bluuebunny/crossref_metadata_2025 huggingface dataset:
The biogeography of seaweeds in Southeast Alaska
Authors: Lindstrom Sandra C.
Published: February 2008

Aim  This article reviews the history of seaweed collections in Southeast Alaska from the early Russian explorers to contemporary efforts. It summarizes other studies of Southeast Alaskan seaweeds from a biogeographical perspective, and compares the known seaweed flora near three population centres (Ketchikan, Sitka and Juneau) with those of other regions within Alaska, and with nearby regions.

Location  For this article, Southeast Alaska includes all inside and outside waters of the Alexander Archipelago from Dixon Entrance (54°40′ N, 133°00′ W) to Icy Point (58°23′10″ N, 137°04′20″ W).

Methods  The literature on seaweeds occurring in Southeast Alaska is reviewed from a biogeographical perspective, and herbarium records for Southeast Alaska from the Alaska Seaweed Database project are used to provide an overview of the biogeography of the area. Records for the population centres of Ketchikan, Sitka and Juneau are compared with records from other areas within Alaska and with nearby regions to determine floristic similarities.

Results  Southeast Alaska has the most diverse seaweed flora of any region of Alaska. A list of species known to occur in Southeast Alaska is appended (in Supplementary Material) and includes their reported occurrences in three population centres (Juneau, Ketchikan and Sitka). Recognition of at least three distinct biogeographical areas associated with these three centres is supported by a comparison of their floras with those of other regions in the North Pacific. A close relationship of some species with conspecifics in the north‐west Atlantic is also noted. In contrast, ecological, physiological and genetic differentiation of Southeast Alaskan seaweeds from conspecifics in Washington State or even from different areas of Southeast Alaska are documented. A ShoreZone coastal habitat system, which is being implemented to inventory and map the entire shoreline of Southeast Alaska, is defining new biogeographical units called ‘bioareas’ on the basis of the distribution of canopy kelps and lower intertidal algal assemblages.

Main conclusions  Southeast Alaska has the most diverse seaweed flora of any region of Alaska. This is a reflection of its extensive coastline, with varied past and present environmental conditions. Different parts of Southeast Alaska show similarities to different areas outside Southeast Alaska. Despite this, much remains to be learned about the biogeography of seaweeds in Southeast Alaska, and many questions remain to be answered.
The evolution of H ii galaxies: testing the bursting scenario through the use of self-consistent models
Authors: Martín-Manjón M. L. , Mollá M. , Díaz A. I. , Terlevich R.
Published: February 2008

We have computed a series of realistic and self-consistent models of the emitted spectra of H ii galaxies. Our models combine different codes of chemical evolution, evolutionary population synthesis and photoionization. The emitted spectrum of H ii galaxies is reproduced by means of the photoionization code cloudy, using as ionizing spectrum the spectral energy distribution of the modelled H ii galaxy, which in turn is calculated according to a star formation history and a metallicity evolution given by a chemical evolution model that follows the abundances of 15 different elements. The contribution of emission lines to the broad-band colours is explicitly taken into account.

The results of our code are compared with photometric and spectroscopic data of H ii galaxies. Our technique reproduces observed diagnostic diagrams, abundances, equivalent width–colour and equivalent width–metallicity relations for local H ii galaxies.
Lentivirus Tau (P301S) expression in adult amyloid precursor protein (APP)‐transgenic mice leads to tangle formation
Authors: Osinde M. , Clavaguera F. , May‐Nass R. , Tolnay M. , Dev K. K.
Published: February 2008

Aims: In this study, we aimed to investigate the interaction between amyloid‐ and Tau‐associated pathologies to gain further insights into the development of Alzheimer's disease. We examined the formation of neurofibrillary tangles (NFT) in adult mouse brain without the prior overexpression of Tau at embryonic or early post‐natal stages to dissociate any developmental mechanisms. Methods: Lentivirus technology was used to examine the effects of overexpressing mutant Tau‐P301S in the adult mouse brains of both wild‐type and amyloid precursor protein (APP)‐transgenic mice. Results: We find that injection of lentivirus Tau‐P301S into the hippocampus of adult wild‐type mice increases levels of hyperphosphorylated Tau, as early as 3 months post injection. However, no NFT are found even after 13 months of Tau expression. In contrast, the overexpression of Tau‐P301S in adult APP‐transgenic animals results in the formation of Gallyas‐stained NFT. Conclusions: Our current findings are the first to show that overexpression of Tau‐P301S in adult mice overexpressing APP, but not wild‐type mice, leads to enhanced Tau‐related pathology.
An efficient stereological sampling approach for quantitative assessment of nerve regeneration
Authors: Canan S. , Bozkurt H. H. , Acar M. , Vlamings R. , Aktas A. , Sahin B. , Temel Y. , Kaplan Suleyman
Published: February 2008

