bluuebunny/crossref_metadata_2025 huggingface dataset:
Excretion of Sugars by Chlorella Species Capable and Incapable of Symbiosis with Hydra viridis
Authors: Kessler E. , Kauer G. , Rahat M.
Published: February 2014

The excretion of some sugars (maltose, glucose, and glucose‐6‐phosphate) was studied at pH 2.5–6.0 in 38 strains of Chlorella belonging to 15 species of which 7 are capable and 8 incapable of symbiosis with Hydra viridis. A high rate of maltose excretion below pH 4.0 (Cernichiari et al., 1969) was found only in C. vulgaris (non‐symbiotic) and C. mirabilis (non‐symbiotic). The other Chlorella species are characterized by quite different patterns of sugar excretion. C. spec. (= “C. paramecii”; symbiotic) excretes very high amounts of maltose in the whole range from pH 2.5–6.0. C. kessleri (symbiotic), C. luteoviridis (symbiotic), and C. fusca var. fusca (non‐symbiotic) show a predominant excretion of glucose‐6‐phosphate from pH 2.5–6.0. Some strains also exhibit a high excretion of glucose above pH 4.0 (C. spec. = “C. paramecii”) or below pH 3.0 (C. fusca var. vacuolata). Several species, e.g. C. saccharophila var. saccharophila (symbiotic), C. sorokiniana (non‐symbiotic), and C. protothecoides (symbiotic), excrete only very small amounts of sugars. There is no obvious correlation between sugar excretion and the ability or inability of the Chlorella species to form stable symbioses with Hydra viridis.
Untersuchungen zur Konstruktion des Bestäubungsapparates von Thalia geniculata (Marantaceen); Investigations on the Construction of the Pollination Apparatus of Thalia geniculata (Marantaceae)
Authors: Claßen‐Bockhoff Regine
Published: February 2014

Der Bestäubungsmechanismus der Blüte von Thalia geniculata wird im Zusammenhang mit speziellen Blütenstrukturen (schiefe Leiste, Schwiele, Häutchen, Trigger, Narbenfortsatz) erläutert. Im Gegensatz zu anderen Marantaceen‐Gattungen verläuft die Griffelbewegung nicht bogen‐, sondern S‐förmig. Der Griffel steht aktiv unter Spannung und ist nur an einer Stelle reizbar. Mittels Zeitlupenaufnahmen wird die Bewegung rekonstruiert: Sie verläuft in 3 Phasen und dauert etwa 0,03 Sek. Die enorm hohe Geschwindigkeit der Griffelbewegung und die Tatsache, daß die Blüte nur eine einzige Bestäubungschance besitzt, verlangen präzise Synorganisations‐ und Synchronisationsprozesse, die im einzelnen dargestellt werden.

The pollination mechanism of the flower, Thalia geniculata, and the unusual construction of the style and staminodes is illustrated. As early as the bud stage, pollen of the single stamen is deposited onto the pollen tray at the top of the style. Special structures of the staminodes — “oblique ledge” (schiefe Leiste, sL), “callosity” (Schwiele, Schw) and “hood” (Kapuze, Ka) — are in the optimal position for pollination. The style functions only as a secondary pollen presenter. It is under active tension and only sensitive at a defined site. The proboscis of a visiting insect is guided into the flower by special structures: “callosity”, “pellicle” (Häutchen, H) and an appendage to the stigma (Narbenfortsatz, Nf). The insect touches the style and starts its explosive S‐shaped movement via a trigger mechanism. Slow motion pictures (5000 pictures/s) show that the revolving movement occurs in 3 phases in approximately 0.03 s. During this very short time the style becomes erect, scrapes the pollen from the proboscis into its stigmatic cave and deposits its own pollen onto the proboscis in the form of a sticky paste.

In Th. geniculata the 2 flowers of a partial inflorescence together form one attractive symmetrical, melittophilous blossom. They are pollinated, by Xylocopidae (even in SE Asia, where the plant is not indigenous). Each flower has only a single chance to be pollinated. If xenogamy fails, self‐pollination is possible.
Early Effects of Penconazole on H+ and K+ Transport, Electrolyte Leakage and Transmembrane Electrical Potential in Egeria densa Leaves
Authors: Marrè Maria‐Teresa , Albergoni F. G. , Venegoni A. , Moroni A.
Published: February 2014

The early effects of penconazole (PCZ) at relatively high concentration (10−4 to 5 × 10−4 M) on changes in pH and in titratable acidity of the medium, transmembrane electrical potential difference (Em), electrolyte leakage and cell morphology were investigated in Egeria densa leaves. At the lowest (10−4 M) concentration and in the presence of a very low (10 μM) K+ concentration, triazole induced an early, moderate hyperpolarization of Em, associated with a decrease of net K+ uptake, suggesting some increase in the passive permeability to K+. This Em hyperpolarization was no longer detectable at high (2 mM) K+out concentration. At high PCZ concentrations (3 × 10−4 M and 5 × 10−4 M) the early hyperpolarization detectable in the presence of a low K+out concentration became transient, and was followed by a marked depolarization. PCZ, at these concentrations, suppressed acidification of the medium, stimulated electrolyte leakage and, in the mesophyll cells, induced some shrinking of the cytoplasm and its disconnection from the cell walls. These results are interpreted as due to an early effect of this triazole leading to the disorganization of the plasma membrane.
Dynamic Organization of Plant Microtubules at the Three Distinct Transition Points During the Cell Cycle Progression of Synchronized Tobacco BY‐2 Cells
Authors: Hasezawa S. , Nagata T.
Published: February 2014

