bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in Chloride Fluxes and Cytosolic pH Induced by Abscisic Acid in Elodea densa Leaves
Authors: Beffagna Nicoletta , Romani Giulia , Gatti Lucia 
Published: February 2014

AbstractThe effects of ABA on intracellular pH, net H+ extrusion, Cl− fluxes and Em values were studied in Elodea densa leaves, and the possible relationships between the ABA‐induced changes of cytosolic pH and of Cl− and H+ fluxes were investigated. Cytosolic and vacuolar pH were calculated by the weak acid and weak base distribution method. The data show that, also in this material (a water plant without stomata), ABA induces a decrease in both net H+ extrusion and intracellular pH, and strongly inhibits Cl− efflux. No significant effect of ABA is detectable on Em values, either at short or long intervals in the presence or absence of K+. Cl− efflux is apparently independent of the activity of the plasmalemma H+ pump and of the Em values. Conversely, it strongly depends on the value of cytosolic pH, a larger efflux occurring for the lower pH values both in the presence and in the absence of ABA. These results indicate that the ABA‐induced cytosolic acidification cannot be the cause but, possibly, a consequence of the decrease in Cl− efflux, and are consistent with the hypothesis of a primary role of ABA in regulating Cl− efflux, presumably by directly affecting a class of Cl−‐permeable channels.
Root Browning in Pinus banksiana Lamb. and Eucalyptus pilularis Sm. 1. Anatomy and Permeability of the White and Tannin Zones
Authors: McKenzie B. Elizabeth , Peterson Carol A. 
Published: February 2014

AbstractGrowing tree roots are characteristically brown with white tips. The browning process, which occurs as the white region matures, has often been attributed to the deposition of suberin in various tissues. However, in pouch‐grown tree seedlings of jack pine (Pinus banksiana Lamb.) and eucalyptus (Eucalyptus pilularis Sm.), browning was not linked to suberization but was caused by the deposition of condensed tannins in the walls of all cells external to the stele. Therefore, we propose using the term “tannin zone” to refer to this region of the root. Vitality tests indicated that the cells of the epidermis and cortex were alive in white regions but were dead in brown regions. Following sequential treatment with berberine hemisulfate and potassium thiocyanate, the cortical walls external to the endodermal Casparian band were full of berberine thiocyanate crystals, indicating that they were permeable to berberine. These walls should also be permeable to water and ions, which have smaller molecular dimensions than the tracer dye. Based on the anatomy and permeability of the tannin zone, we predict that its capacity for ion uptake would be reduced compared to the white zone because of a reduced absorptive plasmalemma surface area. In jack pine, some uptake could be effected by the passage cells of the endodermis. The tannin zone should be even less absorptive in eucalyptus because the exodermis remains an apoplastic barrier and the endodermis lacks passage cells. It is difficult to predict the difference between the tannin and white zones with respect to water uptake. Death of the cells external to the endodermis would reduce the resistance of the root to water movement, but deposition of tannins would increase it. The deposition of suberin lamellae in increasing numbers of endodermal cells may also retard water flow. The anatomy and physiological properties of the tannin zone are unique from those of the distal, white zone and the proximal, cork‐clad zone.
Calcium, Calcium Oxalate Crystals, and Leaf Differentiation in the Common Bean (Phaseolus vulgaris L.)*
Authors: Zindler‐Frank Elisabeth 
Published: February 2014

AbstractYoung plants of Phaseolus vulgaris were grown in nutrient solutions at different levels of calcium concentration. When the calcium concentration was low more palisade parenchyma and less extended bundle sheath was formed at the adaxial side of minor veins of the leaves as compared to leaves of plants grown with higher calcium supply. The number of calcium oxalate crystals in the bundle sheath extensions was positively correlated to the amount of calcium fed to the plants. The ion induces additional cell divisions in the bundle sheath extensions. A high supply of calcium leads to the formation of a second type of crystal in the bundle sheath.
Flagellar Photoresponses of Chlamydomonas Cells Held on Micropipettes: III. Shock Response
Authors: Rüffer Ursula , Nultsch W. 
Published: February 2014

