bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient Stimulation of Oxygen Uptake Induced by Sulfhydryl Reagents in Egeria densa and Potamogeton crispus Leaves
Authors: Bellando M. , Sacco S. , Albergoni F. , Rocco P. , Marrè Maria Teresa 
Published: February 2014

Abstract:A vigorous and transient increase of O2 uptake associated with a simultaneous release of CO2 was elicited in Egeria densa and in Potamogeton crispus leaves by treatment with N‐ethylmaleimide (NEM) and by other ‐SH group reagents (iodoacetate, p‐(chloromercuri)benzenesulfonate (p‐CMBS), Ag+, Hg2+, Cu2+). The NEM‐induced respiratory burst was apparent even in the absence of photosynthesis (darkness, or presence of DCMU) as well as in the presence of the respiration inhibitors cyanide and propyl gallate or SHAM, separate or in combination. In contrast, a complete suppression of the respiratory burst was induced by diphenylene iodonium and by quinacrine, inhibitors of the plasma membrane NADPH oxidase activated in the pathogen‐elicited oxidative burst in granulocytes and in plants. The respiratory burst induced by NEM and by the uncoupler CCCP were additive. The intensity of the respiratory burst was markedly decreased by increasing the pH of the medium from 5 to 8, and partially decreased by the presence of K+ in the medium. Azide inhibited the burst (as well as basal respiration) at pH 6.5 but not at pH 5. The stimulation of QO2 by SH reagents was associated with an early, pronounced membrane depolarization together with a rapid increase of the release into the medium of K+ and other electrolytes, and with a rapid decrease of the intracellular ATP, ADP and G6 P contents. The possible relationships between this SH reagent‐induced respiratory burst and the associated effects on Em and electrolyte leakage are discussed.
Mechanism of Protein Targeting to the Chlorarachniophyte Plastids and the Evolution of Complex Plastids with Four Membranes — A Hypothesis
Authors: Bodyl A. 
Published: February 2014

Abstract:Chlorarachniophyta are phototrophic amoeboflagellates, with plastids surrounded by four membranes. Contrary to other plastids of this type which occur in chromists, their outermost membrane bears no ribosomes. It is argued that the nuclear‐encoded chlorarachniophyte plastid proteins are first transported into the ER, then to the Colgi apparatus, and finally to the plastids. The same import mechanism could be originally present in the chromist ancestor, prior to the fusion of their plastids with the RER membranes. According to the most recent concept, the complex plastids of Chromista and Chlorarachniophyta have evolved through replacement of the cyanobacterial plastids. The assumption that these plastids had an envelope composed not of two, but of three membranes makes it possible to avoid the erlier discerned difficulties with conversion of a eukaryotic alga into a complex plastid. My scenario provides an additional support to the hypothesis on polyphy‐letic origin of four‐membraned plastids.
Biochemical Characterization of Plasma Membrane Vesicles of Cyanophora paradoxa*
Authors: Heimann Kirsten , Becker B. , Harnisch Helga , Mukherjee K. D. , Melkonian M. 
Published: February 2014

Abstract:Plasma membrane vesicles (PMVs) were isolated from Cyanophora paradoxa Korshikov (Claucocystophyta) and purified by differential and sucrose density gradient centrifugation. PMVs were identified ultrastructurally and biochemically using marker enzymes. Analysis of monosaccharides revealed a sugar content of 37.3% of dry weight of delipidated PMVs with high amounts of fucose (28 mol% of total carbohydrate), galactose (23%), mannose (21%) and the minor constituents xylose, rhamnose, glucose and N‐acetylglucosamine. Proteins were analyzed by SDS‐PACE. More than 20 polypeptides were resolved and several were identified as glycopeptides, as shown by PAS staining and lectin blots. Fucose linked α‐1→6 to N‐acetylglucosamine (AAA‐binding), mannose linked α‐1→2,3,6 to mannose (CNA‐binding) and terminally bound galactose (RCA‐binding) were identified on several polypeptides. Sterols (β‐sitosterol and an additional unknown sterol, 40% of total lipids) and diacylglycerol (43%) are the major lipid components in the PMVs of C. paradoxa. Minor components are PE, PC, PC and an unknown glycolipid. Fatty acid analysis revealed 12 different fatty acids, predominantly 16:0,18:0 and the polyunsaturated acids 20:4 and 20:5 (together 69% of total fatty acids), α‐Linolenic acid, common in higher plant PMs, could only be detected as a minor constituent (< 1 %) of PMVs of C. paradoxa.
The G4 Gene of Arabidopsis thaliana Encodes a Chlorophyll Synthase of Etiolated Plants
Authors: Oster U. , Rüdiger W. 
Published: February 2014

