bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunocytochemical Localization of Phycoerythrin‐545 and of a Chlorophyll a/c Light Harvesting Complex inCryptomonas maculata(Cryptophyceae)
Authors: Rhiel E. , Kunz J. , Wehrmeyer W. 
Published: February 2014

AbstractAntisera, raised against the subunits of phycoerythrin‐545 and total chlorophyll a/c light harvesting complex (chl a/c LHC) ofCryptomonas maculata, were tested for specificity by immunodiffusion and Western‐immunoblotting experiments. They were further used for immunogold‐labeling of Lowicryl sections of control and nitrogen deficient cells. In control cells (+ N) the antiserum against the chl a/c LHC labeled the thylakoid membranes uniformly. On the other hand, the label against the subunits of the water soluble phycoerythrin‐545 was almost completely restricted to the thylakoid lumen. Nitrogen deficient cells (–N) compared to control cells exhibited labels against the chl a/c LHC with very similar densities per unit area. For the subunits of phycoerythrin‐545 a three‐ to four‐fold weaker gold label per unit area was measured. These results confirm some of the earlier conclusions, e.g. the persistence of the chl a/c LHC even under conditions of nitrogen‐deficiency and the extensive degradation of the biliprotein (Rhiel et al., 1985, 1986, 1987).
Immunofluorescent Staining of Microtubules in Plant Tissues: Improved Embedding and Sectioning Techniques using Polyethylene Glycol (PEG) and Steedman's Wax
Authors: Brown R. C. , Lemmon B. E. , Mullinax J. B. 
Published: February 2014

AbstractMethods for the indirect immunofluorescent staining of microtubules in embedded and sectioned plant tissues are described and compared. Root tips of Vicia faba, Saccharum officinale, Allium cepa, and root nodules of Glycine max were fixed using conventional methods, embedded in polyethylene glycol or Steedman's wax, sectioned with a glass knife on a rotary microtome, and dewaxed in water or alcohol. The addition of dithiothreitol (DTT), dehydrating at low temperatures and reducing the infiltrations times were found to reduce background fluorescence in Allium cepa. Steedman's wax yields a block that is similar to paraffin and is easier to section than PEG. Routine methods for indirect immunofluorescence were used to stain sections for tubulin/microtubules. The major microtubule arrays of mitotic cells are illustrated in this paper. The principal advantage of this technique is the preservation of cell‐to‐cell continuity in multicellular tissues. This method provides a much needed technique for the study of the cytoskeleton during growth and differentiation of plant tissues.
Immunological Characterization of Gamete Autolysins in Chlamydomonas reinhardtii
Authors: Waffenschm Sabine , Kuhne Dipl.‐Biol. Wolfgang , Jaenicke Lothar 
Published: February 2014

AbstractPolyclonal antibodies were raised in rabbits against the C. reinhardtii cell wall lytic enzyme, autolysin, which dissolves the cell wall of gametes prior to cell fusion. The purified immunoglobulins react with both the native and the deglycosylated forms of this gametic autolysin and specifically inhibit enzyme activity. In addition, the immunoglobulins selectively detect the gametic autolysin in immunoblots of crude extracts and do not cross‐react with the autolysin of the vegetative cells. The antibodies have been used to study the time of synthesis of the enzyme during gametogenesis and to compare gametic autolysins of different strains of Chlamydomonas.
The Osmometer Model of the Root: Water and Solute Relations of Roots of Phaseolus coccineus
Authors: Steudle E. , Brinckmann E. 
Published: February 2014

