bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Casparian Strip of Clivia miniata Reg. Roots: Isolation, Fine Structure and Chemical Nature*
Authors: Schreiber L. , Breiner H.‐W. , Riederer M. , Düggelin M. , Guggenheim R. 
Published: February 2014

AbstractThe root endodermis of Clivia miniata Reg. was successfully isolated using the cell wall degrading enzymes cellulase and pectinase. The enzymes did not depolymerize those regions of the primary cell walls of anticlinal endodermal root cells where the Casparian strips were located. Since the endodermis of C. miniata roots remained in its primary developmental state over the whole root length, endodermal isolates essentially represented Casparian strips. Thus, sufficient amounts of isolated Casparian strips could be obtained to allow further detailed investigations of the isolates by microscopic, histochemical and analytical methods. Scanning electron microscopy revealed the reticular structure of the Casparian strips completely surrounding the central cylinder of the roots. Whereas in younger parts of the root only the anticlinal cell walls of the endodermis remained intact in the isolates, in older parts of the root the periclinal walls also restricted enzymatic degradation due to the deposition of lignin. Extracts of the isolates with organic solvents did not reveal any wax‐like substances which might have been deposited within the cell wall forming a transport barrier, as is the case with cutin and suberin. However, several histochemical and analytical methods (elemental analysis and FTIR spectroscopy) showed that the chemical nature of the Casparian strips of C. miniata roots can definitely be a lignified cell wall. These findings are in complete agreement with studies carried out at the beginning of this century on the chemical nature of the Casparian strips of several other plant species. The implications of these results concerning apoplasmatic transport of solutes and water across Casparian strips are discussed.
Source‐sink Characteristic of Photoassimilate Transport in Fertile and Sterile Plants of Chara vulgaris L.*
Authors: Schulte C. , Kirst G. O. , Winter U. 
Published: February 2014

AbstractIn cuttings of Chara vulgaris consisting of 3–4 internodal cells with whorls (branchlets) transport of photoassimilates was investigated by 14C‐labelling. The distribution of radioactivity in different component parts of the plant was shown as percentage and calculated in relation to fresh weight. Sucrose was identified as the main transported carbohydrate. In fertile Ch. vulgaris plants, developing oogonia and antheridia were important sinks for transported carbohydrates. Polarity of transport in the internodal cells (nutrients and assimilates) remains constant, as the main characteristic, from base to apex in fertile as well as in sterile plants. In sterile plants, the branchlets being the main source for photoassimilates and the apex the sink, transport from branchlets is mainly in the direction of the internodes. In the case of fertile plants gametangia are additional sinks redirecting transport of assimilates into the branchlets.
Cyanobacteria of Rocks and Soils of the Orinoco Lowlands and the Guayana Uplands, Venezuela
Authors: Büdel B. , Lüttge U. , Stelzer R. , Huber O. , Medina E. 
Published: February 2014

AbstractThe occurrence of 23 cyanobacterial species, belonging to 9 different genera and 5 cyanobacterial lichen species of 5 different genera on exposed, open rock surfaces of inselbergs and on soil in savannas of the Orinoco lowlands and the Guayana uplands is described. Their distribution patterns and frequency within the different habitats are given. The filamentous procaryotic blue‐green algae/cyanobacteria Stigonema ocellatum and Scytonema crassum, together with the unicellular cyanobacterium Gloeocapsa sanguinea were the most frequent species on rocks, whereas the filamentous cyanobacterium, Schizothrix telephoroides, dominated in cyanobacterial mats on the savanna soil. All species showed intensively coloured sheaths, either brown or yellow in the case of Stigonema ocellatum and Scytonema crassum, or red in Gloeocapsa sanguinea and Schizothrix telephoroides. In addition, a number of cyanobacterial lichens occurred.
Precursors of the Cocoa‐Specific Aroma Components are Derived from the Vicilin‐Class (7S) Globulin of the Cocoa Seeds by Proteolytic Processing
Authors: Voigt J. , Biehl B. 
Published: February 2014

