bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carotenoid Mutants of Mucor circinelloides
Authors: Ruiz‐Hidalgo María José , López‐Matas María Angeles , Velayos A. , Fraser P. D. , Bramley P. M. , Eslava A. P. 
Published: February 2014

AbstractThe wild‐type of the filamentous fungus Mucor circinelloides accumulates the yellow pigment β‐carotene. At a continuous blue‐light fluence rate of 0.1 W/m2 the β‐carotene content increases about eight fold over the dark controls. Among the mutants isolated after exposure of spores to either N‐methyl‐N'‐nitro‐N‐nitrosoguanidine or ICR‐170, a red mutant accumulating lycopene, white mutants accumulating phytoene and white mutants without carotenoids were found. The biosynthesis of carotenoids in M. circinelloides shows similarities with that of the fungus Phycomyces blakesleeanus such as the presence of mutants in the same structural genes and the induction by light of the pathway. However, negative end‐product regulation by β‐carotene on the biosynthetic pathway, as in Phycomyces, is absent in M. circinelloides. In contrast to Phycomyces carB and carR mutants, carotenoids in corresponding mutants of M. circinelloides are photoinduced.
Carbohydrate Accumulation Affects the Redox State of Ascorbate in Detached Tobacco Leaves
Authors: Polle Andrea , Eiblmeier Monika 
Published: February 2014

AbstractA decreased utilization of NADPH for CO2 fixation as a result of carbohydrate accumulation in chlorotic leaves is generally believed to be associated with an increase in oxidative stress. Molecular oxygen may serve as an alternative electron acceptor of photosynthesis under these conditions. In order to test this hypothesis mature leaves of tobacco plants (Nicotiana tabacum) were detached, fed with glucose (50 mM) via the petiole, and used to study the effect of carbohydrate accumulation on the pigment content and the components of the superoxide dismutase‐ascorbate‐glutathione cycle. During a period of five days the concentration of total soluble carbohydrates increased substantially in leaves supplied with glucose in comparison with control leaves supplied only with water. This increase was accompanied by a twofold decrease in the chlorophyll content. In detached water‐fed leaves the levels of most of the antioxidative components increased, whereas glucose feeding had no or only little additional effect on the activities of the protective enzymes, but caused a 1.6‐ and 4‐fold increase in the contents of glutathione and ascorbate, respectively. In relation to the total foliar ascorbate pool, the amount of reduced ascorbate increased from about 30 % to 60 % upon feeding with glucose. These results do not support the idea that the accumulation carbohydrates per se cause an increased rate of superoxide production which necessitates increased activities of antioxidative enzymes. It rather appears that glucose‐fed leaves have an increased reductive capacity that can be released via glutathione into the ascorbate pool, thereby, regulating the redox state of ascorbate.
Allopolyploid Origin of Arabidopsis suecica (Fries) Norrlin: Evidence from Chloroplast and Nuclear Genome Markers
Authors: Mummenhoff K. , Hurka H. 
Published: February 2014

AbstractThe origin of the presumed allopolyploid Arabidopsis suecica has been explored through isozyme electrophoresis and mutational analysis of chloroplast (cp) DNA. Nuclear encoded isozymes are inherited biparentally and were used to indicate A. thaliana and Cardaminopsis arenosa as parental species. Analysis of the maternally inherited cpDNA provided strong evidence for A. thaliana as maternal parent. The isozyme data suggest multiple origin of A. suecica, because the alloploid shows polymorphisms at the same loci that are polymorphic in its progenitors. The molecular data are in agreement with the hypothesized recent origin of A. suecica at the Late glacial/Holocene boundary in Fennoscandia, in areas opened up by retreating glaciers.
The Involvement of Protein Synthesis Elongation Factor 1α in the Organization of Microtubules on the Perinuclear Region during the Cell Cycle Transition from M Phase to G1 Phase in Tobacco BY‐2 Cells
Authors: Kumagai F. , Hasezawa S. , Takahashi Y. , Nagata T. 
Published: February 2014

