bluuebunny/crossref_metadata_2025 huggingface dataset:
Complete Genome Sequence of Bacillus amyloliquefaciens TA208, a Strain for Industrial Production of Guanosine and Ribavirin
Authors: Zhang Guoqiang , Deng Aihua , Xu Qingyang , Liang Yong , Chen Ning , Wen Tingyi
Published: April 2011

Here, we report the complete genome sequence of
Bacillus amyloliquefaciens
TA208, a strain for industrial production of guanosine and synthesis of ribavirin by assimilation of formamide. Comparison of its genome sequence with those of strains DSM7 and FZB42 revealed horizontal gene transfer represented by unique prophages and restriction-modification systems and indicated significant accumulation of guanosine.
The Sensor Kinase KinB Regulates Virulence in Acute Pseudomonas aeruginosa Infection
Authors: Chand Nikhilesh S. , Lee Jenny See-Wai , Clatworthy Anne E. , Golas Aaron J. , Smith Roger S. , Hung Deborah T.
Published: April 2011

Two-component sensors are widely used by bacteria to sense and respond to the environment.
Pseudomonas aeruginosa
has one of the largest sets of two-component sensors known in bacteria, which likely contributes to its unique ability to adapt to multiple environments, including the human host. Several of these two-component sensors, such as GacS and RetS, have been shown to play roles in virulence in rodent infection models. However, the role and function of the majority of these two-component sensors remain unknown.
Danio rerio
is a recently characterized model host for pathogenesis-related studies that is amenable to higher-throughput analysis than mammalian models. Using zebrafish embryos as a model host, we have systematically tested the role of 60 two-component sensors and identified 6 sensors that are required for
P. aeruginosa
virulence. We found that KinB is required for acute infection in zebrafish embryos and regulates a number of virulence-associated phenotypes, including quorum sensing, biofilm formation, and motility. Its regulation of these phenotypes is independent of its kinase activity and its known response regulator AlgB, suggesting that it does not fit the canonical two-component sensor-response regulator model.
The use of CellaVision competency software for external quality assessment and continuing professional development
Authors: Horiuchi Yuki , Tabe Yoko , Idei Mayumi , Bengtsson Hans-Inge , Ishii Kiyoshi , Horii Takashi , Miyake Kazunori , Satoh Naotake , Miida Takashi , Ohsaka Akimichi
Published: April 2011

Aims

Quality assessment of blood cell morphological testing, such as white blood cell (WBC) differential and its interpretation, is one of the most important and difficult assignments in haematology laboratories. A monthly survey was performed to assess the possible role of the proficiency testing program produced by CellaVision competency software (CCS) in external quality assessment (EQA) of the clinical laboratories of affiliated university hospitals and the effective utilisation of this program in continuing professional development (CPD).

Methods

Four monthly proficiency surveys were conducted in collaboration with four clinical laboratories affiliated with the teaching hospitals of Juntendo University of Medicine in Japan.

Results

EQA results by the CCS proficiency testing program revealed a difference of performance levels of WBC differential and morphological interpretation and a discrepancy in the WBC differential criteria among laboratories. With regard to the utilisation of this proficiency program as a tool for CPD, this program successfully improved the performance of the low-scoring laboratories and less experienced individuals.

Conclusions

The CCS proficiency testing program was useful for the quality assessment of laboratory performance, for education, and for the storage and distribution of cell images to be utilised for further standardisation and education.
To feel what others feel: two episodes from 18th century medicine
Authors: Justman Stewart
Published: April 2011

In the late 18th century two medical fashions—Mesmerism in France and the Perkins ‘tractor’ in the USA and England—appealed to the principle that a single universal force acts on all of us and is responsible for health and illness. This principle served both fashions well, as it made it all the easier for those who came within their force fields to experience the sort of sensations that other subscribers to the fashion also seemed to feel. The first research on what is now known as the placebo effect was in connection with these two movements. The propensity to feel what we suppose or imagine that others like us feel remains even now one of the channels of the placebo effect.
A climatology of cloud chemistry for the eastern United States derived from the mountain cloud chemistry project
Authors: Mohnen Volker A. , Vong Richard J.
Published: April 2011

