bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitric oxide in plants: the history is just beginning
Authors: Beligni M. V. , Lamattina L. 
Published: March 2003

ABSTRACTNitric oxide (NO) is a bioactive molecule that exerts a number of diverse activities in phylogenetically distant species, as well as opposing effects in related biological systems. It was firstly described in mammals as a major messenger in the cardiovascular, immune and nervous system, in which it plays regulatory, signalling, cytoprotective and cytotoxic effects (Ignarro, Annual Review of Pharmacology and Toxicology 30, 535–560, 1990; Anbar, Experientia 51, 545–550, 1995). This versatility is mainly achieved through interactions with targets via either a redox or an additive chemistry (Stamler, Cell 78, 931–936, 1994). For this reason, metal‐ and thiol‐containing proteins serve as major target sites for NO: these include signalling proteins, receptors, enzymes, transcription factors and DNA, among others. Furthermore, NO is a small, highly diffusible molecule. It rapidly crosses biological membranes and triggers various different processes in a short period of time. In this context, NO can co‐ordinate and regulate cellular functions of microsomes and organelles such as mitochondria. The ubiquity of NO reactions, as well as the finding that the biochemical and molecular mechanisms underlying many physiological processes are well conserved between diverse species, have opened the exploration of NO chemistry in different organisms. Among these, plants were not the exception. The research in plants has been focused on three main fields: (i) the search for NO or any source of NO generation; (ii) the examination of the effects of NO upon exogenous treatments; and (iii) the search for the same molecules involved in NO‐sensitive transduction pathways as in animals (e.g. cGMP, Ca2+, calmodulin). As it is evident from this review, recent progress on NO functionality in plants has been impressive. With the use of biochemistry, molecular genetics and structural biology, together with classical physiological approaches, an explosion of new discoveries will surely begin. It is certainly a good time for plant biologists.
The essentials of direct xylem pressure measurement
Authors: Wei C. , Steudle E. , Tyree M. T. , Lintilhac P. M. 
Published: March 2003

ABSTRACTThis paper discusses the essentials of the oil‐filled pressure probe technique in the measurement of negative xylem pressures, focusing in particular on the technique and physics underlying our recent, successful experiment which has rekindled the debate on the validity of the Cohesion–Tension theory. We illustrate a number of general problems associated with the cell pressure probe and xylem pressure probe techniques, and propose appropriate criteria for micropipette construction. We enumerate factors dealing with the cavitation problem and suggest methods for eliminating air seeds in the system. We introduce reliable criteria for the successful measurement of xylem pressure, and emphasize the importance of the probe pressure relaxation test. Several problems regarding the controversy over the Cohesion–Tension theory are also discussed. We discuss the correlation between xylem pressure and the transpiration rate, the existence of absolute negative xylem pressure in intact plants, the most negative values of xylem pressure measured by the pressure probe, the agreement between the pressure probe and pressure bomb techniques, and the vulnerability to cavitation (tensile strength) of pressure probes.
cDNA cloning of a mechanical/abiotic stress‐inducible calmodulin‐related gene from dodder‐infected alfalfa
Authors: Borsics T. , Lados M. 
Published: March 2003

AbstractPlants respond to various biotic and abiotic stresses by the specific induction of a certain set of genes. This study involved a search for transcripts induced in alfalfa (Medicago sativa L. bv Verko) upon infection with dodder (Cuscuta trifolii Bab. et Gibs). A 570 bp cDNA, designated PPRG1, was isolated by differential display. Southern blot analysis indicates that PPRG1 is a member of a new small gene family in alfalfa. PPRG1 encodes a putative 19·2 kDa calmodulin‐related protein with 59% amino acid homology to the touch‐inducible TCH2 gene isolated from Arabidopsis. The level of PPRG1 transcript shows a rapid transient increase to mechanical stimuli such as rain, touch and wounding, to osmotic and salt stresses and to external treatment with the plant hormone abscisic acid. Constantly elevated levels of PPRG1 mRNA can be observed during cold stress, whereas heat treatment does not induce PPRG1 expression. These results implicate roles for Ca2+ and PPRG1 in the transduction of signals from the environment.
Nitric oxide interferes with plant photo‐oxidative stress by detoxifying reactive oxygen species
Authors: Beligni M. V. , Lamattina L. 
Published: March 2003