AbstractUsing high‐speed microcinematography flagellar shock responses of a great number of Chlamydomonas cells, free‐swimming as well as immobilized on micropipettes, were investigated in this study. Responses were elicited by flashes, by blue, red or white light steps or occurred “spontaneously”. A large variety of shock responses has been found, in part due to various kinds of flagellar deactivations. Typical courses of flagellar responses are described in detail. The major part of the analyzed responses consists of a transition back from undulatory beats, characteristic for shock responses, to the normal breaststroke beats, probably as a result of a decreasing Ca++ concentration at the axoneme. It is known that undulatory beats are triggered by a transient strong influx of Ca++ ions into the flagella. Responses are initiated simultaneously in the two flagella but are finished independently. Differences in cis (= next to the stigma) and trans (= far from it) flagella were observed but were not consistent. The origin of the deactivations during the shock responses is discussed, as well as an involvement of basal body‐associated structures in flagellar beating and in the change between the two beating modes. The comparison of the two fundamentally different types of beating and a close study of transitional beats may convey insight into the complexity of flagellar beating in Chlamydomonas.
Effects of Ri T‐DNA from Agrobacterium rhizogenes on Growth and Hyoscyamine Production in Datura stramonium Root Cultures
Authors: Piñol M. T. , Palazón J. , Cusidó R. , Serrano M. 
Published: February 2014

Abstract:Transformed root lines of Datura stramonium were established following infection of aseptic stem segments with Agrobacterium rhizogenes strain A4. These root lines were examined for their alkaloid productivity in relation to growth rate and the presence in the nuclear genome of rol(A, B and C) and tms genes. The amount of polypeptides coded by rolB and rolC genes, and the transcript levels of rolA, rolB and rolC genes were also investigated. Southern blot analysis using [32P]‐la‐belled fragments of the T‐DNA as probes, revealed the lack of tms genes and the presence of the three rol genes in the genome of the all root lines. The growth rates of these transformed root lines were not always correlated with their hyoscyamine biosynthesis ability. However, all transformed root lines, showed a positive correlation between hyoscyamine production and the level of polypeptide coded by rolC gene.
Population‐specific Traits and their Implication for the Evolution of a Drought‐adapted Ecotype in Armeria maritima
Authors: Köhl Karin 
Published: February 2014

Abstract:Traits contributing to drought resistance of Armeria maritima were investigated by comparing six populations of this species from sandy grasslands, heavy metal mines and salt marsh sites. The sandy soil ecotype that is influenced by periodic drought was found to allocate constitutively a higher proportion of biomass to the root system, especially to the fine roots, than the other two ecotypes. The selective advantage of this lower shoot‐root ratio is presumably the delayed onset of the critical water saturation deficit because of the ability to take up additional water from deeper soil layers. Under water stress, all populations of A. maritima showed a decrease in the shoot‐root ratio. Additionally, under moderate long‐term water stress a decrease in (= more negative) osmotic potential was found in leaves of plants from all populations. Lowest osmotic potentials were shown by the salt marsh ecotype and the highest by one of the heavy metal populations. Osmotic adjustment was achieved passively by a reduction in osmotic volume. Accumulation of osmotically active compounds was seen only under severe water stress, when the considerable betaine contents found in all populations of A. maritima even under control conditions were further increased by severe drought. The evolution of traits related to drought adaptation in the sandy soil ecotype of A. maritima is discussed.
Pollen in Bee‐Flower Relations Some Considerations on Melittophily*
Authors: Westerkamp Ch. 
Published: February 2014

Abstract:Pollen and nectar are usually lumped together as floral rewards for pollinating bees, but they play totally different roles for flowers and bees (Table 1), as well as in the relationship between them. While flowers are specialized for certain pollinators via nectar, bees specialize on certain flowers via pollen. While flowers need pollen as a prerequisite for pollination, it is the essential larval food in bees. Thus, there is a strong competition between them for pollen. Foraging for pollen must be divided into three phases: uptake in the flower, reloading into and homeward transport within a carrying container. Bees have specializations for transport but hardly any for pollen uptake ‐ and thus for pollination. Bees actively harvesting pollen usually do not pollinate. This only happens as a consequence of contamination of the bee by pollen. From these data a scenario is provided for the evolution of bees and bee flowers. Specialized bee flowers are often characterized by their ability to hide pollen from the bees and at the same time use them as optimal pollinators. If the relationship of bees and flowers is mutualistic at all it is best described as a balanced mutual exploitation.
Form‐Pfs Plastids, Stem Anatomy and Systematic Affinities of Stylobasium Desf. (Stylobasiaceae)
Authors: Behnke H.‐D. , Kiritsis Ute , Patrick Susan J. , Kenneally K. F. 
Published: February 2014

