bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wounding‐ and Elicitor‐induced Formation of Coloured Chalcones and Flavans (as Phytoalexins) in Hippeastrum x hortorum*
Authors: Wink M. , Lehmann P. 
Published: February 2014

Abstract:Hippeastrum x hortorum bulbs produce red pigments upon wounding. Analysis by TLC, HPLC, MS and NMR revealed that this pigment, which is absent in unwounded tissue, is a mixture composed of an orange‐coloured chalcone (3,2′4′‐trihydroxy‐4‐methoxychalcone) and 3 flavans (7,4′‐dihydroxy‐8‐methylflavan, 7,3′‐dihydroxy‐4′‐methoxyflavan and 7‐hydroxy‐3′‐4′‐methylenedioxyflavan). The colourless flavans can be oxidised to red‐coloured dimers or polymers. The induction of these “phytoalexins” is achieved by wounding and can be further amplified by biotic and abiotic elicitors; e.g. cell walls of yeast appeared to be a potent elicitor. Immediately after wounding or elicitation the apparent activities of phenylalanine ammonium lyase (PAL) and peroxidase, which are probably involved in the biosynthesis of the red pigments increase substantially (both enzymes are hardly measurable in unwounded tissue) and reach a transient maximum after 2 − 3d whereas pigment formation becomes visible after 2d and reaches a maximum after 9 to 12 d. Since cycloheximide inhibits the formation of the phytoalexins, a de novo synthesis of the corresponding enzymes is likely. Total phytoalexin extracts showed an inhibition of bacterial growth (e.g. of Bacillus subtilis, B. megaterium) and of feeding by polyphagous larvae of the moth Syntomis mogadorensis. These data imply that the wounding‐ and elicitor‐induced phytoalexins appear to function as defence compounds against microorganisms and herbivores.
Gaertnera and Pagamea: Genera Within the Psychotrieae or Constituting the Tribe Gaertnereae? A Wood Anatomical and Palynological Approach
Authors: Jansen S. , Robbrecht E. , Beeckman H. , Smets E. 
Published: February 2014

Abstract:The possible alliance between Gaertnera and Pagamea (Rubiaceae‐Rubioideae), two genera from the Old and New World, respectively, is investigated on the basis of wood anatomy and pollen morphology. Nowadays, the main point of discussion about the taxonomic position of these genera is whether they belong to the Psychotrieae or constitute a tribe Gaertnereae characterised by their secondarily superior ovary and sheathing stipules. Both the wood and pollen of the genus pair are found to show specific features absent in other genera of the Psychotrieae, e.g. parenchyma bands in the xylem and endexine thickenings on the polar sites of the pollen apertures. Nevertheless Gaertnera and Pagamea share many other characters with the Psychotrieae. Wood and pollen convincingly demonstrate the very close affinity of the two genera. The sister pair differs in so many features from other Psychotrieae, that Gaertnera and Pagamea should constitute at least a subtribe Gaertnerinae, formally recognized here. The general lack of profound studies on the affinities within the very large tribe Psychotrieae makes further comments on the taxonomic relationships of the Gaertnerinae difficult.
Effects of Local Variations in Soil Moisture on Hydrophobic Deposits and Dye Diffusion in Corn Roots
Authors: Watt M. , VAN DER Weele C. M. , McCully M. E. , Canny M. J. 
Published: February 2014

Abstract:The effects of local soil water content (SWC) alone on the development of hydrophobic deposits and on diffusivity of root tissues were studied in primary roots of maize seedlings whose top regions were growing at a constant rate in damp soil. Corn primary roots were grown through 30 cm‐profiles of soil with pre‐set dry (8% SWC), or wet (23% SWC), middle layers, and moist (15% SWC) top and bottom layers. When the root tissues in the soil of variable SWC were maturing (approximately 17% of the total root length), the tips of the roots were in damp soil several centimeters away and growing at the rate characteristic of this environment. Histochemistry and fluorescence microscopy on root sections of similar age showed that in these roots local SWC had no effect on hypodermal and endodermal suberization: both had equally developed Casparian bands and suberized lamellae. However, local SWC did alter the hydrophobic deposits in the walls of the epidermis; they increase in dry soil. To study tissue diffusivity, root portions from dry or wet soil were divided in the transverse direction, and half was dipped in sulphorhodamine G (SRG), sectioned, and observed with fluorescence optics. The other half was studied with a cryo‐scanning electron microscope to observe the contents of the cortical intercellular spaces. The rate of SRG diffusion in a portion of root from dry or wet soil was independent of local SWC but was positively correlated with numbers of fluid‐filled intercellular spaces. The implications of these observations for the movements of ions through the root cortex are discussed.
Stimulation of Plastidogenesis Induced by 5‐Azacytidine in Euglena gracilis Klebs
Authors: Pancaldi Simonetta , Bonora A. , Gualandri Rita , Muzzoli Mariavittoria , Fasulo Maria Palmira 
Published: February 2014