Aims: The aim of the present study was to find the most efficient sampling strategy for stereological analysis of peripheral nerve, including the number of myelinated nerve fibres, axon cross‐sectional area and myelin sheet thicknesses of nerve fibres. Methods: Two groups of rats underwent experimental resection of the tibial and peroneal nerves. The first group received tibial‐peroneal end to end autograft repair (n = 6). Tibial and peroneal nerves were isolated, transected, and separated 1 cm distal to the trifurcation, where they lay adjacent to each other by a 1‐cm gap, then repaired with an autologous nerve graft taken from the tibial nerve. The proximal stump of the tibial nerve and distal stump of the peroneal nerve were connected to each other by means of the nerve graft. The second group received tibial‐peroneal repair with a flexible collagen tube (n = 6). After 90 days of recovery, animals were sacrificed and nerve segments were removed and sectioned for microscopy. Three different sampling strategies, that is, small, medium and large step sizes were applied to obtain each quantitative parameter. Results: There are no significant differences between these sampling strategies with respect to total number of myelinated nerve fibres, axon cross‐sectional area and myelin sheet thicknesses of nerve fibres. Conclusion: Findings show that one can achieve the desired estimate precisely with a rather large and less time‐consuming sampling approach. In addition, it was observed that the size discrepancy of nerve regeneration can be improved by collagen tube conduit even with a 1‐cm gap.
Appropriate Timing of CD40 Ligation for RNA‐Pulsed DCs to Induce Antitumor Immunity
Authors: Miura S. , Kagamu H. , Tanaka H. , Yoshizawa H. , Gejyo F.
Published: February 2008

Dendritic cell (DC) based anti‐cancer immunotherapy is believed to be a promising treatment. However, appropriate conditioning including the method of antigen loading and stimulation for DC maturation is still unclear. Total RNA pulsing is one of the most attractive methods to load antigen, since RNA is easily replicated by the PCR technique and is absolutely free of tumor cell contamination. On the other hand, CD40 ligation is capable of producing one of the most potent signals for immature DCs to start functional maturation, which is required to induce adaptive immunity, resulting in altered migration ability to secondary lymphoid organs and augmented antigen presenting activity. Here, we demonstrate that DCs pulsed with total RNA extracted from tumor cells required CD40 stimulation with an appropriate sequence to present tumor‐associated antigens. RNA derived antigens were presented for both CD4+ and CD8+ T cells in an antigen‐specific manner. Dendritic cells that were pulsed with RNA followed by the stimulation through CD40 successfully primed antitumor effector T cells in draining LNs and subsequently induced antitumor protective immunity.
Neutrophilic figurate erythema
Authors: Özdemir Mustafa , Engin Burhan , Toy Hatice , Demirkesen Cuyan
Published: February 2008

We herein report a 39‐year‐old woman presented with annular plaque with central clearing on the back, extremities, and breasts. The lesions had raised, firm erythematous borders included a trailing scale. On histologic examination, a perivascular inflammatory cell infiltrate composed of neutrophils and mononuclear inflammatory cells in the upper dermis was shown. We consider our case to represent idiopathic figurate erythema with a dominant infiltration of neutrophils.
Comparison of efficacy of azithromycin vs. doxycycline in the treatment of rosacea: a randomized open clinical trial
Authors: Akhyani Maryam , Ehsani Amir Houshang , Ghiasi Maryam , Jafari Alireza Keshtcar
Published: February 2008

Background  Rosacea is a common inflammatory disorder of the skin. Systemic antibiotics currently used in the treatment of rosacea are sometimes associated with uncomfortable side effects. Therefore, a need for an effective agent with few side effects and good patient compliance exists. Azithromycin, a macrolide antibiotic with prolonged mode of action, has recently been found to be an effective alternative in the treatment of inflammatory acne.

Methods  For evaluation of the efficacy of azithromycin in the treatment of rosacea, we planned a randomized, open, clinical trial study to compare the efficacy of azithromycin with doxycycline in the treatment of this disease. Sixty‐seven patients were randomized to receive either azithromycin 500 mg thrice weekly (on Monday, Wednesday, and Saturday) in the first, 250 mg thrice weekly (on Monday, Wednesday, and Saturday) in the second, and 250 mg twice weekly (on Tuesday, and Saturday) in the third month. The other group was given doxycycline 100 mg/day for the three months. Clinical assessment was made at baseline, at the end of first, second, third, and 2 months after treatment. Side affects were recorded. The limitation of this study is that there was no blindness.

Results  Statistically significant improvement was obtained with both drugs. Neither drug was shown to be more effective than the other. In the azithromycin group four patients had diarrhea, while epigastric burning was seen in two patients using doxycycline.

Conclusion  This study indicates that azithromycin is at least as effective as doxycycline in the treatment of rosacea.
Primary mucinous carcinoma of the skin: a population‐based study
Authors: Breiting Line , Christensen Lise , Dahlstrøm Karin , Breiting Vibeke , Winther Jeanette Falck
Published: February 2008

Background  Primary mucinous carcinoma of the skin (PMCS) is a rare malignant tumor deriving from the sweat glands. It is typically located on the head and is often mistaken for a metastasis from a more common primary tumor of the breast or gastrointestinal tract. We present the first population‐based study of PMCS.

Materials and Methods  Data on PMCS was obtained from the Danish Cancer Registry, which has recorded incident cases of cancer on a nationwide basis since 1943. We extracted all patients diagnosed 1978–2003 with PMCS.

Results  Fifteen cases of PMCS have been registered during the study period of 26 years, seven in men and eight in women. The patient was typically in his or her 60th or 70th decennium. Seven cases were found on the scalp or neck, five on the eyelids, two on the face, and one on the trunk. Only one recurred, and apart from one regional metastasis, no distant spread or PMCS related deaths were reported.