Abstract:The gene coding for a putative chlorophyll synthase gene (C4) from Arabidopsis thaliana was amplified by the polymerase chain reaction and cloned into the expression vector pQE‐ 31. Lysates of bacteria (E.coli) that had been transformed with this construct were used for in vitro enzymatic assays. The chlorophyll synthase catalyzed esterification of chlorophyllides a and b at the same rate but preferred geranylgeranyl‐PP over phytyl‐PP. This corresponds to the enzyme specificity previously described for etiolated plants and differed from that of green plants.
In Situ Localization of Phenylpropanoid Biosynthetic mRNAs and Proteins in Parsley (Petroselinum crispum)
Authors: Reinold Susanne , Hahlbrock K. 
Published: February 2014

Abstract:Using in situ RNA/RNA hybridization, enzyme immunolocalization, and histochemical techniques, several phenylpropanoid biosynthetic activities and products were localized in tissue sections from various aerial parts of parsley (Petroselinum crispum) plants at different developmental stages. The enzymes and corresponding mRNAs analyzed included two representatives of general phenylpropanoid metabolism: phenylalanine ammonia‐lyase (PAL) and 4‐coumarate: CoA ligase (4CL), and one representative each from two distinct branch pathways: chalcone synthase (CHS; flavonoids) and S‐adenosyl‐L‐methionine: bergaptol O‐methyltransferase (BMT; furanocoumarins). In almost all cases, the relative timing of accumulation differed greatly for mRNA and protein and indicated short expression periods and short half‐lives for all mRNAs as compared to the proteins. PAL and 4CL occurred almost ubiquitously in cell type‐specific patterns, and their mRNAs and proteins were always coordinately expressed, whereas the cell type‐specific localization of flavonoid and furanocoumarin biosynthetic activities was to a large extent mutually exclusive. However, the distribution patterns of CHS and BMT, when superimposed, closely matched those of PAL and 4CL in nearly all tissues analysed, suggesting that the flavonoid and furanocoumarin pathways together consituted a large majority of the total phenylpropanoid biosynthetic activity. Differential sites of synthesis and accumulation indicating intercellular translocation were observed both for flavonoids and for furanocoumarins in oil ducts and the surrounding tissue. The widespread occurrence of both classes of compounds, as well as selected, pathway‐specific mRNAs and enzymes, in many cell types of all parsley organs including various flower parts suggests additional functions beyond the previously established roles of flavonoids in UV protection and furanocoumarins in pathogen defence.
Variations of the Surface Sculpture and Cell Wall Ultrastructure of the Zygospores in Chlamydomonas geitleri (Chlorophyta)
Authors: Sulek J. 
Published: February 2014

Abstract:The superficial cell wall ornamentation in the zygospores of the alga Chlamydomonas geitleri Ettl (Chlorophyta) is formed by thickenings of the cell wall which are shaped into a network of anastomosing ribs, sometimes with local wart‐like protuberances. Clearly different sculpture patterns (given by presence, arrangement and/or morphological modification of sculpture elements) were accompanied by many transient forms. Sculpture variations occurred even in clonal cultures. In the zygospore cell wall of C. geitleri, the inner, outer and middle layer can be distinguished from the morphological point of view. The relatively thin outer (sporopollenin) layer covers the whole surface of the zygospore wall. The thicker inner layer adhering to the zygospore protoplast forms, either solely or together with the middle layer (possessing a fine meshwork substructure), variously shaped thickening of the zygospore cell wall. Discussed are the ultrastructural morphology of the cell wall in Chlamydomonas zygospores, the striking similarity of the cell wall ultrastructure of zygospores in C. geitleri to the ultrastructure of the cell wall of vegetative cells in some green algae (subfamily Scotiellocystoideae), as well as the extensive morphological variability of the zygospore wall sculpture in C geitleri and its species specificity.
Stem Anatomy of Uebelmannia (Cactaceae) — with Special Reference to Uebelmannia gummifera
Authors: Nyffeler R. 
Published: February 2014

