bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Emergence of Lifestyle Reasoning in Return Considerations among British Pakistanis
Authors: Bolognani Marta 
Published: February 2014

AbstractThis article discusses the growing popularity of lifestyle reasoning in return considerations among Pakistani migrants and their children in Britain. Although lifestyle arguments are by no means new to scholarship on return migration, I argue that British Pakistanis' settlement history has led to return reasoning beyond purely economic considerations. Changes in status, power, and position, with respect to both countries of origin and settlement, have translated to a more confident capacity to aspire, and therefore to think along lifestyle considerations, whether the decision is to settle or to return. Lifestyle reasoning can therefore to be considered a sign of British Pakistanis' change in confidence about their position in the country of settlement.
Policy Implications

If the UK wants to engage with Pakistani returnees, it needs to recognize the variety of returns beyond the economic: political, lifestyle and relationship returns are all present in the array of typologies enacted by British Pakistanis

Any UK policy about return should consider that both pull and push factors influence return decisions, and those are articulated around economic, political, lifestyle, and relationship considerations.

Policy makers should consider lifestyle return reasoning a symptom of the maturation of British Pakistani citizenship in the country of settlement, rather than systematic evidence of their alienation.
Reorientation of Microfibrils and Microtubules at the Outer Epidermal Wall of Maize Coleoptiles During Auxin‐Mediated Growth
Authors: Bergfeld R. , Speth V. , Schopfer P. 
Published: February 2014

AbstractAuxin‐mediated elongation growth of isolated subapical coleoptile segments of maize (Zea mays L.) is controlled by the extensibility of the outer cell wall of the outer epidermis (Kutschera et al., 1987). Here we investigate the hypothesis that auxin controls the extensibility of this wall by changing the orientation of newly deposited microfibrils through a corresponding change in the orientation of cortical microtubules. On the basis of electron micrographs it is shown that cessation of growth after removal of the endogenous source of auxin is correlated with a relative increase of longitudinally orientated microfibrils and microtubules at the inner wall surface. Conversely, reinduction of growth by exogenous auxin is correlated with a relative increase of transversely orientated microfibrils and microtubules at the inner wall surface. These changes can be detected 30–60 min after the removal and addition of auxin, respectively. The functional significance of directional changes of newly desposited wall microfibrils for the control of elongation growth is discussed.
Photosensing and Processing of Sensory Signals in Halobacterim halobium
Authors: Schimz A. , Hildebrand E. 
Published: February 2014

AbstractHalobacteria detect changes in light intensity by retinal proteins, the number and identity of which are not yet unequivocally established. The sensory receptors are different from those for light energy conversion. The cells having no preferred swimming direction spontaneously reverse about every 10 s. An oscillator model has been proposed to explain this periodicity. Depending on wavelength and sign, a stimulus leads either to one prolonged interval between two reversals, the attractant response, or to a shortened interval, the repellent response. Sensory signals generated by stimulation of P‐565 and of P‐370 are integrated at a common link. Signals from other receptors may be processed by separate links. The nature of the sensory signals is not known, but the membrane potential can be excluded as a candidate. On the basis of the oscillator hypothesis the output signals of the integration links act on the oscillator and thus shift the time at which it triggers a reversal of the flagellar motor. Experiments indicate that cGMP and calcium play antagonistic roles in the oscillatory activity. Reversible methylation of specific membrane proteins influences the time during which successive signals are integrated. This reaction is assumed to terminate the lifetime of the excitatory signals and thus to allow the system to adapt.
Calmodulin Sensitivity of the Flagellar Membrane Adenylate Cyclase and Signaling of Motile Responses by cAMP in Gametes of Chlamydomonas reinhardtii
Authors: Pasquale S. M. , Goodenough U. W. 
Published: February 2014

AbstractCyclic AMP (cAMP) has been shown to be a primary signal of the agglutination‐induced mating events of flagellar tip activation, cell wall loss, and mating structure activation in the unicellular alga Chlamydomonas reinhardtii (Pasquale and Goodenough, Cell Biol. 105 (1987), 2279–2293). The flagellar membrane adenylate cyclase of Chlamydomonas is here shown to be inhibited in vitro by EGTA, La3+, and trifluoperazine, and to be stimulated in the presence of calcium by incubation with exogenous calmodulin. Also, the motility of detergent‐extracted models of Chlamydomonas is shown to be enhanced by cAMP. These observations suggest the hypothesis that the twitching motility characteristic of agglutinating Chlamydomonas gametes may be signaled by cAMP produced locally within the flagella by a calmodulin‐sensitive adenylate cyclase.
Receptor G‐Protein Interactions in the Development of Dictyostelium
Authors: Lilly P. , Klein P. , Theibert A. , Vaughan R. , Pupillo M. , Saxe K. , Kimmel A. , Devreotes P. N. 
Published: February 2014