Dynamic changes of microtubule (MT) configuration have been examined during the cell cycle progression in tobacco BY‐2 cells, which have been highly synchronized by aphidicolin treatment. Although it has been shown previously that four cell cycle stages display characteristic features of MTs (Hasezawa et al., 1991), distinct changes of MT configuration were observed at the interfaces of G2/M, M/G1 and G1/S, and the frequency of appearance of such distinct structures were quantitatively examined. Among others, it is the first observation that at M/G1 disintegrating phragmoplasts coexisted with short MTs in the perinuclear envelopes, but the MTs disappeared in the later stage, when cortical MTs were organizing. Thus it is supposed that cortical MTs originate from the transiently observed short MTs in the perinuclear region. This observation offered also an experimental system to analyze the molecular changes of MTs at the three interfaces during cell cycle progression in plant cells, as the mass culture of tobacco BY‐2 cells is readily available.
The Formation of Free Lipid Radicals During the Electromanipulation of Protoplasts (Vicia faba)
Authors: Biedinger Ursula , Bickert Chr , Youngman R. J. , Schnabl Heide
Published: February 2014

Membrane lipid degradation of plant protoplasts of Vicia faba was characterized by the determination of ethane formation after electrofusion and electropermeabilization. Incubation of protoplasts with ascorbate or α‐tocopherol before electromanipulation led to a decrease in ethane production. Fusion product yield could be increased by incubation with α‐tocopherol.

Using a simple model system, we investigated the active species involved in lipid peroxidation under conditions typically used for electromanipulation. The formation of lipid free radicals by electric pulses could be demonstrated.
Cytosolic Ca2+‐Concentrations and Distributions in Rhizoids of Chara fragilis Desv. Determined by Ratio Analysis of the Fluorescent Probe Indo‐1
Authors: Hodick D. , Gilroy S. , Fricker M. D. , Trewavas A. J.
Published: February 2014

Rhizoids of Charafragilis Desv. were iontophoretically loaded with the Ca2+‐sensitive ratio dye indo‐1. After loading, the rhizoids regained their preinjection‐membrane potential within 2 to 5 min and survived the procedure for more than 24 h, but their growth in length was permanently inhibited. Microfluorimetric measurements of the indo‐1 fluorescence‐ratio showed spontaneous fluctuations of the cytoplasmic Ca2+‐concentration, usually declining from high values after loading to 425 ± 80 nM (± SD, n = 7) as determined by in‐vitro calibration. Increasing the extracellular K+‐concentration (0.1 mM to 10 mM) or Ca2+‐concentration (1 mM to 10 mM) led to increases of 100 to 200 nM in cytoplasmic Ca2+‐concentration. The spatial distribution of cytosolic Ca2+ in the rhizoid tips was visualised in ratio images computed from low‐light video‐pictures. These images showed a fairly homogeneous distribution of Ca2+ throughout the tip cytoplasm with concentrations being in the same range as determined by microfluorimetry. A tip‐to‐base gradient in cytoplasmic Ca2+, thought to be a prerequisite for cell polarity and tip growth, was found in only 1 out of 16 successfully microinjected cells. Additionally, a progressive compartmentalization of the fluorochrome indo‐1, probably in the proplastids and the very abundant endoplasmic reticulum of the rhizoids, was observed.
Calcium Oxalate Crystal Formation and Growth in Two Legume Species as Altered by Strontium
Authors: Zindler‐Frank Elisabeth
Published: February 2014

Young plants of Phaseolus and Canavalia were grown in nutrient solutions where calcium had been partially or totally replaced by either strontium or sodium. The deleterious effect of this replacement on growth and development was greater with strontium than with sodium. As the calcium content of the nutrient solution was decreased fewer calcium oxalate crystals were formed in leaf tissues. There were fewer crystals formed when calcium was replaced by strontium than by sodium. Changes in solubility characteristics of the crystals indicated that they had incorporated strontium.
Ricinoleic Acid Catabolism in Peroxisomes
Authors: Gerbling Heidrun , Gerhardt B.
Published: February 2014

Peroxisomes from castor bean endosperm and mung bean hypocotyl completely degrade ricinoleic acid (12‐D‐hydroxy‐9‐cis‐octadecenoic acid) to acetyl‐CoA. Concomitant NADH formation occurred with a stoichiometry of 9 nmol NADH formed per 1 nmol ricinoleate degraded. At the C8‐intermediate level, where the hydroxy group of ricinoleic acid forms a barrier to β‐oxidation, 2‐hydroxyoctanoate and 2‐oxooctanoate were detected as intermediates. 2‐Hydroxyoctanoate was oxidized to 2‐oxooctanoate with H2O2 producing a reaction exhibiting 1:1 stoichiometry of the products. The peroxisomes appeared to oxidize both isomers of racemic 2‐hydroxyoctanoate. 2‐Oxooctanoate was metabolized to heptanoyl‐CoA (propionyl‐CoA and acetyl‐CoA) in a NAD‐dependent, but ATP‐independent, reaction. Heptanoate was not detected as an intermediate. Imidazole, an inhibitor of α‐oxidation, did not effect the degradation of ricinoleate or 2‐oxooctanoate. Arsenite, an inhibitor of oxidative decarboxylation, inhibited the metabolism of ricinoleate at the C8‐intermediate level, according to the accumulation of 2‐oxooctanoate and the stoichiometry of concomitant NADH formation. Arsenite completely inhibited the metabolism of 2‐oxooctanoate. It is concluded that the barrier caused by the hydroxy group of ricinoleic acid and prevention of β‐oxidation at the C8‐intermediate level, is circumvented by an α‐hydroxy acid oxidase reaction followed by an oxidative decarboxylation allowing return to the β‐oxidation track.
The Tonoplast Localization of Two Basic Isoperoxidases of High pI in Lupinus
Authors: Barceló A. Ros , Ferrer M. A. , Florenciano E. García , Muñoz R.
Published: February 2014