Conclusion  PMCS is a rare, slow‐growing tumor which rarely metastasizes and is associated with low mortality. The age‐standardized incidence rate, based on data from a population‐based cancer registry of high quality and validity, is less than 0.1 per million. However, the precise number may be higher, since PMCS is an indolent tumor, which may be mistaken for a benign tumor and thus not always examined histologically.
PRECLINICAL STUDY: Proteomic analysis of methamphetamine‐induced reinforcement processes within the mesolimbic dopamine system
Authors: Yang Moon Hee , Kim Seyoon , Jung Min‐Suk , Shim Jung Hee , Ryu Na Kyung , Yook Yeon Joo , Jang Choon‐Gon , Bahk Young Yil , Kim Kee‐Won , Park Jong Hoon
Published: February 2008

Methamphetamine (MAP) is a commonly used, addictive drug, and a powerful stimulant that dramatically affects the central nervous system. In this study, we used the conditioned place preference (CPP) paradigm in order to study the reinforcing properties of MAP and the herewith associated changes in proteins within the mesolimbic dopamine system. A CPP was induced by MAP after three intermittent intraperitoneal injections (1 mg/kg) in rats and protein profiles in the nucleus accumbens, striatum, prefrontal cortex, cingulate cortex and hippocampus were compared with a saline‐treated control group. In addition, a group of animals was run through extinction and protein profiles were compared with a non‐extinguished group. Protein screening was conducted using two‐dimensional electrophoresis analysis which identified 27 proteins in the group that showed MAP‐induced CPP. Some of the proteins were confirmed by Western lot analysis. Identified proteins had functions related to the cytoskeleton, transport/endocytosis or exocytosis (e.g. profilin‐2 and syntaxin‐binding protein), and signal transduction, among others.
A preliminary comparison of the prevalence of transfusion reactions in recipients of platelet components from donors with and without human leucocyte antigen antibodies
Authors: Fadeyi E. A. , Adams S. , Sheldon S. , Leitman S. F. , Wesley R. , Klein H. G. , Stroncek D. F.
Published: February 2008

Background  Human leucocyte antigen (HLA) antibodies have been implicated in transfusion‐related acute lung injury, but the probability that the transfusion of a blood component containing HLA antibodies will cause a reaction is not known. This study compared the prevalence of reactions associated with the transfusion of platelet components with and without HLA antibodies.

Study Design and Methods  This retrospective study tested 96 consecutive apheresis platelet donors for HLA class I and II antibodies. Matched control donors without HLA antibodies were selected and records were reviewed to determine the proportion of components from each group that caused reactions. In addition, all apheresis platelet donors involved with two or more reactions were identified and tested for HLA class I antibodies.

Results  Five of the 96 donors had antibodies to class I or class II antigens and, of these, four had components transfused. The prevalence of reactions to components from these four donors with HLA antibodies and the 12 matched control donors without antibodies was similar (three reactions to 167 transfusions or 1·8% vs. three to 295 or 1·0%, respectively, P = 0·32). A retrospective review of the transfusion records from all platelet donors found that components from 22 caused two or more reactions and three (13·6%) had antibodies to HLA class I compared to 4·2% of the consecutively selected donors (P = 0·12). None of the patients experienced transfusion‐related acute lung injury.

Conclusion  Reactions associated with transfusion of apheresis platelets containing HLA antibodies are unusual.
Signals, Motors, Morphogenesis ‐the Cytoskeleton in Plant Development1
Authors: Nick P.
Published: February 2008

Abstract: Plant shape can adapt to a changing environment. This requires a structure that (1) must be highly dynamic, (2) can respond to a range of signals, and (3) can control cellular morphogenesis. The cytoskeleton, microtubules, actin microfi‐laments, and cytoskeletal motors meets these requirements, and plants have evolved specific cytoskeletal arrays consisting of both microtubules and microfilaments that can link signal transduction to cellular morphogenesis: cortical microtubules, preprophase band, phragmoplast on the microtubular side, transvacuolar microfilament bundles, and phragmosome on the actin side. These cytoskeletal arrays are reviewed with special focus on the signal responses of higher plants. The signal‐triggered dynamic response of the cytoskeleton must be based on spatial cues that organize assembly and disassembly of tu‐bulin and actin. In this context the great morphogenetic potential of cytoskeletal motors is discussed. The review closes with an outlook on new methodological approaches to the problem of signal‐triggered morphogenesis.
N‐Ethylmaleimide Modifies the Conformation of the Plasma Membrane H+‐ATPase, Strengthening the Inhibitory Action of the C‐terminal Domain1
Authors: Locoro Biancamaria , Papini R. , Michelis Maria Ida De
Published: February 2008

Abstract: The effect of cysteine modification with N‐ethylmalei‐mide (NEM) on the activity of the plasma membrane (PM) H+‐ATPase and on its activation state was investigated in PM isolated from aged red beet parenchyma slices. Treatment of PM with increasing concentrations of NEM (0.1–1mM) drastically reduced H+‐ATPase activity. The inhibiting effect of PM treatment with NEM was stronger when the H+‐ATPase activity was assayed at pH values (7.1–7.2) higher than that optimal for enzyme activity (6.3). If the PM H+‐ATPase was activated by proteolytic cleavage of the C‐terminal domain or by its displacement by fusicoccin prior to NEM treatment, the inhibitory effect of NEM on the W‐ATPase activity became independent of the pH of the assay medium. Moreover, inhibition by NEM of H+‐ATPase activity also became independent of the pH of the assay medium if the C‐terminal was proteolytically cleaved or displaced by lysophosphatidylcholine after NEM treatment of the PM. Controlled trypsin treatment of NEM‐treated PM produced, beside the 90 kDa truncated PM H+‐ATPase, fragments of 60 to 30 kDa of the enzyme that were undetectable after trypsin treatment of control PM. These results indicate that PM treatment with NEM modifies the H+‐ATPase conformation, exposing trypsin cleavage sites scarcely accessible in control PM and strengthening the autoinhibitory action of the C‐terminal domain.
Reduction of mRNA Levels for the 28.5 kDa Iron‐Sulfur Core Protein of Mitochondrial Complex I Inhibits Pollen Maturation in Transgenic Tobacco
Authors: Schmidt‐Bleek Kathariria , Grohmann L. , Brennicke A.
Published: February 2008