AbstractOxidative stress within chloroplasts is originated due to light‐dependent O2 reduction. This may be exacerbated by bipyridinium herbicides, which act at photosystem I as artificial electron acceptors. Their oxidation produces a superoxide anion that further dismutates to H2O2 and then, by the Fenton reaction, H2O2 may be reduced to the hydroxyl radical (OH•). Reactive oxygen species (ROS), when produced in high amounts, provoke severe damage to the plant cell. Herein it is reported that two nitric oxide (NO) donors, sodium nitroprusside (100 µm) and S‐nitroso‐N‐acetylpenicillamine (200 µm), greatly reduced lipid peroxidation and the protein loss caused by the application of a high dose of the bipyridinium herbicide diquat to potato leaf pieces or isolated chloroplasts. Nitric oxide donors also protected the RNA against oxidative damage. Photo‐oxidative toxicity was correlated with an increase in photosynthetic electron transport and ROS production, but the rate of electron transport was restored and the ROS free amount was markedly reduced in the presence of NO. The specific activity of superoxide dismutase was not affected by diquat or NO donors, whereas just a small increase in catalase activity was observed after 24 h of treatment. These results provide strong evidence that NO is a potent antioxidant in plants and that its action may, at least in part, be explained by its ability to directly scavenge ROS.
Oxygen control of ethylene biosynthesis during seed development in Arabidopsis thaliana (L.) Heynh
Authors: Ramonell K. M. , Mcclure G. , Musgrave M. E. 
Published: March 2003

AbstractAn unforeseen side‐effect on plant growth in reduced oxygen is the loss of seed production at concentrations around 25% atmospheric (50 mmol mol−1 O2). In this study, the model plant Arabidopsis thaliana (L.) Heynh. cv. ‘Columbia’ was used to investigate the effect of low oxygen on ethylene biosynthesis during seed development. Plants were grown in a range of oxygen concentrations (210 [equal to ambient], 160, 100, 50 and 25 mmol mol−1) with 0·35 mmol mol−1 CO2 in N2. Ethylene in full‐sized siliques was sampled using gas chromatography, and viable seed production was determined at maturity. Molecular analysis of ethylene biosynthesis was accomplished using cDNAs encoding 1‐aminocyclopropane ‐1‐carboxylic acid (ACC) synthase and ACC oxidase in ribonuclease protection assays and in situ hybridizations. No ethylene was detected in siliques from plants grown at 50 and 25 mmol mol−1 O2. At the same time, silique ACC oxidase mRNA increased three‐fold comparing plants grown under the lowest oxygen with ambient controls, whereas ACC synthase mRNA was unaffected. As O2 decreased, tissue‐specific patterning of ACC oxidase and ACC synthase gene expression shifted from the embryo to the silique wall. These data demonstrate how low O2 modulates the activity and expression of the ethylene biosynthetic pathway during seed development in Arabidopsis.
Root elongation and branching is related to local hexose concentration in Arabidopsis thaliana seedlings
Authors: Freixes S. , Thibaud M‐C. , Tardieu F. , Muller B. 
Published: March 2003

AbstractRoot architecture can be profoundly affected by the carbon availability in the plant. We hypothesized that this effect could be mediated by the carbon status of root cells involved in elongation and branching processes. Arabidopsis thaliana plants were grown at several photosynthetic photon flux densities (PPFD) and were supplied with various sucrose concentrations in the root medium. Hexose and sucrose concentration was estimated in individual roots in the apical growing region of the primary root and of secondary roots as well as in the zone of primordia development. Local sugar concentration was high in fast‐growing and in highly branched roots and robust relationships between root elongation rate or branching and hexose concentration (but not sucrose) were found that were common to all situations experienced. Moreover, these relationships accounted for the plant‐to‐plant variability within a treatment as well as for the variability among individual secondary roots within a plant. These results support the view that local hexose concentration integrates changes in carbon availability from several sources and acts as a signal to induce at least part of the response of the root architecture to the environment.
The use of chlorophyll fluorescence excitation spectra for the non‐destructive in situ assessment of UV‐absorbing compounds in leaves
Authors: CEROVIC Z. G. , OUNIS A. , CARTELAT A. , LATOUCHE G. , GOULAS Y. , MEYER S. , MOYA I. 
Published: March 2003