The chemical composition of clouds collected in the eastern United States has been intensely monitored over a 4-year period as part of the Mountain Cloud Chemistry Project. On the basis of these measurements we prepared a climatology for cloud chemistry, using simple statistical analyses tools and incorporating meteorological and cloud physical and chemical information. Five mountain stations have been established for cloud collection covering the northern and southern Appalachian Mountain range: Whiteface Mountain, New York; Mount Moosilauke, New Hampshire; Shenandoah Mountain, Virginia; Whitetop Mountain, Virginia; and Mount Mitchell, North Carolina. This review presents the major result from this 4-year measurement program. Cloud cover and cloud base over the eastern United States were deduced from the global real-time nephanalysis archives produced by the U.S. Air Force, augmented by local observations. Both active and passive cloud collectors were deployed to sample cloud water on an hourly basis, i.e., with sufficient time resolution to resolve synoptic scale phenomena. Chemical analysis of cloud water was performed by a central analytical laboratory with occasional on-site analysis to satisfy quality control procedures. Reliable methods now exist for collecting cloud-water samples in sufficient quantities for detailed chemical analysis. The chemical composition of cloud water varied significantly between sites. However, the differences in cloud-water ion concentration do not necessarily establish a geographic gradient between the sites but rather reflect differences in air-mass trajectories associated with the synoptic air-flow pattern and differences in sample location above cloud base. The dependence of cloud-water ion concentrations on synoptic weather type and observed differences in relative frequencies of warm sector, marine flow, and post-cold frontal synoptic types between northern and southern sites suggest that the north–south differences in cloud-water ion concentrations are related to cloud climatology at the northern sites. When air-mass trajectories shift from southwest to northwest, the concentrations of H+, SO42−, NO3− and NH4+ normally decrease but the southern sites continue to receive high concentrations under northwest flow. The height of cloud-water sample collection above cloud base was found to be an additional source of variability in both cloud-water chemistry and liquid-water content. Seasonal variation in cloud-water chemical composition was investigated at one site only. Sulfate levels were found to be significantly lower in supercooled clouds (i.e., during the 'cold' season) than in 'warm' clouds, but nitrate levels remained about the same.Key words: cloud chemistry, cloud frequency, air-mass trajectories, ANOVA.
The toxicity of petroleum oils to birds
Authors: Leighton Frederick A.
Published: April 2011

Mortality of aquatic birds occurs regularly as a consequence of spills of petroleum oils. There are three different ways in which such oils can affect birds. (i) External contamination of feathers is the most common form of exposure, and the effect of oils on feathers is the single most devastating effect of oil on birds. Feathers absorb oil, become matted, and lose the critical properties of water repellency, insulation, and flight. Death results from combinations of hypothermia, starvation, and drowning. (ii) Avian embryos are highly sensitive to oil that contaminates the egg shell; amounts as little as 1–10 μL are lethal to embryos during the first half of incubation. (iii) Birds ingest oil when preening oiled plumage or ingesting oiled nutrients. At least three toxic effects of ingested oil are well documented: a nonspecific response as a stressor that is additive or synergistic with those of other stressors, impairments in reproduction ranging from lowered fertility to abandonment of reproductive effort, and severe oxidant damage to red blood cells. The effect of oil pollution on bird populations is very difficult to document and is likely to remain uncertain because of the many ecological factors that may occur in association with an oil-spill event.Key words: oil, petroleum, pollution, bird, toxicity, poison.
Bioaccumulation and toxicology of nickel: implications for wild mammals and birds
Authors: Outridge P. M. , Scheuhammer A. M.
Published: April 2011

The tissues of wild mammals and birds from uncontaminated environments generally contain from ~0.1 to 5 μg nickel∙g dry weight−1, whereas in Ni-polluted environments, tissues accumulate from -0.5 to 10 (mammals) and -0.5 to 80 (birds) μg nickel∙g dry weight−1. The highest concentrations in these ranges are usually associated with tissues directly exposed to the external environment (fur, feathers, skin). Bone frequently contains higher Ni concentrations than other internal tissues. Ni concentrations in the most commonly analysed internal organs (liver, kidneys) range from nondetectable to about 3 μg∙g dry weight−1, the kidneys often containing higher concentrations than the liver. There is some evidence that birds may tend to accumulate higher Ni burdens in polluted habitats than do mammals. For mammals, reduced growth and survival occur in response to chronic exposure to 500–2500 μg Ni∙g diet−1 (10–50 mg∙kg body weight−1∙d−1). Effects on reproduction and essential trace metal (especially iron) metabolism have been reported at levels as low as 5 μg∙g−1 in food or drinking water (0.2–0.4 mg∙kg body weight−1∙d−1), but these findings have not always been corroborated. Toxicological data on birds are more limited than those pertaining to mammals. Newly hatched chickens suffered reduced growth rates when fed ≥300 μg∙g diet−1, and chicks began to die when fed diets containing ≥500 μg∙g−1. In newly hatched mallard ducklings, chronic exposure to ≥800 μg∙g diet−1 resulted in ataxia, tremors, and significant mortality, whereas adult mallards fed 800 μg∙g−1 showed no evidence of systemic or reproductive toxicity. Tissue concentrations of Ni were not reliable indicators of potential toxicity in either mammals or birds, because significant effects, including mortality, frequently occurred in the absence of elevated tissue Ni concentrations. However, when there is evidence of elevated tissue Ni concentrations (>10 μg∙g−1 in the kidneys, and (or) >3 μg∙g−1 dry weight in the liver), Ni exposure sufficient to cause significant toxic effects should be suspected. Nickel has been reported in aquatic macrophytes and lower plants (but not in invertebrates or zooplankton) in the vicinity of Ni smelters in Canada in concentrations that approach or exceed dietary levels known to cause adverse effects in young animals. Sensitive species of wildlife ingesting this vegetation for considerable periods of time could experience Ni-related toxicity. In addition, wildlife food chains involving aquatic organisms (plants, invertebrates, fish) risk alterations in community structure in Ni-contaminated environments as Ni-sensitive taxa are eliminated or their abundance is reduced.Key words: nickel, toxicology, wildlife.
Insect population responses to environmental stress and pollutants
Authors: Pimentel David
Published: April 2011