Abstract: The multi‐subunit enzyme complex I of the mitochondrial respiratory chain is an assembly of nuclear and organ‐ellar encoded proteins with distinct roles and functions. The nuclear encoded 28.5 kDa iron‐sulfur protein is located at the centre of electron transfer to ubiquinone. Functional importance and regulatory tolerance of this subunit were investigated in transgenic tobacco plants carrying antisense constructs driven by the CaMV 35S promoter. In all of the regenerated transgenics vegetative growth is undisturbed, while in many transformants flower development is abnormal and pollen fertility is reduced. Maximal observed suppression of the steady‐state 28.5 kDa mRNA level reaches only about 30%. Apparently, further reduction is lethal to the vegetative tobacco plants, suggesting that the 28.5 kDa subunit is regulated from the steady‐state level onwards with little tolerance and no additional possibilities for compensation. This contrasts with the higher flexibility of the NADH‐binding subunit of complex I, which vegetatively survives a 70% reduction of its mRNA level.
A Garden Experiment on Susceptibility to Rabbit‐Grazing, Sapling Growth Rates, and Age at First Reproduction for Eleven European Woody Species
Authors: Grubb P. J. , Kollmann J. , Lee W. G.
Published: February 2008

Abstract: Eleven European shrub and tree species have been grown for 13 years in a randomized array (with 2 or 3 provenances for 5 of 11 species) in an experimental garden in southern England. A plague of rabbits in the second year damaged a greater proportion of plants in species with faster height growth, including those that are the commonest colonizers of pastures; most plants recovered rapidly. Apparently, resilience rather than resistance enables these plants to be invaders of abandoned grasslands. Among the shrubs there was little evidence of a trade‐off between initial rate of height growth and final height. The small tree Crataegus monogyna overtook the tallest shrub (Cornus sanguinea) in the 12th year. Among the shrubs, after 12 years, there was a trend for basal area to be greater in taller species; the trees had notably low basal area for their height. Most individuals of the shrub species reproduced before those of Crataegus and Sorbus aria (in 3–6 years rather than 5–13). Among the shrubs, the earliest to reproduce were fast‐growing (Rosa canina, then Ligustrum vuigare, Prunus spinosa and Rhamnus catharticus), but then species with a wide range of growth rates all reproduced at the same time (Euony‐mus europaeus, Juniperus communis and Viburnum opulus slow‐growing, Cornus sanguinea and V. lantana fast‐growing). The results are discussed in relation to theories of resource allocation, and the behaviour of the particular species in the field.
Influence of Microclimate on the Occurrence of Cyanobacteria in the Phyllosphere in a Premontane Rain Forest of Costa Rica
Authors: Freiberg Elke
Published: February 2008

Abstract: The occurrence of cyanobacteria in the phyllosphere of several understory plants was investigated during a one and a half year study in a primary premontane rain forest in Costa Rica. Altogether, seven species of epiphyllous cyanobacteria were identified and are discussed here. The ecology of the two most frequent species in the understory, Scytonema javanicum and Sc. hofmannii, was studied in further detail. Within the Understory, the relative abundance of these species, as well as of epiphyllous bryophytes, was more influenced by air humidity than by light. The humidity, characterized as potential evaporation, also had influence on the pseudosuccession of the phyllosphere vegetation. While at moist sites bryophytes and both species of Scytonema appeared nearly simultaneously on 6–9‐month‐old leaves, at dryer sites Sc. javanicum, and especially Sc. hofmannii, appeared 6–9 months after bryophytes had established. On 13–15‐month‐old leaves bryophytes and Scytoriema were usually well established. On average, 20–30% of the leaf area of 2–5‐year old leaves of Spathacanthus hoffmannii (Acan‐thaceae, an abundant understory shrub) were covered by bryophytes, 2–3% by Sc. javanicum, and 0.1–0.2% by Sc. hofmannhi. An influence of phorophyte species on the occurrence and abundance of these two species of Scytonema could not be detected. However, Sc. hofmannii was more frequent on leaves with higher bryophyte cover, while Sc. javanicum was independent from bryophytes. A comparison of leaves from the understory and from the canopy showed that the composition and abundance of cyanobacteria species changed with height above forest floor.
Concentration and Delivery of Abscisic Acid in Xylem Sap are Greater at the Shoot Base than at a Target Leaf Nearer to the Shoot Apex
Authors: Jokhan Anjeela D. , Harink R.J. , Jackson M. B.
Published: February 2008

