bluuebunny/crossref_metadata_2025_split huggingface dataset:
Austropeltum glareosum gen. et sp. nov., a New Lichen from Mountain Plateaux in Tasmania and New Zealand*
Authors: Henssen A. , Döring H. , Kantvilas G. 
Published: February 2014

AbstractAustropeltum gen. nov. is described as a monotypic genus of the family Stereocaulaceae. It differs from other genera of the family by a sqamulose habit. The single species, Austropeltum glareosum sp. nov. is characterized by an heteromerous thallus with a thick, heavily gelatinized upper cortex, and stalked, lecideine, glomerate apothecia. The apothecial stalk is a pseudopodetium, which is delimited from the subhymenium by a pigmented boundary tissue. Asci are eight‐spored and possess an amyloid tube‐structure; the simple ascospores are fusiform and colourless. Filiform conidia are produced laterally and terminally in marginal pycnidia. A. glareosum grows over gritty soil on exposed mountain summits and plateaux in New Zealand and Tasmania.
The Ca2+ Pump of the Plasma Membrane of Arabidopsis thaliana: Characteristics and Sensitivity to Fluorescein Derivatives
Authors: De Michelis Maria Ida , Camelli Antonella , Rasi‐Caldogno Franca 
Published: February 2014

AbstractThe transport and hydrolytic activities of the plasma membrane (PM) Ca2+ pump were characterized in a PM fraction purified from seedlings of Arabidopsis thaliana by the aqueous two‐phase partitioning technique.Ca2+ uptake could be energized by ATP and by ITP (at about 70% the rate sustained by ATP). This characteristic was used to measure the hydrolytic activity of the enzyme as Ca2+‐dependent ITPase activity. The PM Ca2+ pump displayed a broad pH optimum around pH 7.2, was drastically inhibited by erythrosin B (EB), and was half‐saturated by 60 μM ITP. It was stimulated by CaM, specially at low, non‐saturating Ca2+ concentrations. All of these characteristics closely resemble those of the PM Ca2+ pump in other plant materials.Analysis of the effects of EB and other fluorescein derivatives (eosin Y and rose bengal) showed that: i) EB behaved as a competitive inhibitor with respect to ITP; ii) the PM Ca2+ pump was drastically inhibited by concentrations of fluorescein derivatives (submicromolar), much lower than those required to inhibit the PM H+‐ATPase; iii) the different fluorescein derivatives were diversely efficient in inhibiting the activities of the Ca2+ pump and of the H+‐ATPase of the PM (eosin Y was about 10000‐fold, EB 1000‐fold and rose bengal only 50‐fold more active on the Ca2+ pump than on the H+‐ATPase); and iv) the effectiveness of EB in inhibiting the Ca2+ pump was strongly affected by the protein concentration in the assay medium.
Nitrogen Acquisition from Atmospheric NH3 by Lolium perenne
Authors: Wollenweber B. , Raven J. A. 
Published: February 2014

AbstractAmmonia (NH3) is the third most abundant N species in the atmosphere and, due to various natural and anthropogenic sources, can reach high concentrations in some areas. While some plants show effects of toxicity, others are capable of using this N‐form and grow well without any utilization of soil‐N. Acquisition of atmospheric NH3 will affect the acid‐base balance of the plants as absorption and dissolution causes an alkalinisation (production of OH−) and assimilation of NH3 results in an acidification (generation of H+). As there is only a limited capacity for biochemical disposal of excess H+ in shoots, pH regulation may involve H+/OH− extrusion into the media via roots and transport of (in)organic ions between roots and above‐ground parts of the plant.Our aim therefore was to assess NH3 acquisition by Lolium perenne and to study the effects of gas phase NH3 on growth, acid‐base balance and mineral composition of the plants. The experiments therefore included application of a range of 14NH3 to the shoots and of 15N as NO3−, NH4+ or NH4NO3 to the roots, from which the amount of gas phase NH3 acquisition could be quantified. Analysis of the mineral composition provided data for calculation of acid‐base balance as well as for water use efficiencies of the plants.The results indicate that over the range of NH3 supplied, plants from all treatments could utilize gas‐phase NH3 as demonstrated by increases in growth and in N and C use efficiencies. Plants receiving NO3− via their roots had a higher capacity to use gaseous NH3 than those growing with NH4+. NH3 assimilation in shoots reduced both the acid load with NH4+ nutrition and the alkaline load with NO3− supply to the roots. The results of the experiments are discussed in relation to possible acid‐base regulation mechanisms of the whole plant.
The Role of Protons in the Auxin‐induced Root Growth Inhibition ‐ A Critical Reexamination
Authors: Lüthen H. , Böttger M. 
Published: February 2014