Abstract:When etiolated Euglena gracilis was treated with 10 mM 5‐azacytidine (5‐azaC), an inhibitor of DNA methylation, stimulation of plastidogenesis in both dark and light conditions was observed. The phenomenon occurred in 10–15% of the cells possibly due to the asynchronicity of the cultures. The main features of this sub‐population, as evaluated by electron and fluorescence microscopy, were the following: 1. the presence in darkness of differentiating proplastids that were red fluorescent under UV, positive to TCNBT cytochemical reaction (specific for PSII) and negative to DAB (specific for PSI); 2. the acceleration of proplastid differentiation during the first 20–30 h of illumination; 3. the occurrence in both culture conditions of concentric lamellar bodies (LBS). These structures were considered to be proplastids blocked in the first step of evolution, since they emitted a red fluorescence, were contained within compartments limited by a triple‐layered envelope, were reactive to TCNBT in darkness and to both TCNBT and DAB in light conditions. Even if the action mechanism of 5‐azaC on plastidogenesis in Euglena remains to be defined, the induced stimulatory effect on plastid differentiation pointed to a relationship between DNA methylation and plastid development. Furthermore, the presence of LBS opens the possibility of studying early aspects of plastid development in Euglena.
Uptake of the Herbicide Diuron as Visualised by the Fluorescence Imaging Technique
Authors: Lichtenthaler H. K. , Lang M. , Sowinska Malgorzata , Summ P. , Heisel Francine , Miehe J. A. 
Published: February 2014

Abstract:A new fluorescence imaging system for monitoring the uptake of the PSII‐herbicide diuron (OCMU) was tested in tobacco leaves. UV‐laser‐induced (Λexc = 355 nm) fluorescence images were collected for blue fluorescence F440 (Λem = 440 nm), green fluorescence F520 (Λem = 520 nm), red chlorophyll fluorescence F690 (Λem = 690 nm) and for far‐red chlorophyll fluorescence F740 (Λem = 740 nm). Diuron‐treated leaf parts exhibited a higher red and far‐red chlorophyll fluorescence emission (F690 and F740) than untreated leaf halves, whereas the blue and green fluorescence, F440 and F520, remained unaffected. As a consequence, the fluorescence ratios blue/red (F440/F690) and blue/far‐red (F440/F740) significantly decreased in diuron‐treated leaf parts. The time course of diuron uptake into the leaf could be followed by fluorescence images taken 10 and 30 min after diuron application. The novel high resolution fluorescence imaging method supplies information on the herbicide uptake of each point of the leaf area. Its great advantage as compared to the point data fluorescence measurements applied so far is discussed.
Variability of the Low Molecular Weight Globulin, Conglutin δ, Within Lupin Species
Authors: Species Within Lupin , Esnault M. A. , Pichereau V. , Klingler J. 
Published: February 2014

Abstract:Conglutin δ, a 2S globulin, was purified and compared in six species or varieties of lupin seeds. A common pattern is suggested, present in all species, corresponding to a protein which could exist as a monomer or a dimer. The first form contains one subunit, from 11 to 16.2 kDa, according to the species. It possesses a quaternary structure closely related to conglutin δ1 and was previously described in the narrow‐leaved lupin. The second form contains two similar subunits (23 to 26 kDa) and could be the conglutin δ2. These two subunits are associated even when SDS is used and are probably disulfide‐linked subunits. Each subunit is composed of two disulfide‐linked polypeptides. One is acidic with molecular weight from 14 to 17.3 kDa and the second is acidic to neutral, from 2.4 to 4.5 kDa. Three species (L. luteus, L. arboreus and L. pilosus) present a supplementary subunit, with different molecular weight and p than that previously described and which never associates in a dimer form. It has been purified in L. luteus. When native, this protein is oligomeric. The subunit of 12 kDa in this species is composed of a polypeptide of 9 kDa (pl 4.5) disulfide‐linked to one of 3 kDa (pl 6.5). This supplementary protein remains partly associated with the first in the yellow lupin (L. luteus). It probably corresponds to a new protein, different from conglutin δ.
Phototropism and Protein Phosphorylation in Higher Plants: Unilateral Blue Light Irradiation Generates a Directional Gradient of Protein Phosphorylation Across the Oat Coleoptile
Authors: Salomon M. , Zacherl M. , Rüdiger W. 
Published: February 2014