Abstract:The vascular system of the stem of Stylobasium was investigated during its primary and secondary phases with both light and electron microscopic methods. It contains collateral bundles arranged in a ring, separated by rays which undergo regular cambial growth. The phloem consists of short sieve elements connected to sieve tubes by simple sieve plates, companion cells of the same length, and phloem parenchyma cells. During their autophagy‐like differentiation and maturation, typical of all angiosperms, the sieve elements of Stylobasium have a peculiar feature, whereby they develop and retain form‐Pfs plastids (containing protein filaments and starch). The sieve‐element plastids of the two Stylobasium species, and of some 100 species belonging to taxa of which Stylobasium had been considered to be a possible member, have been studied by transmission electron microscopy. With the exception of a few species with form‐Pcs plastids (containing a single small protein crystal in addition to starch), the great majority of taxa studied are characterized by S‐type sieve‐element plastids (containing starch only). The presence of form‐Pfs plastids in Stylobasium supports its separation into the unigeneric Stylobasiaceae and the placement of this family close to other form‐Pfs or form‐Pcfs‐containing taxa. While other characters would exclude an affiliation to the Magnolianae (form‐Pfs plastids in Canella) or Caryophyllales (form‐Pfs plastids in Microtea), an association with the form‐Pcfs families Connaraceae and Mimosaceae is positively considered and corresponds to their frequent allocation close to the Rutales and Sapindales. Within the Rutales/Sapindales the sizes of sieve‐element plastids (average diameter) range from very large (e.g. in the Julianaceae) to comparatively small (e.g. in Aceraceae) and are used to group the families. The sieve element characters of the Coriariaceae (tiny plastids with almost no starch, wide sieve plate pores, copious P‐protein) suggest their removal from Rutales/Sapindales into the neighbourhood of the Cucurbitaceae.
Distribution of the Character States “Early Sympetaly” and “Late Sympetaly” Within the “Sympetalae Tetracyclicae” and Presumably Allied Groups*
Authors: Erbar Claudia , Leins P. 
Published: February 2014

Abstract:Within the Asteridae (“Sympetalae Tetracyclicae”) two main developmental patterns can be distinguished as regards the formation of corolla tubes, namely “early” and “late sympetaly”. Since the character “ontogeny of sympetaly”, after intensive studies, proved to be valuable for systematic considerations, we now recognize two blocks of orders within the Asteridae (and related groups): the Asteridae A‐block and the Asteridae B‐block (Figs. 82 and 83). By and large this bipartition referring mainly to the corolla tube development corresponds well with major lineages indentified by recent molecular data (see, e.g., Chase et al., 1993). Asteridae A‐block is characterized predominantely by “late sympetaly” the “early sympetaly” in Rubiales and Oleales can be interpreted as derived within this block or can be linked with that in Asteridae B‐block. Asteridae B‐block is uniform throughout in its “early sympetaly”. In this block it is a primitive character, as judged from its occasional occurrence in the choripetalous Cornales and Apiales (Apiaceae, Araliaceae, Pittosporaceae), which can be regarded as ancestral for block B.
Experimental Studies on the Competitive Balance Between two Central European Roadside Grasses With Different Growth Forms
Authors: Ryel R. J. , Beyschlag W. , Heindl B. , Ullmann I. 
Published: February 2014