The ultrastructural localization of peroxidase (EC 1.11.1.7) activity in cambial initial and xylem parenchyma cells of etiolated Lupinus albus hypocotyls (cv. Multolupa) revealed that, unlike phloem tissues, most of the enzymatic activity is located as dark electron‐dense deposits on the tonoplast. Subcellular fractionation studies of plasmolyzed hypocotyls revealed that this enzymatic activity is apparently due to two basic peroxidase isoenzymes of isoelectric points 9.5 and 9.7 for B3 and B4, respectively. These isoenzymes are found mainly in young (5‐day old) seedlings, and are probably involved, as indicated by other authors, in the metabolism of quinolizidine alkaloids in Lupinus species.
The Biomechanics of Tree Fork Design
Authors: Mattheck C. , Vorberg U.
Published: February 2014

Two biomechanically different types of tree fork are described: the “compression fork” where the two jointed stems are pressed against each other at the contact face by the action of reaction wood, and the “tension fork” where the two connected stems are bent away from each other by gravity or wind action leading to tensile stresses in the connective zone.

It is well known that trees permanently try to improve their own designs by adaptive growth in order to maintain a state of constant mechanical stress at the tree surface. In the case of these two different types of tree fork, adaptive growth also takes different ways in order to avoid high localized stress peaks which could lead to failure of the tree under wind loading.

In this paper only the tension fork is assessed with respect to its shape optimization by computer simulation of adaptive growth. It is shown that the tensile fork is shape optimized in a very perfect way in order to avoid any dangerous localized stress peaks (notch stresses) which could lead to failure of the tree.
Ion Transport and the Transpiration Stream
Authors: Smith J. A. C.
Published: February 2014

In a long‐term experiment with maize grown at different humidities, Tanner and Beevers (1990) demonstrated that the amount of water lost by the plants in transpiration (plus guttation) could be reduced by a factor of three without any adverse effect on growth. As a consequence, the authors questioned the importance of the transpiration stream in supplying the shoot with minerals, arguing that there are other causes of mass flow in the xylem (such as Münch counterflow from phloem to xylem, and water consumed by growing sink tissues) that may, in the limit, be capable on their own of providing the shoot with minerals. This hypothesis is discussed here in the light of recent work on xylem water relations. It is shown to involve the incorrect premise that, if transpiration were required for long‐distance ion transport, plants should grow less well at high humidity. Instead, solute flux to the shoot can be demonstrated by experiment to remain constant over a wide range of transpiration rates, since the concentration of solutes in the xylem sap varies inversely with transpiration rate. Independent evidence suggests that the non‐transpirational component of mass flow in the xylem is small and is unlikely to be able to provide the shoot adequately with minerals in the absence of transpiration. A simple corollary of this view is that plant growth should be reduced at very low transpiration rates, a prediction that should be testable at sufficiently high humidities under carefully controlled conditions.
Sucrose Utilization of the Ectomycorrhizal Fungi Amanita muscaria and Hebeloma crustuliniforme Depends on the Cell Wall‐bound Invertase Activity of their Host Picea abies
Authors: Salzer P. , Hager A.
Published: February 2014

The role of apoplastic invertase (β‐d‐fructofuranoside — fructohydrolase, EC 3.2.1.26) of the host Picea abies for carbohydrate uptake and growth of two of its natural ectomycorrhiza partners was studied. For that purpose, hyphae of Amanita muscaria (Pers. ex Fries) Hock. and Hebeloma crustuliniforme (Bull. ex Fries) Quell., as well as roots and suspension cultured cells of Picea abies (L.) Karst. were used. Apoplastic invertase activity was demonstrated on roots and suspension cultured cells of spruce (in the latter case with 21.7 nkat (g fresh weight)−1). Inhibition of the root cell wall invertase activity (pH optimum 4.5) by increasing the apoplastic pH allowed determination of the permanent release of sucrose from the root. However, under in vivo conditions at a lower cell wall pH the hydrolysation products glucose and fructose were predominantly found. In contrast to spruce cells and certain fungi, such as Saccharomyces (Novick et al., 1981) or Phycomyces (Ruiz‐Herrera et al., 1989) invertase activity of the mycorrhizal fungi Hebeloma and Amanita was negligibly low. Furthermore, sucrose could not be consumed by Amanita and Hebeloma. As a consequence, cultures of these mycorrhizal fungi starved when kept on media with sucrose as sole carbohydrate source. But addition of invertase initiated hyphal growth immediately. Studies on carbohydrate uptake of host and fungal cells confirmed that the monosaccharides glucose and fructose were readily incorporated by spruce and fungal cells, with a clear preference for glucose. From these results it is suggested that apoplastic invertase activity of the host Picea abies is a precondition for the utilization of sucrose by the studied mycorrhizal fungi during the nutritional interaction of the symbiotic partners.
Chloroplast and Nuclear Transcripts for Plastid Proteins in Arabidopsis thaliana: Tissue Distribution in Mature Plants and During Seedling Development and Embryogenesis
Authors: Degenhardt J. , Fiebig C. , Link G.
Published: February 2014