AbstractAccording to the acid growth theory of auxin action, it has been proposed that auxin decreases root growth by inhibiting the proton pump, thus causing an alkalinization of the apoplast. This paper critically tests this hypothesis with corn (Zea mays L.) roots. It was found that: i) the pH‐growth curve for roots exhibits a broad optimum ranging from pH 4.5 to 9. ii) Any acid‐induced growth is of very short duration, iii) The low sensitivity of root growth to external pH is independent of both the pump activity and the buffer capacity of the bathing solution, iv) Neither incubation in acidic buffer nor stimulation of the proton pump reverts the auxin‐induced root growth inhibition. It is concluded that the auxin‐induced root growth inhibition is not mediated by cell wall alkalinization.
Changes in the Carotenoid Pattern During the Synchronous Life Cycle of Scenedesmus
Authors: Senger H. , Schrader Elisabeth , Bishop N. I. 
Published: February 2014

AbstractThe wild type (WT) of Scenedesmus obliquus and a mutant lacking chlorophyll b and the light‐harvesting complexes (WT‐LHC1) were synchronized by a light‐dark regime. Both cultures contained the same type of carotenoids. However, concentrations and patterns of carotenoids were different during their synchronous life cycles. The concentration of total carotenoids followed more or less that of chlorophyll. The WT contained more carotenoids per cell mass, but slightly less per chlorophyll. It is discussed that part of the carotenoids of the mutant, lacking the peripheral antenna of PSII, might be located in the chlorophyll b‐less apoprotein or in an enlarged core antenna of PSII.During the life cycle of Scenedesmus the carotenes are initially synthesized and most of the α‐carotene is immediately oxidized to lutein which is inserted in the antennae systems of PSII and PSI. The further oxidation of lutein to loroxanthin seems to depend on both the change from dark to light, and on stages of the life cycle itself. Although the major part of β‐carotene appears to be inserted in the reaction centers, a fraction of the total pool is rapidly converted to violaxanthin, following the onset of illumination. The conversion may serve to protect against photooxidation. Further conversion of violaxanthin to neoxanthin occurs to a greater extent in the mutant, WT‐LHC1. The results demonstrate (1) the close connection between the carotenoid pattern and the modulation of the photosynthetic apparatus during the life cycle of Scenedesmus and (2) the flexibility of the organism in compensating for the absence of the light‐harvesting complexes of photosystems II by adjusting the carotenoid distribution.
Photosynthetic Characteristics of the Palisade Mesophyll and Spongy Mesophyll in the CAM/C4 Intermediate Plant, Peperomia camptotricha*
Authors: Nishio J. N. , Ting I. P. 
Published: February 2014

AbstractSeveral photosynthetic parameters were examined in the different tissue layers of leaves from the recently characterized crassulacean acid metabolism/C4 intermediate plant, Peperomia camptotricha (Nishio and Ting, 1987). Light appears to control the development of certain photosynthetic characteristics within the tissue layers, while factors other than light seem to dictate others. Analysis of the chlorophyll content (including P700) and chlorophyll‐proteins indicated that more light harvesting chlorophylls were associated with reaction centers in the tissues that were shaded by overlying tissue. Electron transport activity and chlorophyll‐protein analysis indicated that the ratio of photosystem I to photosystem II in the spongy mesophyll (the abaxial tissue type and hence most shaded) was elevated relative to the overlying chlorophyll‐rich median palisade mesophyll. The elevated photosystem I relative to photosystem II in the spongy mesophyll of Peperomia camptotricha may be related to C4 metabolism and an increased requirement for ATP.
Sub‐cellular Localization of Calcium in Azolla‐Anabaena Symbiosis by Chlortetracycline, ESI and EELS
Authors: Canini Antonella , Albertano Patrizia , Caiola Maria Grilli 
Published: February 2014

