bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Phenylalanine Ammonia Lyase and Chalcone Synthase within Trunks of Robinia pseudoacacia L.
Authors: Magel Elisabeth , Hübner Barbara 
Published: February 2014

Abstract:During heartwood formation, a kind of apoptosis in the inner parts of woody axes, phenolic substances are accumulated by in situ biosynthesis. In Robinia pseudoacacia L, these compounds are mainly flavonoids. In the present work, we performed a study to show if there is a correlation between measurable activities and detectable protein levels of phenylalanine ammonia lyase (PAL; EC 4.3.1.5) and chalcone synthase (CHS; EC 2.3.1.74), key enzymes of general phenylpropanoid metabolism and flavonoid biosynthesis, respectively. After separation of total protein extracts by one‐dimensional micro‐gel electrophoresis, newly emerging polypeptides were detectable within the sapwood‐heartwood transition zone, pointing toward a transient activation of metabolism shortly before cell death occurs. Most prominent was a polypeptide around 46 kDa. By immunoblotting, this band was identified as a CHS subunit. Thus, the exclusive presence of both enzyme protein and extractable enzyme activity of CHS in the heartwood bordering tissue was shown. In contrast, levels of PAL protein were similar in all xylem tissues which contain living cells. PAL activity, however, was measurable only in the differentiating xylem and the sapwood‐heartwood transition zone. From these results we conclude that during heartwood formation, CHS and PAL differ in their mode of regulation. It seems likely that CHS activity is regulated at the level of enzyme protein while PAL regulation is most probably post‐translational.
Eye Attached Hemipollinaria in the Hawkmoth and Settling Moth Pollination of Habenaria (Orchidaceae): A Study on Functional Morphology in 5 Species from Subtropical South America
Authors: Singer R. , Cocucci A. A. 
Published: February 2014

Abstract:Morphological adaptations to sphingophily and pollination by moths was studied in 5 South American Habenaria species. For H. gourlieana and H. hieronymi direct evidence of hawkmoth (Agrius cingulatus and Manduca sexta) and settling moth (Rachiplusia nu) pollination, respectively, by hemipollinaria attachment on the eyes, is presented. In two other species (H. paucofilia, H. rupicola) pollination by settling moths and eye attachment of the hemipollinaria can be inferred by indirect evidence (placement of scales and massulae on the flowers) and by flower structure. For the fifth species (H. montevidensis) pollination by small moths or mosquitoes with hemipollinaria attachment on the proboscis is postulated. A comparative study in floral features revealed clear morphological divergence between sphingophilous and phalaenophilous species. In addition to deeper spurs the former have slender, exerted, and upturned petal lobes (acting as mechanical guide to the hovering visitors), a much developed median rostellar lobe (acting as deflecting surface of the hawkmoths towards the viscidia), flexible and sinuous hemipollinarium caudicles (appropriate for frontal strikes against the stigma when hemipollinaria are brought by the hawkmoths dangling against the flower). Male efficiency was compared between 4 species with overlapping flowering time in the same area. Male efficiency factors were unexpectedly low in all species. Only in one species (H. hieronymi) each pollen donation accounted for more than one pollination. H. gourlieana is part of a more or less rich sphingophilous flora interacting with the same two long‐tongued hawkmoth species. Interspecific competition for pollen placement on the pollinator's body surface is probably low on account of different pollination mechanisms.
Pollination of Pteroglossaspis ruwenzoriensis (Rendle) Rolfe (Orchidaceae) by Beetles in Argentina
Authors: Singer R. B. , Cocucci A. A. 
Published: February 2014

Abstract:Beetle pollination by Euphoria lurida (Scarabaeidae: Cetoninae) is documented for Pteroglossaspis ruwenzoriensis (Orchidaceae: Epidendroideae: Cymbideae: Eulophiinae) in its natural habitat in Central Argentina (South America). Flower features with special emphasis on those related to beetle pollination are given. These include: long rigid and well exposed inflorescences, sturdy inconspicuous and deep flowers with small entrance, emission of a yeast‐like fragrance, jelly‐like nectar, short column, and a head‐attaching pollinarium with a broad saddle‐like viscidium. Pollinator behaviour and pattern of flower opening favour cross pollination and probably long distance pollen dispersal. Flowering, which lasts about 3 weeks, peaks in summer past mid‐January. In natural conditions about 68 flowers are pollinated for every 100 pollinaria removals.
Ammonium and Methylammonium Transport in Egeria densa Leaves in Conditions of Different H+ Pump Activity
Authors: Venegoni A. , Moroni A. , Gazzarrini S. , Marrè Maria Teresa 
Published: February 2014