AbstractWater and solute relations of young roots of Phaseolus coccineus have been measured using the root pressure probe. Biphasic root pressure relaxations were obtained when roots were treated with solutions containing different osmotic test solutes. From the relaxations, the hydraulic conductivity (Lpr), the permeability coefficient (Psr), and the reflection coefficient (σsr) of the roots could be evaluated. Lpr was 1.8 to 8.4 . 10−8 m . s−1 . MPa−1 and Psr (in 10−10 m . s−1): methanol, 27–62; ethanol, 44–73; urea, 5–11; mannitol, 1.5; KCl, 7.1–9.2; NaCl, 2.1; NaNO3, 3.7. The hydraulic conductivity was similar when using osmotic and hydrostatic pressure gradients as driving forces. The hydraulic conductivity of individual root cortex cells (Lp) was by two orders of magnitude larger than Lpr (Lp = 0.3 to 4.7 . 10−6 m . s−1 . MPa−1) which indicated a predominant cell‐to‐cell rather than an apoplasmic transport of water in the Phaseolus root. Except for distances shorter than 20 mm from the root apex, the hydraulic resistance of the roots was limited by the radial movement of water across the root cylinder and not by the hydraulic resistance within the xylem. Reflection coefficients were low: methanol: 0.16–0.34; ethanol: 0.15–0.47; urea: 0.41–0.51; mannitol: 0.68; KCl: 0.43–0.54; NaCl: 0.59; NaNO3: 0.54. The transport coefficients (Lpr, Psr, σsr) have been critically examined for influences of unstirred layers and active transport. The low σsr suggests that the common treatment of the root as a rather perfect osmometer (σsr = 1) analogous to plant cells should be treated cautiously. The reasons for the low σsr and the possible implications of the absolute values of the transport parameters for the absorption of water and nutrients are discussed.
Ultrastructural and Morphological Characteristics of Cultivated Wheat Growing on Copper‐Polluted Fields
Authors: Eleftheriou Ass. Prof. Dr. E. P. , Karataglis S. 
Published: February 2014

AbstractA cultivated Greek variety of wheat (Triticum aestivum L. cv. Vergina) growing in fields naturally polluted by outcrops of copper ores was investigated. Wheat plants show a negative response to increasing quantities of soil copper, including reduced growth and chlorosis. Copper toxicity was demonstrated in the laboratory by a rooting test; the frequency of mitoses declines sharply with increasing copper concentration in the nutrient solution.The mesophyll cells of polluted plants display a circular shape (in transverse sections) with a few chloroplasts parietally distributed, in contrast with the elongate or pleomorphic shape of control leaves that contain numerous chloroplasts crowded at the cell periphery. Ultrastructurally, the chloroplasts of polluted plants contain a poorly developed internal membrane system consisting of thylakoids arranged parallel to each other with only a few, rudimentary grana. In addition, a number of statistically significant differences were found, including the number of starch grains and plastoglobuli, chloroplast surface area, volume fraction of starch grains and, most important, the volume fraction of the internal membrane system. All ultrastructural changes are attributed to the toxic effect of high concentrations of soil copper.
A Comparative Ultrastructural Investigation of Some Nannochloris Species (Chlorococcales) with Particular Reference to the Systematic Position of Nanochlorum eucaryotum
Authors: Menzel Karola , Wild Aloysius 
Published: February 2014

AbstractNanochlorum eucaryotum was described by Wilhelm et al. (1982) as a new algal species with an uncertain taxonomic position. Whereas some features were chlorococcacean, others suggested an isolated position in the sense of a “pre‐eucaryote” (Wilhelm, 1983; Zahn, 1984; Geisert et al., 1987). Our comparative ultrastructural, physiological and biochemical examinations of coccoid microalgae (Menzel, 1988) gave no arguments for the separation of Nanochlorum eucaryotum from the genus Nannochloris. This paper is concerned with the ultrastructural composition of the cell wall and mode of reproduction in Nanochlorum eucaryotum as well as in three Nannochloris species. The systematic position of Nanochlorum eucaryotum is discussed in comparison with representatives of the genus Nannochloris. As a result, Nanochlorum eucaryotum has been included in the genus Nannochloris.
Chaotic Floral Phyllotaxis and Reduced Perianth in Achlys (Berberidaceae)
Authors: Endress Peter K. 
Published: February 2014

AbstractAmong the 16 genera of the Berberidaceae Achlys is the only one with a reduced perianth, an irregular floral phyllotaxis, and variable stamen number. Early floral stages show an unstable (chaotic) arrangement of the organ primordia. Only the single carpel of the gynoecium has a more fixed position in that the placenta is formed in the adaxial half of the flower. The irregularities in the androecium may be caused by the lack of influence of a perianth on floral symmetry. On the other hand, the regular orientation of the carpel is perhaps due to the early polarity of the flower, whereby the abaxial half of the flower is larger (with further developed stamen primordia) at the time when carpel polarity is established.
Detection of a Phytochrome‐like Protein in Macroalgae
Authors: López‐Figueroa F. , Lindemann P. , Braslavsky S. E. , Schaffner K. , Schneider‐Poetsch H. A. W. , Rüdiger W. 
Published: February 2014