Abstract:The three species of Uebelmannia (Cactaceae: Cactoideae; endemic to Minas Cerais, Brazil) are noteworthy for their tough, bumpy stem surface and the presence of conspicuous mucilage cavities restricted to the outer part of the stems. The anatomy of the mature structures and their ontogeny was investigated from microtome sections. The uncommon surface relief is caused by groups of unequally elongated hypodermis cells. The mucilage cavities consist of solitary and considerably enlarged mucilage cells (U.buiningii and U. pectinifera). In U.gummifera groups of mucilage cells disintegrate and form large cavities which are finally united into longitudinal ducts. A comparison of these stem features with species of the superficially similar genera Islaya and Wigginsia (representing tribe Notocacteae), does not indicate a close phylogenetic relationship between Uebelmannia and members of tribe Notocacteae. Finally, some short comments touch on the adaptational aspect of the characteristic stem features of Uebelmannia.
Pollination and Breeding System of two Co‐Occurring Hirtella Species (Chrysobalanaceae) in Central Brazil
Authors: Arista M. , Oliveira P. E. , Gibbs P. E. , Talavera S. 
Published: February 2014

Abstract:The phenology, major floral characteristics, breeding systems and fruiting success of two co‐occurring species of Hirtella: H. glandulosa and H.gracilipes (Chrysobalanaceae) were studied in Central Brazil. The two species occur as trees in mesophyllous forests but H. glandulosa is frequent also in dense savanna areas. Both species flower at the end of the dry season (September) and have flowers with one‐day longevity. In both species flowers produce nectar and are pollinated exclusively by butterflies. The number of visits recorded and pollination rate in each species were significantly different and indicate that pollinators prefer H. glandulosa flowers. Natural and controlled fruit sets were low in both species. The index of self‐incompatibility (ISI) was 0.17 in H. glandulosa and 0.86 in H. gracilipes. Although ISI in H. glandulosa could denote an incompatibility system, the presence of fruits with aborted embryos at different degrees of development point to an inbreeding depression situation. Low pollen viability and fruit set in H. gracilipes suggested reproductive problems which may be linked to hybridization events.
Hydrodynamics and Biomechanics of the Submerged Water Moss Fontinalis antipyretica ‐ a Comparison of Specimens from Habitats with Different Flow Velocities
Authors: Biehle C. , Speck T. , Spatz H.‐Ch. 
Published: February 2014

Abstract:Flow velocity has an influence on the hydrodynamic and biomechanical properties, as well as on the morphology and the anatomy of the submerged water moss Fontinalis antipyretica Hedw. Cross‐sections of the plant stems show two main types of tissues. The strengthening tissue in the outer part is characterized by thick‐walled cells with a small lumen, the parenchyma in the centre by thin‐walled cells with a large lumen. The specimens from habitats of different flow velocities differ in the proportions of the strengthening tissue and the branching angle of the leaves.A flow tank with a special sensitive two‐component balance inserted into the bottom of the flume was used to measure the hydrodynamic drag, which acts on the plant stems at different flow velocities. The drag forces increase with the length of the plant.Mechanical properties such as elasticity and ultimate strength of the plant stems were tested in tension. Relating the data to the relative proportions of the strengthening tissue results in different estimates of Young's moduli for the strengthening tissue of plants from the different sites. The critical strains to which the stems can be extended are remarkably high. Loading and unloading cycles reveal viscoelastic behaviour of the stem tissues. In the first cycle plastic deformation is also observed, but only to a lesser degree in subsequent cycles.
Influence of the Parasite Pilostyles ingae (Rafflesiaceae) on some Physiological Parameters of the Host Plant, Mimosa naguirei (Mimosaceae)*
Authors: Fernandes G. W. , De Mattos E. A. , Franco A. C. , Lüttge U. , Ziegler H. 
Published: February 2014