AbstractAssociation of the organization of microtubules (MTs) in the perinuclear region with a 49‐kDa protein, that is immunologically cross‐reactive to a 51‐kDa protein isolated from sea urchin centrosomes and has been shown to play some roles in the organization of MTs in animal cells (Toriyama et al.: Cell Motil. Cytoskeleton 9, 117–128, 1988), was examined during the cell cycle transition from M phase to G1 phase using the highly synchronized tobacco BY‐2 cells under confocal laser scanning microscopy (CLSM). After double staining with an antibody against the 51‐kDa protein and with an antibody against tubulin, it was revealed that the 49‐kDa protein was closely associated with the organization of MTs on the perinuclear regions during this stage under the CLSM. Notably, microfilaments (MFs) were not associated with the organization of MTs in the perinuclear region. This observation suggests that the 49‐kDa protein plays a specific role in the organization of MTs on the perinuclear regions during the cell cycle transition from M phase to G1 phase. To understand the molecular characteristics of the 49‐kDa protein further, the search for cDNA encoding the 49‐kDa protein was conducted in a cDNA expression library prepared from rapidly growing tobacco BY‐2 cells using monoclonal antibodies against the 51‐kDa protein. Determination of the base sequence of the isolated clone revealed that it encodes protein synthesis elongation factor (EF)‐1α. Thus the significance of the involvement of the 49‐kDa protein as EF‐1α in the organization of MTs on the perinuclear regions is discussed in relation to other cellular functions.
Multiple Stress Factors affecting Growth of Rock‐inhabiting Black Fungi
Authors: Sterflinger Katja , Krumbein W. E. 
Published: February 2014

AbstractBlack fungi, belonging to the Dematiaceae, with yeast‐like growth patterns, were isolated from rock surfaces in the Mediterranean. They tolerate high temperatures and sodium chloride stress although they are neither thermophilic nor halophilic organisms. Environmental stress factors not only affect growth velocity of the fungi but also the colony shape. A shift of the smooth and flat colonies developed under optimal culture conditions to more clump‐like growth similar to the colony shape on the natural rock substratum is caused by both high temperature and osmotic stress. The “principle of uniformity” is proposed as a new term to interpret specific morphotypes of pleomorphic fungi of different taxonomic assignment.
Sieve‐Element Characters of the Proteaceae and Elaeagnaceae: Nuclear Crystals, Phloem Proteins and Sieve‐Element Plastids
Authors: Behnke H.‐D. 
Published: February 2014

AbstractThe sieve‐element characters of 34 species from the Proteaceae and Elaeagnaceae have been studied by transmission electron microscopy. While nondispersive protein bodies and dispersive P‐protein are typical components of both families, specific forms and/or their distinctive origin accentuate some taxa. Within the Grevilloideae, subfamily of Proteaceae, a number of Australian species and genera contain protein crystals of nuclear origin arranged into rosette‐like bodies, while in the other members studied from the same subfamily no nondispersive protein bodies were found. Several Australian and South African genera of the Proteoideae contain compound‐spherical nondispersive protein bodies that reside in the cytoplasm from their very beginning. In the Elaeagnaceae three different P‐protein bodies are present of which one is tubular and dispersing, another is nondispersive and of irregular‐stellate form, and a third is globular (resembling a P‐protein from Cucurbita). The great majority of the species studied from the Proteaceae contains form‐Ss sieve‐element plastids, Lomatia ilicifolia and Macadamia ternifolia are distinct in having form‐Pcs plastids. The average diameter of stem sieve‐element plastids in the family is 1.38 μm. The Elaeagnaceae (three species investigated) is a pure form‐So family (average diameter: 0.8 μm). There are no specific sieve‐element characters that would support any relationship between the Proteaceae and Elaeagnaceae. While affinities of the former to pre‐Gondwanan parts of the Rosanae/Myrtanae are discussed, a reconsideration of the Elaeagnaceae as a possible member of the Violanae (identical features with Cucurbitaceae) is proposed.
The Vacuolar ATPase of Red Beet Storage Tissue: Electron Microscopic Demonstration of the “Head‐and‐Stalk” Structure*
Authors: Getz H. P. , Klein M. 
Published: February 2014