AbstractDevelopment in Dictyostelium results in the production of a multicellular aggregate. Aggregation depends on chemotaxis to cAMP and cell‐to‐cell relay of cAMP signalling. The cAMP signalling response involves surface receptor‐mediated GTP‐dependent activation of adenylate cyclase. Studies of the mutant synag 7 indicate that a soluble protein may be involved in this activation. Wild‐type supernatants are required to restore GTP‐dependent adenylate cyclase activity to mutant lysates.The surface cAMP receptor which initiates this response and is implicated in chemotaxis has been purified and an antiserum raised. The receptor undergoes a ligand‐induced mobility change, probably due to serine phosphorylation, when analyzed by SDS‐PAGE. Modulation of this transition is correlated with adaptation of the cells. Analysis of cells at various stages of development indicate that the receptor is most rapidly synthesized in the preaggregation stage. The antiserum was used to clone the cDNA for the receptor. Clones that have been sequenced account for about 33 000 D of the 37 000 D receptor. Hydropathy plots reveal 3 (or 4) potential membrane spanning domains; unsequenced regions are large enough to encode an additional 4 membrane spanning regions. Comparison to bovine rhodopsin reveals homology in those regions elucidated so far. Thirteen potential phosphorylation sites are present in the cytoplasmic domain and may be involved in ligand‐induced phosphorylation.
Genetics of Circadian Clocks
Authors: Feldman J. F. 
Published: February 2014

AbstractThe isolation of circadian clock mutants in Neurospora crassa and Drosophila melanogaster have identified numerous genes whose function is necessary for the normal operation of the circadian clock. In Neurospora many of these mutants map to a single locus called frq, whose properties suggest that its gene product is intimately involved in clock function. In Drosophila mutations at the per locus also suggest a significant role for the product of this gene in the insect clock mechanism. The per gene has been cloned and its gene product identified as a proteoglycan, most likely a membrane protein involved in affecting the ionic or electrical properties of cells in which it is located. Future progress in elucidating the mechanisms of circadian clocks are likely to come from continued analysis of clock mutants, both at the genetic and molecular levels.
Microculture and Electrofusion of Defined Protoplasts of the Moss Funaria hygrometrica
Authors: Mejía A. , Spangenberg G. , Koop H.‐U. , Bopp M. 
Published: February 2014

AbstractProtoplasts isolated from protonemata of Funaria hygrometrica wild type and developmentally abnormal mutants were individually selected and cultured in microdroplets of defined, unconditioned culture medium. Up to 60 % of the microcultured wild type protoplasts regenerated whole plants after 4 weeks. Electrofusion in different combinations of defined protoplast pairs of wild type and mutated forms was performed. The products derived from one‐to‐one electric field induced fusion were efficiently microcultured and somatic hybrids were regenerated.
Evidence for a Malate Transport into Vacuoles Isolated from Catharanthus roseus Cells
Authors: Marigo G. , Bouyssou H. , Laborie D. 
Published: February 2014

AbstractMalate uptake was investigated with vacuoles isolated from Catharanthus roseus cells. The uptake process showed saturation kinetics, was inhibited by organic anions, and was very strongly dependent on the pH of the medium. These data support the classical concept of an anion carrier or channel mechanism and suggest that the Hmal− form was the transported species. Moreover, malate transport was stimulated by the proton gradient across the tonoplast. The H+ translocating enzymes ATPase and PPiase are able to favour malate uptake and, in combination, exert a synergistic effect on this transfer.
Light‐ and Clock‐Controlled Leaflet Movements in Samanea saman*: A Physiological, Biophysical and Biochemical Analysis**
Authors: Satter Ruth L. , Morse M. J. , Lee Youngsook , Crain Richard C. , Coté Gary G. , Moran Nava 
Published: February 2014