Abstract: Samples of xylem sap from 5‐week‐old Ricinus corn‐munis L. were obtained after severing a lamina, or shoot, from plants pressurized at the roots with air to raise hydrostatic xylem water potentials to atmospheric. In situ sap flow gauges, and mass flow measurements, showed that removing the lamina approximately doubted sap flow rate through the petiole stub that remained attached to the plant. This was a consequence of flow out of the roots being diverted along this low‐resistance pathway and away from leaves higher in the canopy. Leaf and whole shoot excision temporarily released extra solutes in to sap as it discharged from the cut petiole or from the hypo‐cotyl stump. This contamination prevented the use of sap extracted from detached lamina by overpressurizing in a Scholan‐der bomb. To minimise distortions to sap flow and wound‐induced contamination, estimates of in planta concentration and delivery (concentration × sap flow rate) of ABA and osmolality in xylem sap were made using sap flow rates measured before excision and concentrations in flowing sap collected approximately 30 mm after excision. At this time, effects of excision on solute contamination had subsided. The approach revealed that withholding water from upper roots increased ABA delivery from roots into the shoot base 3‐fold. However, approximately half this ABA was lost en route to the youngest fully open leaf. This loss of ABA may explain the slow stomatal response to drying of upper roots shown by R. communis.
Adaptations to Flooding Stress: From Plant Community to Molecule
Authors: Blom C. W. P. M.
Published: February 2008

Abstract: This review highlights four major topics in plant flooding research: the processes underlying vegetation zonation in the floodplain, the challenges of using model species to reveal adaptive responses in shoots and roots, the role of micro‐organisms in flooded soils in relation to plant growth, and the molecular regulation of the hormone ethylene which is heavily involved in the adaptation reaction of flood‐resistant plants. Model species and vegetation strategies are used to unravel mechanisms of vegetation zonation in the river flood‐plain. In the case of woodlands, hydrological conditions determine to a large extent their zonation patterns under natural conditions. For softwood species, such as Salicaceae, the interaction between water levels and timing of seed dispersal is the dominating process determining their establishment success on river banks. Their strategy is well adapted to irregular, high and prolonged floods. Hardwood species, Quercus, Fraxinus, UImus and Acer, are flood‐sensitive and inhabit the higher sites. They mainly have heavy seeds and germinate under shaded conditions. The most shade‐tolerant hardwood species are the least well adapted to flooding. Anthropogenically influenced parts of the floodplain are characterized by grasslands with elevation level and management practices determining the species composition. Low‐lying grasslands have flood‐tolerant species; elevated zones are seldom flooded and have flooding‐sensitive species. Following Grime (1998[59]), plant species of major vegetation types within the floodplain zone can be divided into three categories–dominants, subordinates and transients–illustrating the diversity in plant species in relation to environmental properties. Model species that are indicative of the different conditions in the various zones are chosen to help in the understanding of morphological and physiological adaptations at the plant level. The formation of aerenchymatous roots and the capacity to elongate shoot parts upon submergence are among the main responses of surviving plants. The role of hormones in the adaptation reaction is emphasized. Owing to high porosities in roots of flood‐tolerant plants, radial oxygen loss greatly influences nitrification and denitrification processes in the flooded soil. Nutrient cycles are restored by root‐derived oxygen and the oxygenated rhizosphere is detoxified. A new development in flooding ecology is the unravelling of the molecular regulation of hormonally controlled processes. The expression of an ethylene receptor gene in Rumex palustris is highlighted. This paper ends with some suggestions for future flooding research.
Formation of Aerenchyma and the Processes of Plant Ventilation in Relation to Soil Flooding and Submergence
Authors: Jackson M. B. , Armstrong W.
Published: February 2008

Abstract: Enhanced development of gas‐spaces beyond that due to the partial cell separation normally found in ground parenchymas and their derivatives creates tissue commonly termed “aerenchyma”. Aerenchyma can substantially reduce internal impedance to transport of oxygen, nitrogen and various metabolically generated gases such as carbon dioxide and ethylene, especially between roots and shoots. Such transport lessens the risk of asphyxiation under soil flooding or more complete plant submergence, and promotes radial oxygen loss from roots leading to oxidative detoxification of the rhizo‐sphere. Aerenchyma can also increase methane loss from waterlogged sediments via plants to the atmosphere. This review of the formation and functioning of aerenchyma particularly emphasises research findings since 1992 and highlights prospects for the future. Regarding formation, attention is drawn to how little is known of the regulation and processes that create schizogenous aerenchyma with its complex cell arrangements and differential cell to cell adhesion. More progress has been made in understanding lysigenous aerenchyma development. The review highlights recent work on the processes that sense oxygen deficiency and ethylene signals, subsequent transduction processes which initiate cell death, and steps in protoplast and wall degeneration that create the intercellular voids. Similarities between the programmed cell death and its causes in animals and the predictable patterns of cell death that create lysigenous aerenchyma are explored. Recent findings concerning function are addressed in terms of the diffusion aeration of roots, rhizosphere oxygenation and sediment biogeochemistry, photosynthesis and ventilation, pressurised gas‐flows and greenhouse gas emissions and aspects of ventilation related to secondary thickening.
Structural Features Underlying Hardseededness in Geraniaceae
Authors: Meisert A. , Schulz D. , Lehmann H.
Published: February 2008