We have investigated the distribution of transcripts for chloroplast proteins involved in photosynthesis and carbon assimilation in Arabidopsis thaliana. The probes that were used for assessment of transcripts represent the chloroplast genes psbA (encoding the D1 protein of photosystem II) and rbcL (for the large subunit of RubisCO) as well as the nuclear rbcS gene family for the RubisCO small subunit. With any of these probes we find a tissue‐specific distribution of transcripts in mature plants, with the highest concentration in rosette leaves and almost undetectable amounts in roots. The transcripts detected by each of these probes reveal similar spatial distribution and temporal kinetics during seedling development, with maximal levels around 70 h after sowing. They each show higher levels under light‐grown as compared to dark‐grown conditions, indicating a coarse control that ensures roughly coordinated levels throughout plastid differentiation. Embryonic transcripts are present in much higher concentration within the ground meristem and protoderm than in the procambium, which seems to reflect the different degree of determination towards the subsequent function in photosynthesis. Transcripts were detected in all characteristic stages throughout embryogenesis including the (non‐green) proembryo stage, suggesting that chlorophyll accumulation is not essential for expression of these genes at the RNA level. Both processes, hence, appear to be triggered by earlier molecular events that remain to be characterized.
Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (Zea mays L.)
Authors: Mikušs M. , Bobák M. , Lux A.
Published: February 2014

Protein bodies (PBs) from the epidermis and cortex of the radicle, as well as from coleorhizal and scutellar parenchyma of dry maize seeds were studied with the emphasis on presence and elemental composition of globoid crystals. PBs with variable structure were found in investigated tissues. Radicular epidermis was the only investigated tissue containing structurally uniform populations of PBs. They were filled by a homogeneous matrix without globoid crystals or their remnants. PBs structure and amount of proteinaceous matrix varied in the same cell of coleorhiza and scutellum. In the case of radicular cortex, the structure of PBs differed between analyzed individuals. Globoid crystals of various sizes were found in PBs from scutellum, coleorhiza, and from inner layers of radicular cortex. The largest globoid crystals (up to 2.0 μ in diameter) were seen in the scutellum. Energy‐dispersive X‐ray microanalysis revealed the presence of P,K. Mg, and some traces of Fe and Zn in the majority of globoid crystals from the scutellum. Globoid crystals from coleorhiza and radicular cortex were rich in Zn and Ca. The presence of considerable Zn was usually accompanied by high Ca, at the expense of K and Mg. As EDX analyses revealed significant differences in Zn and Zn/P values between analyzed tissues, it is probable that the majority of Zn is preferably accumulated in globoid crystals of some tissues of maize germ.
Okadaic Acid as a Probe to Analyse the Cell Cycle Progression in Plant Cells
Authors: Hasezawa S. , Nagata T.
Published: February 2014

Previously we have demonstrated the dynamic change of microtubules (MTs) during cell cycle progression using highly synchronized tobacco BY‐2 cells and characterized the specific transition points of MT organization (Hasezawa and Nagata, 1991). In this study the effect of okadaic acid (OA), a specific inhibitor of protein phosphatase 1 and 2A, on such changes of MTs during cell cycle was examined. These experiments revealed that cell cycle was arrested before the formation of the preprophase band (PPB), at anaphase and at the border of M/G1. Although the block at the anaphase seemed to be analogous to that observed in animal cells (Yamashita et al., 1990), the other two blocks were specific to plant cells. It is interesting that these two blocks coincided with the transition points of MT organization, as revealed in the previous study (Hasezawa and Nagata, 1991). Thus it is proposed that phosphorylation is involved in MT organization, although the effect of OA has been shown mainly to be the activation of cdc‐2/histone H1 kinase in animal cells. Another inhibitor of protein phosphatase 1 and 2A, calyculin A (CLA), showed very similar effects on the cell cycle progression. The use of such inhibitors to dissect the cell cycle progression of plant cells is discussed.
External pH Modifies the Intracellular pH and the Mode of Photosynthetic CO2‐Assimilation in Photoautotrophic Cell Suspension Cultures of Chenopodium rubrum L.
Authors: Hüsemann W. , Callies R. , Leibfritz D.
Published: February 2014

Photoautotrophic cell supension cultures of C. rubrum exhibit a C3‐type of photosynthesis. Yet, up to 20% of total CO2‐fixation is directly incorporated into malate and aspartate during short‐term photosynthesis. The rate of 14C‐labeling of malate and aspartate was doubled if the pH of the medium of the cells was increased from the normal value of 4.5 to 6.0 or 7.0. In vivo 31P‐NMR spectroscopy demonstrated that an increase in the external pH from 4.5 to 6.3 increased the cytosolic pH by 0.3 units and the vacuolar pH by about 1.3 units. Possible mechanisms for the effect of extracellular pH on intracellular pH and PEP‐carboxylase‐dependent carboxylation reactions are discussed.
Somatic Hybridization of Dihaploid Potato Protoplasts as a Tool for Potato Breeding*
Authors: Möllers C. , Wenzel G.
Published: February 2014