AbstractIn this study a method was designed to assess non‐destructively the type of UV‐screening compounds present in the leaf epidermis. The method is based on the recording and calculation of the ratio of UV‐excitation spectra of chlorophyll fluorescence (FER) from the adaxial and abaxial sides of bifacial leaves, or from older and younger segments of monocotyledonous leaves. The logarithm of this ratio (logFER) matched the absorption spectrum of the UV‐absorbers present in the leaf, as confirmed by its overlap with the absorption spectrum of the methanolic extract of the leaf or of the isolated epidermis. By using the logFER approach, it was possible to demonstrate that the concentration but not the classes of compounds present in the epidermis that are responsible for UV‐screening is affected by the side and the age of the leaves. In contrast, measurements from the leaves of seven dicots and one monocot indicated large difference in the classes of these compounds between species. Finally, it was shown that the logFER in the UV is independent of the emission wavelength, and that the method can be used for quantitative measurements. This method expands to the spectral domain the use of ChlF for the estimation of the leaf epidermal transmittance.
Changes in populations of the eyespot fungiTapesia yallundaeandT. acuformisunder different fungicide regimes in successive crops of winter wheat, 1984–2000
Authors: Bierman S. M. , Fitt B. D. L. , Van Den Bosch F. , Bateman G. L. , Jenkyn J. F. , Welham S. J. 
Published: March 2003

Effects of regular treatments with the fungicides carbendazim and prochloraz applied to whole plots divided into subplots with different initial population mixtures of carbendazim‐sensitive or carbendazim‐resistantTapesia yallundaeorT. acuformiswere studied in successive crops of winter wheat from 1984/85 to 1999/2000. In unsprayed and carbendazim‐sprayed whole plots, a stable coexistence of about 50% each ofT. yallundaeandT. acuformisdeveloped within five seasons, but in whole plots sprayed with prochloraz or prochloraz plus carbendazim, the proportion ofT. acuformisincreased to > 80%. A discrete time difference equation model was derived from knowledge of the biology of eyespot and competition theory to describe the population changes. The model was fitted to the data from treatments where coexistence occurred [subplots in unsprayed (1985–92) and carbendazim‐sprayed (1985–89) whole plots], using nonlinear least squares regression. The optimized value of the resource overlap coefficient was small, suggesting niche differences between the two species. Populations were nearly 100% carbendazim‐resistant in carbendazim‐sprayed whole plots by July 1985 (one season) and in whole plots sprayed with prochloraz plus carbendazim by July 1986 (two seasons). In prochloraz‐sprayed whole plots, the proportion of carbendazim‐resistant isolates decreased more rapidly than in unsprayed whole plots in the 1980s, but by July 1992 a shift in populations in unsprayed and prochloraz‐sprayed whole plots towards predominantly carbendazim‐resistant strains had occurred.
Thick root of cucumber: other susceptible plants and the effect of pH
Authors: Van Der Gaag D. J. , Paternotte P. , Hamelink R. 
Published: March 2003

Thick root is a relatively new disorder of cucumber grown in artificial substrates. Plants of cucumber, tomato, sweet pepper, lupin, anthurium, Cucurbita ficifolia, C. maxima and two lines from crosses between C. maxima and C. moschata were grown in thick root disease (TRD)‐infested nutrient solutions containing the TRD agent. Plants from each species or line, except anthurium, developed TRD symptoms. Growth of diseased plants, except those of the line C. maxima ×C. moschata RS841, was significantly reduced compared with the nondiseased controls. Two weeks after infestation, by adding TRD‐affected nutrient solution to fresh nutrient solution, the presence of the infective TRD agent was shown in each of the nutrient solutions in which the plants had been grown, including anthurium. No infective TRD agent could be shown in nutrient solution that had not been in contact with roots of living plants. The minimum pH for thick root formation was shown to be between 5·0 and 5·5. Nutrient solutions with pH values ranging from 4·0 to 6·5 and infested with the TRD agent lost their infectivity within 8 days. The infective period decreased with decreasing pH (pH 4·0–6·5) and a pH effect on the infectivity of a nutrient solution was shown within 1 h of infestation. The data show that the risk of TRD can be reduced by decreasing the pH of the nutrient solution.
Apoptosis of the Teratocarcinoma Cell Line Tera‐1 Leads to the Cleavage of HERV‐K10gag Proteins by Caspases and/or Granzyme B
Authors: BEYER T. D. , KOLOWOS W. , DUMITRIU I. E. , VOLL R. E. , HEYDER P. , GAIPL U. S. , KALDEN J. R. , HERRMANN M. 
Published: March 2003