Abstract:The weakly‐competitive grass, Puccinellia distans (Jacq.) Parl., and the highly competitive grass, Elymus repens (L.), coexist on roadsides in Central Europe which are regularly mowed. The effect of mowing on this existence was evaluated in situ at the roadside and in experimental field plots under non‐limiting water and nutrient conditions. In four experimental garden plots, tussocks of P. distans were transplanted into monocultures of E. repens early in the growing season. After establishment, two of the plots were mowed and two left unmowed. In the unmowed plots, P. distans was quickly overtopped and died, while in mowed plots, P. distans was able to persist throughout the growing season. Despite persistence in the mowed plots, the number of tillers of P. distans declined throughout the growing season as numbers of tillers of E. repens increased. It was concluded that mowing could enhance coexistence in situations of unlimited nutrients and water where the faster growing and aggressive E. repens would exclude P. distans without mowing. At the roadside, six plots were established at a site containing both species early in the growing season. Weekly mowing was performed on three of the plots while the others were left unmowed. In mid‐July, when the grasses were beginning to senesce and had produced seed‐heads, foliage area for P. distans was significantly higher in the mowed than the unmowed plots while the reverse was true for E. repens. While P. distans had higher foliage area in the mowed plots, it was able to persist to seedhead production in the unmowed plots. Simulations conducted with a multispecies canopy photosynthesis model indicated that reductions in carbon gain for P. distans due to shading by foliage of E. repens did not correspond well with foliage area for P. distans at the start of experiment or in the mowed and unmowed plots in mid‐July. In both the mowed and unmowed plots, the portion of foliage consisting of P. distans increased with closeness to the roadway and corresponded inversely with soil depth. At soil depths of greater than 15 cm, P. distans did not occur. More effective exploitation of shallow soil may shift the competitive balance toward P. distans and be a significant factor in the coexistence of these two species in the shallow soils at the roadside. Differences in leaf temperatures at the roadside that might result from different leaf widths were also evaluated. The narrower‐leaved P. distans was hypothesized to have lower midday leaf temperatures at sites close to the asphalt and perhaps be closer to the temperature optimum for photosynthesis during warm summer days. In situ leaf temperature measurements made with small thermocouples attached to intact leaves, however, were not significantly different for the two species, and coexistence was not likely to be affected by leaf temperatures.
Rapid Effects of Boron Deficiency on Cell Wall Elasticity Modulus in Cucurbita pepo Roots
Authors: Findeklee P. , Goldbach H. E. 
Published: February 2014

Abstract:Rinsing roots of Cucurbita pepo with an essentially boron‐free nutrient solution results in a significant reduction of the cell wall elasticity modulus as determined by the cell presure probe (measuring always in the same cells). This points to a role of boron in crosslinking cell wall macromolecules. Longer exposure to boron deficient conditions, however, increased again and above the initial values. This trend became visible between 20 and 30 minutes after starting the deficiency treatment. There is no indication for a loss of turgor during the time course of the experiments, suggesting that boron primarily affects cell wall physical properties and that membrane leakiness, as observed by other groups, is a secondary event. Several testable hypotheses for the action of boron are presented.
Induction of a new Lipoxygenase Form in Cucumber Leaves by Salicylic Acid or 2,6‐Dichloroisonicotinic Acid*
Authors: Feussner I. , Fritz I. G. , Hause B. , Ullrich W. R. , Wasternack C. 
Published: February 2014

Abstract:Changes in lipoxygenase (LOX) protein pattern and/or activity were investigated in relation to acquired resistance of cucumber (Cucumis sativus L.) leaves against two powdery mildews, Sphaerotheca fuliginea (Schlecht) Salmon and Erysiphe cichoracearum DC et Merat. Acquired resistance was established by spraying leaves with salicylic acid (SA) or 2,6‐dichloroisonicotinic acid (INA) and estimated in whole plants by infested leaf area compared to control plants. SA was more effective than INA. According to Western blots, untreated cucumber leaves contained a 97 kDa LOX form, which remained unchanged for up to 48 h after pathogen inoculation. Upon treatment with SA alone for 24 h or with INA plus pathogen, an additional 95 kDa LOX form appeared which had an isoelectric point in the alkaline range. For the induction of this form, a threshold concentration of 1 mM SA was required, higher SA concentrations did not change LOX‐95 expression which remained similar between 24 h and 96 h but further increased upon mildew inoculation. Phloem exudates contained only the LOX‐97 form, in intercellular washing fluid no LOX was detected. dichloroisonicotinic localization revealed LOX protein in the cytosol of the mesophyll cells without differences between the forms.
Mitochondrial DNA in Mon‐Mon and Di‐Mon Pairings of Pleurotus ostreatus
Authors: Fischer M. , Wolfrath H. 
Published: February 2014