Abstract:Blue light induces the phosphorylation of a 116 kDa oat protein found in plasma membrane preparations from coleoptile tips. We developed a very sensitive in vitro method that allowed us to determine the tissue distribution of protein phosphorylation after applying unilateral and bilateral blue light pulses in vivo. We found that following unilateral in vivo irradiation the degree in phosphorylation of the 116 kDa protein is significantly higher at the irradiated than at the shaded side of the coleoptile tip. This asymmetry can be considered as previously missing criterion that protein phosphorylation represents an early event within the transduction chain for phototropism.
Silicon Storage in Selected Dicotyledons
Authors: Neumann D. , Lichtenberger O. , Schwieger W. , zur Nieden U. 
Published: February 2014

Abstract:Silicon was localized in some dicotyledons (Minuartia verna, Silene cucubalus, Thlaspi coerulescens, Viola calaminaria, Nicotiana tabacum, Pisum sativum) by analytical transmission electron microscopy as apoplastic crystalline inclusions of SiO2 in intercellular spaces of the leaf parenchyma, between cell wall and plasma membrane and inside the vacuoles. Ca‐silicate, and in some plants Sn‐silicate, forms the peripheral parts of the crystalline inclusions. These unstable compounds are converted spontaneously in the plant cells into the more stable SiO2, which forms the central part of all crystalline inclusions. The function of silicon in these plants is discussed.
Activation of Chloroplast Fructose‐1, 6‐Bisphosphatase of Pisum sativum by Mole Mass Change
Authors: Grotjohann N. 
Published: February 2014

Abstract:Separation of extracts, obtained from isolated intact P. sativum chloroplasts, by fast protein liquid chromatography (FPLC) on superose 6, reveals a 1,400 kDa‐FBPase II form at pH 6.0 and a 380 kDa form at pH 7.5. Addition of F1,6P2, Mg++ and ATP cause dissociation of the large form into the smaller one, which leads to an approximate 4‐fold increase in activity. Reversibility of the mole mass change could be shown for the influence of pH and of fructose‐1, 6‐bisphosphate on purified enzyme samples, separated from crude leaf extracts. Compared to thelarge enzyme form, the small form has higher activity and is specific for the substrate fructose‐1, 6‐bisphosphate, while the large form is not. Activation of FBPase II in the light and inactivation in the dark is discussed on the basis of different oligomeric forms of the enzyme caused by changes in the concentration of intermediates and effectors in the chloroplast stroma. The conclusion is drawn that oligomerization of key enzymes might provide an effective mechanism for enzyme activation/inactivation in vivo.
Nuclear Location of a Diadenosine 5′,5′”‐P1,P4Tetraphosphate (Ap4A) Hydrolase in Tomato Cells Grown in Suspension Cultures1
Authors: Hause B. , Feussner K. , Wasternack C. 
Published: February 2014

Abstract:Diadenosine 5′,5′”‐P1,P4‐tetraphosphate (Ap4A) cleaving enzymes are assumed to regulate intracellular levels of Ap4A, a compound known to affect cell proliferation and stress responses. From plants an Ap4A hydrolase was recently purified using tomato cells grown in suspension. It was partially sequenced and a peptide antibody was prepared (Feussner et al., 1996). Using this polyclonal monospecific antibody, an abundant nuclear location of Ap4A hydrolase in 4‐day‐old cells of atomato cell suspension culture is demonstrated here by means of immunocytochemical techniques using FITC (fluorescein‐5‐isothiocyanate) labeled secondary antibodies. The microscopic analysis of the occurrence of Ap4A hydrolase performed for different stages of the cell cycle visualized by parallel DAPI (4,6‐diamidino‐2‐phenylindole) staining revealed that the protein accumulates within nuclei of cells in the interphase, but is absent in the nucleus as well as cytoplasm during all stages of mitosis. This first intracellular localization of an Ap4A degrading enzyme within the nucleus and its pattern of appearance during the cell cycle is discussed in relation to the suggested role of Ap4A in triggering DNA synthesis and cell proliferation.
Seasonal Dynamics of Plant Diversity on lnselbergs in the Ivory Coast (West Africa)
Authors: Porembski S. , Barthlott W. 
Published: February 2014