Using electrofusion of protoplasts from different dihaploid potato breeding clones, 308 somatic hybrids, i.e. 16.7% of the totally regenerated plants, were obtained. The results indicate that factors such as ‘combining ability’ strongly influence hybrid formation in these intraspecific fusion experiments. Hybrid identification was predominantly carried out by isoenzyme analysis of the peroxidases and/or esterases in polyacrylamide‐gradient gel electrophoresis. Further confirmation of the hybrid character was obtained by scoring phenotypic markers (petal colour, stem anthocyanin production, tuber characteristics, etc.) and, in some combinations, by evaluating tolerance against the herbicide metribuzin and nematode resistance against Globodera rostochiensis (Ro 1). The successful inheritance of metribuzin tolerance and nematode resistance confirm that monogenic dominant inherited traits are combined in the hybrids.
Cryopreservation of Embryogenic Suspension Cultures of Barley (Hordeum vulgare L.)*
Authors: Fretz A. , Jähne A. , Lörz H.
Published: February 2014

Anther‐derived suspension cultures of Hordeun vulgare L. were cryopreserved by slow cooling and storage in liquid nitrogen for up to 55 days. Cells were pre‐cultivated in L3 suspension medium supplemented with sorbitol. For freeze preservation the cells were treated with different combinations of cryoprotectant agents such as DMSO, proline, glycerol and sucrose. After rapid thawing high viabilities of up to 77% could be achieved. Cell growth commenced 2‐ 3 weeks later. The frequency of plantlet regeneration was 1%.
Influences of Blue and Red Light on the Photosynthetic Apparatus of Chlorella kessleri*
Authors: Grotjohann Regina , Rho Myung‐Sook , Kowallik W.
Published: February 2014

In white light of 33.2 μmol . m−2 . s−1 oxygen evolution of Chlorella kessleri is about 30 % higher after growth in blue light than after growth in red light of the same quantum fluence rate. When determined by the light‐induced absorbance change at γ 820 nm, blue light‐adapted cells possess about 60% more reaction centres per total chlorophyll in photosystem II. Correspondingly, the cells exhibit about 30% more Hill activity of PS II. Conversely, red light‐adapted cells contain relatively more reaction centres and higher electron flow capacities of photosystem I. The distribution of total chlorophyll among the pigment‐protein complexes, CPI, CPIa, CPa, and LHC II, corresponds to these data. There is more chlorophyll associated with the light‐harvesting complex of PS II, LHC II, in cells under blue light conditions, but more chlorophyll bound to both complexes of PS I, CPI and CPIa, in cells under red light conditions. The respective ratios of chlorophyll a/chlorophyll b of all complexes are identical for blue and red light‐adapted cells. This results in a higher relative amount of chlorophyll b in blue light‐adapted cells.

Total carotenoids per total chlorophyll are increased by 20% in red light‐adapted cells. Their distribution among the pigment‐protein complexes is unknown, however the ratios of lutein, neoxanthin and violaxanthin extractable from LHC II are different in blue (32.1:35.9:32.0) and in red (51.4:26.7:21.9) light‐adaptod cells.
Conservation and Structural Divergence of Organellar DNA and Gene Expression in Non‐Photosynthetic Plastids During Ontogenetic Differentiation and Phylogenetic Adaptation
Authors: Feierabend J.
Published: February 2014

Plastids of non‐photosynthetic cells or tissues, such as chromoplasts or leukoplasts, which develop during the course of ontogenetic differentiation contain DNA which is identical to chloroplast DNA with respect to size, organization and gene content. Also in ribosome‐deficient bleached plastids, produced in leaves by experimental treatments or mutation, chloroplast DNA remains unaltered. The chloroplast DNA of various bleached mutant strains of Euglena has suffered major deletions or rearrangements, but is, however, never totally lost. Also leukoplasts of parasitic higher plants contain DNA. In the organellar DNA of several parasitic plants photosynthetic genes are conserved. In the heterotrophic flagellate Astasia and in the holoparasite Epifagus virginiana (Orobanchaceae) the size of the plastid DNA is greatly reduced by major deletions and most or all photosynthetic genes or genes related to the chloroplastic respiratory chain are lost. The residual plastid genomes have, however, retained genes for RNAs, tRNAs and ribosomal polypeptides and these are transcribed, although plastidic RNA‐polymerase genes are lost in Epifagus. These findings demand the existence of a nuclear‐encoded RNA‐polymerase. The relevance of the conservation of plastid DNA and of plastidic gene expression in non‐photosynthetic cells is discussed, remains, however, at present elusive. Open reading frames of unknown function might be of particular significance for non‐photosynthetic plastids.
Nuclear DNA Polymorphisms Among Strains of Microseris bigelovii (Asteraceae: Lactuceae) Amplified from Arbitrary Primers
Authors: van Heusden A. W. , Bachmann K.
Published: February 2014

The autogamous annual Microseris bigelovii occurs in isolated populations along a narrow strip of land along the Pacific Coast from Southern California to Victoria, B. C. — Thirteen inbred strains were derived from 11 representative populations. Nuclear DNA from these strains was amplified using single arbitrary 10‐base‐pair primers. 194 amplification products were obtained with 22 primers. Of these, 44 were shared by all strains, 32 were present or absent in only one of the strains. The remaining 118 amplification products were shared by 2 to 11 strains. Attempts to construct a cladogram of the 13 inbred genotypes revealed 5 monophyletic groups. Two of these consist of duplicate isolates from two populations each, two comprise two strains each derived from neighboring populations, and one comprises the three populations from Victoria, B. C., which are postulated to be the result of local differentiation after a single founder event. The Victoria populations share the only known chloroplast mutation in M. bigelovii with a strain from the San Mateo County south of San Francisco. Beyond the local groups of strains we found more or less random allele associations rather than cladistic groupings, with overall genetic distances (UPGMA) more or less related to geographic distance. Achene transport, too rare for direct observationmust be effective to allow gene flow among populationsin M. bigelovii.
In Vitro and in Vivo Phosphorylation of Stomatal Phosphoenolpyruvate Carboxylase from Vicia faba L.
Authors: Schnabl Heide , Denecke M. , Schulz M.
Published: February 2014

