bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of Molecular Methods on the Systematics of Angiosperms
Authors: Wagenitz C. 
Published: February 2014

Abstract:A comparison is made between the systematics of selected orders and families based on morphology and other “classical” characters on the one hand, and the results of molecular methods on the other hand. It can be shown that taxa defined by a broad array of characters from morphology, anatomy, embryology and phytochemistry usually are confirmed by molecular results. On the other hand a family like the Saxifragaceae s.l. delimited solely on the basis of floral morphology has been shown to be grossly polyphyletic. Some quite surprising results of the molecular analyses usually agree with some embryological or phytochemical characters, and sometimes even with characters of vegetative morphology and anatomy. As a special case “unequal ancient splits” are discussed, where one clade contains few genera and species usually retaining many primitive characters, and the other shows great diversity and contains the more advanced members.
Impact of Atmospheric Sulfur Deposition on Sulfur Metabolism in Plants: H2S as Sulfur Source for Sulfur Deprived Brassica oleracea L.
Authors: De Kok L. J. , Elisabeth C. , Stuiver E. , Rubinigg M. , Westerman Sue , Grill D. 
Published: February 2014

Abstract:Brassica oleracea L. was rather insensitive to atmospheric H2S: growth was only negatively affected at ≥0.4 μl I−1. Shoots formed a sink for H2S and the uptake rate showed saturation kinetics with respect to the atmospheric concentration. The H2S uptake rate was high in comparison with other species, which may reflect the high sulfur need of Brassica. The net uptake of sulfate by roots of hydroponically grown plants was substantially reduced after one week of exposure to 0.25 μl l−1 H2S, indicating that plants switched in part from sulfate to H2S as sulfur source for plant growth. Plants were sulfur deficient after two weeks of sulfur deprivation, illustrated by reduced growth, which was more pronounced for shoots than for roots, and in enhanced shoot dry matter content. The latter could for the greater part be attributed to enhanced levels of soluble sugars and starch. Sulfur deficiency was further characterized by a low pigment content, extremely low levels of sulfate and water‐soluble non‐protein thiols, and by enhanced levels of nitrate and free amino acids, particularly in the shoots. Furthermore, sulfur deficient plants contained a lower total lipid content in shoots, whereas its content in roots was unaffected. The level of sulfolipids was decreased in both roots and shoots. When sulfur deprived plants were exposed to 0.25 μl I−1 H2S for one week, all sulfur deficiency symptoms were abolished and growth was restored. Furthermore, plants were able to grow with 0.4 μl I−1 H2S as the sole sulfur source. Water‐soluble non‐protein thiol content was enhanced in both shoots and roots of H2S exposed plants, irrespective of the sulfate supply to the roots, whereas plants grown with H2S as sole sulfur source contained very low sulfate levels. The interaction between atmospheric and pedospheric sulfur nutrition in plants is discussed.
Microscopic Study of Mature Seed Coats and Aborted Structures of Interspecific Cotton Hybrids
Authors: Shimony C. , Sass N. , Yucha R. , Saranga Y. 
Published: February 2014

Abstract:Seed coats and fibers of aborted structures (termed “motes”) and mature seeds from an interspecific hybrid (ISH) of cotton (Gossypium hirsutum x G. barbadense) were studied by microscopy to determine (a) the developmental stages at which motes of various sizes stop growing and (b) the origin of lint‐contaminating fragments. Small motes (1–2 mm wide, up to 3 mm long) were identified as ovules whose growth had been arrested before anthesis or soon afterwards, medium‐size motes (1–3 mm wide, 3–5 mm long) as those whose growth had been arrested up to 10 days post‐anthesis, and large motes (3–5 mm wide, 5–8 mm long) as those which had stopped growing about 20 days post‐anthesis. Microscopic examination of lint‐contaminating fragments showed that they derive mainly from medium‐size motes and partly from mature seed coats. Reducing the number of medium‐size motes by breeding can, therefore, improve the lint quality of ISHs of cotton.
Biomechanics of Isolated Plant Cuticles
Authors: Wiedemann P. , Neinhuis C. 
Published: February 2014