Insects and other related arthropods make up about 90% of all plant and animal species in the world. They are vital to the functioning of the ecosystem and biosphere, and neither of these systems can operate effectively without insect interactions. Because of their major ecological and economic roles in nature and society, the beneficial and pest activities of insects need to be clearly understood. Insect populations are being stressed directly by the action of temperature, moisture, and a wide array of chemical Ö öpollutants (pesticides, fertilizers, air pollutants, and numerous other chemicals) that are dispersed through air, water, and soil. Insects are affected by this same group of stresses indirectly, through their food plants, parasites, and predators. Depending on the species and the particular stress affecting it, insect populations respond by increasing or decreasing in numbers. The responses of insect populations to various direct and indirect environmental stresses and chemical pollutants are assessed. Some insect populations increase, while others decline. The responses were determined by the particular environmental stress, the insect species, and the stage at which they were exposed to the stress.Key words: insects, environment, pollutants, stress, water, herbicides.
A cladistic analysis of the Old World species of Lotus L. (Fabaceae: Loteae)
Authors: Arambarri Ana M
Published: April 2011

The diagnostic characters of the genus Lotus L. are a claw with a thickened infolded margin, diadelphous stamens, and a style hardened from the base. This genus contains about 100 species that are distributed throughout the world. To investigate the phylogeny of the Old World species of Lotus, subgenus Edentolotus, sections Krokeria, Xantholotus, and Erythrolotus, a cladistic analysis was performed using 31 morphological characters. To test the phylogenetic relationships among species of Lotus-Edentolotus and Dorycnium, Pedrosia, and Tetragonolobus, these taxa were included as part of the ingroup. The polarity of the characters was based on the outgroup comparison method, using Anthyllis as one outgroup and Tripodion as another. The analysis with Anthyllis as outgroup yielded eight equally parsimonious trees (with all characters equally weighted), each with 62 steps, a consistency index of 0.53, and a retention index of 0.75. All trees (including the strict consensus tree from the eight initial trees) showed that genus Lotus, subgenus Edentolotus, and sections Xantholotus and Erythrolotus are polyphyletic, with only section Krokeria appearing as monophyletic. On the other hand, the groups of species Lotus angustissimus, Lotus corniculatus, Lotus creticus, and Lotus peregrinus are monophyletic. Identical results were derived from the data matrix using Tripodion as the outgroup. Results are compared with previous cytogenetic and biochemical evidence.Key words: cladistic analysis, Fabaceae, Loteae, Lotus, Old World species, phylogeny.
The effects of recreation disturbance on subalpine seed banks in the Rocky Mountains of Montana
Authors: Zabinski Catherine , Wojtowicz Todd , Cole David
Published: April 2011

We investigated the soil seed bank in a subalpine ecosystem with patchy disturbance from camping. Soil cores were collected from three site types, heavily impacted, lightly impacted, and undisturbed, that differed in area of bare ground and depth of surface organic matter. We hypothesized that the density and composition of the seed bank would vary with depth of surface organic matter and distance from established vegetation. Seedling emergence was determined in the greenhouse. Seed density was significantly lower on disturbed sites, averaging 441 seeds/m2 on heavily impacted sites, 1495 seeds/m2 on lightly impacted sites, and 4188 seeds/m2 on undisturbed sites. Seed density declined exponentially with distance from established vegetation and increased with depth of surface organic matter. The number of species present did not vary across site types, but 10 species that occurred on lightly impacted and undisturbed sites were not present on heavily impacted sites. We concluded that disturbance that causes removal of surface organic matter can affect natural revegetation by lowering the density of propagules and affecting the species represented in the seed bank.Key words: seed bank, subalpine, patchy disturbance, recreation impacts.
Molecular forms and kinetic properties of phosphoenolpyruvate carboxylase from barnyard grass (Echinochloa crus-galli(L.) Beauv.: Poaceae)
Authors: Hamel Nathalie , Simon Jean-Pierre
Published: April 2011