Abstract:Previous data in Egeria densa leaves demonstrated a strong inhibitory effect of Cs+ on passive K+ influx and on K+‐induced, ATP‐dependent electrogenic proton extrusion. In this paper we analyzed, using the same material, the effects of Cs+ on ammonium (NH4+) and methylammonium (CH3NH3+) transport in order to elucidate whether a common transport system for K+ and NH4+ could be demonstrated. The effects of Cs+ on NH4+‐ and CH3NH3+‐induced titratable H+ extrusion (–ΔH+) and on transmembrane electrical potential difference (Em) in E. densa leaves were analyzed in parallel. All experiments were run either in the absence or presence of fusicoccin, corresponding to low or high H+‐ATPase activity and membrane hyperpolarization and leading, in this material, to respectively active or passive transport of K+. The results suggest the presence in E. densa leaves of two distinct pathways for NH4+ uptake: one in common with NH4+ and (with lower affinity) CH3NH3+, insensitive to Cs+, and a second system, operating at higher H+‐ATPase activity and Em hyperpolarization, strongly inhibited by Cs+ and impermeable to CH3NH3+. In agreement with this hypothesis, Xenopus laevis oocytes injected with the KAT1 RNA of Arabidopsis thaliana were permeable to K+ and NH4+, but not to CH3NH3+.
Cyanobacteria and Cyanobacterial Lichens from Inselbergs of the Ivory Coast, Africa
Authors: Büdel B. , Becker U. , Porembski S. , Barthlott W. 
Published: February 2014

Abstract:This study focuses on the saxicolous lichens and cyanobacteria of the open, exposed rock surface of inselbergs. Twenty‐three species of cyanobacteria and 17 cyanobacterial lichen species (“cyanolichens”) from several inselbergs and other rocky outcrops of three major climatic regions, savanna, transition zone and rain forest, are reported from the Ivory Coast. Inselbergs are isolated and frequently mountains consisting of Precambrian granites or gneisses that abruptly rise from the surrounding plains. Cyanobacteria were found to be the dominating organisms on all rock surfaces. The lichens found mainly belong to the family Peltulaceae and a few were present from the family Lichinaceae. Nine species of the cyanolichens and most of the cyanobacteria are new for the Ivory Coast. A gradient in total species number (cyanolichens and cyanobacteria) occurs from the savanna to the rain forest, with a decrease in species number towards the rain forest. Saxicolous cyanobacterial lichens reached a higher species number in the savanna type ecosystem (11) than on inselbergs in the rain forest (7). The cyanolichens and cyanobacteria found are characteristic for larger, light‐exposed rock surfaces and species like P. congregate, P. lingulata, P. tortuosa and P. umbilicata preferentially occur on the granite or sandstone of inselbergs.
UV Effects on Pigments and Assimilation of 15N‐Ammonium and 15N‐Nitrate by Natural Marine Phytoplankton of the North Sea
Authors: Döhler G. , Hagmeier E. 
Published: February 2014