AbstractThe subcellular localization of calcium in cells of symbiotic partners located within leaf cavities of Azolla was investigated by using chlorotetracycline, ESI and EELS analysis. Loosely membrane‐bound calcium was evidenced by using CTC or EGTA and CTC, in cytoplasmic regions of Azolla hair cells and in cytoplasm of the cyanobiont. Tightly membrane‐bound calcium revealed by CTC, and ESI and EELS analysis, was observed in cyanophycin granules and carboxysomes of the cyanobiont. A third calcium type, revealed by ESI and EELS analysis, was localized at the level of cell walls of simple and branched Azolla hairs, in the envelope of heterocysts, and in the cell walls of the cyanobiont.
Age‐Dependent Modifications and Further Localization of the CX 26‐like Protein from Vicia faba L.
Authors: Hunte Carola , Janßen Martina , Schulz Margot , Traub O. , Willecke K. , Schnabl Heide 
Published: February 2014

AbstractA strong age dependency together with alterations in the cellular distribution of CX 26 immunorelated protein(s) was found for differently developed leaves of Vicia faba L. With increasing age, an immunoreactive 40 kD band was observed in the soluble and microsomal fraction. In the cell wall protein preparation of young and fully differentiated leaves the 40 kD band was the minor constituent. A 33 kD polypeptide was dominantly localized in the microsomal fractions of all developmental stages and in SDS‐extracts of total cell proteins of young leaves. A 21 kD protein together with a 16 kD polypeptide was associated with the cell wall fraction. The 21 kD protein, assumed to represent a plasmodesmatal constituent, was reduced with age. In SDS extracts, prepared from the different developmental stages of the leaves and of mesophyll protoplasts, the age‐dependent appearance of the several immunostained bands was most obvious. A correlation of the 16, 33, and 40 kD bands to a turnover of the 21 kD protein is suggested. The reduced amount of the 21 kD protein with increasing age may be contemplated as an indication for a relative decrease of symplastic connections between cells of maturing leaves. This is in agreement with the results obtained by immunofluorescence studies using guard cell protoplasts. Here, observations pointed also to a reduction and final loss of CX 26‐related protein at the protoplast surfaces.
The Modified Stomata of the Floral Nectary of Vicia faba L.
Authors: Davis A. R. , Gunning B. E. S. 
Published: February 2014

AbstractA comparison of developmental features and physiological responses between the modified stomata (MS) of the floral nectary and the stomata of leaves of Vicia faba L. has revealed several significant differences. In mature tissues, the frequency per unit area of MS is three times that of foliar stomata, and when only the distal quarter of nectary projections is considered, it is twelve fold higher. The walls of guard cells (GCs) of MS near the pore were four to five times thinner than those of their foliar counterparts. Average pore widths of the nectary MS remained constant throughout the day and night, contrary to those of leaves; maximal foliar apertures were similar to average pore widths of MS of nectaries. Experiments with plasmolytica demonstrated a higher osmotic potential in nectary MS, and that sister GCs of the nectary only occasionally closed their pores by movements, even when they were plasmolysed, whereas GCs of leaves were found to be plasmolysed only after their pores had shut. Abscisic acid (ABA) was always detected naturally in floral nectar. The results of experiments involving K+‐localization and the secretion of large quantities of ABA in nectar suggested that GCs of the MS lack operational systems involving K+‐influx and ABA‐receptor sites. All information gained is consistent with the earlier conclusion that the MS do not have a regulatory role in nectar secretion by flowers of V. faba.
A Comparative Study by δ13C‐Analysis of Crassulacean Acid Metabolism (CAM) in Kalanchoë (Crassulaceae) Species of Africa and Madagascar
Authors: Kluge M. , Brulfert Jeanne , Lipp J. , Ravelomanana D. , Ziegler H. 
Published: February 2014