AbstractLeaflet movements in the legume Samanea saman are under joint control by light and a circadian oscillator. The movements are driven by massive fluxes of K+, Cl−, and H+ through pulvinar motor cell membranes. Light and the oscillator affect leaflet movements by altering the activity of ion transport systems. Some effects of light on ion transport may be mediated by the phosphatidylinositol (PI) cycle, since brief irradiation of the pulvinus with white light accelerates PI turnover.
Untersuchungen über die Überlebensfähigkeit von Endospermkulturen der Douglasie (Pseudotsuga menziesii) in vitro
Authors: Glock H. , Hattemer H. H. , Steinhauer A. 
Published: February 2014

ZusammenfassungFür die Untersuchung von Umwelteffekten wurde die Wirkung von vier verschiedenen Medien auf Endosperme von Samen der Douglasie (Pseudotsuga menziesii) getestet.Die Experimente waren so angelegt, daß die Untersuchung der Variation und die Wirkung der Umweltbedingungen für die Interpretation den Vorrang hat. Das Ziel der Versuche war, Kulturbedingungen zu ermittlen, die ein Wachstum und womöglich den Erhalt der Haploidie erlauben; damit sind im wesentlichen die Umwelteffekte, d. h. die Wirkung der drei Bereiche, organismische, interzelluläre und intrazelluläre Umwelt (zur Erläuterung dieser Begriffe s. Glock und Gregorius, Biosystems 17 (1984), 23–24), beschrieben.Es bestätigte sich auch hier wieder, daß der genotypische Effekt bei der Interpretation der Ergebnisse nicht übersehen werden darf, denn die Endosperme der verschiedenen Sameneltern verhielten sich sowohl bei der Explantation als auch bei späteren Verpflanzungen verschieden, wie in der Darstellung genetischer Effekte zu sehen ist. Ebenso war die Reaktion von Endospermen eines Samenelters unter sich ähnlicher als die von den Endospermen verschiedener Sameneltern.Some Experiments on Survival of Endosperm Cultures of Douglas Fir(Pseudotsuga menziesii) in vitroThe main object of the experiments was to characterize the environmental effects (= in vitro culture methods) acting upon tissue cultures of Douglas Fir endosperms.The aim of the experiments was to find out culture conditions which can enhance growth and survival and perhaps maintain haploidy of the endosperms and to describe the effect of the different types of environment: the intercellular, the intracellular and the organismic environment (see Glock and Gregorius, Biosystems 17 (1984), 23–34).It was found that genotypic effects were very important: the endosperms of different seed parents showed very different results, during the explantation phase as well as after transplantations. This is shown in the description of the genetical effects. The reactions of the endosperms of one seed parent were more similar to each other than the reaction between the groups of endosperms coming from different seed parents.
Immunogold Localization of Chloroplast Protein in Spinach Leaf Mesophyll, Epidermis, and Guard Cells
Authors: Rother Th. , Acker G. , Scheibe PD Dr. R. 
Published: February 2014

AbstractImmunogold labelling on ultrathin sections of Lowicryl K4M embedded lower epidermis of spinach (Spinacia oleracea L.) with adhering mesophyll cells has been applied to localize five proteins, namely ribulose‐1,5‐bisphosphate carbocylase/oxygenase (EC 4.1.1.39), chloroplast coupling factor (EC 3.6.1.34), NADP‐malate dehydrogenase (EC 1.1.1.82), chloroplast fructose‐1,6‐bisphosphatase (EC 3.1.3.11) and thioredoxin m by electron microscopy in stomata. Comparative data of labelling densities of the localized proteins in chloroplasts of spongy parenchyma, epidermis and guard cells are presented. All five proteins could be detected in guard cell chloroplasts at levels little different from those found in chloroplasts of spongy parenchyma and of epidermis cells. The two light‐activated enzymes NADP‐malate dehydrogenase and fructose‐1,6‐bisphosphatase are reduced in stomata to about one third of the mesophyll concentration. Aldehyde‐sensitivity of the inspected enzymes and suitability of cryosections for immunolocalization studies on plant tissues, in comparison with resin‐embedded specimens, was investigated. Fixation with 2% glutaraldehyde resulted in no detectable decrease of antigenicity. Cryosections were found to be less suitable for immunogold labelling, since labelling densities were lower than on resin. Only labelling of the thylakoid‐bound coupling factor was comparable using both techniques.
Transmission of Electric Signals in Sieve Tubes of Zucchini Plants
Authors: Eschrich W. , Fromm J. , Evert R. F. 
Published: February 2014