Abstract:Effects of ambient solar UV radiation in the field and of artifical UV irradiation under controlled laboratory conditions were studied with natural phytoplankton populations from Helgoland, German Bight, North Sea. The pattern of pigments varied after UV‐A or UV‐B plus a low dose of UV‐A radiation: UV‐A usually induced a stimulation of pigment biosynthesis; whereas UV‐B plus UV‐A led to a reduction of the contents of chlorophyll a, diadinoxanthin, fucoxanthin, peridinin and an unknown carotenoid; content of diatoxanthin was significantly enhanced. The damaging effect on nitrogen assimilation by UV was more pronounced after artificial UV‐B plus UV‐A irradiance compared to the influence of ambient solar UV under field conditions. The uptake of inorganic nitrogen was dependent on the dose and exposure time of UV radiation as well as on the species composition. The uptake of 15N‐nitrate by natural phytoplankton collected in spring was more sensitive to UV irradiation than the assimilation of 15N‐ammonium. UV‐A radiation with a small part of shorter wavelengths at 315 nm (Philips‐lamps in conjunction with the cut‐off filter WG 320) caused a reduction of up to 12% whereas a stimulation of the 15NH4+ uptake was observed after exposure to UV‐A without any UV‐B (Philips lamps TL 60W/09N). Pattern of 15N‐incorporation into free amino acids and pool sizes varied in dependence on the applied nitrogen compound and on the irradiation conditions. The impact of UV radiation on the pattern of 15N‐Iabelled free amino acids and the pool sizes was different. 15N enrichment into all the tested amino acids was reduced after 5 h UV‐B plus UV‐A exposure and after application of 15NH4+. A depression of the glutamate and glutamine pools was observed after addition of 15N‐nitrate alone. Pools of all main amino acids from phytoplankton in summer 1993/94 were inhibited by UV irradiance. Results are discussed with reference to the UV target (e.g. enzymes, pigments) and the adaptation to the environmental conditions.
Development, Genetics and Molecular Biology of Mosses
Authors: Reski R. 
Published: February 2014

Abstract:The first descriptions of sex chromosomes in plants, of the continuity of chromosomes during the mitotic cycle and of non‐Mendelian inheritance as well as the introduction of UV‐mutagenesis to genetic research are landmarks in biological sciences first achieved by scientists working on bryophytes. Haploidy of the tissue facilitates mutant isolation and many developmental moss mutants have been isolated. Early moss development is triggered by auxin, by cytokinin and by light, mainly acting via phytochrome and a blue‐light receptor. Due to the simplicity of the plants, development can be pinpointed to the differentiation of a single cell and be analysed in living tissue, making mosses ideal candidates for the analysis of development in an integrated approach of cell and molecular biology. Molecular genetic techniques have been applied mainly to Physcomitrella patens (Hedw.) B.S.G., where efficient protocols for transformation of nuclear DNA have been established and several nuclear, chloroplast and mitochondrial genes have been analysed. These studies reveal that Physcomitrella may be an appropriate model to study plant development in molecular terms. Recently, it has been shown that, in this species, nuclear genes can be targeted very efficiently by homologous recombination, now opening the door to reverse genetics for plant biologists.
Responses of Photosynthesis, Carbohydrates and Antioxidants in Needles of Norway Spruce to Slow and Rapid Changes in Ozone
Authors: Wieser G. , Havranek W. M. , Loidoldt‐Nagele M. , KronfuG G. , Polle A. 
Published: February 2014

Abstract:The goal of the present study was to examine the effects of slow and rapid changes of ozone (O3) concentrations on the physiological behaviour of current‐year needles of Norway spruce (Picea abies(L.) Karst.). For this purpose five‐year‐old spruce seedlings were exposed in growth chambers for 49 days to either charcoal‐filtered air, slowly increasing O3concentrations from zero up to 100 nl I−1in weekly steps of 25 nl I−1, or immediately to 100 nl I−1of O3. During the investigation period gas exchange, carbohydrate and antioxidant contents of the current flush were measured. In needles which experienced slowly increasing O3concentrations, cumulative O3uptake was approximately 30 % lower than in needles continuously fumigated with 100 nl I−1of O3. The higher 03uptake in the permanent 100 nl I−1O3treatment caused a pronounced decline in net photosynthesis, in the efficiency of CO2uptake and in the starch content of the seedlings. Initially the ascorbate pool increased, but after 5 weeks of exposure ascorbate concentrations declined and were comparable to values obtained in charcoal‐filtered controls, while the thiol contents were enhanced during fumigation with permanent 100 nl I‐−1O3. On the contrary, slowly increasing O3caused a significant increase in total needle ascorbate throughout the fumigation period, which probably prevented an O3‐induced decline in the photosynthetic machinery as photosynthesis was not affected although the thiol contents were not enhanced. Furthermore, starch content was slightly higher than in O3‐free controls. These results suggest that seedlings of Norway spruce have the possibility to acclimate to O3stress, as slowly increasing O3concentrations seemed to increase resistance and the seedlings were able to compensate.
Responses of Glutathione and Glutathione S‐Transferase to Cadmium and Mercury Exposure in Pedunculate Oak (Quercus robur) Leaf Discs
Authors: Gullner G. , Uotila M. , Kömives T. 
Published: February 2014