The thermal, kinetic, and electrophoretic properties of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) were analyzed in plants from two ecotypes of barnyard grass (Echinochloa crus-galli (L.) Beauv.: Poaceae) originated from sites of contrasting climates in Quebec (QUE) and Mississippi (MISS). The thermostability, cold inactivation, the apparent energy of activation (Ea), the Michaelis-Menten constant (Km), and Vmax/Kmratios for phosphoenolpyruvate (PEP) and Mg2+were analyzed with desalted Sephadex G-25 crude PEPC extracts, with partially purified PEPC from the polyethylene glycol (PEG) 13% fraction and with purified PEPC obtained after elution from DEAE-Sepharose affinity chromatography. PEPC from illuminated leaves from both ecotypes consisted of one isomorph with the same electrophoretic mobility in polyacrylamide gels, similar molecular masses for the native enzyme (400 kDa) and for each subunit of the tetramer (100 kDa), and a same isoelectric point (pI) of 4.95. The only kinetic property for PEPC for which differences of physiological importance among ecotypes were observed at the three levels of purification was Kmfor PEP for which values for QUE plants were significantly lower at low assay temperatures. Differences among ecotypes for thermostability were only observed in assays with crude and partially purified PEPC extracts, while no differences were found for cold inactivation rates, Km(Mg2+) estimates at any level of purification or for Vmax/Kmratios (PEP or Mg2+) from purified PEPC. Significant differences among the two ecotypes were found for catalytic constant (Kcat) estimates obtained with purified PEPC. However, results show higher catalytic efficiency for PEPC from MISS plants at high assay temperatures but no indication of an improved catalytic efficiency for PEPC from QUE plants at low assay temperatures. The lack of ecotypic differences for most thermal and kinetic properties observed with purified PEPC casts doubts about the evolutionary interpretations of results obtained in previous kinetic comparative analyses, which were based on crude or partially purified enzymatic preparations of PEPC extracted from E. crus-galli plants.Key words: phosphoenolpyruvate carboxylase, enzyme kinetics, thermal adaptation, barnyard grass, electrophoresis, Echinochloa crus-galli.
Evidence for environmental determination of uredinia and telia production in Chrysomyxa pirolata (inland spruce cone rust)
Authors: Crane Patricia E , Hiratsuka Yasuyuki
Published: April 2011

Chrysomyxa pirolata Wint., the cause of inland spruce cone rust, is a serious pathogen in natural spruce forests and seed orchards. Cone infection is caused by basidiospores produced by telia on alternate hosts in the genera Pyrola, Moneses, and Orthilia. The disease cycle of this rust and the influence of moisture on the differentiation of telia on Pyrola asarifolia Michx. were studied over two growing seasons at a wet site adjacent to a spruce seed orchard and a drier site adjacent to another orchard at Smoky Lake, Alberta, and at Edmonton and Hinton, Alberta. The proportion of uredinia to telia varied with microsite conditions, with more frequent production of telia in moist sites. The effect of moisture on formation of telia was tested by subjecting infected plants with immature sori to 90-100% relative humidity under various temperature and light conditions. Plants under high humidity, regardless of other conditions, formed mainly telia from immature sori, even if uredinia had already formed on parts of the leaves before the experiments. Telia formation, however, was much slower at 4-6°C than at 22°C. Cross-sections of sori showed that young uredinia could sometimes convert to telia. Results of a field experiment also suggested that increasing moisture increases the percentage of telia produced on plants. The production of undifferentiated sori that can become either uredinia or telia in response to environmental conditions may allow the fungus to maximize vegetative proliferation when conditions are unfavorable for sexual reproduction. It might also explain the large variation in cone rust levels from year to year in a given location.Key words: Picea, Pyrola, telia induction, seed orchard, Uredinales.
Floral nectary structure and nectar chemical composition of some species from Robinson Crusoe Island (Chile)
Authors: Bernardello Gabriel , Galetto Leonardo , Anderson Gregory J
Published: April 2011

Floral nectary structure and nectar composition of 12 species, including 11 endemics, are reported from Robinson Crusoe Island (Juan Fernández Archipelago, Chile). These species are mostly hummingbird pollinated. Nectary morphology follows the general pattern within each of the families, suggesting it is an ancestral feature. The mean nectar concentration (± SD) as a percentage of weight (weight/total weight of solution) was 28.3 ± 20.7. Sucrose, fructose, and glucose were identified in most samples. In Nicotiana cordifolia, an unknown monosaccharide was also detected. When more than one sample per species was examined, there was usually variability in sugar ratios. Statistical tests indicated that population size does not influence this variability. However, there were differences when the pollinator type was compared, with a trend of a higher sucrose proportion and a lower coefficient of variation of sucrose in the species pollinated by hummingbirds. This would indicate a specialization in the nectar composition of the hummingbird-pollinated species. Cuminia eriantha, N. cordifolia, and Rhaphithamnus venustus also possess amino acids in their nectar. In the non-hummingbird-pollinated species, the presence of nectaries and nectar serves as an indication of the ancestral pollination system of the first colonizers rather than the current condition, which is wind pollination or self-compatibility for most of the species. Thus, the presence of nectar in flowers does not necessarily indicate extant biotic pollination.Key words: angiosperms, Robinson Crusoe Island, nectary structure, nectar sugar composition, sugar concentration, hummingbird pollination.
Cell wall differentiation during early somatic embryogenesis in plants. II. Ultrastructural study and pectin immunolocalization on chicory embryos
Authors: Chapman Audrey , Blervacq Anne-Sophie , Hendriks Théo , Slomianny Christian , Vasseur Jacques , Hilbert Jean-Louis
Published: April 2011