Abstract:Based on enzymatically amplified regions of the mitochondrial DNA (mtDNA), stock‐specific markers were obtained for two stocks of Pleurotus ostreatus. A length mutation was detected within a region encoding for DNA of the mitochondrial ribosomes. The inheritance of mtDNA was uniparental both in Mon‐Mon and Di‐Mon interstock pairings. Replacement of the recipient mtDNA to a large extent was finished 3 to 4 months after hyphal contact of paired mycelia. Dissolution of mitochondrial mosaics was somewhat faster in Di‐Mon than in Mon‐Mon pairings. As became evident in Di‐Mon pairings, the spread of the dominating mtDNA is independent from nuclear migration, and these processes could go in opposite directions. While in compatible Di‐Mon pairings two different types of nuclear background develop with respect to the mating type factors, only one certain mtDNA phenotype remained after dissolution of the mitochondrial mosaic. The spread of the mtDNA occurred at a distinctly slower rate than nuclear migration. Three weeks after hyphal contact the dominating mtDNA had not reached the growing edge of the recipient mycelium, whereas clamp formation was noted after 11 days at the latest. The data presented in this study indicate that no apparent correlation exists between mtDNA and nuclear background.
Micro‐Foraging Routes of Bicolletes pampeana (Colletidae) and Bee‐Induced Pollen Presentation in Cajophora arechavaletae (Loasaceae)
Authors: Schlindwein C. , Wittmann D. 
Published: February 2014

Abstract:In flowers of Cajophora arechavaletae Urb. the stamens are hidden from flower visitors in naviculate petals. In the male phase the stamens successively migrate at irregular intervals to the centre of the flower where they present pollen. Therefore, non‐specialised pollinators cannot predict the time of pollen presentation. The oligolectic females of Bicolletes pampeana are effective pollinators of Cajophora arechavaletae. Females and males can elicit stamen movements by pressing the scales of the nectaries outwards with their head while taking up nectar. If this stimulus is responded to, up to 3 stamens move and reach the centre of the flower on average after 2.4 min. Experiments showed that the stimulus of nectar scale pressing was responded to maximally when the inter‐stimulus interval was at least 14 min. B. pampeana females have evolved a foraging strategy which is adapted to the unique pollen presentation of C. arechavalete flowers. On microforaging routes they trapline 30–60 flowers and, therefore, most frequently come back to the same flower after intervals of about 3 min. This is exactly the period after which a female can expect pollen in the centre of the flower if her previous stimulus was responded to. Competition between the females causes them to return to the flowers at such short intervals.
Physiological, Biochemical, and Molecular Characters for the Taxonomy of the Subgenera of Scenedesmus (Chlorococcales, Chlorophyta)
Authors: Kessler E. , Schäfer Michaela , Hümmer Carola , Kloboucek Annette , Huss V. A. R. 
Published: February 2014

Abstract:Biochemical and physiological properties of 16 Scenedesmus species representing the three subgenera Scenedesmus, Acutodesmus, and Desmodesmus are not suitable for species differentiation. All Scenedesmus species studied thus far produce secondary carotenoids, e.g. astaxanthin and canthaxanthin, under nitrogen‐deficient conditions. In addition, with the exception of one strain, hydrogenase activity under anaerobic conditions is generally present. Sequence analyses of ribosomal 18S RNAs indicate that the subgenus Desmodesmus is phylogenetically well separated from the other subgenera, whereas the separation of Scenedesmus and Acutodesmus appears less convincing and is dismissed in favour of a single subgenus, Scenedesmus. Three taxa formerly assigned to the genus Chlorella are shown to be unicellular species of the genus Scenedesmus. “Chlorella” fusca var. vacuolata and “C.” fusca var. rubescens, which is closely related to S. obliquus, belong to the Scenedesmus/‘Acutodesmus group. “C.” fusca var. fusca is closely related to S. communis and thus belongs to the subgenus Desmodesmus. Inclusion of Kermatia pupukensis into the genus Scenedesmus is also strongly supported by the RNA data which furthermore indicate a relationship with the subgenus Desmodesmus.