Redistribution, post‐translational modifications and coclustering with viral antigens contribute to the immunogenicity of apoptotic cell‐derived autoantigens. Almost all known targets of the humoral autoimmune response in systemic lupus erythematosus (SLE) are cleaved by caspases or granzyme B during apoptosis. Antibodies against retroviral proteins can frequently be detected in the sera of SLE patients without overt retroviral infections. These antibodies may represent cross‐reactive antibodies or may have been induced by proteins encoded by endogenous retroviral sequences. We used Tera‐1 cells that abundantly express a group‐specific antigen of human endogenous retroviruses, HERV‐K10gag polyprotein, to investigate its processing during apoptosis. Tera‐1 cells induced to undergo apoptosis showed an altered HERV‐K10gag processing compared with viable cells. In addition, granzyme B was able to cleave HERV‐K10gag isolated from viable Tera‐1 cells.Similar to nuclear autoantigens, endogenous retroviral proteins are cleaved during the execution phase of apoptosis. These post‐translational modifications may result in the generation of T‐cell neoepitopes or a changed epitope hierarchy of retroviral proteins. Therefore, immunogenicity of retroviral antigens in SLE patients may result from a similar mechanism as described for nuclear autoantigens.
Staphylococcal Enterotoxin B Upregulates Fas‐Mediated Apoptosis of Peripheral Blood Mononuclear Cells in Childhood Atopic Dermatitis
Authors: Sohn M. H. , Kim J.‐W. , Kim W. K. , Jang G. C. , Kim K.‐E. 
Published: March 2003

AbstractStaphylococcal infection‐producing superantigens, such as staphylococcal enterotoxin B (SEB), are presumed to play an important role of inflammatory processes in atopic dermatitis (AD). The aim of this study was to elucidate the apoptotic response of peripheral blood mononuclear cells (PBMCs) from children with AD. PBMCs from AD children were sampled and cultured with SEB stimulation. Levels of apoptosis and Fas expression were measured using flow cytometry; the soluble Fas ligand (sFasL) was also measured using the enzyme‐linked immunosorbent assay method, and the expression of FasL in PBMCs was observed using reverse transcriptase‐polymerase chain reaction. There was no difference in the initial levels of apoptosis and Fas expression in precultured PBMCs of AD patients and healthy donors. After culturing for 48 h under SEB stimulation, the apoptosis level and Fas expression were significantly upregulated in the PBMCs from AD children compared with that from the normal controls. In patients, the sFasL was significantly increased, and the expression of FasL was observed in messenger RNA of peripheral monocytes. These results suggest that the Fas/FasL system is involved in the apoptosis induced by SEB in AD, with simultaneous increases in sFasL and expression of FasL.
The Vigny limestones: a record of Palaeocene (Danian) tectonic‐sedimentary events in the Paris Basin
Authors: Montenat Christian , Barrier Pascal , D'Estevou Philippe Ott 
Published: March 2003

AbstractDanian marine sedimentation in the Paris Basin occurred between two major erosional phases. The earlier was responsible for the stripping of presumably deposited Maastrichtian sediments and of a variable thickness of Campanian chalk. The later occurred during the late Palaeocene and resulted in the erosion of almost all Danian deposits, which are now limited to small and scattered outcrops. One of these outcrops corresponds to reefal and peri‐reefal limestones of middle to late Danian age, exposed in the quarries of Vigny (NW of Paris). Danian deposits here show intricate relations with the surrounding Campanian chalk. Danian sedimentation was contemporaneous with faulting, which generated signifiant sea‐floor relief and resulted in contrasting depositional areas: topographic highs with coralgal reefs, and depressions where calcirudite channel fill accumulated. Normal faulting occurred along WNW–ESE master faults. The generation of submarine fault scarps gave rise to various types of gravity‐driven phenomena, including the sliding and slumping of large blocks of reefal limestone and the deposition of carbonate debris flows. Along with the redeposition of the Danian carbonates, flows of fluidized and reworked Campanian chalk resulted from the peculiar physical properties of the undercompacted chalks. Erosion and faulting occurred predominantly during the Palaeocene and represent a major episode in the physiographic evolution of the Paris Basin.
The genus Pnyxiopalpus gen.n. (Diptera: Sciaridae)
Authors: Vilkamaa Pekka , Hippa Heikki 
Published: March 2003