In Cichorium hybrid clone 474 (C. intybus L. var. sativum × C. endivia L. var. latifolia), direct somatic embryogenesis was induced from roots. Using transmission electron microscopy, we followed the ultrastructural changes of the outer cell wall in relation to embryo developmental stage. During the transition from an embryogenic cell to a somatic embryo, the differentiation of the outer cell wall involved both deposition and rearrangement processes. During the first divisions, the cell wall of few-celled embryos still enclosed in the root tissue appeared as a large amorphous layer of cellulose, thicker than the cell walls of the root cortex cells. When the proembryo emerged from the root cells, the outer wall surface exhibited a fibrillar material designated as the supraembryonic network. As this network disappeared, the outer cell wall changed organization, and two domains were distinguished. At the torpedo stage, the outer cell wall was more compact without any gaps and the protoderm was differentiated. Immunolocalization of an epitope recognised by JIM5 antibody revealed the unesterified nature of the supraembryonic network. Such pectins were also located at the outer third of the outer cell wall of protodermal cells as well as in the intercellular spaces. Highly methylesterified pectins recognized by JIM7 antibodies were slightly present in the cell walls during the embryogenesis process. The different stages of the outer cell wall differentiation as well as the development of the transient supraembryonic network are described, and its possible roles in somatic embryogenesis are proposed.Key words: cell differentiation, cell wall, Cichorium (chicory), pectin, somatic embryogenesis, transmission electron microscopy.
Canadian Society of Plant Physiologists Gold Medal Review / Synthèse médaillée d'or de la Société canadienne physiologie végétaleThe fascinating world of folate and one-carbon metabolism
Authors: Cossins Edwin A
Published: April 2011

Folate was first isolated from spinach leaves in 1941 and characterized as pteroylglutamic acid. Although plants, fungi, and bacteria synthesize folate de novo, animal cells lack key enzymes of the folate biosynthetic pathway and a dietary source of folate is required for normal growth and development. Folates have importance in human nutrition, health, and disease, and antifolate drugs are commonly used in cancer chemotherapy. In the majority of living cells folates occur as one-carbon substituted tetrahydropteroylpolyglutamate derivatives. These folates donate one-carbon groups during the synthesis of purines, formylmethionyl-tRNA, thymidylate, serine, and methionine. In the last 30 years, research on the folate biochemistry of plant species has intensified and been aided by the development of improved methods for folate isolation and characterization. These studies have resulted in basic information on the nature of plant folylpolyglutamates, folate biosynthesis, the enzymology of several folate-dependent reactions, and the roles of chloroplasts, mitochondria, and the cytosol in the pathways of one-carbon metabolism.Key words: plants, folates, folate biosynthesis, folate-dependent enzymes, one-carbon metabolism.
A neotype for Drepanophycus spinaeformis Göppert 1852
Authors: Li Cheng-Sen , Hueber F M , Hotton C L
Published: April 2011

The species Drepanophycus spinaeformis Göppert 1852 was described as a fossil plant closely allied with the fucoid algae. Many years later the type, a single figured specimen, was lost along with its associated collection. Subsequent studies described and assigned additional fossils to the species and redefined it as a land plant, a lycopsid. Through all of the descriptions and assignments of specimens to the species, no single specimen was designated as the type to bear the name in the absence of a holotype. The purpose of this paper is to designate a specimen as the neotype, the bearer of the name, and to emend the taxonomic description of the species.Key words: Drepanophycus, neotype, lycopsid, cauline sporangia, Lower Devonian, Canada.
Spatial distribution and succession of epiphytes on Tsuga heterophylla (western hemlock) in an old-growth Douglas-fir forest
Authors: Lyons Betsy , Nadkarni Nalini M , North Malcolm P
Published: April 2011

We examined the distribution and abundance of nonvascular epiphytes on western hemlock trees in an old-growth coniferous forest focusing on patterns of epiphyte distribution at different spatial scales, epiphyte abundance amongst trees differing in size, and crown structures associated with epiphyte abundance. Total epiphyte cover was greatest in four canopy microhabitats: the upper canopy strata, crowns of large trees, lower crown branches, and inner branch plots. Epiphyte functional groups were stratified vertically within the stand and horizontally within branches. Alectorioid and "other" lichens were most abundant in the upper canopy and outer branch plots. Cyanolichens and Sphaerophorus globosus (Huds.) Vain. were most abundant in the lower to mid canopy. Although cyanolichens were most abundant in middle branch plots, Sphaerophorus was most abundant in inner branch plots. Bryophytes were most abundant in the lower canopy and inner branch plots. At the stand level, canopy height and tree size were the main influences on epiphytes. Within trees, plots closer to the tree trunk and lower in the crown had the greatest abundance of epiphytes. In this forest, understory trees were colonized first by bryophytes, not by alectorioid and "other" lichens as is common for small trees in young stands.Key words: epiphyte succession, lichens, western hemlock, old growth, forest canopy, crown structure.
Molecular forms and thermal and kinetic properties of purified glutathione reductase from two populations of barnyard grass (Echinochloa crus-galli(L.) Beauv.: Poaceae) from contrasting climatic regions in North America
Authors: Hakam Nadia , Simon Jean-Pierre
Published: April 2011

