bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractWe 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

AbstractProtein 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

AbstractPreviously 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

AbstractPhotoautotrophic 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

AbstractUsing 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

AbstractAnther‐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

AbstractIn 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

AbstractPlastids 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

AbstractThe 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

AbstractThe 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

AbstractIn 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

AbstractInvestigations 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

AbstractThe 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

AbstractUsing 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

AbstractThe 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

AbstractThe 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

AbstractFollowing 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

AbstractVariations 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

AbstractThe 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.