AbstractMembrane potentials of −;160 to −210 mV were recorded with microelectrodes inserted into meta‐phloem sieve tubes of intact zucchini plants (Cucurbita pepo L. var. medullosa Alef.). The effects of darkness, white light and colored light on membrane potential were studied. Reference electrodes were in contact with the apoplast via fluid‐filled cavities or “drinks”. Electrolyte solutions (100 mM) in the cavities could be quickly replaced by flushing with 100 mM solutions of sucrose, KCl, sorbitol, or EDTA without altering osmolarity. KCl and EDTA caused depolarization of the sieve tube membrane potential, while sucrose caused depolarization or hyperpolarization of the sieve tube membrane potential in mature or growing plant parts respectively. Recovery of the original voltage was recorded when rapid (sucrose) or slow (sorbitol) transients occurred. When two measuring circuits were installed, one in a growing fruit and the other in the petiole of the subtending mature leaf, the alteration of the sieve tube membrane potential at one site was accompanied by an alteration of the potential at the other site after a few seconds. The responses were opposite in the exporting leaf and importing fruit when sucrose was applied. The signal, transmitted via the sieve tubes, reached maximum velocities of 10 cm per second.
Movement of Abscisic Acid Across the Plasmalemma and the Tonoplast of Guard Cells of Valerianella locusta
Authors: Baier M. , Hartung W. 
Published: February 2014

AbstractUptake experiments and efflux compartmental analyses of abscisic acid (ABA) with acid treated epidermal peels of Valerianella locusta were performed to elucidate the mechanisms of transport of ABA across the plasmalemma and tonoplast of guard cells.ABA uptake across the plasmalemma is linearly correlated with external ABA concentration in the incubation medium. Under alkaline conditions ABA‐uptake was not significantly above background, indicating that ABA uptake occurs mainly by diffusion of undissociated ABAH as the most permeable species, which is trapped afterwards in the alkaline cytosol as impermeable ABA−. Efflux analysis of ABA revealed a saturable component of ABA transfer across the tonoplast. A Woolf‐Augustinsson‐Hofstee analysis suggested the existence of two transport systems for ABA at the tonoplast. The high affinity transport system had a KM of 0.21 mol m−3 and a Vmax 85.8 amol ABA cell−1 h−1. Using the data of the uptake and efflux experiments we calculated the permeability coefficients of ABA for the plasmalemma and the tonoplast of guard cells, which are 2.46 10−7 m s–1 and 1.26 10−8m s−1, respectively. The distribution of the pH‐probe (14C)‐DMO between medium, cytosol and vacuole was investigated and used to calculate cytosolic and vacuolar pH. The vacuolar pH is too low to explain the high vacuolar ABA concentration by trapping of ABA−, whereas the cytosol is sufficiently alkaline to act as an efficient anion trap. Therefore we conclude that ABA transport across the guard cell tonoplast is catalyzed by a saturable uptake component.
Gas Exchange and Water Vapor Uptake in the Atmospheric CAM Bromeliad Tillandsia recurvata L.: The Influence of Trichomes
Authors: Schmitt Dipl.‐Biol. A. K. , Martin C. E. , Lüttge U. E. 
Published: February 2014

AbstractTillandsia recurvata is an epiphytic atmospheric CAM bromeliad without functional roots. As an adaptation to very exposed and often dry habitats T. recurvata takes up liquid water via trichomes, which cover the plant.Gas exchange measurements also show an absorption of water vapor at the trichomes simultaneously with an increase in relative humidity at the beginning of the dark period. A similar amount of water is lost again when the relative humidity is decreased. Experiments with heat‐killed plants show that this was due exclusively to physical equilibration of the hygroscopic walls of the dead trichome cells. This effect would have prevented an accurate calculation of transpiration and conductance, but can be accounted for by substracting water vapor exchange of heat‐killed plants from that of the living tissue which yields the true water vapor conductance of the tissue. This is found to be rather low (3.37 mmol H2O kg−1 s−1) in comparison to other plants, and the proportion of total conductance due to trichomes is relatively high (0.53 mmol H2O kg−1 s−1). This explains the slow rates of photosynthesis and growth found in this plant.
Nitrogen Fixation and Nitrogen Assimilation in a Temperate Saline Ecosystem
Authors: Wollenweber B. , Zechmeister‐Boltenstern S. 
Published: February 2014