The thermal, kinetic, and electrophoretic properties of purified glutathione reductase (GR; EC 1.6.4.2) were analyzed in plants from two ecotypes of barnyard grass (Echinochloa crus-galli (L.) Beauv.: Poaceae) originating from sites of contrasting climates in Quebec (QUE) and Mississippi (MISS). Crude and purified GR preparations from plants of both ecotypes consisted of one homodimer isomorph with the same electrophoretic mobility in polyacrylamide gels, a similar molecular mass for the native enzyme (98 kDa) and for each subunit of the dimer (44 kDa), and an identical pI of 5.9. The electrophoretic profile of GR purified from cold-acclimated plants at 14°C light (L) : 8°C dark (D) for 10 days was similar to that of GR from plants grown at 26°C L : 20°C D. Specific activities of purified GR from QUE plants were significantly higher than those of MISS plants. In vitro GR activities from QUE and MISS plants were not differentially affected by thermodenaturation at 55 or 65°C or by cold treatments at 2°C. Apparent energies of activation (Ea) of GR purified from QUE and MISS plants were similar with the exception of estimates of Ea(oxidized glutathione) for Q10(15-5°C) for which significantly lower values were obtained for QUE plants. No differences of physiological significance were observed for Km(Michaelis-Menten constant) values of GR purified from QUE and MISS plants. However, both Vmaxand Kcat(turnover numbers) estimates were significantly higher for GR purified from QUE plants over most of the range of assay temperatures, suggesting superior catalytic efficiency for the enzyme of the cold-adapted ecotype from Québec.Key words: barnyard grass, ecotypes, electrophoresis, enzyme kinetics, glutathione reductase, thermal adaptation.
Floral development and structure of Davidsonia (Cunoniaceae)
Authors: Moody Michael , Hufford Larry
Published: April 2011

Few data on floral development and morphology are available for the monotypic Australian genus Davidsonia. New data on floral form and development are presented for Davidsonia, and comparisons are made to allied clades. Phylogenetic analysis allies Davidsonia with core Cunoniaceae. Flower maturation on each branch of the cauliflorous inflorescences is basipetal, beginning with the terminal flower. Flowers are hypogynous, radially symmetrical, and have a uniseriate perianth that consists of a campanulate calyx. Davidsonia has been traditionally allied with Cunoniaceae, and it shares various basic floral attributes, especially gynoecial states, with some members of this family. The bicarpellate gynoecium of Davidsonia has an ovary that is completely synorganized and biloculate, two separate styles that have prominent ventral commissures, and terminal, papillate stigmas. Davidsonia differs most from core Cunoniaceae in androecial morphology, including the development of the androecium and the form of stamens. The stamens of Davidsonia display a mosaic of states present among members of Oxalidales (including Cephalotaceae, Cunoniaceae, Elaeocarpaceae, and Tremandraceae) in which the genus is nested. Although Davidsonia shares various floral states with Cunoniaceae, it can best be perceived as displaying a mosaic of features that occur more broadly among Oxalidales.Key words: Cunoniaceae, Davidsonia, flower development, morphology, Oxalidales.
Caractérisation des types cellulaires cladomophore et pleuridiophore chez la rhodophycée céramiacée Antithamnion plumula : apport de l'analyse des cinétiques de croissance
Authors: Buis Roger , L'Hardy-Halos Marie-Thérèse , Lambert Cécile
Published: April 2011

The analysis of the elongation kinetics of the cladomophoric and pleuridiophoric cell types in Antithamnion plumula (Ellis) Thuret was carried out using a bilogistic model (the sum of two nonsynchronous generalized logistics). The growth structure or discretization of the growth pattern into a series of phases Gi, defined by the paired values, absolute speed (V) - acceleration (Γ), was inferred. The growth structure was qualitatively similar in the two cell types {G1, G2, G1, G2, G3, G4} although, quantitatively, clear differences appeared. The pleuridiophores were distinguished from the cladomophores by the greater importance of the first phases G1 and G2 (i.e., increasing, then decreasing positive acceleration, respectively). Likewise, during these two phases, the specific growth rate, R, was significantly higher in the pleuridiophores. According to the cell type, there are thus, independently of possible differences in size, differential properties of a strictly kinetic order in the elongation process. These data mean that at the beginning of their growth, the pleuridiophoric cells are in a "juvenile" condition, whereas the cladomophoric cells are relatively in a more "mature" state. A biological interpretation is put forward.Key words: Rhodophyceae, Antithamnion, cell growth, growth kinetics, logistic model, morphogenesis.
Occurrence of Piloderma fallax in young, rotation-age, and old-growth stands of Douglas-fir (Pseudotsuga menziesii) in the Cascade Range of Oregon, U.S.A.
Authors: Smith J E , Molina R , Huso M MP , Larsen M J
Published: April 2011

