebble conglomerates and quartzose sandstones. Depositional sites with abundant pyrite are: (1) within the matrix of bar‐type, clast‐supported conglomerates; (2) on scoured or winnowed surfaces; and (3) on stratification planes. The grains are internally compact or porous, with truncation of internal structure at outer margins indicating fragmentation and rounding of pyritic source‐rocks during erosion and sediment transport. A large range in textures reflects source‐rock lithologies, with known varieties linked to sedimentary‐hosted diagenetic pyrite, volcanic‐hosted massive sulphide deposits and hydrothermal pyrite. Laser ablation sulphur isotope analysis of pyrite reveals a broader range in δ34S values (− 5·3 to + 6·7‰) than that of previously reported conventional bulk‐grain analyses (− 1 to + 4‰). Rounded pyrite from the Steyn Reef has significant variation in δ34S values (− 4·7 to + 6·7‰) that establishes heterogeneous sulphur compositions, with even adjacent grains having diverse isotopic signatures. The heterogeneity supports a placer origin for rounded pyrite. Euhedral pyrite and pyrite overgrowths which are undoubtedly authigenic have restricted δ34S values (− 0·5 to + 2·5‰), are chemically distinct from rounded pyrite and are probably the products of metamorphism or hydrothermal alteration. The placer origin of rounded pyrite indicates that pyrite was a stable heavy mineral during erosion and transport in the early atmosphere. Its distribution in three sequences (Witwatersrand Supergroup, Ventersdorp Contact Reef and Black Reef), and in other sequences not linked to Witwatersrand‐type Au‐U ore deposits, implies deposition of redox‐sensitive detrital heavy minerals during the Late Archaean. Consequently, rounded grains of detrital pyrite are strong indicators of an oxygen‐poor atmosphere. While not confirming a placer origin for gold in Witwatersrand Au‐U ore deposits, the palaeoenvironmental significance of rounded pyrite negates its link to hydrothermal mineralization.
World revision of Ortheziola Šulc (Homoptera: Coccoidea: Ortheziidae) with descriptions of eleven new species
Authors: Kozár Ferenc , Miller Douglass R. 
Published: March 2003

SummarySoil samples and museum collections were analysed from all zoogeographic regions of the world. From this material eleven new species of OrtheziolaŠulc are described from Africa and the U.K., five additional species are redescribed and a key is presented for the identification of all sixteen species. A slightly modified concept of the genus is presented and several new characters are given as diagnostic of the genus. A phylogenetic hypothesis is given based on analysis of the morphological features of adult females. Results show that Ortheziola is most diverse in eastern Africa where relatively more advanced species occur. Basal species occur primarily in western Africa and Asia.
Phylogenetic relationships among genera of Aphidiinae (Hymenoptera: Braconidae) based on DNA sequence of the mitochondrial 16S rRNA gene
Authors: Kambhampati Srinivas , Völkl Wolfgang , Mackauer Manfred 
Published: March 2003

SummaryPhylogenetic relationships among forty‐nine taxa representing twenty‐four genera of Aphidiinae (Hymenoptera: Braconidae) were investigated using DNA sequence of a portion of the mitochondrial 16S rRNA gene and parsimony analysis. Seven species in six other subfamilies of Braconidae were used as outgroup. The results suggested that members of Aphidiinae are monophyletic. The basal lineage of Aphidiinae was Aclitus in weighted and unweighted parsimony analyses and Praini was basal relative to Ephedrini. With the exception of Pauesia and Aphidius, all genera were monophyletic. The results support generic status for Euaphidius, but not for Lysaphidus. Diaeretus leucopterus was internal to a clade composed of three Pauesia species, suggesting that the latter genus may be paraphyletic. A combined analysis that included DNA sequence of 16S rRNA, NADH1 dehydrogenase and 28S rRNA resulted in more robust cladograms with topologies similar to those inferred from the 16S rRNA gene sequence alone. The results are compared to previously proposed phylogenies of Aphidiinae based on morphological and molecular characters.
A wheat histone H3 promoter confers cell division‐dependent and ‐independent expression of the gus A gene in transgenic rice plants
Authors: Terada Rie , Nakayama Takuya , Iwabuchi Masaki , Shimamoto Ko 
Published: March 2003

SummaryTo investigate developmental regulation of wheat histone H3 gene expression, the H3 promoter, which has its upstream sequence to −1711 (relative to the cap site as +1), was fused to the coding region of the gus A gene (−1711H3/GUS) and introduced into a monocot plant, rice. Detailed histochemical analysis revealed two distinct types of GUS expression in transgenic rice plants; one is cell division‐dependent found in the apical meristem of shoots and roots and in young leaves, and another is cell division‐independent detected in flower tissues including the anther wall and the pistil. In this study, replication‐dependent expression occurring in non‐dividing cells which undergo endoreduplication could not be discriminated from strict replication‐independent expression. The observed expression pattern in different parts of roots suggested that the level of the H3/GUS gene expression is well correlated with activity of cell division in roots. To identify 5′ sequences of the H3 promoter necessary for an accurate regulation of the GUS expression, two constructs containing truncated promoters, −908H3/GUS and −185H3/GUS, were analyzed in transiently expressed protoplasts, stably transformed calli and transgenic plants. The results indicated that the region from −909 to −1711 contains the positive cis‐acting element(s) and that the proximal promoter region (up to −185) containing the conserved hexamer, octamer and nonamer motifs is sufficient to direct both cell division‐dependent and ‐independent expression. The use of the meristem of roots regenerated from transformed calli for the analysis of cell division‐dependent expression of plant genes is discussed.