AbstractA phytochrome‐like protein was detected in extracts from the red algae Corallina elongata and Gelidium sp., from the brown algae Cystoseira abiesmarina and Cystoseira tamariscifolia, and from the green algae Ulva rigida, Enteromorpha compressa and Chara hispida. Relative amounts of the photoreversible protein were determined by measurement of Δ (ΔA) values of the crude extract. SDS gel electrophoresis and immunoblotting with monoclonal antibodies directed to phytochrome from etiolated maize and oat seedlings revealed only one phytochrome‐related band with apparent molecular weight of 130 kDa. The absorption difference spectrum after partial purification showed a “normal” absorption band (λmax = 670 nm) for the Pr form but only a very weak band (λmax = 705 nm) for the “Pfr form”.
Fatty Acid Composition of the Peribacteroid Membrane and the ER in Nodules of Glycine max Varies after Infection by Different Strains of the Microsymbiont Bradyrhizobiumjaponicum
Authors: Bassarab S. , Schenk Sigrid U. , Werner D. 
Published: February 2014

AbstractThe fatty acid composition of ER, Golgi and peribacteroid membrane (PBM) from root nodules formed on Glycine max after infection with different strains of Bradyrhizobium japonicum has been analysed by gas chromatography. In each plant‐microsymbiont combination the fatty acid composition (FAC) of the PBM is distinct from ER and Golgi. The similarity between ER and PBM fatty acid composition is significantly stronger than between Golgi and PBM. In addition the fatty acid composition of all membrane systems in nodules is affected by the microsymbiont strain. A comparison of four strains of Bradyrhizobium japonicum grown in agar surface culture and isolated as the symbiotic bacteroids reveals a decrease in oleic acid during bacteroid differentiation.
Investigations on the Starch Content and Ultrastructure of Spruce Needles Relative to the Occurrence of Novel Forest Decline
Authors: Forschner W. , Schmitt V. , Wild A. 
Published: February 2014

AbstractThe starch content and ultrastructure of needles of Norway spruce trees [Picea abies (L.) Karst.] taken from three natural habitats, undamaged or with symptoms of novel forest decline, were investigated during the course of three years.The starch content was clearly dependent on the seasons, with a maximum in spring and a decline during summer and autumn, leading to a minimum in winter. Needles of damaged trees from one habitat exhibited in all three years from August to October a significantly higher starch content than their undamaged counterparts. Microscopic investigations of these needle samples exhibited severe damage symptoms to the phloem in macroscopically green needles, though more intensely in the needles with yellowing symptoms. The phenomenon of starch accumulation is interpreted as a delay in starch mobilization, caused by a reduction in assimilate transport capacity of the needle phloem.The lower degree of starch accumulation in needles of damaged trees from a second natural habitat corresponded well to the lesser extent of phloem damage. The difference in damage patterns are discussed in terms of the differing air pollution situations acting on both habitats.
Two Proton Pumps Operate in Parallel Across the Tonoplast of Vacuoles Isolated from Suspension Cells ofChenopodium rubrumL.*
Authors: Hoffmann Bernd , Bentrup Friedrich‐Wilhelm 
Published: February 2014

AbstractThe kinetics of vacuolar acidification upon addition of ATP and/or pyrophosphate (PPi) has been assayed on single immobilized vacuoles by computer‐aided microfluorimetry of 9‐aminoacridine, and by acridine orange absorption photometry on vacuole suspensions isolated from green suspension cells ofChenopodium rubrumL. Two proton pumps at the tonoplast, an ATPase and a pyrophosphatase (PPase), operate in parallel to acidify the vacuole with different contributions adding up to a transtonoplast Δ pH of 2.6 pH units at external pH 7.2. The saturable components of proton pumping reach half maximal velocity with 0.32 ± 0.06 mM ATP and 23 ± 2.5 μM PPi, respectively. At saturating substrate concentrations, ATPase and PPase hydrolyse ATP and PPi, respectively, at a ratio of 2.3. The same ratio holds for the corresponding proton fluxes maintaining a given steady‐state vacuolar pH. We conclude that both pumps operate at the same stoichiometry.
Lipid Profiles of Leaf Tonoplasts from Plants with Different CO2‐Fixation Mechanisms*
Authors: Haschke H.‐P. , Kaiser G. , Martinoia E. , Hammer U. , Teucher T. , Doene A. J. , Heinz E. 
Published: February 2014