Abstract: The proportion of hard Geraniaceae seeds ranges from 0 to 100%, depending on species. By analysing the characteristics of hardseededness through the pathway of water uptake in soft seeds provided localization of the chalazal area in water uptake. This represents the most important feature of seed coat permeability. The structural difference between hard‐and softseededness was clarified by comparing different species with exclusively permeable or impermeable seeds. Soft seeds form a wide opening at the chalazal slit, while hard ones close the slit using adjacent palisade cells so effectively continuing the impermeable barrier.
Phylogenetic Relationships within Paxillus s. I. (Basidiomycetes, Boletales): Separation of a Southern Hemisphere Genus
Authors: Bresinsky A. , Jarosch Margit , Fischer M. , Schönberger Ines , Wittmann‐Bresinsky Birgit
Published: February 2008

Abstract: This study aimed to test the monophyly and present a generic concept of Paxillus s. I. Of special interest were the Southern hemisphere representatives of this genus. Using the primer combination LR0R‐LR5, DNA sequence data were generated from the nuclear encoded 28S gene. A data set containing 900 bases was created for 30 different species. Phylogenetic analysis showed 3 main monophyletic groups, also supported by morphological, anatomical, ecological and chemical data. Taxonomic interpretation of these clearly differentiated groups corresponded to the genera PaxilIus s. str. and Tapinella and lead to the proposal of a new Southern hemisphere genus, Austro‐paxillus, mycorrhizal with Nothofagus. New combinations are proposed.
Nectar Dynamics and Sugar Composition in Flowers of Silene and Saponaria Species (Caryophyllaceae)
Authors: Witt Taina , Jürgens A. , Geyer R. , Gottsberger G.
Published: February 2008

Abstract: Nectar production in Saponaria officincilis and in five species of Silene (S. ciba, S. dioica, S. noctiflora, S. nutans, S. vulgaris) was examined during two consecutive years (May to July 1993, and May to June 1994) in the Botanical Garden of the University of Giessen. Nectar volume and sugar concentration were studied in relation to time of day, flower sex, flower age, and flowering stage. Nectar amount in all species studied (except S. dioica) increased in the afternoon or in the evening until midnight (or until the early morning in S. nutans). After midnight and until midday, nectar volume in non‐visited flowers (except S. dioica) decreased. Nectar volume in non‐visited S. dioica flowers increased constantly with flower age, indicating a stable nectar secretion rate, possibly favouring both day‐ and night‐active flower visitors. Even at the time of highest nectar secretion, all species studied presented several nectarless flowers. Sucrose dominance in the nectar of the nocturnal species S. nutans and Saponaria officinalis fits well with the general syndrome of flowers pollinated by hawkmoths. The syndrome also applies to the nocturnal but regularly selfing, S. noctiflora. The more generalis‐tic species S. dioica and S. vulgaris, which are regularly visited by bumblebees as well as nocturnal moths, secreted hexose‐domi‐nant nectar. Unexpectedly, Silene alba, the only nocturnal species that strictly excluded day‐active flower visitors by closing flowers during the day, also secreted hexose‐dominant nectar. In some cases, nectar volumes and nectar concentration differed significantly between hermaphroditic, male, and female flowers. Female flowers of S. alba, S. dioica, and S. nutans contained significantly less concentrated nectar than male or hermaphroditic (S. nutans) ones. In S. noctifiora and S. vulgaris the difference was not statistically significant but nectar concentration did show the same tendency.
The Shape of the Female Fitness Curve for Cynoglossum officinale: Quantifying Seed Dispersal and Seedling Survival in the Field
Authors: Rademaker MariëIle C. J. , de Jong T. J.
Published: February 2008

Abstract: When hermaphroditic plants shift their sex allocation to produce more seeds and less pollen, it is frequently assumed that the female component of fitness is strictly proportional to the number of seeds produced. However, if producing more seeds results in more competition between seedlings, the female fitness gain curve levels off with high investments in seeds. The shape of this curve is relevant for sex allocation theory, but rarely have data been collected. For Cynoglossum officinale we described the relationship between the number of seeds produced on the mother plant and the number and weight of seedlings in September of the following year. As expected, around large plants of C. officinale more seedlings were retrieved after the germination period in March. The seedlings of large plants were dispersed over an area similar to that of small plants. As a result, seedlings around large plants had a significantly higher chance to have a neighbouring sibling within one dm2. Survival and growth of single or grouped (density > 2) seedlings did not differ significantly. As a result, total dry weight of seedlings in September was a linear function of the number of seeds on the parent plant. Our data indicate a linear female fitness gain curve.
The Forgotten Component of Plant Water Potential
Authors: Canny M. J.
Published: February 2008

Abstract: Experts in plant water relations are challenged to explain why the standard expression for the water potential of an intact, transpiring leaf omits one of the pressure components, namely the tissue pressure of the living leaf cells. Two questions are posed: A) Is there a reason for omitting this component? B) If not, what evidence exists that it may be ignored? When this component contributes significantly, the water potential cannot be interpreted in the accustomed way as measuring tension in the xylem sap.
The Forgotten Component of Plant Water Potential: A Reply ‐ Tissue Pressures are not Additive in the Way M. J. Canny Suggests
Authors: Tyree M. T.
Published: February 2008

Abstract: Martin Canny's concepts of “tissue pressure” and its derivative “compensating pressure” are reviewed. Tissue pressure arises when the volume change of some living cells exerts a pressure on adjacent living or dead cells. Contrary to previous assertions, tissue pressure cannot cause a permanent change in pressure potential or water potential of adjacent cells. Tissue pressure induces only a transitory increase of pressure and water potential. After equilibrium is reestablished, the same or a more negative pressure or water potential results. The idea that tissue pressure can prevent or repair xylem embolism is without merit.
CPTA Modulates Levels of Carotenogenic Proteins and their mRNAs and Affects Carotenoid and ABA Content as well as Chromoplast Structure in Narcissus pseudonarcissus Flowers
Authors: Al‐Babili S. , Hartung W. , Kleinig H. , Beyer P.
Published: February 2008