Abstract:The mechanical properties of isolated cuticles of leaves (Yucca aloifolia, Clusia fluminensis, Nerium oleander, Hedera helix) and one fruit (Lycopersicon esculentum) were investigated by means of a tensile test. Samples of the leaves and the fruit were cut to identical size (12.5 × 50 mm) and the cuticles were enzymatically isolated, cleaned, and air dried. The morphology of the isolated cuticular membranes (CM) was investigated by scanning electron microscopy (SEM) and showed considerable differences. The thickness of the CM was determined by a digital image analysis system and ranged between 2.4 and 13.4 μm. The CM were subjected to a tensile test and the results are presented as stress‐strain diagrams. From the latter, Young's moduli were calculated, a measure for the stiffness which allows the direct comparison of different materials. The obtained values ranged between 0.1 and 1.3 CPa. Hydration of CM caused a decrease of Young's moduli of about 35–50%. A possible role of the cuticle as a factor for the stabilization of plant organs is discussed.
Effect of a Treatment with Naphthaleneacetic Acid on the Arrangement of Lateral Roots in Onion (Allium cepa L): General Pattern and Coordination between Ranks
Authors: Lloret P. G. , Pulgarín A. , Casimiro I. , Molina M. , Casero P. J. 
Published: February 2014

Abstract:Lateral roots in Allium cepa arise in longitudinal rows opposite the protoxylem poles of adventitious roots. The number, spacing within ranks and positional relationship to laterals in different ranks were analysed in control roots and those treated with an auxin (α‐naphthaleneacetic acid). Treatment increased numbers of laterals per rank and distributed the more evenly in all ranks. Laterals of control roots were concentrated in two neighbouring ranks. Auxin‐treated roots showed a more regular distribution of laterals between ranks and close spacing of laterals along each rank. Comparisons with theoretical random distributions suggest a dispersed spacing model for lateral root arrangement with mutual repulsion between successive lateral roots within each rank both in control and auxintreated roots. On the other hand, there is some interaction between laterals in different ranks in 0.1 mM NAA‐treated roots.
Disruption of a spe‐like Open Reading Frame Alters Polyamine Content and psbA‐2 mRNA Stability in the Cyanobacterium Synechocystis sp. PCC 6803
Authors: Mulo Paula , Eloranta Terho , Aro Eva‐Mari , Maenpää Pirkko 
Published: February 2014

Abstract:In Synechocystis 6803, transcripts of the psbA‐2 gene encoding the reaction‐center protein D1 of photosystem II are short‐lived in light but stable in darkness. No dark‐stabilization was observed if the genomic region downstream from the psbA‐2 gene was disrupted. The deleted fragment was found to include an open reading frame (ORF) with striking similarity to the spe gene encoding arginine decarboxylase (L‐arginine carboxylase, EC 4.1.1.19), which is involved in the biosynthesis of polyamines. The spermidine content of the mutants with a disrupted ORF was observed to be lower than in the wild‐type suggesting that polyamines may play a role in the stability of the psbA‐2 mRNA.
A phi Layer in Roots of Ceratonia siliqua L
Authors: Pratikakis E. , Rhizopoulou Sophia , Psaras G. K. 
Published: February 2014

Abstract:The central cylinder of the primary root of the carob tree (Ceratonia siliqua) is encircled by a layer of cells with wall thickenings, known as a phi (φ) cell layer. The development of the φ layer and the chemical composition of the cell wall thickenings have been studied in roots of C. siliqua. The results reveal the presence of condensed tannins in the mature phi thickenings and that the development of the φ layer is asynchronous: at 0–1 cm from the root tip φ thickenings appear before endodermis differentiation at the sites opposite phloem, at 1–4 cm new φ thickenings are developed at the sites opposite xylem, at 4–7 cm the φ layer consists of two layers of cells and it completely encloses the central cylinder.
Localization of Pyrophosphatase and V‐ATPase in Chlamydomonas reinhardtii
Authors: Robinson D. G. , Hoppenrath Mona , Oberbeck K. , Luykx P. , Ratajczak R. 
Published: February 2014