Abstract:Inselbergs are isolated monolithic outcrops which are characterized by large areas of exposed crystalline rock. Due to harsh edaphic and microclimatic conditions, inselbergs are completely differentiated from their surroundings. Consequently they host a very distinct vegetation which is being investigated on a global scale over a six year period. The seasonal dynamics of Selected plant communities (Afrotrilepis pilosa mat, shallow depression, ephemeral flush vegetation) on granitic inselbergs in the Comoe National Park (NE Ivory Coast) were studied during the rainy period from May to November 1991 by recording all vascular plant species at 12 intervals. For the habitats investigated, the seasonal vegetation dynamics were related to the rainfall pattern. Maximum values both in species diversity and richness were attained in the first third of the rainy period. Drought in August and September caused a decline in species number and diversity in the shallow depression and ephemeral flush vegetation, resulting in mortality of more than 20% of the species. The individual communities studied differed considerably in species diversity and richness. We conclude that ephemeral flush and shallow depression communities are more species rich than the mat community which is dominated by the highly competitive and specialized K‐strategist Afrotrilepis pilosa (a poikilohydric Cyperaceae) due to stochastic climatic perturbations which allow the maintenance of species rich non‐equilibrium assemblages with r‐strategists as major components.
Stand Structure and Regeneration of the Subalpine Hagenia abyssinica Forests of Mt. Kenya
Authors: Lange Sigrun , Bussmann R. W. , Beck E. 
Published: February 2014

Abstract:The uppermost forest belt on Mt. Kenya (Kenya, East Africa), ranges from 2900 to 3400 m a.s.l. and is dominated by the evergreen “Kosso” tree, Hagenia abyssinica (Bruce) J.F. Cmel. (Rosaceae). The ecology of this tree, with emphasis on regeneration, was investigated. Twenty‐five phytosociological relevés, representing several types of Hagenia forests were produced, and attributed to various associations of the alliances Hagenio abyssinicae — Hypericion revoluti Bussmann 1994 and Hagenio abyssinicae — Juniperion procerae Bussmann 1994 (Bussmann and Beck 1995a). Biometric data of young and adult Hagenia trees were collected.Kosso trees of the individual relevés were either of almost equal size, and presumably age, or could be grouped into only two size categories. This uniformity of the Hagenia populations suggests simultaneous regeneration after major disturbance. Charcoal horizons were found in soil profiles at various sites in the Hagenia zone of Mt. Kenya, indicating former burning of these forests. Therefore, fire is thought to be the disturbing factor, which triggers the regeneration of the Hagenia forests.Germination of Hagenia seeds was investigated under various ecological conditions at Mt. Kenya and in greenhouses. Crucial factors for successful germination were high temperatures and bare soil. Light intensity or potentially allelopathic decomposition compounds, leaching from the abundantly shed leaves, had no significant effect on the germination rates. Fire apparently promotes germination by clearing and heating the prospective seed bed. In areas suffering from a high activity of herbivores, the regeneration capability of Hagenia is greatly decreased or abolished. A fire‐requiring regeneration cycle of the Hagenia forests of Mt. Kenya is concluded from the phytosociological and ecological data.
Phytogeny of some Species of Cyrtandra (Gesneriaceae) Inferred from the atpB/rbcL cpDNA Intergene Region
Authors: Samuel R. , Pinsker W. , Kiehn M. 
Published: February 2014

Abstract:The PCR‐amplified atpB/rbcL spacer region of ten Cyrtandra species and representatives of the genera Didymocarpus, Didissandra, and Monophyllaea was sequenced and used for phylogenetic analyses. In Cyrtandra 83 variable positions were found over a length of 890bp. The data suggest that the Samoan species included in our study originated by at least two independent colonization events, while for the Hawaiian species the situation is not clear yet. With respect to generic relationships, Monophyllaea shows considerable divergence (9.9%) from the remaining taxa and thus is used as outgroup. Didymocarpus is most closely related to Cyrtandra, their genetic divergence (2.2%) being only slightly higher than the average distance within Cyrtandra (1.9%). The promoter regions for the atpB and rbcL genes, which have been described from Rubiaceae, were identified and found to be located at homologous positions. Of the two atpB promoters found in Rubiaceae only the distal one appears functional, the proximal promoter has been eroded by mutations and is disrupted in Didissandra by a 14bp insertion.
Gene Control in Somatic Embryos of Digitalis lanata: Expression of the β‐Glucuronidase Gene Fused to a Plastocyanin Promoter
Authors: Thomar S. , Dumke‐Lehmann Ulrike , Diettrich Beate , Luckner M. 
Published: February 2014