Abstract: To investigate mechanisms leading to enhanced carotenoid formation, daffodil (Narcissus pseudonarcissus) flowers were treated with the lycopene cyclase (LYC) inhibitor CPTA. Under these conditions, chromoplasts underwent strong morphological changes and the lycopene accumulated was found sequestered in crystals. During this process the total carotenoid content increased about 2‐fold. This increase was accompanied by an upregulation of the transcript levels of phytoene synthase (PSY), phytoene desaturase (PDS) and lycopene cyclase (LYC). In contrast, η‐carotene desaturase (ZDS) was not a target for CPTA‐induced upregulation, although its product lycopene was accumulated. At the protein level, CPTA induction of carotenogenic enzymes was also observed, again with the exception of ZDS. Lycopene accumulation, caused by CPTA treatment, was also accompanied by a decrease of β‐carotene derivatives, especially zeaxanthin. Our data suggest that carotenoid biosynthesis may undergo an end‐product regulation via an effector probably originating from a β‐carotene derivative. Increased concentrations of abscisic acid (ABA) measured after CPTA treatment may be involved in this regulatory phenomenon, pointing to the presence of an additional xanthophyll‐independent source of this phytohormone.
Carbon Costs Associated with N2 Fixation in Vicia faba L and Pisum sativum 1. over a 14‐Day Period
Authors: Schuize J. , Adgo E. , Merbach W.
Published: February 2008

Abstract: Long‐term (14 days) carbon costs of N2 fixation were studied in pot trials. For this purpose the CO2 release from the root space of nodulated and non‐nodulated (urea nourished) Vicia faba L. and Pisum sativum L. plants was compared and related to the amount of fixed or assimilated N. Additional measurements of shoot CO2 exchange and dry matter increment were carried out in order to calculate the overall carbon balance. The carbon costs for N2 fixation in Vicia faba 1. (2.87 mg C/mg NfiX) were higher than in Pisum sativum L. (2.03 mg C/mg Nfix). However, the better carbon efficiency in Pisum sativum 1. did not lead to a better growth performance compared to Vicia faba L. Vicia faba L. compensated for the carbon and energy expenditure by more intensive photosynthesis in the N2‐fixing treatment. This was not the case with Pisum sativum L., where the carbon balance indicates that the carbon costs of N2 fixation restricted root growth. It is proposed that low carbon costs for N2 fixation indicate an adaptation to a critical carbon supply of roots and nodules, e.g., during the pod‐filling of grain legumes.
Cloning and Characterization of Cystathionine γ‐Synthase from Solanum tuberosum L.1
Authors: Riedel K. , Mangelsdorf C. , Streber W. , Willmitzer L. , Höfgen R. , Hesse H.
Published: February 2008

Abstract: The first step of methionine biosynthesis in higher plants, the condensation of O‐phosphohomoserine and L‐cys‐teine forming the thioether cystathionine, is catalyzed by the enzyme cystathionine γ‐synthase (CgS). We have isolated a cDNA encoding CgS from a leaf Λ ZAP Il‐library of Solanum tuberosum L. The nucleotide and deduced amino acid sequence showed homology to the other CgS sequences from Arabidopsis thalianc., Zea mays, Mesembryanthemum crystailinum and Frogar‐ia vesca. The truncated cDNA without putative leader peptide, when cloned into a bacterial expression vector, complemented the E. coil metBi mutant strain LE392. Enzyme activity of the potato CgS and E. coil metB were comparable in the auxotrophic background. Transcript levels of CgS in different tissues of potato plants were determined by Northern blot analysis. Expression was found in all tissues with elevated levels in flowers and source leaves. The pattern of gene expression during a day!mei night period implied light‐dependent control of CgS transcription typical for enzymes localized in plastids. The expression of CgS was shown to be light‐inducible.
Phylogenetic Analysis of the C‐Terminal Sequence of rbcL1
Authors: Wildner G. F. , Schlitter J. , Stützel T.
Published: February 2008

Abstract: At the C‐terminal end of Rubisco's large subunit major differences in sequence length and in charges of the amino acid residues occur in unicellular organisms and in plants. This C‐terminal segment of the large subunit participates in large movements during the catalytic cycle. It participates in the closing mechanism of the binding niche for the substrate RuBP, changing from an ordered structure in the “open” enzyme conformation to a position, stretched over the protein surface, in a “closed” conformation. We analyzed the sequence variability in the C terminus in rbcL to investigate whether this structurally important entity evolved in an ordered process. Cyanobacteria and chlorophytes show similar C‐terminal sequences (DXX), whereby D‐473 is the last strictly conserved amino acid residue for all rbcLs. Contrary to the gymnosperms (D + 2 residues), the C termini of the angiosperms show variable lengths from D + 2 to D + 17 residues. The plant orders of Asterales, Batales, Cap‐parales, Caryophyllales, Fabales, Gentianales, Lamiales, Ru‐biales, Myrtales, Scrophulariales, and Solanales contain species with particularly elongated C termini. Recent studies regarding enzyme kinetics demonstrated that molecules with longer C termini are better adapted for a wider temperature range. We speculate that longer C termini confer properties to the enzyme that modulate the success of different species in different environments. This is supported by the fact that “modern” (e.g., phylogenetically young taxa in an actual radiation process) generally display a long C terminus, while conservative taxa have a relatively short C terminus.
Reflectance Measurements of Glossy Petals of Ranunculus lingua (Ranunculaceae) and of Non‐Glossy Petals of Heliopsis helianthoides (Asteraceae)
Authors: Galsterer Sabine , Musso M. , Asenbaum A. , Fürnkranz D.
Published: February 2008