AbstractTonoplast preparations were obtained from leaves of Hordeum vulgare (C3), Kalanchoë daigremontiana (obligate CAM) and Mesembryanthemum crystallinum (C3 and inducible CAM). Lipid analyses showed reproducible patterns comprising free sterols, glycolipids of plastidic origin, glucose‐containing lipids (steryl glucoside, acylated steryl glucoside, cerebroside) and phospholipids. Predominant components were sterols, cerebrosides, phosphatidyl choline and phosphatidyl ethanolamine. Very long chain fatty acids were found in phosphatidyl serine and hydroxy fatty acids in cerebrosides. Isolation of tonoplasts via protoplasts and vacuoles may have resulted in reduced levels of free sterols. The data show a similarity between tonoplasts and plasma membranes with respect to lipid profiles. Lipid composition was neither affected by different CO2‐fixation mechanisms nor by salt‐induced changes in Mesembryanthemum crystallinum.
Changes in the Subcellular Distribution of Free Amino Acids in Relation to Light Conditions in Cells of Chara corallina
Authors: Mimura T. , Sakano K. , Tazawa M. 
Published: February 2014

AbstractSubcellular concentrations of free amino acids in internodal cells of a Characeae, Chara corallina, were measured in the dark and in the light. Using an intracellular perfusion technique, we measured concentrations of amino acids in the vacuole, in the flowing sol endoplasm and in the cortical gel layer. The sol endoplasm was predominantly the cytosol. On the basis of microscopic observations, the gel layer appeared to be occupied predominantly by a layer of chloroplasts, while the sol endoplasm was free from chloroplasts.Both in the light and in darkness, the major amino acids in the internodal cells were isoasparagine, glutamic acid, aspartic acid, serine, glycine and alanine, as reported by Sakano and Tazawa (1984). The same major amino acids are found in each of the three compartments. The pattern of distribution of amino acids in the vacuole was similar to that in the sol endoplasm, but quite different from that in the gel layer. The total level of amino acids in the light was lower than that in darkness. The amino acid composition did not change very much, but the subcellular distribution of amino acids differed significantly between cells subjected to illumination and those kept in the dark. Concentrations of amino acids in both the vacuole and the gel layer decreased, whereas those in the sol endoplasm were almost constant.
Regulation of the Synthesis of Isocitrate Lyase and the Corresponding mRNA in the Green Alga Chlorogonium
Authors: Schmidt A. , Zetsche K. 
Published: February 2014

AbstractIn the unicellular green alga Chlorogonium elongatum the level of isocitrate lyase (ICL), the rate of its synthesis and the level of ICL‐mRNA measured by in vitro translation are considerably increased after addition of acetate to the culture medium of autotrophically precultured cells.Almost identical increases are obtained independently of whether the cells are cultured after the addition of acetate in the dark (heterotrophically) or in the light (mixotrophically). Transfer of heterotrophic cells to autotrophic conditions results in a fast decrease of ICL‐mRNA and ICL protein, while a transfer to mixotrophic conditions causes no alterations in both molecular species. Therefore the concentration of ICL and its translatable mRNA is controlled only by acetate and is unaffected by light.
Photoinhibition of Photosynthetic Oxygen Production and its Recovery in the Subtidal Red Alga Polyneura hilliae
Authors: Nultsch W. , Pfau J. , Huppertz K. 
Published: February 2014

AbstractIn the marine red alga Polyneura hilliae photoinhibition of photosynthesis was investigated by measuring the photosynthetic oxygen production. The extent of photoinhibition in this alga depends on the fluence rate as well as on the time of exposure. Strongly photoinhibited algae recover slowly. Full recovery is reached only in weak light after 3 days. Two phases of recovery can be distinguished: a first relatively fast phase of recovery that is independent of light, and a second slow phase which begins after about 6 hours and requires weak light. Consequently, even in complete darkness partial recovery is observed.An action spectrum of photoinhibition and its comparison with the in vivo absorption spectrum of Polyneura demonstrates that photoinhibition is mainly caused by light which is absorbed by phycobiliproteins, chlorophyll a and carotenoids. This fact and the ineffectiveness of light above 686 nm clearly indicate that the main photoinhibition site in this alga is PS II.No photosynthetic oxygen production is detectable after 3 h irradiation at 402 nm, 150 μmol quanta m−2s−1. As photosynthetic activity recovers slowly and to a limited extent, the suppression of oxygen production is apparently only in part the result of photoinhibition sensu strictu and in part due to permanent photodamage.
Hummingbird Pollination in Two Species of Vellozia (Liliiflorae: Velloziaceae) in Southeastern Brazil*
Authors: Sazima M. , Sazima I. 
Published: February 2014