Abstract:Microsomal membranes of Chlamydomonas reinhardtii possess PPase and V‐ATPase activities. By immunogold labelling we have shown that H+‐pyrophosphatase (PPase) is localized to membranes of lytic and contractile vacuoles of Chlamydomonas, in which the density of antigen in the latter is much higher. In addition, PPase is conspicuously present in trans cisternae and transpole elements of the Colgi apparatus. Such a distribution for PPase has hitherto not been reported. A positive in situ identification for PPase at the plasma membrane, including the flagellar membrane, was also made, and has also been confirmed by Western blotting and activity measurements on isolated plasma membranes. V‐ATPase antisera which cross react with polypeptides of this transport complex from maize roots failed to recognize anything in Western blots of Chlamydomonas microsomal membranes. Thus immunogold labelling for V‐ATPase was not possible with Chlamydomonas. On the other hand, surfaces of contractile vacuole membranes as revealed by deepetching were covered by conspicuous 9 − 11.5 nm diameter smooth particles which had a central hole. These were very similar to those previously identified by Heuser et al., (1993) as the V,‐head of V‐ATPase in Dictyostelium contractile vacuoles. Another type of membrane image, designated “intermediate‐sized vesicle”, was found associated with the contractile vacuole. It was characterized by densely‐packed 6 − 7.5nm diameter polygonal particles, which upon rotation analysis showed both 5‐ and 6‐fold symmetries, also with a central hole. These particles are interpreted as representing either PPase complexes or the V0 body of the V‐ATPase in etched fractured membrane surfaces. We have incorporated these findings into a model of contractile vacuole function.
Tracing the Path of Oxygen into Birdsfoot Trefoil and Alfalfa Nodules using Iodine Vapor
Authors: Jacobsen Karin Ruth , Rousseau R. A. , Denison R. F. 
Published: February 2014

Abstract:Although physiological control of nodule 02 permeability is an active area of research, the gas diffusion pathway between the atmosphere and the infected zone has not been firmly established. Previous studies have used infiltration of ink or dyes to identify points of entry, but such water‐soluble tracers could give a misleading picture of gas diffusion pathways. We therefore used iodine vapor (and its reaction with starch) to trace gas‐phase pathways into the infected zone of determinate birdsfoot trefoil (Lotus corniculatus) and indeterminate alfalfa (Medicago sativa) nodules. We also used histochemical methods to identify suberized or lignified layers that could act as barriers to gas diffusion. Birdsfoot trefoil nodules were surrounded by a suberized periderm, but nonsuberized cells and intercellular spaces were observed in the periderm between lenticels and their associated vascular bundles. Iodine entered birdsfoot trefoil nodules only through lenticels. The periderm appears to provide a significant barrier to gas diffusion. Although airspaces were rare in the nodule parenchyma (also referred to as the “inner cortex”), we found some evidence that a few air‐filled pathways cross this secondary barrier, also in the vicinity of vascular bundles. Alfalfa nodules were cylindrically surrounded by a suberized endodermis which ended near the meristematic tip; iodine entered principally at the end of the endodermis near the meristem. Future research on physiological control of nodule O2 permeability should concentrate on strategic “choke points”, associated with lenticels in determinate nodules, or in the zone proximal to the meristem in indeterminate nodules.
Cytological Characterization of Multicellular Structures in Embryogenic Microspore Cultures of Brassica napus L.
Authors: Hause G. , Hahn H. 
Published: February 2014

Abstract:We investigated an embryogenic microspore culture from Brassica napus L. cv. “Topas”, 3 days after induction of embryogenesis, using light and electron microscopical techniques. According to our observations, 6 groups of uni‐ or multicellular structures could be distinguished by differences in size, wall structure, structure and distribution of organelles and the degree of vacuolisation. Only one multicellular group represents real proembryos which are able to form embryos and to regenerate plants. These 6 groups could be detected in living cultures using an inverted microscope. The cell size and the degree of vacuolization are especially useful markers to distinguish the groups. Separate cultivation of the multicellular complexes of the 6 groups in culture plate inserts from the third day of culture proved that only one group contains real proembryos.
Growth and Alkaloid Patterns of Roots of Tabernaemontana pachysiphon and Rauvolfia mombasiana as Influenced by Environmental Factors
Authors: Höft M. , Verpoorte R. , Beck E. 
Published: February 2014

Abstract:The influence of environmental factors on the indole alkaloid content and biomass of the roots of Tabernaemontana pachysiphon and Rauvolfia mombasiana, two species of considerable local medicinal use in tropical East Africa, was investigated. Both species, belonging to the Apocynaceae, are frequent constituents of the residual tropical forests, prefering sites of different ecological conditions. Experimental plants, raised from seeds, were grown for 16 months in a temperature‐ and humidity‐controlled greenhouse. Environmental factors at variance were water and nutrient supply, and light intensity. At sufficient water and nutrient supply, the more drought and nutrient shortage‐tolerating heliophilous Rauvolfia mombasiana showed increased alkaloid accumulation, concurrently with reduced root biomass. Under the same conditions, the drought‐sensitive and higher levels of nutrient‐requiring ombrophilous Tabernaemontana pachysiphon produced more root biomass but accumulated less alkaloids in the roots. The results indicate that the accumulation of indole alkaloids in the roots, as well as biomass allocation to the roots, is influenced in an opposite manner by the nutrient and water supply to the heliophilous and the ombrophilous species.
Partitioning of Soluble Calcium in the Water Hyacinth (Eichhornia crassipes (Martius) Solms) in Lake Victoria, Uganda
Authors: Tabuti J. R. S. , Oryem‐Origa H. , Mutumba G. M. , Kashambuzi J. T. 
Published: February 2014