Abstract: A spectrophotometric comparison of the reflectance of glossy petals of Ranunculus lingua (Ranunculaceae) and non‐glossy petals of Heliopsis helianthoides (Asteraceae) was made in relation to the angle of incidence of the incoming light. Additionally, the reflectance of petals of R. flammula, R. acris and R. repens (Ranunculaceae) was measured for comparative purposes. In the examined Ranunculus species, gloss is present around mirror geometry over the whole spectral range measured, including the UV region where it accentuates the UV peak, and even at the basal UV‐absorbing area of the petals. According to a colour hexagon evaluation of the reflectance data, these gloss phenomena diminish the colour contrast of the petal against the background. Nevertheless, due to their brightness, they may serve as an attractant or predictor for pollinators and other visiting insects, possibly acting as a beacon while approaching the flower. The position of the reflectance maximum in the UV around 340 nm is in accordance with the sensitivity maximum of the UV photoreceptor of potential pollinators like Apidae. The mean reflectance values of the four examined Ranunculus species do not show any clear correlation with their anatomical make‐up
Allozyme Diversity and Interspecific Differentiation o the Two Diploid Bromegrass Species, Bromus tectorum L. and B. sterilis L (Poaceae)
Authors: Oja Tatjana
Published: February 2008

Abstract: Genetic diversity among 50 accessions of Bromus tectorum and 43 of B. sterilis from different sites of their Eurasian ranges has been studied by electrophoretic analysis of ten enzymes encoded by 18 loci. The two species proved clearly differentiated by alternate allozymes at seven isozymes. Populations of both taxa showed differentiation into eleven (B. tectorum) and six (B. sterilis) multilocus allozyme lineages (MLALs). The extent of interspecific allozyme divergence estimated by Manhattan distance exceeded more than three times intraspecific differentiation between the multilocus lineages. Only two MLALs in each species have wide geographical distribution from the Near East to Europe. Other MLAL5 were found each for only one or two populations and were region‐specific. Most geographically marginal European populations had widespread MLALs.
Speciation and Phylogenetic Distances within Paxillus s. str. (Basidiomycetes, Boletales)
Authors: Jarosch Margit , Bresinsky A.
Published: February 2008

Abstract: This study aimed to elucidate the phylogenetic relationships within Paxillus 5. str. Collections of the Paxillus involu‐tus complex from different habitats have been compared. DNA sequence data were generated from the nuclear encoded 28S gene and the ITS region. Phylogenetic analyses of the two data sets showed three clearly differentiated groups within Paxillus s. str. Collections from gardens and park areas under Betula, Cory‐lus, Populus, Quercus and Tub showed to have a very close relationship to the North American species Paxillus vernalis, but are separated from P. involutus collections found in forests as well as from P. filamentosus. Possible taxonomic conclusions are discussed.
Expansins in Plant Growth and Development: an Update on an Emerging Topic
Authors: McQueen‐Mason S. J. , Rochange F.
Published: February 2008

Abstract: Expansins are a class of proteins identified by their ability to induce the extension of isolated plant cell walls. Expansins are encoded by an extensive multigene family in higher plants, several members of which have been shown to be expressed in a tissue‐specific manner. Besides playing an apparently key role in wall expansion, and hence in cell growth, expansins have been implicated in an increasing number of processes during plant growth and development. These include: leaf organogenesis, fruit softening, and wall disassembly. A second class of closely related proteins (referred to as β‐expansins) has been identified. Other recent advances in expansin research include the recovery of transgenic plants with altered level of expansins, and the production of recombinant expansins in het‐erologous expression systems.
Actin‐Binding Proteins in Plant Cells
Authors: de Ruijter N. C. A. , Emons A. M. C.
Published: February 2008

Abstract: Actinoccurs in all plant cells, as monomers, filaments and filament assemblies. In interphase, actin filaments form a cortical network, co‐align with cortical microtubules, and extend throughout the cytoplasm functioning in cytoplasmic streaming. During mitosis, they co‐align with microtubules in the preprophase band and phragmoplast and are indispensa ble for cell division. Actin filaments continually polymerise and depolymerise from a pool of monomers, and signal transduction pathways affecting cell morphogenesis modify the actin cytoskeleton. The interactions of actin monomers and filaments with actin‐binding proteins (ABP5) control actin dynamics. By binding to actin monomers, ABPs, such as profilin, regulate the pool of monomers available for polymerisation. By breaking filaments or capping filament ends, ABPs, such as actin depoly‐merising factor (ADF), prevent actin filament elongation or loss of monomers from filament ends. By bivalent cross‐linking to actin filaments, ABPs, such as fimbrin and other members of the spectrin family, produce a variety of higher order assemblies, from bundles to networks. The motor protein ABPs,. which are not covered in this review, move organelles along ac tin filaments. The large variety of ABPs share a number of functional modules. A plant representative of ABPs with particular modules, and therefore particular functions, is treated in this review.