AbstractTonoplast membranes were prepared from tissue homogenates and from vacuoles isolated from beetroot storage tissue (Beta vulgaris L., ssp. conditiva) for transmission electron microscopic analysis of the structure of the beetroot vacuolar ATPase using the negative staining technique. By comparison of the specific inhibitor sensitivities of the ATPase activity, i.e. ATP hydrolysis and H+‐pumping, the purity of the tonoplast preparations with respect to contamination with mitochondrial inner membranes was assessed to avoid confusion with mitochondrial F1F0‐ATPase. Membranes prepared in Hepes/Tris or BTP/Mes‐containing media rarely showed typical head‐and‐stalk structures although characteristic nitrate‐ and bafilomycin A1‐sensitive ATP‐hydrolysis and H+‐pumping could be measured. However, typical head‐and‐stalk structures were observed regularly when these buffers were replaced by K‐phosphate buffer. Under these conditions, the beetroot vacuolar ATPase is characterized by a large head group with a central cleft, a thin stalk, connecting it to the membrane and by basal components projecting from the base of the stalks near the vacuolar membrane and forming a distinct layer of electron‐light particles between the vacuolar membrane and the layer of non‐stained head groups.
Sugar Transport into Storage Tubers of Stachys sieboldii Miq.: Evidence for Symplastic Unloading and Stachyose Uptake into Storage Vacuoles by an H+‐Antiport Mechanism*
Authors: Niland S. , Schmitz K. 
Published: February 2014

AbstractFollowing assimilation of 14CO2 by leaves of Stachys sieboldii, 14C‐stachyose is translocated into the tubers. Stachyose is accumulated and stored in the vacuoles of the pith parenchyma. Protoplasts and vacuoles were isolated and the uptake of sugars was examined. Uptake of sucrose and sucrosyl oligosaccharides of the raffinose family by protoplasts was very low compared to glucose. Transport parameters for glucose indicated a carrier mediated transport in the lower concentration range which was superimposed by diffusion at higher concentrations (> 10 mM). The very low sugar uptake by protoplasts and the sparse enzyme activities of stachyose synthase in the storage parenchyma as well as acid invertase and α‐galactosidase in the cell walls indicated symplastic unloading of stachyose in the tubers. Experiments on 14C‐stachyose uptake by isolated vacuoles confirmed previous observations by Keller (1992).Isolated vacuoles exhibited ATP and PP hydrolysis and were capable of generating a proton gradient across the tonoplast by a V‐type H+‐ATPase and H+‐PPase. This was demonstrated by fluorescence quenching of quinacrine. Fluorescence could be restored by the addition of gramicidin and partly recovered by the addition of stachyose; mannitol, sorbitol and glucose had no effect. Fluorescence recovery depended on the concentration of stachyose and revealed saturation kinetics (Km = 28 mM). Comparable results have been obtained with tonoplast vesicles by Greutert and Keller (1993).Experimental data presented here provide circumstantial evidence for symplastic unloading of stachyose in the tubers of Stachys sieboldii and demonstrate that the stachyose concentration in the cytoplasm of storage parenchyma cells is kept low by active stachyose transport into the vacuoles. The results suggest a stachyose/H+‐antiport system.
Pattern of Proteins after Heat Shock and UV‐B Radiation of some Temperate Marine Diatoms and the Antarctic Odontella weissflogii
Authors: Döhler G. , Hoffmann M. , Stappel U. 
Published: February 2014

AbstractSynthesis of stress proteins after heat shock and different periods of UV‐B radiation were investigated with marine diatom species from the North Sea Ditylum brightwellii, Lithodesmium variabile, Odontella sinensis, Thalassiosira rotula and the Antarctic diatom Odontella weissfloggii from the Weddell Sea. Algae were grown in an artifical sea‐water medium under controlled laboratory conditions: light/dark regime of 12:12 h (7.2 W m−2), normal air (0.035 vol.% CO2) and 18° or 4 °C. All the tested diatom species can produce heat shock proteins (HSPS) of the 70 kDa family by in vivo labelling with [35S]‐methionine. The same results were obtained for Odontella sinensis, Ditylum brightwellii and Odontella weissflogii by estimation of the in vitro translation products with poly‐A‐mRNA isolated from these organisms. However, Odontella weissflogii, a species relatively insensitive to UV‐B irradiance, did not synthesize UV‐induced HSPS, whereas the UV‐sensitive diatom Odontella sinensis, as well as Lithodesmium variabile, produced all the observed HSPS after UV‐B exposure. In addition, a protein of 43 kDa was found after UV‐B irradiance of the temperate Odontella sinensis. The temperate marine diatom Thalassiosira rotula synthesized 70 kDa and 5 7 kDa proteins after a heat shock and a UV‐B exposure of 2 h, but a 40 kDa protein could not be detected, whereas a 60 kDa protein was found after 2 h UV‐B exposure. The results are discussed in view of a possible adaptation of O. weissflogii to an enhanced UV dose.
Root Browning in Pinus banksiana Lamb. and Eucalyptus pilularis Sm. 2. Anatomy and Permeability of the Cork Zone
Authors: McKenzie B. Elizabeth , Peterson Carol A. 
Published: February 2014