Yellow mycelia and cords of Piloderma fallax (Lib.) Stalp. were more frequently observed in old-growth stands than in younger managed stands of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Piloderma fallax frequency and percent cover data were collected from 900 plots in three replicate stands in each of three forest age classes over 2 years in both spring and fall. Piloderma fallax is strongly associated with stand age; it occurred in 57% of plots in old-growth, 6% of rotation-age, and 1% of young stands. Presence of Piloderma fallax was related to the percent cover of coarse woody debris (CWD) in decay class 5. Piloderma fallax was approximately 2.5 times more likely to occur in a plot with CWD decay class 5 present than in plots without. The probability that it would occur in a plot increased by approximately 20% for every 10% increase in percent cover of CWD decay class 5. However, the percent cover of Piloderma fallax was not strongly related to the percent cover of CWD in decay class 5. Frequency of occurrence did not differ among sampling times. Occurrence of Piloderma fallax may indicate suitable substrate for ectomycorrhizal fungi associated with CWD and may be important in forest management for the maintenance of biodiversity and old-growth components in young managed stands.Key words: Piloderma fallax, coarse woody debris, Pseudotsuga menziesii, forest management, ectomycorrhizal fungi, biodiversity.
Low genetic diversity at allozyme loci inJuglans cinerea
Authors: Morin Ricardo , Beaulieu Jean , Deslauriers Marie , Daoust Gaëtan , Bousquet Jean
Published: April 2011

Butternut (Juglans cinerea L.) is a minor component of the temperate deciduous forest region of northeastern North America, but it is severely affected by the butternut canker (Sirococcus clavigignenti-juglandacearum Nair, Kostichka, and Kuntz) in the southern part of its natural range. Genetic diversity and population structure in as-yet unaffected or only slightly affected natural populations were evaluated at 12 isozyme loci. The genetic diversity estimates were low with values much below those estimated in other species of the same genus or in boreal tree species, with 25 and 13.9% polymorphic loci at the species and population levels, respectively; 1.3 and 2.3 alleles per locus and per polymorphic locus, respectively, at the species level; and an average observed heterozygosity of 0.028. Population differentiation was low, with the exception of one unique population. The implications for advanced conservation are discussed.Key words: butternut, isozymes, Sirococcus, canker, population structure.
Germination and survival of tree species in disturbed forests of the highlands of Chiapas, Mexico
Authors: Camacho-Cruz Angélica , González-Espinosa Mario , Wolf Jan H.D , De Jong Bernardus HJ
Published: April 2011

Germination and seedling survival of native tree species were studied in nursery (June-November 1998) and forest stands with varying dominance by pines in the central highlands of Chiapas (Mexico; June 1998 - November 1999). Species used are regarded as typical of mid- and late-successional habitats: Cornus disciflora Sessé & Mociño ex DC., Cornus excelsa H.B.K., Drimys granadensis L.f. var. mexicana (DC.) A.C. Smith, Liquidambar styraciflua L., Persea americana L., Quercus laurina H. & B., and Ternstroemia lineata (DC.) ssp. chalicophyla (Loesener) Bartholomew. Nursery treatments included presence and composition of litter collected from replicated plots of three forest types: old-growth forest, mixed pine-oak forest, and pine-dominated forest. Germination and seedling emergence of P. americana in the nursery were complete for all factor combinations. Cornus disciflora and L. styraciflua showed highest germination (p < 0.05) when sown in soil from old-growth forest and covered with litter of oak-broad-leaved species. In the field, differences (p < 0.05) among forest types (degree of pine dominance) were observed for C. disciflora (lowest germination in pinelands, 17%), D. granadensis (highest survival in old-growth forest, 23%), and Q. laurina (higher survival in pinelands, 54%). Natural recruitment and survival of seedlings were higher in old-growth forests. We conclude that oak litter may favor germination and early establishment of the studied species. However, the reintroduction of some of the studied species (C. excelsa, Q. laurina, and T. lineata) may be attempted with direct sowing on the forest floor of severely disturbed and species-poor pinelands.Key words: Cornus, Liquidambar, litter, Persea, Pinus, Quercus, seedling establishment, seeds.
Scleroconidioma, a new genus of dematiaceous Hyphomycetes
Authors: Tsuneda A , Thormann M N , Currah R S
Published: April 2011

Scleroconidioma sphagnicola gen.nov. et sp.nov. (Hyphomycetes) is described from necrotic patches of Sphagnum fuscum (Schimp.) Klinggr. found in a bog in Alberta, Canada. In the leaves of the host and in culture the fungus forms minute dematiaceous stromata. Hyaline, bacilliform conidia are extruded in succession from papillate conidiogenous cells that develop on the stroma surface. Hyaline bacilliform conidia, as well as a more variable and pigmented conidial type, also arise from short conidiogenous cells or directly from vegetative hyphae in culture. Discrete tufts of white, setiform hyphae also form on agar media and constitute an additional distinctive feature of the new taxon.Key words: taxonomy, mitosporic fungi, stromata, conidiogenesis, Sphagnum.
Species differentiation of North American spruce (Picea) based on morphological and anatomical characteristics of needles
Authors: Weng Chengyu , Jackson Stephen T
Published: April 2011

