bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemistry, Anatomy and Morphology of Foliicolous Species ofFellhaneraandBadimia(Lichenized Ascomycotina: Lecanorales)
Authors: Lücking R. , Lumbsch H. T. , Elix J. A. 
Published: February 2014

AbstractA comparison of secondary chemistry and a variety of anatomical and morphological characters ofFellhaneraandBadimia(Pilocarpaceae) has been conducted in an effort to clarify the systematic position of both genera. Based on our results we conclude thatFellhaneraandBadimiaare closely related and separated mainly by the slightly different paraphyses, amyloid reactions of their asci, apothecial size, and the presence or absence of campylidia.Fellhanera badimioidessp.n. is described, and the following systematic changes are proposed:Badimia cateilea(Vain.) comb.n.B. lecanorina(Zahlbr.) comb.n.,B. tuckermanii(R.Sant.) comb.n. andFellhanera stanhopeae(Müll. Arg.) comb.n.
Expression of Polarity during early Development of Microspore‐derived and Zygotic Embryos of Brassica napus L. cv. Topas
Authors: Hause B. , van Veenendaal W. L. H. , Hause G. , van Lammeren A. A. M. 
Published: February 2014

AbstractMicrospore derived (MS‐)embryogenesis and zygotic embryogenesis of Brassica napus L. cv. Topas were investigated by light and scanning electron microscopy to reveal the expression of polarity during the transition phase from globular to heart and torpedo shape.During the first 5 days of MS‐embryo formation, the cell wall of the former microspores remained intact and a globular mass of cells developed within. Pollen walls ruptured after 5 days of culture; embryos proceeded through heart‐shape and torpedo‐shape stages within 15 days in a way comparable to, but faster than observed during zygotic embryogenesis.Expression of polarity in globular and elongating MS‐embryos was analyzed by detection of the distribution of activated calmodulin as well as of free cytosolic calcium by using confocal scanning laser microscopy, and by the detection of starch. Calmodulin was evenly distributed in globular embryos and only exhibited clear polar distribution in elongated embryos. Free cytosolic Ca2+ accumulated in the protoderm of globular embryos and in the central cylinder of torpedo shaped embryos, but never showed polar distribution. Accumulation of starch granules at the root poles of both sexual as well as MS‐embryos, however, indicated polar distribution before the transition from globular to heart shape stage. Since the local rupture of the pollen wall of 6‐day‐old MS‐embryos was never preceded by the decrease of starch at that site, it is likely that the rupture of the pollen wall plays an important role in the local activation of cell metabolism and thus in the determination of the polarity axis in MS‐embryos.
Influence of Drought, Rain and Artificial Irrigation on Photosynthesis, Gas Exchange and Water Relations of the Fynbos PlantProtea acaulos(L.) Reich at the End of the Dry Season
Authors: Herppich Margaretha , Herppich W. B. , VON Willert D. J. 
Published: February 2014

AbstractProtea acaulos, a prostrate fynbos shrub, often experiences very low air humidity at leaf temperatures over 10°C higher than mean air temperature. We determined to what degree this particular microclimate influenced photosynthetic performance, leaf conductance and water relations of non‐irrigated and trickle‐irrigated plants. Measurements were made at the end of the dry summer season in the sand plain lowland fynbos on the west coast of South Africa. Independent of water supply, plants showed a pronounced midday depression of gas exchange. While in non‐irrigated plants leaf water potential dropped to − 2.0 MPa around noon, it never fell below −1.0 MPa in irrigated plants. On the other hand minimum pressure potential was similar in irrigated and non‐irrigated plants. The latter showed higher turgor after rain, due to osmotic acclimation, which resulted from a reduction in maximum water volume. The main osmoticum was 1,5‐anhydro‐D‐glucitol. Leaf temperature, directly or via the vapour pressure deficit between leaf and air (Δw), rather than plant water status, was the determinant of the midday depression of gas exchange. High Δw caused stomatal closure during times of saturating light, thus limiting photosynthetic CO2uptake and availability and enhancing the susceptibility for photoinhibition. This, as well as high leaf temperature per se, decreased the efficiency of photochemistry of photosystem II. Initial fluorescence remained constant until temperatures exceeded 35 °C, above which changes in fluorescence indicated both photoinhibition and heat stress. Unlike other fynbos plants,Protea acauloscould not use the improved soil water supply to increase carbon gain under hot summer condition.
Effect of Extracellular Ca2+ and Ca2+‐Antagonists on the Movement and Chemoorientation of Male Gametes of Ectocarpus siliculosus (Phaeophyceae)
Authors: Maier I. , Calenberg M. 
Published: February 2014