AbstractPollination by hummingbirds was observed in two species of Vellozia (Velloziaceae) in southeastern Brazil. Both species have purplish‐pink to dark purple tepals, tube‐like arrangement of stamens, large and protected nectar chamber, and no odour. Tepals are reflexed in V. leptopetala and narrow in V. declinans, further enhancing the tube‐like effect given by the long yellow anthers. Nectar is very dilute (ca. 10%). Three species of hummingbirds were observed pollinating these Vellozia species: Colibri serrirostris, Augastes scutatus, and Chlorostilbon aureoventris. The first species established feeding territories in the vicinity of V. leptopetala flowers. A bee‐pollinated Vellozia flower‐type may give rise to a hummingbird‐flower by relatively simple adjustments, consisting mainly of the reflexion of tepals, increase in stamen length, enhancement of reddish pigments, enlargement of nectar chamber and dilution of nectar. Vellozia declinans may be likened to one of the hypothetical stages of this trend towards ornithophily, whereas V. leptopetala is possibly one of the extremes within the genus.
Blue Light‐Dependent Chloroplast Differentiation in Cultured Plant Cells: Evidence for Transcriptional Control of Plastid Genes*
Authors: Richter G. , Ottersbach N. 
Published: February 2014

AbstractA DNA‐protein complex capable of RNA synthesis (transcriptionally active chromosome, TAC) was isolated from plastids of dark‐grown and blue light irradiated cell cultures of Chenopodium rubrum. The transcriptional activity of TAC increased rapidly upon irradiation of dark‐grown cells with blue light. Analysis of the RNA synthesized showed that plastid rRNA genes as well as genes coding for membrane and stroma proteins were specifically transcribed; their quantities depended on the developmental stage of the plastids produced by blue light exposure. The in vitro transcription rate seems to reflect fairly well the in vivo situation insofar as its enhancement in blue light irradiated cells is in good accordance with the observed steady‐state level of plastid mRNAs. The results obtained support the notion that the blue light‐dependent accumulation of plastid mRNAs in vivo is caused by an increase in the transcription rate of the corresponding genes. Thus an alternative exists to the light‐induced transformation of etioplasts to chloroplasts in seedlings where primarily posttranscriptional and translational controls are effective.
Comparison of Properties of the Proteolytic Degradation of Unassembled Nuclear‐encoded Subunits of Ribulose‐1,5‐bisphosphate Carboxylase and of the Coupling Factor of Photophosphorylation CF1*
Authors: Feierabend J. , Bergmann C. , Otto S. 
Published: February 2014

AbstractThe proteolytic degradation of unassembled small subunit polypeptides of ribulose‐1,5‐bisphosphate carboxylase and of the δ‐subunit of the coupling factor of photophosphorylation CF1 were analyzed and compared in vitro in the presence of stroma or membrane preparations from ribosome‐deficient plastids isolated from 32°C‐grown rye leaves (Secale cereale L.). Extracts obtained from 70S ribosome‐deficient rye leaves after radioactive labeling were used as substrate source for the unassembled polypeptides. Soluble stroma as well as membrane preparations from isolated plastids contained proteolytic activities catalyzing the degradation of both the small subunits of ribulose‐1,5‐bisphosphate carboxylase and CF1‐δ in vitro. Maximal in vitro degradation was observed at pH 2–3 for the unassembled small subunits, but at pH 6–7 for the purified holoprotein of ribulose‐1,5‐bisphosphate carboxylase, and at pH 6.0 for unassembled CF1‐δ. Degradation of unassembled small subunits of ribulose‐1,5‐bisphosphate carboxylase at pH 3.0 was stimulated by Cu2+ but not by Ca2+, Mg2+ or ATP. At pH 3.0 the degradation of unassembled small subunits of ribulose‐1,5‐bisphosphate carboxylase was not inhibited by various protease inhibitors but was even stimulated. At pH 7.0 its degradation was inhibited by HgCl2 and diazoacetyl nor‐leucine methyl ester + Cu‐acetate. The degradation of CF1‐δ was markedly inhibited by phenylmethylsulphonyl fluoride (PMSF) and to a lesser extent by 1,10‐phenanthroline. According to present results different proteolytic systems appear to be involved in the degradation of unassembled small subunits of ribulose‐1,5‐bisphosphate carboxylase and of unassembled CF1‐δ.