AbstractAs nitrogen is known to be a limiting factor for plant growth, we were interested in the relationship between soil microbial activity and the nitrogen assimilation of 5 different halophytes from 4 saline sites near the lake “Neusiedlersee”, Austria. The following were studied between May and October 1985: nitrogen fixation (15N2 and acetylene reduction): N‐mineralization; several soil characteristics and in vivo nitrate reductase activity of roots and shoots of these plants. NO−3, org. N‐ and carboxylate contents of both roots and shoots, as well as the effect of NO−3‐fertilization on the amounts of these substances, were determined on plants growing in the field during a 3‐day period in September 1985.Fertilization led to a decrease in acetylene reduction activity at most sites, and an increase in the nitrate reductase activity of the shoots of all plants. Overall, carboxylate and organic nitrogen contents of these halophytes did not change in response to fertilization. Only in the roots of Aster tripolium and Atriplex hastata was there a marked increase in the nitrate reductase activity in response to fertilization. Species growing at the same site, such as Plantago maritima and Lepidium crassifolium showed contrasting levels of assimilatory activity. Apparent low rates of ammonification and nitrification were detected in soils from the 4 sites. The results are discussed in relation to the nitrogen and carbon economies of the microorganisms and plants.
Intracellular Solutes, Photosynthesis and Respiration of the Green Alga Blidingia minima in Response to Salinity Stress
Authors: Karsten Dipl. Biol. Ulf , Kirst Gunter O. 
Published: February 2014

AbstractThe effects of different salinities ranging from 7–68‰ on the internal inorganic and organic solute concentrations, and on the photosynthesis and respiration have been investigated in the green alga Bladingia minima (Näg. ex Kütz.) Kylin. The levels of the main osmotic solutes K+, sucrose and proline increased with increasing salinities and vice versa, while Na+, Mg2+, Cl− and PO3–4 played a minor role in the osmotic acclimation. In contrast to related Enteromorpha species, B. minima exhibited high NO−3 concentrations, which decreased under hypo‐ and hypersaline conditions. B. minima differs also from Enteromorpha by accumulating the tertiary sulphonium compound DMSP in osmotically significant amounts under gentle hypersaline conditions.B. minima revealed typical characteristics of a “sun‐plant” having a high light compensation point together with a saturation of photosynthesis at high photon flux densities. The alga showed a broad photosynthetic stability under osmotic stress; only with extreme hypersaline conditions was photosynthesis partly inhibited. The rate of respiration remained constant in hypersaline media, and was stimulated under hyposaline conditions.
Tumor Transformation of Petunia hybrida via Pollen Co‐Cultured with Agrobacterium tumefaciens
Authors: Hess D. , Dressier Dipl.‐Biol. K. 
Published: February 2014

AbstractPollen preparations usually show a high nuclease activity. Therefore, to avoid DNA degradation, co‐cultures of pollen and Agrobacterium tumefaciens were evaluated as a new tool in gene transfer experiments. As a model system, Petunia pollen was co‐cultured with an A. tumefaciens wild strain. The co‐cultured pollen was used for pollination of Petunia flowers. The seeds obtained were germinated and one cotyledon per seedling was removed and put stalk upwards on nutrient agar. In 80% of the cotyledons a callus developed from the cut surface of the stalks which was screened for tumor transformation on hormone‐free medium. In repeated subculturing some calli maintained growth on hormone‐free medium. Two of these calli were habituated. One callus, the best growing one, showed on Southern blot analysis a distinct hybridization signal at 3.2 kb when probed with Hind III fragment 22 DNA, covering two genes responsible for hormone free growth. This is the exact size that could be expected when plant material has been transformed with T‐DNA. Another callus gave a hybridization signal at 2 kb which could only be explained with chromosomal rearrangement. In these two calli there was no co‐transformation of the nos‐gene: nopaline synthase activity could be detected from none of the calli, and none of the calli DNAs hybridized when probed with the nos‐gene. Bacterial contamination could be excluded by probing the DNAs with virfragments.