AbstractEssential precursors of the cocoa‐specific aroma components are formed during fermentation of cocoa seeds in the tropics. During the past decades, indications have accumulated that these aroma precursors are derived from seed proteins by acid‐induced proteolysis. This has been recently corroborated by in vitro studies on the formation of the aroma‐related components. It has been shown that the essential proteolysis products are derived from the vicilin‐class (7S) globulins of the cocoa seeds by the cooperative action of an endogenous aspartic endoprotease and a carboxypeptidase.
Electrophoretic Analysis of Genetic Variation within and between Populations of Quercus cerris, Q. pubescens, Q. petraea and Q. robur (Fagaceae) from Eastern Austria
Authors: Samuel R. , Pinsker W. , Ehrendorfer F. 
Published: February 2014

AbstractAllozyme variation at 14 loci was studied electrophoretically in 19 population samples of Quercus cerris, Q. pubescens, Q. petraea, and Q. robur. Genetic variation, measured as mean heterozygosity, was found to be high within populations but low among populations. A significant deficit of heterozygotes was observed in most of the populations of Q. pubescens, Q. petraea, and Q. robur. At the species level, Q. cerris (sect. Cerris) appears to be clearly separated from the rest (sect. Quercus). Q. pubescens, Q. petraea, and Q. robur form a cluster of closely‐related species. The degree of genetic differentiation among these species is low, i.e. in the range normally found among con‐specific populations. Nevertheless, allozyme data allow the elaboration of a dendrogram which is in reasonable accordance with the taxonomic classification, but also supports the importance of hybridization and introgression. This is also underlined by the fact that the allelic differentiation at the Got‐2 locus corresponds with the phenotypic classification (petraea‐like, hybrids, and robur‐like) in samples from mixed populations.
Atomic Force Microscope Information on Pollen Exine Substructure in Nuphar
Authors: Rowley J. R. , Flynn J. J. , Takahashi M. 
Published: February 2014

AbstractImages of individual exine units from the tectum of Nuphar luteum (L.) Sm. pollen were made using atomic force microscopy. These units were recorded as being 120 to 160 nm wide. Exine‐units sectioned transversally were circular and had a central circular (core) zone 40 nm or more in diameter. Exine unit‐structures in Nuphar have an outer (binder) substructure coiled around a core zone.
Mitochondrial DNA and its Inheritance in Pleurotus ostreatus and P. pulmonarius
Authors: Fischer M. , Seefelder St. 
Published: February 2014

AbstractSix stocks each of the basidiomycetes Pleurotus ostreatus and P. pulmonarius were checked for intraspecific polymorphism and inheritance of mitochondrial DNA (mtDNA). Polymorphisms were extensive in both species after digestion with the endonucleases Hae III and Hind III, and they were stock‐specific with one exception. The range of mtDNA sizes was similar for both taxa, lying between approximately 56 kb and 70 kb for P. ostreatus and 60 kb and 78 kb for P. pulmonarius.The inheritance of mtDNA was uniparental throughout. In pairings of monokaryons exhibiting specific mtDNA types, only one parental mtDNA type was recovered in the resulting dikaryons; while the mitochondria of the donor mycelium spread out, the mitochondria of the recipient mycelium apparently are lost. Certain mtDNA types were more often inherited than others. By examining this dominance of mtDNA types one could establish parentage for both species.
Light‐dependent Proton Excretion of Wheat (Triticum aestivum L.) and Maize (Zea mays L.) Roots
Authors: Gorr G. , Obst G. , Döring O. , Böttger M. 
Published: February 2014

AbstractWe investigated the change of root net proton excretion of seedlings of Triticum aestivum L. and Zea mays L. with daily variation of illumination using a multi‐channel pH‐stat system. We found an increase of net proton excretion during darkness and a drop after the beginning of illumination. Inhibition of carotenoid biosynthesis by norflurazone and photooxidation of chlorophylls did not change the periodicity or its induction. The induction of diurnal periodicity was possible with blue, green and red light. After induction the oscillation of net proton excretion continued for at least two cycles under constant light. We conclude that net H+ excretion of wheat and maize roots may be regulated by an endogenous clock or by a signal from the leaves. The nature of such a hypothetical signal remains unknown.
Oxygen Dependence of Elongation Growth and Oxygen Uptake in Maize Coleoptiles
Authors: Ding Bao‐Lian , Schopfer P. 
Published: February 2014