Abstract:Digitalis lanata was transformed by agrobacteria‐mediated gene transfer with a chimeric reporter gene encoding for β‐glucuronidase (CUS) from Escherichia coll under the control of the plastocyanin 3 (Pc3) promoter from Spinada oleracea (Pc3::uidA fusion gene). Transformed cell lines were regenerated to plants via somatic embryos. CUS activity was determined fluorometrically and histochemically. The Pc3::uidA fusion gene was expressed in the late globular and bipolar stages of somatic embryos. Expression started in globular embryos (stage‐1‐globules) in that part of the parenchymatic tissue which later on formed the cotyledons. No GUS activity was detectable in the parenchymatic tissue forming the root pole, in cells of the developing procambium or in epidermal cells. These tissues were free of GUS activity also in bipolar embryos. The parenchymatic cells of the cotyledons and the primary cortex of the hypocotyl of germinating embryos showed GUS activity, in contrast to the epidermal cells and the cells of the central cylinder.
Ginkgo biloba Expresses Calreticulin, the Major Calcium‐Binding Reticuloplasmin in Eukaryotic Cells
Authors: Nardi M. C. , Giacomelli E. , Dainese P. , Fitchette‐Lainé A.‐C. , Faye L. , Baldan B. , Navazio L. , Mariani P. 
Published: February 2014

Abstract:Calreticulin, the main Ca2+ binding protein in the endoplasmic reticulum of eukaryotic cells, was characterized in Ginkgo biloba L. pollen and seeds. Electrophoretic analysis of the partly purified extracts showed the presence of two protein bands of 57 and 50kDa apparent molecular masses, which strongly cross‐reacted with antibodies against plant calreticulins. Amino acid sequence comparison with other plant and animal calreticulins revealed a much higher similarity of the N‐terminus of Ginkgo calreticulins with the homologue from angiosperms rather than with that from mammals. The finding of calreticulin in Ginkgo is indicative of the conservation also in gymnosperms of Ca2+ homeostatic mechanisms, which seem to rely on the same molecular components as all eukaryotic cells.
On the Compartmentation of Triacylglycerol Synthesis in Developing Seeds of Brassica napus
Authors: Aach H. , Heise K.‐P. 
Published: February 2014

Abstract:Compartmentation of storage lipid biosynthesis in developing erucate‐rich rapeseeds during the period of rapid triacylglycerol accumulation has been investigated by labelling acyl residues and the glycerol backbone in endomembrane lipids of isolated embryos with radioactive precursors, either before (“in vivo”) or after (“in vitro”) subcellular fractionation. In contrast to the low light environment within the pod under normal environmental conditions, the photosynthetic and lipid synthesizing capacities of the embryos were significantly stimulated by their illumination in the isolated state. Both ways of demonstrating “de novo” synthesis of triacylglycerols and erucic acid in endomembrane vesicles show their significantly higher accumulation in oil bodies than in microsomal fractions, where membrane lipids predominate. The increased diacylglycerol acylation in erucate‐rich rape embryos appears to be coupled to an alternative elongation mechanism for oleic acid, with another immediate acyl donor than 18:1‐CoA. The present results are interpreted as a spatial separation of triacylglycerol formation, with very long‐chain fatty acids obtained from residual lipid synthesis and fatty acid elongating capacity located on the endoplasmic reticulum.
Concordant Time‐Dependent Patterns of Activities and Enzyme Protein Amounts of V‐PPase and V‐ATPase in induced (Flowering and CAM or Tumour) and Non‐Induced Plant Tissues*
Authors: Fischer‐Schliebs E. , Ratajczak R. , Weber P. , Tavakoli N. , Ullrich C. I. , Lüttge U. 
Published: February 2014

Abstract:There are two H+‐pumping enzymes at the tonoplast membrane of plant vacuoles, the V‐ATPase and the V‐PPase. One attempt to explain the enigma of “two H+ pumps, one membrane” was the suggestion that the V‐PPase has special functions in young developing and growing tissues in utilization of pyrophosphate produced in particularly active metabolism and in pumping of K+ for vacuolization. This should lead to reciprocal expression of both enzymes with time during development. Here we used stimulation of Kalanchoë blossfeldiana Poellnitz cv. Tom Thumb plants by short‐day treatments to induce crassulacean acid metabolism and flowering and of Ricinus communis L. stem tissue by infection with Agrobacterium tumefaciens strain C58 to induce vigorous growth of tumours, and we compared these stimulated tissues with leaves of non‐stimulated long‐day controls and non‐infected stem tissue, respectively. Activities and protein levels of both enzymes increased (K. blossfeldiana) or remained high (R. communis) in the stimulated tissues and decreased in the non‐stimulated tissues with time. Time‐dependent patterns of the two enzymes were concordant in all of the four cases and not inverse, i.e. two plants with two different conditions each, leading to very different developmental situations.