AbstractChemoorientation in male gametes of Ectocarpus siliculosus in response to sexual pheromones is effected by two distinct mechanisms, chemokinesis and chemoklinotaxis. These are characterized by a strongly asymmetric bending pattern of the anteriorly‐directed flagellum and transient unilateral bending of the hind flagellum, respectively. Removal of extracellular Ca2+ showed that normal flagellar movement and chemokinesis require millimolar concentrations of Ca2+ in the medium. The response to pheromones is strongly inhibited by La3+, whereas the Ca2+‐channel drugs, verapamil and nifedipine, have only little effect. Nifedipine nethertheless effectively inhibited accumulation at pheromone sources. These results are interpreted as an indication for the involvement of two pharmacologically distinct Ca2+‐channels in chemokinesis and chemoklinotaxis. The calmodulin‐antagonist, trifluoperazine, induces, at low concentrations, the same flagellar response in chemokinesis as the pheromone, the mechanism of action remaining unknown.
Subcellular Volumes and Metabolite Concentrations in Potato (Solanum tuberosum cv. Désirée) Leaves1
Authors: Leidreiter Kirsten , Kruse Anne , Heineke D. , Robinson D. G. , Heldt H.‐W. 
Published: February 2014

AbstractCellular and subcellular volumes in mature leaves of potato (Solanum tuberosum cv. Désirée) were determined stereologically from light and electron micrographs. Leaves of ten‐week‐old plants with a total leaf volume of 623 μL per mg chlorophyll (Chl) were found to be composed of 12 % epidermis, 68 % mesophyll, 5 % vascular tissue, 3 % apoplast and 16 % gas space. In the epidermal cells 97 % of the volume was occupied by the vacuole. The mesophyll cells consisted (as expressed per mg Chl) of 323 μL (76 %) vacuole, 35 μL (8 %) chloroplast stroma, 22 μL (5 %) cytosol plus nucleus and peroxisomes, and 4μL, (1 %) mitochondria. A comparison of these values with subcellular volumes previously determined for spinach and barley leaves, shows that the relative sizes of the subcellular volumes are strikingly similar. Subcellular concentrations of carbohydrates, of the phosphorylated intermediates of carbohydrate metabolism, of malate, and of amino acids have been evaluated from measurements of the corresponding subcellular metabolite contents determined using the non‐aqueous fractionation technique. Malate, glucose and fructose were found to accumulate in the vacuole, whereas the concentration of sucrose and amino acids in the cytosol were much higher than in the vacuole. The amino acid concentration in the chloroplast stroma is similar to that in the cytosol. Phosphorylated intermediates of carbohydrate metabolism are confined to the chloroplast stroma and the cytosol, confirming the validity of the fractionation method. Whereas triose phosphates and fructose‐l,6‐bisphosphate are concentrated in the stroma, the concentrations of hexose monophosphates were highest in the cytosol. Since the subcellular metabolite distribution in potato leaves reported here is very similar to that previously described for spinach and barley leaves, we conclude that it may be characteristic for mesophyll cells in general.
Quantitative Stress Responses of the V0V1‐ATPase of Higher Plants Detected by Immuno‐electron Microscopy
Authors: Ratajczak R. , Hille Angela , Mariaux J.‐B. , Lüttge U. 
Published: February 2014

AbstractImmuno‐electron microscopy of negatively stained isolated tonoplast vesicles was used to quantify stress responses of the H+‐transporting tonoplast ATPase (V0V1‐ATPase; EC 3.6.1.1) of the C3/CAM intermediate Mesembryanthemum crystallinum L. and the C3 plant Hordeum vulgare L. This approach has the advantage that it relates quantitative adaptations at the level of membrane enzymes directly to membrane area and thus is independent of concomitant changes of relative amounts of other membrane proteins which may perturb conclusions when data are expressed on a tonoplast protein basis.It was shown that in M. crystallinum the amount of V0V1‐ATPase per unit membrane area increased slightly with ageing and pronouncedly with salinity stress. In H. vulgare under salt stress there was an increase in V0V1‐ATPase amount only in the highly salt tolerant cv. California Mariout and not in the moderately tolerant cv. Carina. This corroborates conclusions from earlier work, where results were expressed on a protein basis, although this was not to be expected a priori. In all comparative ecophysiological studies using tonoplast vesicles at least some key‐point tests with the immunonegative staining technique should be included for the sake of prudence. The data obtained here via immunonegative staining of isolated tonoplast vesicles are in very close agreement with much earlier assessments of area and whole cell‐related activities given by measurements of entire isolated vacuoles and morphometric analysis, which further corroborates the suitability of the approaches.The data presented here for the first time allow calculations of the coverage of the tonoplast surface of M. crystallinum with V0V1‐ATPase holoenzyme protein and with total tonoplast protein, i.e. 1.5 to 2.3 . 10−15 g V0V1‐ATPase per μm2 and 7.4 to 8.8 . 10−15 g protein per μm2, respectively.
Anatomical Structures of the VA Mycorrhiza in the Apocynaceae (Gentianales)
Authors: Weber H. Chr , Klahr A. , Marron‐Heimbuch M. 
Published: February 2014