The in vitro and in vivo phosphorylation of stomatal phosphoenolpyruvate carboxylase [EC 4.1. 1.31] from Vicia faba L. was demonstrated by feeding the concentrated enzyme after 0–70% ammonium sulfate precipitation of guard cell protoplasts with 32P and subsequent analysis of autoradiograms and Western immunoblots, after SDS‐PAGE, of protein samples. The in vitro and in vivo results provide evidence for a radioactive labeling of the two stomatal PEPCase bands (112 and 110 kDa).
Morphology of Heliotropium (Boraginaceae) Dispersal Units1
Authors: Hilger H. H.
Published: February 2014

In flowers of Heliotropium s.l. the primary carpel tips are overtopped by commissural outgrowths. Therefore the stylar cleft mimics a lateral orientation of the carpels. In species in which the fruit splits into four diaspores the separation tissues run through both the median and the transverse fruit planes. In species where only two two‐seeded nutlets are developed the fruit splits within the false septa and each half is composed of parts of both carpels (“syn‐mericarpids”).
Studies on Sporopollenin Biosynthesis in Tulipa Anthers
Authors: Gubatz S. , Wiermann R.
Published: February 2014

Investigations were carried out to clarify sporopollenin biosynthesis. Tracer experiments were focussed on the incorporation of specifically labeled 14C‐phenylalanine into sporopollenin. In addition, the incorporation of further 14C‐labeled substances, such as glucose, acetate, malonic acid, mevalonate and tyrosine, was investigated.

The sporopollenin fraction was isolated and purified by a gentle method including extractions by different solvents, incubations with hydrolyzing enzymes and fractionated saponifications. During the purification procedure the whereabouts of the initially applied radioactivity was followed. After each step the remaining as well as the released radioactivity was determined. Saponification of samples labeled after application of phenylalanine yielded p‐coumaric acid and p‐coumaric acid methyl ester as labeled products.

In comparison with the other substances applied, the highest incorporation rates were obtained with phenylalanine, regardless of the position of labeling. After degradation of the sporopollenin sample labeled with ring‐14C‐phenylalanine, p‐hydroxybenzoic acid was detected as the main labeled product. These results unequivocally show that an integral incorporation of the aromatic ring system occurred.

Tracer experiments were carried out at different stages of development. Their results show that, although the incorporation rates of 14C‐phenylalanine into sporopollenin differ, the substantial incorporation of this substance is not bound to defined stages of development.
Characteristics and Regulatory Properties of the H+‐ATPase in a Plasma Membrane Fraction Purified from Arabidopsis thaliana
Authors: Olivari C. , Pugliarello Maria Chiara , Rasi‐Caldogno Franca , De Michelis Maria Ida
Published: February 2014

The aqueous two‐phase partitioning technique was utilized to isolate a plasma membrane (PM) fraction from etiolated seedlings of Arabidopsis thaliana. The purification procedure adopted yielded a fraction highly enriched in PM as compared to inner membranes, with a recovery of about 30%, as judged from the activities of PM markers such as vanadate‐sensitive ATPase, FC binding and UDP‐glucose sterol glucosyltransferase. The purified PM fraction displayed vanadate‐sensitive H+ pumping activity. Its purity was confirmed by the biochemical characteristics of its ATPase activity assayed in the absence of Ca2+: sensitivity to vanadate (IC50 ca. 1 μM), Mg2+‐dependence, insensitivity to molybdate, oligomycin and nitrate, pH optimum at 6.6.

The PM H+‐ATPase activity was stimulated by fusicoccin and by a controlled treatment of the PM with trypsin. In both cases stimulation was much stronger on the activity assayed at pH 7.5 than on the activity at pH 6.6. Moreover, neither fusicoccin nor the treatment with trypsin stimulated the portion of activity (30 to 40% at pH 7.5) which decayed upon preincubation of the PM in assay medium without ATP.
K+ Channels in the Plasma Membrane of Lily Pollen Protoplasts
Authors: Obermeyer G. , Kolb H.‐A.
Published: February 2014

Using the patch‐clamp technique K+ channels could be observed in the plasma membrane of protoplasts from pollen grains of Lilium longiflorum. With depolarizing membrane potentials the open probability of the different K+ channels increased. Two K+ channel populations occurring occasionally had a single channel conductance of 120 pS and 42 pS, respectively. The most often observed K+ channel had a single channel conductance of 19 pS which showed an increase of channel activity with increasing free cytoplasmic Ca2+ concentration. This channel population might be involved in the pathway of endogenous transcellular K+ currents which are activated during pollen tube tip extension.
The Plastids of the Yew Tree (Taxus baccata L.): Ultrastructure and Immunocytochemical Examination of Chloroplastic Enzymes
Authors: Buns R. , Acker G. , Beck E.
Published: February 2014

The various types of plastids occurring in assimilatory and non‐green tissues of Taxus baccata L. were investigated with respect to their ultrastructure and their content of starch, chlorophyll, Rubisco and the plastidic coupling factor CF1. Chlorophyll was estimated from fluorescence intensity, and the presence of both enzymes was examined by electron microscopy after immunogold labelling.