AbstractAuxin‐mediated elongation growth of maize coleoptile segments is inhibited by reducing the O2 concentration in the incubation medium to GT 100 μmol . 1−1. The half‐maximal elongation rate is reached at 40 μmol . 1−1 O2, i.e. about two orders of magnitude higher than with mitochondrial respiration. O2 uptake of the segments measured under similar conditions with an O2 electrode shows a very similar dependence on O2 concentration. Auxin increases O2 uptake by 5–10% when it induces growth. About 40% of the O2 uptake is insensitive to inhibition by KCN. Auxin has no effect on O2 uptake in the presence of KCN. The possibility that auxin‐mediated elongation growth depends on a KCN‐sensitive oxidative process, other than cytochrome c oxidase‐catalyzed respiration, is discussed.
Developmental Regulation of Susceptibility and Tolerance to Fusarium Root Rot in Beans
Authors: Vögeli‐Lange Regina , Mohr U. , Wiemken A. , Düggelin M. , Guggenheim R. , Boller T. 
Published: February 2014

AbstractThe soil‐borne fungus, Fusarium solani f. sp. phaseoli, attacks roots and hypocotyls of bean (Phaseolus vulgaris) plants causing a devastating disease called root and foot rot. In a study of the host‐pathogen relationship it was found that young bean roots, with the radicle just emerging, were highly tolerant to the pathogen, whereas older bean seedlings, with a fully developed root system, were completely susceptible. Investigations by low‐temperature scanning electron microscopy demonstrated that significantly fewer spores and hyphae were present on the root surface of young bean seedlings as compared to older ones. A similar pattern of attachment was found when bean roots were inoculated with spores of F. solani f. sp. pisi, a related pathogen causing disease on peas but not on beans. Light microscopic studies showed that F. solani f. sp. pisi did not penetrate the root but rapidly formed thick‐walled resting spores on the root surface. F. solani f. sp. phaseoli on the other hand quickly penetrated the root and formed an extensive network of fungal hyphae. These results demonstrate that the ability of fungal propagules to adhere to and to penetrate host tissues are two distinct processes. Furthermore, the data indicate that young bean roots lack a surface component necessary for attachment of fungal spores which may help explain their tolerance to Fusarium root rot.
A Flow Cytometric Analysis of the Nuclear 2C DNA Content in 17 Phaseolus Species (53 Genotypes)
Authors: Nagl W. , Treviranus A. 
Published: February 2014

AbstractThe genus Phaseolus is characterized by a highly stable karyotype of 2n = 22. Despite this constancy, the size of the chromosomes varies, and crossing of species is possible only in a few cases. We determined the 2C nuclear DNA content of a number of Phaseolus species, cultivars and genotypes by flow cytometry, in order to realize the interspecific and intraspecific variation of the 2C value. The data range from 1.03 pg to 2.18 pg without any clear correlation to systematic relationships. The mean DNA values of wild and cultivated forms, as well as those of Andean and Mesoamerican genotypes, do not differ significantly. The variation is interpreted in terms of some nucleotypic adaptations. The data may be useful for molecular biological analyses, as well as for biotechnological and classical breeding programmes.
Phenotypic Plasticity in the Annual Weed Polygonum aviculare
Authors: Meerts P. 
Published: February 2014

AbstractReaction norms of fourteen life history and morphological traits were investigated in four tetra‐ and two hexaploid genotypes of the annual weed species complex, Polygonum aviculare. The plants were cultivated in six treatments consisting of factorial combinations of three pot sizes and two fertility levels. All characters, except life span, were plastic but the relative importance of genotype (G), treatment (T) and interaction (G × T) to total variance was strongly trait‐specific. Consistent genetic differentiation, not correlated with ploidy level, was found in metamer size and life history: genotypes originating from trampled sites had smaller metamers and shorter shoots while those originating from sites with a short growing season, due to weeding activities, had a shorter life span, an earlier flowering date and a higher biomass allocation to reproduction compared to genotypes from less disturbed sites. Significant variation was found in reaction norms for all characters, including a lower amount of plasticity in metamer size in genotypes with numerous metamers and a lower amount of plasticity in total weight in shortlived genotypes. This suggested that variation in phenotypic plasticity reflected developmental constraints imposed by contrasting life span and metamer size in different genotypes. There was no evidence for niche differentiation along the soil resource gradient, suggesting that the species is comprised of “general purpose” genotypes with respect to soil fertility. It is concluded that the Polygonum aviculare complex has evolved a “dual” adaptive strategy i.e. a combination of genetic polymorphism and high phenotypic plasticity.
Molecular Cloning of emip, a Member of the Major Intrinsic Protein (MIP) Gene Family, Preferentially Expressed in Epidermal Cells of Barley Leaves
Authors: Hollenbach Beate , Dietz K. ‐J. 
Published: February 2014