AbstractRoots of 19 Apocynaceae species were studied anatomically with respect to their symbiosis with VAM‐fungi. In plants collected from the field, VAM‐fungi were established in the root cortex. Also, inoculations with different Glomus species on the cultured plants are very successful in the infection and colonization of the root cortex.After penetration of the rhizodermis, the special exodermal short cells become colonized by winding hyphae. Then, in the root cortex of many Apocynaceae species, the VAM‐fungi produce intercellular running hyphae which leads to extensive colonization of the root. Arbuscules develop on intracellular running hyphae, whereas vesicles develop mainly on intercellular hyphae. Except for some special details, this is the most common type of colonization of VAM fungi in flowering plants.But in Amsonia tabernaemontana, Nerium oleander, and Thevetia peruviana, another type of colonization could be observed. In these species, the colonization of the hyphae within the root cortex is only possible by intracellular growth. Intercellular running hyphae in the root are lacking. Therefore, after penetration the colonization in the cortex is cluster‐like and strictly limited. Only by additional penetrations from hyphae in the soil, will roots show heavy infestations. This type of growth of the VAM fungi in the root is well known from the Gentianaceae and was explained as a structural incompatibility.In Catharanthus roseus, Pachypodium lamerei, and Trachelospermum jasminoides, intermediate stages of both types of colonization could be described. The results are discussed in the search for possible stimulants for structural incompatibility.
The Effect of Photoinhibition on Photosynthetic Oxygen Production in the Brown Alga Dictyota dichotoma
Authors: Hanelt D. , Uhrmacher S. , Nultsch W. 
Published: February 2014

AbstractPhotoinhibition of photosynthesis in the brown alga, Dictyota dichotoma, was studied with a PAM fluorometer (Walz, Effeltrich, Germany) and a homemade oxygen measuring device. As a measure of fluorescence, Fv/Fm, and for the photosynthetic yield, ΔF/Fm', were used. Oxygen measurements show clearly that the observed degree, as well as the time course, of photoinhibition depends on the fluence rate of the light used to measure changes of the production rate. After photoinhibition of photosynthesis the depression of oxygen production caused by non‐saturating fluence rates was generally much more pronounced than that caused by saturating or nearly saturating fluence rates. At minimal photoinhibition the initial slope and the convexity of the fluence rate‐response curve of oxygen evolution decrease, whereas the level of light saturation decreases only after strong photoinhibition. Nevertheless, at different degrees of photoinhibition, changes in the degree of the upper bending of the fluence rate‐response curve of oxygen production are also linearly correlated to changes in the fluorescence ratios (Fv/Fm and ΔF/Fm'). The action spectrum of photoinhibition, calculated on the basis of changes of Fv/Fm, indicates that the reaction center of PS I is not involved in photoinhibition. The lower effectiveness of blue light in comparison to effects of green and red light may be due to chloroplast displacement, as in the so‐called strong light position, the light absorbed by the thalli in vivo is decreased.
How Indicative are Changes in Major Metabolites for Freezing Tolerance of Wheat?
Authors: Stuiver C. E. E. , De Kok L. J. , Clement J. M. A. M. , Kuiper P. J. C. 
Published: February 2014