AbstractThe periderm in roots of Pinus banksiana Lamb. and the polyderm in roots of Eucalyptus pilularis Sm. originate from the pericycle. This occurs after the roots have turned brown due to deposition of tannins in the walls of cells external to the endodermis. In both species, cork cells form a continuous sheath around the vascular tissues. The cork cell walls are modified by the presence of suberin, lignin and tannin and it is the latter which imparts a brown colour to the tissue. The first layer of cork cells in both species constitutes an apoplastic barrier which prevents the fluorescent dye, berberine, from entering the vascular tissues, despite the absence of an identifiable Casparian band in the cells. Because the roots are still covered with the cortex and epidermis during early stages of periderm and polyderm formation, it is not possible to tell from the external aspect of the root when it makes a transition from the tannin zone to the cork zone.
Salt‐dependent Protein Composition in the Halotolerant Green Alga, Dunaliella parva
Authors: Golldack Dortje , Dietz K.‐J. , Gimmler H. 
Published: February 2014

AbstractThe extremely halotolerant green alga, Dunaliella parva, tolerates salt concentrations from 0.3 to 3.0 M NaCl. Effects of long‐term adaptation to five distinct salinities were analyzed. Salt‐dependent differences of physiological parameters such as growth rate, pigments, quantitative protein contents, and gas exchange were measured; furthermore the qualitative protein composition in salt‐adapted cells was investigated using SDS‐polyacrylamide gel electrophoresis. Proteins of apparent molecular masses of 26, 35, 39, 50, and 63 kDa were induced or intensified with an increase in external sodium chloride concentration whereas proteins of 85 and 101 kDa were diminished in high salt algae. After selective staining, four modifications of glycoproteins were observed. A glycoprotein of 96 kDa was produced exclusively in low salt cells whereas glycosylations of 105, 135, and 260 kDa were induced by high salt concentrations.
Blue and Red Light‐dependent Alterations in the Ratio of two Forms of Glutamine Synthetase in Chlorella kessleri
Authors: Meya Gudrun , Kowallik W. 
Published: February 2014

AbstractTwo forms of glutamine synthetase (EC 6.3.1.2) can be separated in crude extracts of Chlorella kessleri on the basis of their different surface charges. The two enzyme forms (GS1 and GS2) respond differently upon transferring the cells from darkness to autotrophic growth in white light: the activity of GS2 increases, that of GS1 remains unchanged. The increase in GS2 activity is only brought about by blue light; in red light GS2 activity appears to be uninfluenced, while that of GS1 increases.There are no indications of wavelength‐dependent oligomerization processes as a cause for the observed activity alterations. There is however, a strong influence of inhibitors of protein biosynthesis. Cycloheximide and lincomycin both affect the blue light‐dependent increase in activity of GS2, cycloheximide preventing that of GS1 in red lgiht completely.Since literature data point to localization of GS2 in the chloroplast, and GS1 in the cytosol, the data are discussed in view of two different photoreceptors involved in the regulation of the amounts of GS1 and GS2 in different compartments of the Chlorella cell.
Plant K+ Channels: Similarity and Diversity
Authors: Hedrich R. , Dietrich Petra 
Published: February 2014

Abstract:In this review we compared the electrophysiological properties of plant K+ uptake channels from different plants and tissues. Taking into account the detailed knowledge of K+ channel properties, which has emerged since the application of the patch‐clamp technique on plant cells, as well as results from our recent studies we were able to extract features common among plant K+ channels. In addition, we focused on the diversity that could create plant or tissue‐specificity. Functional fingerprints for the voltage‐dependent K+ uptake channels were generated on the basis of their voltage‐dependence, kinetics, permeability, conductance and pharmacology as well as regulation of K+ channels studied in their natural environment and cloned channels in heterologous expression systems. Finally, sequence information on plant and animal K+ channels cloned so far was used to identify structural motifs that may be related to functional phenotypes.
The Role of the Cytoskeleton and Dictyosome Activity in the Pulsatory Growth of Nicotiana tabacum and Petunia hybrida Pollen Tubes
Authors: Geitmann Anja , Li Yi Qin , Cresti M. 
Published: February 2014