Abstract:plants found at this site were densely covered by flowers of the parasite on their stems indicating heavy development of cellular The holoparasite/host interaction of Pilostyles ingae (Karst.) Hook. f. (Rafflesiaceae) and Mimosa naguirei Barneby (Mimosaceae) was studied in the open campo rupestre vegetation of Serra do Cipó (State of Minas Gerais, Brazil). Infected M. naguirei threads of the parasite in the bark of the hosts. Cellular threads of the parasite are likely to be richer in lipids and hence depleted in 13C. This may explain the significantly more negative carbon isotope ratios (δ13C values) of the bark of infected host plants observed as compared to other tissues of infected and non‐infected host plants. Photosynthetic parameters such as potential quantum yield of photosystem II (Fv/Fm), apparent photosynthetic electron transport rates (ETR) and effective quantum yield of photosystem II (A F/F'm) in light dependence curves, as well as δ13C values of leaves as a relative measure of average intercellular CO2 partial pressure during photosynthesis over the lifetime of the leaves, which is also related to average stomatal conductance via water use efficiency, were remarkably similar. This suggests a well balanced relation between the Mimosa host and the Pilostyles parasite, in contrast to other hemiparasitic angiosperm parasite/host interactions where the parasite (e.g. Striga) is known to have strong detrimental effects on host photosynthesis.
Mitochondrial DNA Variation Follows a Geographic Pattern in Japanese Beech Species
Authors: Koike T. , Kato S. , Shimamoto Y. , Kitamura K. , Kawano S. , Ueda K. , Mikami T. 
Published: February 2014

Abstract:The amount and distribution of mitochondrial (mt) DNA restriction fragment length polymorphism was determined among individual tree samples of two Japanese beech species, Fagus crenata and F.japonica. Individual plants were collected from 16 F. crenata populations throughout the range of the species, and from three F. japonica populations. We detected enough variation to characterize eleven and three chondriome types in F. crenata and F.japonica, respectively. The grouping of beech chondriome types based upon the cladistic analysis of mtDNA polymorphism allowed us to recognize the apparent geographical patterns of mtDIMA diversity: the resulting three main groups occupied distinct geographic areas. This geographic differentiation is likely to reflect the history of the Japanese beech forests after the last glacial period of the Pleistocene. In addition, the mtDNA polymorphism encountered within F. crenata encompassed all the variation observed in F.japonica. Our result suggests the need for re‐evaluation of their phylogenetic relationships.
Moss (Physcomitrella patens) Expressed Sequence Tags Include Several Sequences which are Novel for Plants*
Authors: Reski R. , Reynolds Susan , Wehe M. , Kleber‐Janke Tamara , Kruse S. 
Published: February 2014

Abstract:The moss Physcomitrella patens (Hedw.) B.S.G. is the first land plant in which gene disruption by homologous recombination Is directly accessible. In order to obtain cloned sequences which may be used in such an approach, complementary DNAs (cDNAs) have been isolated by subtractlve hybridisation of representative cDNA libraries from cytoklnin‐treated tissue. Sequencing of these clones from both ends yielded over 35 kb of non‐redundant sequence Information, of which 20 kb results from clones which appear to be novel to plants. Database comparisons have revealed that 39 of the expressed sequence tags (ESTs) generated show significant homology to identified sequences. Analysis of these ESTs shows a high degree of conservation between Physcomitrella and seed plant sequences, and codon usage is found to be very similar to that In dicotyledonous species. Furthermore, 43 sequences showing no significant homology to sequences in the databases represent previously unidentified expressed genes.
Phenology, Seed Development, and Reproductive Success of an Alpine Population of Centianella germanica in Climatically Varying Years
Authors: Wagner J. , Mitterhofer E. 
Published: February 2014

Abstract:During the growing seasons of 1994–1996, the reproductive fitness of an autumn flowering population of G. germanica was assessed at 1980 m in the Austrian Alps. The warmest year of the last two centuries in Austria was 1994, 1995 was a normal year, and the summer of 1996 was exceptionally cold. The Investigations were carried out on large, early‐flowering individuals (L‐plants) and on small, mainly late‐flowering individuals (S‐plants). In both size classes, the sequence of phenophases varied in response to the contrasting climatic conditions of these years. In 1994, peak flowering In L‐plants occurred about one month earlier than in S‐plants; in 1995 and 1996, the periods of full bloom overlapped partially and fully for the two size classes, respectively. Detailed analyses of seed development and thermal time revealed that low temperatures during histogenesis led to remarkable delays in the Initiation of seed and fruit development, whereas seed filling and seed maturation were largely Independent of temperature. Self‐pollination resulted in high seed sets. Irrespective of weather conditions and dates of flowering. In both size classes, the seed: ovule ratio of mature fruits was about 0.9 and 0.75, in apical and basal positions of the stalks, respectively. The fruit: flower ratios, however, depended on temperature; the ratio was around 0.8 in 1994 and below 0.5 in 1996. In the cool year 1996, fruit development was so slow that in many individuals only the fruits in the apical positions of the stalks matured before the onset of winter conditions.
Pyrophosphate as an Energy Donor in the Cytosol of Plant Cells: an Enigmatic Alternative to ATP
Authors: Stitt M. 
Published: February 2014