AbstractThe carbon isotope ratios (δ13C values) of samples of Kalanchoë species collected in Africa were compared with previous data obtained with species from Madagascar. In contrast to the Malagasy species which cover the whole range of δ13C values from −10 to − 30%o, indicating high inter‐ and intraspecific diversity of CAM performance, in the African species nearly all δ13C values were less negative than −18%0. Thus, in the African species the CAM behaviour is characterized by CO2 uptake proceeding mainly during the night. The distribution of δ13C values among the species clearly mirrors the taxonomic groups and the three sections of the genus Kalanchoë sensu lato. The Kitchingia section comprises only groups having CAM with a high proportion of carbon acquisition by the C3‐pathway of photosynthesis. The same holds true for the first three groups of the Bryophyllum section, whereas in the following groups of the section CAM with CO2 proceeding mainly during the night is common. The latter CAM mode is typical also for the majority of groups and species in the section Eukalanchoë.The African Kalanchoë species belong to the Eukalanchoë section, whereas in Madagascar all three sections are abundant. The data support the view that the centre of adaptive radiation of the genus is located in Madagascar. They also suggest that high CAM variability is abundant in the more primitive taxa of the genus, whereas the phylogenetically more derived taxa show a stereotype CAM with CO2 uptake taking place only during the night.
X‐Ray Microanalytical Studies on Mineral Concentrations in Vacuoles of Needle Tissues from Larix decidua (L.) Mill.
Authors: Stelze R. , Holste R. , Groth M. , Schmidt A. 
Published: February 2014

AbstractElemental concentrations in the vacuoles of mesophyll, endodermis and transfusion parenchyma cells were determined by means of electron probe microanalysis on bulk frozen hydrated needles of an outdoor‐grown larch tree. The investigations were done routinely throughout a life cycle of the deciduous larch needle, starting with bud burst in March and ending with leaf abscission in November. It could be shown that the endodermal vacuoles preferentially accumulate S, CI and Ca while the transfusion parenchyma vacuoles transiently store Mg, K and S. Between May and September the inorganic ion level of mesophyll cells is constantly lower than in the endodermal and transfusion parenchyma vacuoles. In autumn, when the degradation of chlorophylls becomes detectable, the elements Mg, S, CI and Ca are found increasingly in the vacuoles of the mesophyll cells. It is concluded that, in mature and intact larch needles, the vacuoles of the endodermis in cooperation with the transfusion parenchyma vacuoles act as efficient ion storage buffers which maintain a constant low ion level in the vacuoles of mesophyll cells.
Vapour Phase Activation, Intracellular Motility and Germination in the Tripororate Pollen of Epilobium angustifolium
Authors: Heslop‐Harrison J. , Heslop‐Harrison Yolande 
Published: February 2014

AbstractThe germinability of newly released pollen of Epilobium angustifolium in liquid medium is low, but it is enhanced by a short period in an atmosphere of 85–95% RH without access to liquid water or solutes. During this period the thickened pectic layers of the intine at the germination apertures of the grains are eroded and prospective tube tips emerge. Concomitantly polarised movement of organelles begins in the vegetative cells, and wall precursor vesicles (P‐particles) accumulate at the apertures. In pollen held continuously in the humid environment transition to cylindrical growth follows, with the establishment of the inverse‐fountain pattern of circulation in the apical part of the tubes.
Underground Plant Movement
Authors: Pütz N. 
Published: February 2014

AbstractA special preparation method makes it possible to observe the underground bulb movement of Nothoscordum. This movement is effected by contractile roots. Straight ahead movement, which seems to be typical for many bulbous plants, is only exceptionally seen in Nothoscordum. Bulb movement in Nothoscordum occurs by tilting and twisting, effected by the pulling force of contractile roots on one side of the bulb. Also, vegetative dispersal of lateral bulbs (daughter bulbs) caused by the pulling force of contractile roots can be documented. Finally, starting from the seedling, the overall bulb movement can be demonstrated, showing how the plant penetrates the substratum thus reaching the optimum depth.
Studies on the Sporogenous Lineage in the Moss Timmiella barbuloides
Authors: Gambardella R. , Alfano F. , Gargiulo M. , Squillacioti C. 
Published: February 2014

AbstractThe formation of the sporoderm in the moss Timmiella barbuloides (Brid.) Moenk. (Pottiales) was investigated by electron and fluorescence microscopy. Exine is the first layer formed. It is initiated during late cytokinesis on the distal surface of the tetrad members by centripetal apposition of lamellae just outside the plasma membrane. The exine then extends along the margins of the spore up to the proximal face where it contributes to the formation of the aperture. Exine deposition is closely related to two extensive systems of microtubules that develop sequentially from discrete microtubule organizing centres associated with the plasma membrane at distal and proximal poles of spores. After spore liberation from the tetrads the exine becomes homogeneous. Discontinuous perine ornamentations of extrasporal origin are then deposited onto the outer surface of the exine while the aperture development is completed. The intine is the last and innermost layer formed. Its deposition is restricted to the proximal hemisphere of the spore with thickness decreasing from the pole to equator.
Isolation of Protoplasts from the Coccal Green Alga Eremosphaera viridis De Bary for Patch‐clamp Measurements
Authors: Linz K. W. , Köhler K. 
Published: February 2014