Abstract:Changes in chlorophyll, non‐protein thiol and glutathione (GSH) levels, and the activity of glutathione S‐transferase (GST) were investigated in cadmium(ll) and mercury(ll) cchloride treated leaf discs of mature pedunculate oak trees (Quercus robur). Both heavy metals caused decreases in chlorophyll content, but mercury was more toxic than cadmium. Cadmium treatments (30–250μiM) resulted in increasing non‐protein thiol levels after 3d, but GSH contents decreased. Mercury (1–20μM) led to a concentration‐dependent decline in both non‐protein thiol and GSH levels. GST activities were not modified significantly by cadmium, but mercury treatments caused a dose‐ and time‐dependent enzyme induction. Both the phytotoxic‐ and GST‐inducing effect of mercury could be prevented by the cysteine precursor L‐2‐oxo‐4‐thiazolidinecarboxylic acid.
Notes on the Evolution of Androecial Organisation in the Magnoliophytina (Angiosperms)
Authors: Decraene L. P. Ronse , Smets E. F. 
Published: February 2014

Abstract:This paper aims to summarize briefly and to update our ideas about androecial architecture formulated in earlier publications. Ontogenetic evidence of stamen development, viz. the initiation, arrangement and relationship of stamens to other floral morphomes, can be translated into a semophyletic scheme reflecting the phylogeny of the androecium. The ancestral androecium is discussed in the light of recent theoriesabout angiosperm phylogeny. Two divergent androecial processes are proposed for the angiosperms starting from a spiral androecium with a moderate number of stamens. However, transitions exist between spiral polyandry, numerous stamens in whorls, and chaotic polyandry. From an androecium with several alternating whorls of paired and single stamens, outer stamen pairs are retained following the successive loss of inner stamen whorls. Single stamens instead of pairs occur at the very end of this line and represent a more advanced condition. This line is mostly present in tri‐ and dimerous flowers. From the same starting point diplostemony (with two alternating whorls of single stamens) originated, again giving rise to various states usually present in pentamerous or tetramerous flowers.
Water Storage in the Lichen Family Umbilicariaceae
Authors: Valladares F. , Sancho L. G. , Ascaso Carmen 
Published: February 2014

Abstract:Quantitative relationships between thallus structure and water storage and retention capacities In 12 species of the lichen family Umbilicariaceae were explored using three recent techniques for plant structure analysis: stereology (3D quantification of microscopic Images), mercury Intrusion porosimetry (determination of pore size distribution of tissues) and low‐temperature scanning electron microscopy (LTSEM). Water storage capacity of the thallus was related neither to thallus density nor surface area of the thallus; It was directly related to the total porosity of the thallus and inversely related to the proportion of thallus volume occupied by cell walls and gelatinous substances. Water retention capacity increased with increasing thallus density and was decreased by slight increases in the surface area of the upper side of the thallus. Water storage and retention capacities exhibited a positive correlation only when the storage capacity was expressed on a surface area basis. LTSEM study of fully hydrated specimens revealed that many intercellular spaces of the upper cortex and upper parts of the algal layer contained liquid water. Intercellular spaces of the lower part of the algal layer and medulla were in general either airfilled or partially occupied by gelatinous substances. Species with rhizinomorphs and substrate‐hygrophytic (water uptake from surface run‐offs) stored more water and retained it longer than aerohygrophytic species (water uptake from the atmosphere) lacking rhizinomorphs. Thallus structure of aerohygrophytic species seems to facilitate rapid gas exchange with the environment, improving water uptake and carbon gain when atmospheric moisture is available but accelerating dehydration when the atmosphere becomes dry.
SNFL3: A Protein Kinase Homologue of Sorghum bicolor with a High Similarity to the Yeast SNF1 Protein Kinase
Authors: Annen Friederike , Stockhaus J. 
Published: February 2014

Abstract:We have identified several protein kinases that are differentially expressed in mesophyll and bundle sheath cells of the C4 plant Sorghum bicolor. Here we describe the characterization of a protein kinase homologue that shows a high amino acid sequence similarity to the SNF1/AMPK family of protein serine/threonine kinases. The mRNA of this gene accumulates to much higher levels in mesophyll cells than in the bundle sheath and can also be detected in root tissue.
Characteristic Trichomes and Indumentum Specialization in African and European Parasitic Scrophulariaceae
Authors: Neumann Ulla , Paré J. , Raynal‐Roques A. , Sallé G. , Weber H. Chr 
Published: February 2014