Abstract: An investigation of soluble calcium partitioning in organs of the water hyacinth growing along the shores of L. Victoria, bordering Jinja town was carried out. The levels of Na+, K+, Mg2+ and Ca2+ in the lake water were also estimated. The pH and electrical conductivity of lake water were determined.There was a differential accumulation of Ca and oxalate between component organs of the water hyacinth. The concentration of oxalate in the various organs was more than twice that of Ca. Soluble Ca decreased with age in all organs except the leaf, while oxalate increased with age in all organs except the rhizome. There were site variations in the partitioning of both Ca and oxalate in the water hyacinth.
Cloning, Recombinant Expression and Characterization of Wild Type‐105‐Trp‐Calmodulin of the Green Alga Mougeotia scalaris
Authors: Zörb Chr , Brunner Katja D. , Perbandt M. , Betzel Chr , Wagner G. 
Published: February 2014

Abstract:The single calmodulin gene (CaM) of the green alga Mougeotia scalaris (Hassall) was cloned, sequenced and the CDNA inserted into the prokaryotic expression vector pGEX‐2T. The recombinant calmodulin protein (CAM) was expressed as a fusion product together with glutathione S‐transferase and isolated on glutathione sepharose. After cleavage and purification, the CaM was characterized by Ca2+‐dependent shift in SDS‐PAGE, by activation of cyclic 3′,5′nucleotide phosphodiesterase (PDE) and sensitivity to the inhibitors trifluoperazine and calmidazolium, with native Mougeotia CaM as control. Using Ca2+ buffers in the PDE test, affinity to Ca2+ of Mougeotia CaM was found to be diminished fivefold compared to maize or bovine brain CaMs. There was also a 20‐fold increase of half maximal activation (Kact) in the PDE test for Mougeotia CaM relative to maize CaM, while the Kact of maize CaM to that of bovine brain CaM was almost the same. The derived amino acid sequences of CaM from Mougeotia and Zea mays revealed three major conservative amino acid exchanges, including unique 105‐Trp (Mougeotia) → Leu (maize). In Mougeotia CaM the 105‐Trp, including the neighbouring side chains of 92‐Phe and 141‐Phe, putatively form a hydrophobic ring interaction, as revealed by molecular modelling.
Light Harvesting and State Transitions in Cyanobacteria
Authors: van Thor J. J. , Mullineaux C. W. , Matthijs H. C. P. , Hellingwerf K. J. 
Published: February 2014

Abstract:Cyanobacteria are oxygenic phototrophic prokaryotes and are considered to be the ancestors of chloroplasts. Their photosynthetic machinery is functionally equivalent in terms of primary photochemistry and photosynthetic electron transport. Fluorescence measurements and other techniques indicate that cyanobacteria, like plants, are capable of redirecting pathways of excitation energy transfer from light harvesting antennae to both photosystems. Cyanobacterial cells can reach two energetically different states, which are defined as “State 1” (obtained after preferential excitation of photosystem I) and “State 2” (preferential excitation of photosystem II). These states can be distinguished by static and time resolved fluorescence techniques. One of the most important conclusions reached so far is that the presence of both photosystems, as well as certain antenna components, are necessary for state transitions to occur. Spectroscopic evidence suggests that changes in the coupling state of the light harvesting antenna complexes (the phycobilisomes) to both photosystems occur during state transitions. The finding that the phycobilisome complexes are highly mobile on the surface of the thylakoid membrane (the mode of interaction with the thylakoid membrane is essentially unknown), has led to the proposal that they are in dynamic equilibrium with both photosystems and regulation of energy transfer is mediated by changes in affinity for either photosystem.
Passion at work and workers' evaluations of job demands and resources: a longitudinal study
Authors: Lavigne Geneviève L. , Forest Jacques , Fernet Claude , Crevier‐Braud Laurence 
Published: February 2014