AbstractA method for enzymatic isolation of protoplasts from the unicellular green alga Eremosphaera viridis for patch‐clamp measurements is described. Viable protoplasts with “patch‐clean” plasma membranes could only be isolated when combining high enzyme concentrations and long incubation times.In whole‐cell recordings the protoplasts exhibited electrical properties similar to those measured in intact cells. Taken together with the protoplasts' ability for rapid deplasmolysis after transfer into hypotonic solution, this indicates the viability of the isolated protoplasts.
Ultrastructure and Germination Percentage of Crocus biflorus Miller subsp. biflorus (Iridaceae) Pollen
Authors: Caiola Maria Grilli , Banas Malgorzata , Canini Antonella 
Published: February 2014

AbstractPollen of Crocus biflorus Miller subsp. biflorus from natural habitats of Tusculum (Frascati, near Rome, Italy) has been studied in order to compare its structure and physiology to pollen of other Crocus species belonging to the Crocus sativus group. Mature pollen grains are rounded, 60 μm in diameter, in‐aperturate (but with surface incisions where exine is lacking). DAPI staining reveals a spindle‐shaped generative nucleus which is intensely fluorescent, and vegetative nucleus which is less fluorescent, and is elongated with numerous lobes. At anthesis the pollen is bicellular, but about 2% of tricellular grains occur among the pollen grains released from the anthers as well as on both naturally or handpollinated stigmas.Pollen germination is low in vitro, but higher in vivo. The pollen tubes are of normal shape. An electron‐dense surface coat is sometimes visible on the exine, which in many cases, is detached from the exine. The vegetative cytoplasm is very rich in glycolipid bodies surrounded by endoplasmic reticulum. The generative cell has a lobed cell wall and is surrounded by the vegetative nucleus.
The Joint Occurrence of Chloroxanthones in Southern Hemisphere Lecanora Species (Ascomycotina; Lecanoraceae)
Authors: Lumbsch H. T. , Feige G. B. , Elix J. A. 
Published: February 2014

AbstractFour species belonging to the Lecanora subfusca group (Lecanoraceae, lichenized Ascomycotina) and containing the 2,5,7‐trichloro‐3‐O‐methylnorlichexanthone chemosyndrome are described: L. elixii Lumbsch, L. epibryon Ach., L. mayrhoferi Lumbsch spec. nov. and L. parmelinoides Lumbsch spec. nov. The species, which are interpreted as being closely related, can be distinguished by a combination of subtle morphological and anatomical characters.
Tidal Dependence of Photoinhibition of Photosynthesis in Marine Macrophytes of the South China Sea*
Authors: Hanelt D. , Li J. , Nultsch W. 
Published: February 2014

AbstractDuring an expedition in spring 1992 to Hainandao, an island in the tropical zone of the South China Sea, the daily courses of photoinhibition of different brown algal species and of the seagrass Thalassia hemprichii were investigated. Experiments were carried out with the new portable chlorophyll fluorometer PAM 2000 (Walz, Germany). As a measure of photoinhibition Fv/Fm was used and as a measure of the photosynthetic yield ΔF/Fm'. Photoinhibition occurred in all algae floating near the water surface and reached its maximum between noon and the early afternoon. In the evening photosynthesis was always fully recovered. The extent of photoinhibition depended on both the depth of the algae and the course of the irradiance during the day. Algae of the sublittoral zone showed only a low degree of photoinhibition at high fluence rates when they were covered by a water column of more than 1 m, even if the water was clear. The seagrass Thalassia hemprichii grew in the middle and upper intertidal zone and showed a significant photoinhibition at low tide only when it was not water‐covered. Apparently, it is able to cope with extreme high light conditions without downregulation of photosynthesis caused by photoinhibition.