All kinds of plastids, irrespective of their location in the tree, contained stromal membranes. Due to their content of CF1 and chlorophyll (except those of the roots) these membranes were addressed as thylakoids. Since the plastids also contain Rubisco, they represent chloroplasts. However, a decreasing gradient of all investigated chloroplastic characters from the plastids of the assimilatory tissue of the needles to those of axial tissues and of the roots was obvious. All kinds of plastids accumulated large amounts of starch especially in spring prior to bud burst but were virtually free of starch during the winter months.
Post‐pollination Events in Species of Chorisia (Bombacaceae) and Tabebuia (Bignoniaceae) with Late‐acting Self‐incompatibility
Authors: Gibbs P. E. , Bianchi Marta
Published: February 2014

The neotropical trees Chorisia chodatii, C. speciosa, Tabebuia caraiba and T. ochracea show late‐acting self‐incompatibility. Accumulated ovule penetrations following self‐pollinations were similar to those in crosses. During the six to eight day period following pollination, in both selfed and crossed ovules, a resting zygote with initial development of the endosperm was formed. Up until the time of rejection of the selfed flowers, no cytological malfunctions were evident in the selfed ovules.
Ecogeographical Differentiation in Nectandra (Lauraceae), and its Historical Implications
Authors: Rohwer J. G. , Kubitzki K.
Published: February 2014

Following a taxonomic revision of Nectandra, a genus of about 114 species of neotropical trees, character gradients are compared against geographical distribution, habitat preferences, and reproductive phenology of individual species, with the aim of reconstructing the spatial and temporal diversification of the genus. It is shown that Nectandra, together with Ocotea, Persea, and other genera of the Lauraceae, originated from a northern hemisphere matrix that immigrated into South America, perhaps as late as after the closure of the Central American land bridge in the Pliocene. The dramatic diversification of the genus within South America was facilitated by its ornithochorous dispersal system, implying ample processes of allopatric speciation. At present, speciation seems to take place preferably by processes of ecotypic (mostly edaphic) specialization, by which widely distributed, ecologically polymorphic species give rise to swarms of ecologically narrowly specialized satellite species.
Changes in Structure and Hydraulic Conductivity for Root Junctions of Desert Succulents as Soil Water Status Varies
Authors: North Gretchen B. , Huang B. , Nobel P. S.
Published: February 2014

Variations in hydraulic conductivity (LP) and the underlying anatomical and morphological changes were investigated for main root‐lateral root junctions of Agave deserti and Ferocactus acanthodes under wet, dry, and rewetted soil conditions. During 21 d of drying, LP and radial conductivity (LR) increased threefold to fivefold at junctions of both species. The increase in LR was accompanied by the formation of an apoplastic pathway for radial water movement from the surface of the junction to the stele for A. deserti and by the rupture of periderm by emerging primordia of secondary lateral roots for F. acanthodes. During 7 d of rewetting, LR decreased for junctions of A. deserti, as apoplastic water movement was not apparent, but LR was unchanged for F. acanthodes. Axial conductance (Kh) decreased during drying for both species, largely because of embolism related to the degradation of unlignified cell wall areas in tracheary elements at the root junction. The resulting apertures in the cell walls of such elements would admit air bubbles at pressure differences of only 0.12‐0.19 MPa. Rewetting restored Kh for both species, but not completely, due to blockage of xylem elements by tyloses. About 40% of the primary lateral roots of the monocotyledon A. deserti abscised during 21 d of drying. For the dicotyledon F. acanthodes, which can form new conduits in its secondary xylem, only 10% of the primary lateral roots abscised during 21 d of drying, consistent with the much greater frequency of lateral roots that persist during drought in the field compared with the case for the sympatric A. deserti.
Reversal of the Direction of Photosynthate Allocation in Urtica dioica L. Plants by Increasing Cytokinin Import into the Shoot
Authors: Fetene M. , Beck E.
Published: February 2014

The natural cytokinin import from the root into the shoot of Urtica dioica plants was enhanced by supplying zeatin riboside (ZR) solutions of various concentrations to a portion less than 10 % of the root system after removal of their tips. After 6 h ZR pretreatment of the plants, 14CO2 was supplied for 3 h to a mature (source) leaf or to an expanding leaf and the 14C‐distribution in the whole plant was determined after a subsequent dark period of 14 h.

ZR substantially increased 14C fixation by the expanding leaves and also enhanced export of carbon and transport to the shoot apex. The effect of the hormone treatment was, however, more pronounced when the 14CO2 was supplied to a mature leaf. In the control plants these leaves exported carbon only to the roots: When the amount of the natural daily ZR input from the roots to the shoot was enhanced by 20%, the bulk of the 14C exported from a mature leaf moved to the shoot apex and only a minor portion of 14C was still detected in the root fraction. A several‐fold increase of the natural daily ZR input into the shoot resulted in a flow of 14C only to the growing parts of the shoot. The results suggest control of the sink strength of the shoot apex by ZR in Urtica diocia.
Illustration of the Genetic Differences in Ozone Sensitivity Between the Varieties Nicotiana tabacum Bel W3 and Bel B Using Various Plant Systems
Authors: Städtler Sabine , Ziegler H.
Published: February 2014