Abstract:Pyrophosphate serves as an alternative energy donor to ATP for sucrose mobilisation via sucrose synthase, for glycolysis via pyrophosphate: fructose‐6‐phosphate phosphotransferase, and for tonoplast energisation via the tonoplast proton‐pumping pyrophosphatase. This review considers the possible roles of these pyrophosphate‐driven reactions. Correlative evidence based on expression patterns, the distribution of proteins and activities in various tissues, and comparisons of the in vitro properties of the enzymes with thein vivometabolite levels indicates an important role in young growing tissues and in stress conditions including anaerobiosis, but interpretation is complicated by the reversibility of the pyrophosphate‐driven reactions and by their duplication by ATP‐dependent reactions. The review then considers the evidence emerging from experiments using reversed genetics to alter expression of sucrose synthase, the pyrophosphate: fructose‐6‐phosphate phosphotransferase, and the tonoplast proton‐pumping pyrophosphatase. This approach has revealed that sucrose synthase plays an essential role in sucrose breakdown in potato tubers, and that pyrophosphate: fructose‐6‐phosphate phosphotransferase catalyses a near‐equilibrium reaction with a net flux in the direction of glycolysis. However, it does not support a special role of the latter enzymes in stress responses. Interpretation is complicated by compensation, which can include expression of other members of a gene family, use of alternative pathways, and relaxation of the feed back regulation in response to decreased expression of the enzyme. In an alternative approach, ectopic overexpression of soluble pyrophosphatase fromE. colihas been used as a tool to decrease the levels of pyrophosphate in the cytosol. Constitutive overexpression leads to dramatic changes in sucrose and starch synthesis, sink‐source relations and plant growth, phloem‐specific overexpression of soluble pyrophosphatase leads to an inhibition of phloem transport, leaf mesophyll‐specific overexpression leads to a small stimulation of sucrose synthesis, and potato tuber‐specific overexpression leads to an inhibition of starch accumulation.
Use of Genetically Improved Nitrogen‐Fixing Cyanobacteria in Rice Paddy Fields: Prospects as a Source Material for Engineering Herbicide Sensitivity and Resistance in Plants
Authors: Vaishampayan A. , Sinha R. P. , Häder D.‐P. 
Published: February 2014

Abstract:Cyanobacteria are the largest and most widely distributed group of photosynthetic prokaryotes on Earth, forming a prominent component of microbial populations in wetland soils, especially in rice paddy fields, and significantly contributing to fertility as a natural biofertilizer. Modern agricultural fields are generally treated with high doses of synthetic nitrogenous fertilizers and pesticides having adverse effects on the soil microflora of naturally occurring N2‐fixing cyanobacteria. This review deals with some of the advances made during the last few decades in the areas of developing ammonia derepressible pesticide‐resistant cyanobacterial mutants for algalization of the wet agricultural fields as a viable and efficient N‐photobiofertilizer.
Carbon Isotope Discrimination in Cyanobacteria of Rocks of Inselbergs and Soils of Savannas in the Neotropics*
Authors: Ziegler H. , Lüttge U. 
Published: February 2014

Abstract:An extensive set of data on carbon isotope ratios in samples of terrestrial cyanobacteria from the surface of rocks of inselbergs and soils of savannas in the neotropics is presented. A comparison of the data shows two surprising features. First, all values deviate from the 13C discrimination of carboxylation by ribulose‐bis‐phosphate carboxylase/oxygenase (RuBISCO) which is generally about −27‰. They are less negative than that by between 0.62‰ and 10.46‰. Second, the values show a considerable variation, minima and maxima being −26.38‰ and −16.54‰, respectively. This variation cannot be explained by differences in dominant taxa in the samples. It must be related to microsite characteristics, most probably the extent in time of coverage by liquid water, where diffusion of CO2 constitutes a limiting step with a lower discrimination against 13C than that of carboxylation via RuBISCO.