AbstractCloning and characterization of a barley gene named emip is reported that encodes a member of the major intrinsic protein family. A λ‐unizap cDNA library synthesized from poly A+−mRNA of leaf epidermis was screened differentially with epidermis‐versus mesophyll‐derived probes. One of the clones epi 3‐2 was sequenced and further analyzed. The open reading frame of the full length clone codes for a polypeptide of 288 amino acids with a molecular mass of 30,634 Da exhibiting a high degree of homology with members of the major intrinsic protein family. Hydropathy analysis predicts six potential membrane‐spanning helices. mRNA levels were high in the growing zone of barley leaves and declined towards the tip of the fully expanded leaf blade. Expression was high in epidermal strips, lower in roots and very low in the leaf mesophyll. In order of decreasing response, wilting, salt shock and heat shock resulted in stimulated expression. mRNA levels remained low during slow salting up experiments. The expressional pattern suggests a role of EMIP in turgor regulation, particularly under stress.
Consumption of Carbonyl Sulphide by Chlamydomonas reinhardtii with Different Activities of Carbonic Anhydrase (CA) Induced by Different CO2 Growing Regimes
Authors: Protoschill‐Krebs G. , Wilhelm C. , Kesselmeier J. 
Published: February 2014

AbstractThe green alga, Chlamydomonas reinhardtii, was grown under high and low CO2 regimes inducing significantly different activities of the extracellular carbonic anhydrase (CA). In close relation to the CA activities, the algae exhibited different consumption rates of the climatically relevant atmospheric trace gas, carbonyl sulphide (COS), thus indicating that CA is responsible for uptake of COS from the medium.
Primary and Lateral Root Development of Dark‐ and Light‐Grown Cotton Seedlings under Salinity Stress*
Authors: Reinhardt D. H. , Rost T. L. 
Published: February 2014

AbstractPrimary root growth dynamics and lateral root development of dark‐ and light grown cotton seedlings (Gossypium hirsutum L., cv. Acala SJ‐2) were studied under control and salinity stress conditions. The seedlings were grown by two methods: A) in paper‐lined, vermiculite‐filled beakers with the plants growing between the paper and the glass wall (Gladish and Rost, 1993), and B) in hydroponics after germination and initial growth in germination paper rolls saturated with the treatment solutions (Kent and Läuchli, 1985). After germination, daily primary root elongation rate gradually incrased to a maximum, then gradually declined to close to zero for dark‐grown seedlings, or to sustained rates of about 10 mm per day for light‐grown control plants. Salinity stress delayed primary root growth and reduced peak elongation rates, without changing the general primary root growth pattern. These results suggest that salinity changed the time‐scale, but did not modify the normal developmental sequence. Lateral root growth was more inhibited by salinity than primary root growth. In addition, elongation of lateral roots was more inhibited by salinity than their initiation and emergence. Light exposure of the shoot favored both sustained primary root growth from 7 days after planting, and lateral root emergence and growth. Salinity effects were more severe on seedlings germinated and grown in hydroponics (method B) than on vermiculite‐grown plants (method A). These results emphasize the importance of growing conditions for the NaCl‐induced effects on cotton root development. In addition, the differential effects of salinity on primary and lateral roots became evident, pointing to diverse control mechanisms for the development of these root types.
Cytological Investigations of Lithobiontic Microorganisms in Granitic Rocks
Authors: Ascaso C. , Wierzchos J. , de los Ríos A. A. 
Published: February 2014