AbstractRelative growth rate of winter wheat at low temperature (day/night, 4/2 °C) was about 0.02 g g−1 fresh weight day−1. There was a substantial increase in dry matter content of shoots and roots, especially during the first week of low temperature exposure, which for the greater part could be attributed to an accumulation of soluble sugars and starch. The freezing tolerance (LT50) of the leaf tissue gradually increased with 6 °C during the 6 weeks exposure, whereas freezing tolerance of roots was hardly affected. Upon low temperature exposure there was an increase in the content of water‐soluble non‐protein thiols (mainly glutathione), soluble sugars, starch, amino acids and total nitrogen in both shoots and roots. The most substantial increases in the content of thiols, sugars and amino acids already occurred within hours or a few days after the onset of the exposure. The nitrate content in shoots showed a rapid and strong decrease during low temperature exposure, however, in roots its content remained unaffected. It is proposed that the observed rapid increases in the content of various metabolites at low temperature are primarily due to an altered balance in their synthesis and their consumption in growth. There was no direct relation between increases in the content of the various metabolites and the degree of freezing tolerance of the tissue.
In vitro Reconstitution of Epicuticular Wax Crystals: Formation of Tubular Aggregates by Long‐Chain Secondary Alkanediols
Authors: Jetter R. , Riederer M. 
Published: February 2014

AbstractCuticles of several plant species are covered by tubular wax aggregates that are known to consist mainly of (S)‐nonacosan‐10‐ol. The present work addresses the question whether minor wax components may additionally contribute to these tubules. Thin layer chromatography was used to prepare secondary alkanediol fractions from leaf cuticular waxes of Nelumbo nucifera and Thalictrum flavum, containing nonacosane‐3,10‐diol, nonacosane‐4,10‐diol, nonacosane‐5,10‐diol, nonacosane‐7,10‐diol, nonacosane‐9,10‐diol and nonacosane‐10,13‐diol. From organic solutions all these compounds crystallized in tubular shapes. Possible crystal structures of relevant alkanediol isomers are proposed, in analogy to the lattice geometries of comparable aliphatic compounds. The resulting structural model shows that nonacosan‐10‐ol and various secondary alkanediols may join in metastable mixed crystals. According to the structural model proposed the admixture of alkanediols to nonacosan‐10‐ol aggregates should enhance the stability of their tubular habit.
Branch Roots of Zea. V. Structural Features that may Influence Water and Nutrient Transport
Authors: Wang X. L. , McCully M. E. , Canny M. J. 
Published: February 2014

AbstractFirst‐order branch roots of field‐grown Zea mays L. were examined by optical and electron microscopy. They were small‐scale versions of nodal roots except for the usual retention of a live epidermis throughout their length. The Casparian strips and suberized lamellae of hypodermis and endodermis developed closer to the root tip than reported for main roots (in the zone 0.5 to 5.5 cm from the tip for the hypodermis, and 0.5 to 4 cm for the endodermis), in branches retaining an apical meristem. The hydrophobic deposits were in place to the distal ends of determinate branches. All hydrophobic deposits were fully formed before the late metaxylem elements were mature. Gaps in the suberized lamellae of both hypodermis and endodermis may permit apoplastic diffusion of solutes through these layers. Pit frequency in the outer tangential walls of the hypodermis and endodermis was 0.3 per 100 μm2, and 0.6 to 0.7 per 100 μm2, respectively, in both branch and main roots. Numbers of plasmodesmata per pit in the branches were 60 and 30 in the hypodermis and endodermis, respectively. Water fluxes from published data were used to calculated the possible flux through plasmodesmata on a symplastic path. Values up to 0.2 pl h−1 for the hypodermis and twice this for the endodermis were obtained.
An Assemblage of Hummingbird‐pollinated Flowers in a Montane Forest in Southeastern Brazil
Authors: Sazima I. , Buzato Silvana , Sazima Marlies 
Published: February 2014

Abstract:Relationships between ornithophilous flowers and hummingbirds have been little studied in southern South America, where hummingbird species richness is low. We studied an ornithophilous flower assemblage and the hummingbird pollinators in a montane forest in southeastern Brazil. Twenty‐three native hummingbird‐pollinated plant species in 21 genera and 14 families were observed. Bromeliaceae, Fabaceae, Gesneriaceae, and Lobeliaceae are represented by more than one species within the assemblage. Flower shapes vary from narrow tube to bowl‐shape, but tubular flowers prevail. The variety of flower shapes and sizes results in diverse pollen placement on the body parts of hummingbird visitors, although pollen is deposited mostly on the bill. Sugar concentration in nectar averages 22.1%, and nectar volume per flower averages 16.9 μl. The plant populations bloom for one month to year‐round, and their flowering approaches the steady‐state pattern. Four flower subsets may be defined within the assemblage, each subset related to the bill size and foraging habits of the most frequent bird visitor. Of the six species of hummingbirds recorded at the study site, four are common and largely resident. The four hummingbirds differ in bill size, body mass, and favoured foraging sites, attributes which reflect their favoured flower subsets. One hermit and one trochiline hummingbird share most of the flower species they use, these two birds being the major pollinators within the flower assemblage. This montane forest community may be viewed as medium‐rich in ornithophilous flower species and poor in hummingbird species.
Expression of Chalcone Synthase Genes in Coleoptiles and Primary Leaves of Secale cereale L. after Induction by UV Radiation: Evidence for a UV‐Protective Role of the Coleoptile*
Authors: Haussühl Kirsten , Rohde W. , Weissenböck G. 
Published: February 2014