Abstract:Pollen tubes of Nicotiana tabacum and Petunia hybrida show pulsatory growth. Phases of slow growth lasting minutes are interrupted by pulse‐like elongations lasting 10–20 seconds involving an increase of growth rate by up to 24‐fold. Inhibition of dictyosome activity with brefeldin A or monensin did not result in an inhibition of pulsatory growth but eventually stopped pollen tube elongation. In contrast to this the inhibition of the cytoskeletal elements with cytochalasin D and colchicine caused the pollen tubes to abandon the pulse‐like elongations. It was concluded that the activity of the dictyosomes does not have a controlling function in the mechanism of pulsatory growth, even though it is necessary for pollen tube elongation, since cell wall material is provided by secretory vesicles deriving from the Golgi apparatus. In contrast the cytoskeletal elements, actin and microtubules, seem to play an important regulatory role in the pulse‐like elongations. In addition, it was observed that during the experiments several pollen tubes burst upon the completion of a pulse‐like expansion, indicating on the one hand that the internal turgor is the driving force of the pulse‐like expansions. On the other hand, the bursting shows that the pollen tube cell wall is rather weak at the end of a pulse, indicating that at this point of time it is either thinner or less stable than during the slow growth phase or at the beginning of a pulse.
Carotenoids and Reaction Center II‐D1 Protein in Light Regulation of the Photosynthetic Apparatus in Aphanocapsa*
Authors: Nonnengießer K. , Schuster A. , Koenig F. 
Published: February 2014

Abstract:A new cyanobacterial isolate, morphologically closely resembling Aphanocapsa, was characterized for its growth requirements, as well as pigmentation, photosynthetic activity and dynamics of the D1 protein in the reaction center (RC) of photosystem II (PSII). It was shown to be able to grow on glucose in the dark in the presence of DCMU. The cyanobacterium turned light yellow at high light intensity in the absence, and dark emerald green in high light in the presence of sublethal concentrations of the DCMU‐type inhibitor atrazine. While total carotenoids per cell slightly decreased with increasing light intensity during growth, the cells still turned pale yellow due to decreased levels of chlorophyll and phycocyanin. In contrast to β‐carotene, zeaxanthin and echinenone which decreased with increasing light intensity during growth, the carotenoid glycoside, myxoxanthophyll, continuously increased in concentration.Extremely high rates of light‐saturated O2 evolution were recorded for the high light cultures after a 0.5 h recovery period in the dark. The recovery measured after 2.5 h was shown to be less effective in darkness than in dim light and was prohibited by chloramphenicol. The degree of recovery was dependent on the light intensity during growth. A fast light intensity‐dependent RC II‐D1 protein turnover was found for the bleached yellow cells rich in myxoxanthophyll. The half‐life of the RC II‐D1 protein, plotted against the light intensity during growth and experimentation, yielded a curve the slope of which was considerably steeper for Aphanocapsa than for Anacystis. Apparently, the isolated strain of Aphanocapsa reacts more vigorously to changes in the environment than other strains tested and may, therefore, turn out to be a suitable organism in the attempt to elucidate the molecular mechanism of light intensity adaptation.
A Remarkable Case of Ornithophily in Calceolaria: Food Bodies as Rewards for a Non‐nectarivorous Bird*
Authors: Sérsic A. N. , Cocucci A. A. 
Published: February 2014

Abstract:In southernmost South America, the pollination biology of Calceolaria uniflora Lam. (Scrophulariaceae) was studied in the field. One of the most striking features of the flower of this species is a corolla appendage folded against the outside of the lower lip. This massive and fleshy structure is pecked off by Thinocorus rumicivorus (Thinocoridae, Charadriiformes) as a food body. The percentage of damaged flowers averaged 64% and was as high as 81% in one study site. Pollen is placed on the front of the bird's head by the exserted stamens with large versatile anthers. This pollination syndrome is unique for the bird involved and exceptional in the kind of reward offered. This Calceolaria species, and probably a second one endemic to the Falkland Islands (Islas Malvinas), are the only ornithophilous species in a mostly oil‐bee pollinated genus. Their reproduction strategy appears to be adapted to an environment lacking in oil‐collecting bees.