The ozone‐sensitive tobacco variety Bel W3 was compared with the tolerant cv. Bel B using amphidiploid and amphihaploid genotypes of both. In search of the first genotypical differences, their reaction to acute ozone treatments was investigated with systems of decreasing degree of complexity: whole plants, grown under field, greenhouse and sterile conditions, excised tissues, calli, CCP, MCP and subcellular reactions. It was common to all systems that a fumigation, which clearly exceeds the threshold of the most tolerant material, led to equal reactions in all genotypes in respect of visible injury and membrane leaching. With whole plants and leaf discs growing conditions were found to influence the ozone threshold more than the genotype. Because the most resistant field‐grown plants vary widely in their reaction, only sterile or greenhouse grown genotypes were compared. With the exception of whole sterile plants (no genotypical threshold differences), amphihaploids were more susceptible to ozone than their respective amphidiploids as to threshold and sensitivity spectra in all systems investigated. Higher ozone thresholds were detected for Bel B in all systems with one exception: MCP exhibited a lower threshold but also a lower degree of damage in the first buffer range of the sensitivity spectrum than those of Bel W3. Post‐fumigation starch accumulation in mesophyll chloroplasts was the most prominent subcellular ozone reaction.
The Cyanelles (Organelles of a Low Evolutionary Scale) Possess a Phosphate‐Translocator and a Glucose‐Carrier in Cyanophora paradoxa
Authors: Schlichting R. , Bothe H.
Published: February 2014

Cyanelles from Cyanophora paradoxa can easily be isolated and assayed for their carrier composition by the silicone oil filtering technique. The present investigation demonstrates a Pi‐translocator transferring phosphate, dihydroxyacetone phosphate and 3‐phosphoglycerate in a counter exchange mode in cyanelles as in chloroplasts of higher plants. The uptake of Pi is inhibited by dihydroxyacetone phosphate, phosphoglycerate and glucose‐6‐P, only poorly by phosphoenolpyruvate and not by 2‐phosphoglycerate. The inhibitors pyridoxalphosphate and 4,4′diisothiocyanostilbene‐2,2K'disulfonic acid at low concentration also affect Pi‐uptake. Cyanelles probably transport photosynthate (reductant and ATP) by triosephosphates. This is the first demonstration of a phosphate translocator in an organism of a low evolutionary scale. Cyanelles also transport glucose which proceeds in two phases. In the lower concentration range (≤ 2.5 mM), glucose penetrates by facilitated diffusion, whereas transport follows first‐order kinetics at higher amounts (> 2.5 mM). In the low concentration range, glucose‐transport is affected by high concentrations of 3‐O‐methylglucose and fructose. The physiological role of the glucose‐transport carrier in Cyanophora is doubtful. It may function in transporting glucose into cyanelles if the carbon level inside them becomes limiting, e.g. in dark periods.
Evaluation of Comparative DNA Amplification Fingerprinting for Rapid Species Identification within the Genus Clusia
Authors: Böhm Martina , Löw R. , Haag‐Kerwer Angela , Lüttge U. , Rausch Th.
Published: February 2014

Understanding the taxonomiy of the tropical genus Clusia (Fam. Clusiaceae, Ord. Theales) has been hampered by the difficulties inherent in studying tropical dioecious, succulent, arborescent, epi‐ or hemiepiphytic taxa. Species identification by morphological traits often requires the terminal inflorescences and/or the succulent capsular fruits. To allow species differentiation based exclusively on vegetative tissue, a frequent necessity during ecological field studies, a procedure has been developed for rapid isolation of genomic DNA from Clusia leaf tissue followed by DNA amplification fingerprinting with a set of single arbitrary oligomer primers (23–27 mers). Fingerprints obtained with independent DNA preparations from one individual as well as DNA preparations from several individuals of the same species were identical for the major amplification products, although minor bands were somewhat variable. Polymorphic fingerprints have been obtained with 3 different primers for 3 Clusia species (C. minor L., C. alata Pl. & Tr., C. multiflora H. B. K.), and the related Oedematopus obovatus Spruce ex. PL (Clusiaceae). The interspecific Randomly Amplified Polymorphic Markers (RAPDs) thus obtained allow a rapid identification of vegetative tissue samples collected in the field, and will assist in a revision of the controversial taxonomy of the genus Clusia.
Adaptation of the Photosynthetic Apparatus of Anacystis nidulans to Irradiance and CO2‐Concentration
Authors: Müller Claudia , Reuter W. , Wehrmeyer W. , Dau H. , Senger H.
Published: February 2014

Homocontinuous cultures of the cyanobacterium Anacystis nidulans (syn. Synechococcus sp. PCC 6301) were grown at white light intensities of 2 and 20 W/m2, and supplied with 0.03 and 3 % CO2 enriched air. The mutual influence of these growth factors on the development of the photosynthetic apparatus was studied by analyses of the pigment content, by low temperature absorbance and fluorescence spectroscopy, by analyses of oxygen evolution light‐saturation curves, and by SDS PAGE of isolated phycobilisomes.

The two growth factors, light and CO2, distinctly affect the absorption cross section of the photosynthetic apparatus, which is expressed by its pigment pattern, excitation energy distribution and capacity. In response to low CO2 concentrations, the phycocyanin / allophycocyanin ratios were lower and one linker polypeptide L30R, of the phycobilisomes was no longer detectable in SDS PAGE. Apparently, low CO2 adaptation results in shorter phycobilisome rods. Specifically, upon adaptation to low light intensities, the chlorophyll and the phycocyanin content on a per cell basis increase by about 50% suggesting a parallel increase in the amount of phycobilisomes and photosystem core‐complexes. Low light adaptation and low CO2 adaptation both cause a shift of the excitation energy distribution in favor of photosystem I. Variations in the content of the “anchor” polypeptides L60CM and L75CM are possibly related to changes in the excitation energy transfer from phycobilisomes to the photosystem II and photosystem I core‐complexes.