Abstract:Four chalcone synthase (CHS; EC 2.3.1.74) clones from rye were isolated and characterized. Two of these clones were used for analysis of CHS gene activities in response to ultraviolet and visible radiation in the coleoptile and the primary leaf of the rye seedling. The time‐dependence of CHS gene activation and the spatial distribution of CHS were studied by investigation of enzyme activities and CHS mRNA levels, including in situ RNA hybridization. In the primary leaf strong induction of CHS gene activity was localized in the epidermal layers and only marginally found in the mesophyll. The coleoptile showed an even higher response to UV irradiation, but CHS gene activity was evenly distributed throughout the tissues. It is suggested that, in addition to its function as a mechanical protection for the primary leaf during seed germination and seedling emergence through the soil, the coleoptile may also protect the emerging seedling from harmful radiation.
Photosynthetic Fluorescence Induction and Oxygen Production in Corallinacean Algae Measured on Site
Authors: Häder D.‐P. , Herrmann Heike , Schäfer J. , Santas R. 
Published: February 2014

Abstract:Photoinhibition of photosynthesis was measured in two Mediterranean Corallinaceae, Jania rubens and Corallina mediterranea, using pulse‐amplitude modulation (PAM) fluorescence and oxygen production on site. Both algae were found to be adapted to low irradiances of solar radiation and easily inhibited by exposure to excessive radiation. Both algae were impaired even in their natural habitat under overhanging rocks which protected them from direct solar radiation, except for a few hours in the early morning. Recovery from photoinhibition of both the photosynthetic quantum yield, defined as Fv′/Fm′, and oxygen production took several hours and was not complete. Judging from both parameters indicated above, Jania seems to be even more sensitive than Corallina, even though the former alga was found in more exposed habitats.
Characteristics of Hg‐ and Zn‐sensitive Water Channels in the Plasma Membrane of Chara Cells*
Authors: Tazawa M. , Asai K. , Iwasaki N. 
Published: February 2014

Abstract:Hydraulic conductivity (Lp) of the plasma membrane of Chara corallina was inhibited by HgCl2 maximally by about 95%. The inhibition was reversed by 2‐mercaptoethanol, reconfirming the observation obtained by Henzler and Steudle (1995). The results suggest that osmotic water transport through Chara cells occurs mostly via mercury‐sensitive water channels containing thiol groups. ZnCl2 dissolved in APW (pH 5.6) also inhibited Lp by about 80% within 1–2 h, while ZnCl2 dissolved in Hepes‐Tris buffer (pH 7.4) inhibited it by about 90% within several minutes. Inhibition of Lp by ZnCl2 was also reversed by 2‐mercaptoethanol, suggesting that zinc acts also on thiol groups of water channel proteins. Cells from which tonoplast had been removed by ECTA were as sensitive to both HgCl2 and ZnCl2 (pH 7.4) as normal cells. This demonstrates that water channels sensitive to thiol reagents really exist in the plasma membrane. On the other hand, ZnCl2 (pH 5.6) did not inhibit Lp of tonoplast‐free cells. This may be accounted for by assuming first that Hg‐ and Zn‐sensitive thiol groups of water channels may exist on the cytoplasmic side, and second that ZnCl2 in acidic medium may exist in ionized species which can be chelated by EGTA after permeation. The polar water permeability, or the endoosmotic Lp being larger than the exoosmotic one, was not affected by lowering the rate of osmosis by decreasing the osmotic gradient for transcellular osmosis down to 0.02 M sorbitol. The polarity disappeared when osmotic water flow through water channels was completely inhibited by HgCl2. Thus the polarity is assumed to be intrinsic to water channels in the plasma membrane.