AbstractThis paper shows the ultrastructure of lithobiontic organisms in a granitic rock from the exterior to the interior, where fissures are found 1–2 mm from the surface. There is clear differentiation at cell level between mycobiont and photobiont cells located on the rock surface which forms part of the lichen thallus and prokaryotic and eukaryotic cells (algae and fungi) found in the fissures. As well as the observations at the ultrastructural level of the microorganisms which live in fissures and cavities, immunolabelling techniques with colloidal gold have been applied to obtain an immunolocalization of Rubisco enzyme in some of the cells. The technique applied here permits Rubisco enzyme to be identified in algae‐like cells belonging to fissures where it is difficult to identify the pyrenoid. The mineral environment of the cells situated inside the fissures is investigated by Energy Dispersive Spectrometry (EDS). The biotite particles present in the fissure walls, as well as some lithobiont microorganisms, show a depletion of potassium from interlayer positions.
Photoautotrophic Cell Suspension Cultures from Mesembryanthemum crystallinum and their Response to Salt Stress
Authors: Willenbrink M. E. , Hüsemann W. 
Published: February 2014

AbstractFor the first time, photoautotrophic cell suspension cultures of Mesembryanthemum crystallinum have been established. The cells are growing in a sugar‐free culture medium in the presence of 2 % (v/v) CO2 as the sole carbon source. A 16 h light photoperiod is applied. Increase in fresh and dry weight during a 21 days growth cycle was more than 3‐fold. Treatment of the cells with 200 mM NaCl from day 10 to day 21 of subculture stimulated cell culture growth, enhanced CO2 fixation and elicited an increase in the extractable activities of enzymes related to CO2 fixation (RubisCO; PEP carboxylase) and malic acid metabolism (NAD / NADP dependent malic enzyme and malic acid dehydrogenase). The cells performed osmotic adjustment to high salinity by uptake of K+, Na+, Cl− and formation of proline as well as by a reduction in cell size. Although sugar and starch content of the cells changed during light/dark transition, a CAM‐related diurnal fluctuation of malic acid was not observed.
Nucleus Basal Body Connector of Dunaliella: Threshold Concentration of Calcium Necessary for in vitro Contraction*
Authors: Merten P. , Lechtreck K.‐F. , Melkonian M. 
Published: February 2014

AbstractDetergent‐isolated flagellar apparatuses of the flagellate green alga Dunaliella bioculata retain remnants of the nucleus (the karyoskeleton) which are linked to the basal bodies by the centrin‐containing nucleus basal body connectors (NBBC). Such complexes were subjected to different calcium concentrations (1 × 10−9 M − 5 × 10−4 M Ca2+) and the distance between the basal bodies and the karyoskeleton was measured by light microscopy. The threshold concentration of Ca2+ for NBBC contraction was determined to be around 5 × 10−8 M Ca2+. At > 10−7 M Ca2+ NBBC were maximally contracted and the distance between the basal bodies and the karyoskeleton was only about 50% of the initial distance. Using a polyclonal antibody generated against centrin (Salisbury et al., 1984), the NBBC were visualized by indirect immunofluorescence in both the extended and contracted state. Our results demonstrate that in vitro contraction of centrin‐containing filaments in green algae is initiated at about the same free Ca2+ concentration in three different centrin‐containing basal apparatus components (i.e. the distal connecting fibre, the flagellar transitional region and the NBBC).
Proton Efflux from the Outer Layer of the Peduncle of Tulip in Gravitropism and Circumnutation*
Authors: Hejnowicz Z. , Sievers A. 
Published: February 2014

AbstractEpidermal plus hypodermal peels from tulip peduncles produced bands of acidity on agar containing bromocresol purple. Peels from horizontally oriented peduncles gave rise to an acidity band which corresponded to the lower side of the peduncle. The band began 3–6 cm beneath the flower and extended basipetally within the region of gravitropic bending. No corresponding band appeared in an agar layer laid on the cortical surface exposed by peeling. Peduncles growing in the normal vertical position showed circumnutations with a period in the range of 4 h. The peels from these stalks produced one or two bands more acid than the remaining part of the peel. Since the acidity band in horizontally positioned stalks corresponds to the zone of faster growth causing gravitropic bending, we infer that the band(s) produced by vertical stalks also correspond to zones of differential growth involved in circumnutation. On the basis of a previous finding that tulip leaves give rise to an oscillating acidity pattern, we infer that vertical stalks also show such a pattern. This inference fits the model proposing the involvement of an internal oscillator in circumnutation. However, the ratio of the circumnutation period to the gravitropic lag phase in tulip peduncles is such as predicted by the gravitropic‐feedback model of circumnutation.