Abstract:Trichomes and their distribution patterns have been observed in the aerial parts of plants of the genera Striga, Buchnera, Rhamphicarpa, Euphrasia, Melampyrum and Rhinanthus, using both light (LM) and scanning electron microscopy (SEM). All trichomes belong to the multicellular, uniseriate category and can be classified as glandular and nonglandular types. On nearly all organs, the two types can be observed side by side. Apart from a large group of ubiquitous trichomes, some characteristic trichome types are reported; they are restricted either to chlorophyllous organs (foliage leaves, bracts, calyx and stem) or to the corolla. In some nonglandular trichomes mineral deposits have been found. Other morphological and anatomical trichome features are discussed with regard to their possible function.
Effect of Seed Freezing and Storage Conditions on Plasma Membrane Properties of Norway Spruce (Piceo abies Karst.) Seedlings
Authors: Rakowski K. J. , Behzadipour M. , Ratajczak R. , Kluge M. 
Published: February 2014

Abstract:Norway spruce (Picea abies Karst.) seeds were frozen and stored for 15 months at + 3, − 25, − 75 or − 196°C. After storage, seeds were germinated for 9−14 days to determine viability and plasma membrane protein composition, H+‐ATPase activity and fluidity. The results indicate no significant differences in viability of seed 14 days after germination. Biochemical analyses revealed increased plasma membrane fluidity in 9‐day‐old Norway spruce seedlings raised from seeds pretreated at − 75 °C. and changes in the temperature profile of membrane fluidity in seedlings after pre‐treatment of seeds at − 25 °C. On the other hand, the same treatments did not result in changes in plasma membrane protein content, protein composition or ATPase activity. There was also no difference in plasma membrane H+‐ATPase activity assayed in the presence of different ATP hydrolysis inhibitors. Based on the presented results, and other experimental data, we suggest that during early seedling growth, adaptation of seeds to − 25 and − 75°C freezing and/or storage temperature results in stability of the plasma membrane protein function and composition and increased fluidity or changes in the temperature‐dependent fluidity profile of these membranes.
On Hybrid Formation in the Rock Fern Asplenium x alternifolium (Aspleniaceae, Pteridophyta)
Authors: Vogel J. Chr , Russell S. J. , Rumsey F. J. , Barrett J. A. , Gibby Mary 
Published: February 2014

Abstract:Length polymorphism in a non‐coding spacer (trnLUAA‐trnFGAA) in the chloroplast DNA was used in the investigation of the origin of the most common and conspicuous European fern hybrid, Asplenium x alternifolium (Aspleniaceae, Pteridophyta). The origins of A. x alternifolium, the hybrid between A. trichomanes s.l. and A. septentrionale s.l. was studied at three ploidy levels, diploid, triploid and tetraploid. The cpDNA technique allowed us to investigate the mode of hybrid formation between sexual species for the first time over a wide geographic range and with a large sample size. Morphological variation in this hybrid has previously been attributed to different reciprocal parental combinations, and to the influence of chloroplast genes on morphogenesis. Our results demonstrate that one parent, A. septentrionale s.l., acts predominantly as the female parent in these hybrids, with only one population of A. x alternifolium showing reciprocal hybridity. The discovery of predominantly unidirectional hybrid formation in this hybrid may be explained by the different breeding systems of the parental taxa. The role of gametophyte ecology is also assessed.
Evidence for Maternal Transmission of Chloroplast DNA in the Genus Asplenium (Aspleniaceae, Pteridophyta)
Authors: Vogel J. Chr , Russell S. J. , Rumsey F. J. , Barrett J. A. , Gibby Mary 
Published: February 2014

Abstract:Little is known about the mode of transmission of chloroplasts in ferns, despite the importance of such knowledge for molecular phylogenetic and biosystematic studies. Andersson‐Kötto (1930, 1931) inferred from crossing experiments that chloroplasts are inherited biparentally in Asplenium scolopendrium L. Here we present evidence from artificial hybridisation that demonstrates maternal inheritance of chloroplast DNA in the genus Asplenium (Aspleniaceae, Pteridophyta) using length variation in a non‐coding spacer (trnLUAA‐trnFGAA) in the chloroplast DNA.