Summary Pnyxiopalpus gen.n. (type‐species P. raptor sp.n.), Oriental in distribution, includes the following species: P. acanthipes sp.n. (Malay Peninsula), P. aculeatus sp.n. (Borneo), P. adebratti sp.n. (Borneo), P. aphrodite sp.n. (Sumatra), P. dentaneus sp.n. (Sulawesi), P. fossor sp.n. (Borneo), P. fuscinellus sp.n. (Borneo), P. hamatus sp.n. (Borneo), P. latifalx sp.n. (Borneo), P. macrocellus sp.n. (Malay Peninsula), P. microdon sp.n. (Sumatra), P. nepenthophilus sp.n. (Malay Peninsula), P. noona sp.n. (Palawan), P. raptor sp.n. (Borneo), P. reticulatus sp.n. (Malay Peninsula) and P. simplex sp.n. (Borneo). Males and females are keyed and described. Pnyxiopalpus has a number of characters previously unknown in Sciaridae. In contrast to other Sciaridae, interspecific morphological variation is greater for the females compared to the males. Based on a parsimony analysis of sixty‐four morphological characters, Pnyxiopalpus is monophyletic, and its sister group appears to be Spathobdella Frey + {[Peyerimhoffia Kieffer + (Faratsiho Paulian + Pnyxia Johannsen)] + [Hyperlasion Schmitz + (Hermapterosciara Mohrig & Mamaev + Parapnyxia Mohrig & Mamaev)]}. According to the most parsimonious solution, the monophyly of Hyperlasion, Lycoriella Frey and Plastosciara Berg in their current sense is questioned. Aptery and one‐segmented maxillary palp, usually regarded as important in sciarid classification, show a lot of homoplasy.
Aeromagnetic map constrains cratonization of the Arabian Shield
Authors: Nehlig Pierre , Asfirane Fawsia , Genna Antonin , Guerrot Catherine , Nicol Nadège , Salpeteur Ignace , Shanti Mohammed , Thiéblemont Denis 
Published: March 2003

A new aeromagnetic map together with new geological and geochronological data has led to a reinterpretation of the geological history of the Arabian Shield.The magnetic anomalies outline an orogenic complex containing a network of mostly left‐lateral strike‐slip faults, including the Nabitah Belt and several peripheral mountain ranges. Oblique accretion resulted in obliteration of early volcanic‐arc magnetic fabrics, which were almost completely replaced by a NW–SE magnetic fabric in the northern Shield; the southern Shield, however, reveals extensive E–W anomalies related to post‐accretion magmatic intrusions. This complex web of orogenic zones is intimately associated with synchronous molasse basins that formed 680–610 Ma.The distribution and chronology of orogenic zones, related to the closing of East and West Gondwana, brings into question several earlier assumptions, such as high continental growth rates, palaeogeodynamic reconstructions, the definitions of the Nabitah and Najd faults, and the significance of molasse basins.
A Brassica napus transcript encoding a protein related to the Kunitz protease inhibitor family accumulates upon water stress in leaves, not in seeds.
Authors: Downing WL , Mauxion F , Fauvarque MO , Reviron MP , De Vienne D , Vartanian N , Giraudat J 
Published: March 2003

SummaryA cDNA clone encoding a Brassica napus drought‐induced 22 kDa (BnD22) protein has been isolated and characterized. The BnD22 transcript accumulated in response to drought reversibly, and to other conditions of leaf water deficit such as rapid water stress or salt acclimation, but not to cold acclimation or heat shock. Exogenously applied abscisic acid induced both changes in leaf morphology similar to the drought‐ adaptive response and a pronounced accumulation of the BnD22 mRNA. In control and drought‐adapted plants, the BnD22 transcript was expressed in an organ‐specific manner: the mRNA level was highest in leaves, low in hypocotyls and undetectable in roots. Sequence analysis indicates that the BnD22 protein is related to the Kunitz family of protease inhibitors. In contrast to most members of this family, and also to most polypeptides expressed in vegetative tissues upon drought, the BnD22 mRNA was absent in seeds, before or during the seed desiccation phase. The BnD22 gene represents a new class of genes which are strictly induced in vegetative tissues upon environmental stress, and its pattern of expression shows that the responses to water deficit differ, at least partially, in seeds and in leaves.