AbstractVallerand et al. developed a dualistic model of passion where two types of passion are proposed: harmonious and obsessive passion. They generally predict adaptive and less adaptive outcomes, respectively. In this study, we examine whether the type of passion that employees hold toward work influences their evaluations of job demands and resources. We hypothesized that a harmonious passion for work would lead to positive evaluations of job control and support in the workplace as well as to low levels of work overload. In contrast, we hypothesized that an obsessive passion for work would lead to evaluations of work overload and to low levels of job control and support. The results of a longitudinal study supported our hypothesis.
The diversity paradox: when people who value diversity surround themselves with like‐minded others
Authors: Hackett Justin D. , Hogg Michael A. 
Published: February 2014

AbstractAn anomaly exists between society's push for diversity and people's preference to be with like‐minded others—a diversity paradox. Research suggests it is endemic to group life to accentuate similarity within groups and maximize differences between groups. Drawing on uncertainty–identity theory, that uncertainty motivates identification with clearly defined groups, we explore whether increasing community identification to alleviate self‐uncertainty is impacted when diversity is important. In a naturalistic experiment, values match and placing importance on diversity each predicted community identification. Uncertainty decreased identification when diversity was important. Greater identification emerged when diversity and value similarity were important. This effect, strong under low uncertainty, did not emerge under high uncertainty. Findings are discussed in terms of the antagonism between society's push for diversity and research on the psychology of groups.
How does stigma spoil relationships? Evidence that perceived discrimination harms romantic relationship quality through impaired self‐image
Authors: Doyle David Matthew , Molix Lisa 
Published: February 2014

AbstractResearch is beginning to reveal negative effects of perceived discrimination on romantic relationship quality among members of devalued groups, yet potential mechanisms driving these effects remain underexplored. In the current work, we examined the mediating role of self‐image. Data from two cross‐sectional studies with samples composed of racial minorities (Study 1) and sexual minorities (Study 2) provided support for a model, whereby the negative association between perceived discrimination and romantic relationship quality is partially mediated by impaired self‐image. As proposed, results from bootstrapping analyses revealed significant indirect effects of perceived discrimination on relationship quality through self‐image. Implications of social identity threats for the romantic relationships and families of members of stigmatized groups are discussed along with other potential mechanisms.
Individual prediction model for lamivudine treatment response in hepatitis B virus e antigen‐positive chronic hepatitis B patients
Authors: Lee Hyun Woong , Kang Wonseok , Ahn Sang Hoon , Lee Heon Ju , Hwang Jae Seok , Sohn Joo Hyun , Jang Jae Young , Han Ki Jun , Kim Ja Kyung , Kim Do Young , Paik Yong Han , Lee Chun Kyon , Choi Ik‐Seong , Lee Kwan Sik , Han Kwang‐Hyub 
Published: February 2014

AbstractBackground and AimsAlthough prolonged lamivudine (LAM) therapy is associated with the emergence of LAM‐resistant mutations, it is still a commonly used therapy in many Asian countries because of its established long‐term safety and low cost. The aim of our study was to assess the predictors of long‐term LAM treatment response and to establish an individual prediction model (IPM) for hepatitis B virus e antigen (HBeAg) seroconversion in HBeAg‐positive chronic hepatitis B (CHB) patients.MethodsThis was a multicenter analysis of 838 patients treated with LAM between January 1999 and August 2004. Of these, 748 patients were followed up for at least 24 months.ResultsThe median age was 43.0 years (range, 19–79 years) and the mean duration of LAM monotherapy was 34.2 ± 0.7 months. In the multivariate analysis, age (odds ratio [OR] = 0.974, P < 0.001), baseline alanine aminotransferase level (OR = 1.001, P = 0.014), and baseline hepatitis B virus DNA level (OR = 0.749, P < 0.001) were independent factors for HBeAg seroconversion. Based on the predictors, an IPM was established. Patients were classified into high (> 50%), intermediate (30–50%), or low (≤ 30%) response groups based on their probability of HBeAg seroconversion according to the IPM. The cumulative HBeAg seroconversion rate at 6 years for the high, intermediate, and low response groups was 66.0%, 48.5%, and 21.8%, respectively (P < 0.001).ConclusionsAn IPM was developed based on predictors of HBeAg seroconversion in HBeAg‐positive CHB patients on LAM monotherapy. This model will allow screening of LAM responders prior to the commencement of antiviral treatment.