Differentiation of most North American spruce (Picea) species can be done based on needle morphology and anatomy. Picea breweriana S. Watson, Picea chihuahuana Martìnez, Picea mariana (Mill.) BSP, Picea martinezii Patterson, and Picea rubens Sarg. needles have two continuous resin ducts extending from near the base to near the tip. Picea engelmannii Parry ex Engelm., Picea glauca (Moench) Voss, Picea pungens Engelm., Picea mexicana Martìnez, and Picea sitchensis (Bong.) Carr. needles have variable numbers of short, intermittent resin ducts or sacs. Within each of these groups, most species could be differentiated based on cross-sectional shape, resin-duct diameter, and resin-duct position. Picea mariana and P. rubens, and P. glauca and P. engelmannii are two pairs with similar needles, but they can be differentiated using linear discriminant analysis based on resin-duct diameter and position in cross section. Paleoecological and paleoclimatological studies may be facilitated by species-level identification of plant macrofossils because of different ecological adaptations of each species. Resin-duct continuity patterns are generally consistent with current taxonomic classifications, except for P. glauca. Based on our results, together with DNA and crossing studies, P. glauca is apparently more closely related to P. engelmannii and P. sitchensis than to P. rubens and P. mariana, with which it is often classified. Picea pungens is probably more distantly related to P. engelmannii than has been assumed in some previous classifications. Picea martinezii and P. chihuahuana may be very closely related to each other.Key words: spruce, Picea, North America, needle, resin duct, anatomy.
Genotypic diversity and clone size in old-growth populations of coast redwood (Sequoia sempervirens)
Authors: Rogers Deborah L
Published: April 2011

Coast redwood (Sequoia sempervirens (D. Don) Endl.) has long-lived individual trees that can reproduce both sexually and asexually. Allozyme markers indicate that, in old-growth populations in northern California, 15-34% of clones are multistemmed. Of those, they have few stems per clone, and none are very spatially pervasive. There is much variety in the clonal configurations observed, including circular, linear, and (or) disjunct arrangements. Visual assessment is a poor predictor of clonal identity and fairy ring structures more often than not contain multiple genotypes. In this first allozyme study of coast redwood, high levels of genetic variation are observed, higher than those observed for most other western conifers. These levels are perhaps related to the species' hexaploid condition, ancient phylogenetic lineage, and historically broader natural range. There are also generally high levels of genotypic diversity. Upland sites, with more frequent and intense fires, do not differ significantly in genotypic diversity from the more mesic lowland sites. Population structure in coast redwood seems to resemble the classic pattern for many open-pollinated conifers: much diversity within and little among populations. However, this is not a rangewide study. The current levels and structure of genetic and genotypic diversity in old-growth populations suggests episodic recruitment. The long-lived nature of individual stems and the capacity for asexual reproduction may allow clones to exist indefinitely, thus challenging some of the generalizations in evolutionary theory that are based on sexually reproducing species.Key words: clones, asexual reproduction, allozyme diversity, conifer, gymnosperm, polyploid.
Conditions de germination et rôle des herbivores dans la dispersion et le recrutement d'une espèce clonale : Juncus gerardi Lois.
Authors: Amiaud Bernard , Bonis Anne , Bouzillé Jan-Bernard
Published: April 2011

The finding of new individuals of a clonal plant, Juncus gerardi, raised the question of modalities for the colonization of new sites by this species. Indeed, the existence of seedlings has not been observed in the field, nor reported in the literature for European marshes. Among the parameters limiting recruitment, we examined the soil seed bank, which appeared extremely small. Many seeds could be found in bovine feces but few were found in equine feces. Futhermore, bovines are not only important for seed dispersion, but also for the improvement of the germinative capacities: the seed germination rate of Juncus gerardi was doubled after digestive transit. Germination testing showed that this species is largely tolerant to salinity (from 0 to 26,4 mS·cm-1). The germination rate was maximal with a thermoperiod of 10-20°C but null for a 0-10°C thermoperiod. Germination was improved by immersion and was light dependent. The critical phase for colonization success in new habitats could be primarily seedling survival. Recruitment success in Juncus gerardi seems to be a rare event, requiring the combination of favorable conditions related to climate and gap openings in swards.Key words: germinative capacities, feces, clonal plant, grazers, endozoochory, pastures.
Sensitivity to, and accumulation of, cadmium in Betula pendula, Picea abies, and Pinus sylvestris seedlings from different regions in Sweden
Authors: Österås Ann Helén , Ekvall Lars , Greger Maria
Published: April 2011

This study compared the sensitivity to, and uptake and distribution of, cadmium (Cd) in three tree species, Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and European white birch (Betula pendula Roth), as well as different populations of these species. Seedlings of each species from three regions (southern, central, and northern parts of Sweden) were cultivated in nutrient solution and treated with varying concentrations of Cd. Sensitivity was determined by using the Weibull function on root and shoot dry weight and root length measurements. Cd uptake and translocation were analysed. The results on root sensitivity revealed that birch and spruce were the least and most sensitive species, respectively, to both the external and tissue levels of Cd. In terms of shoot sensitivity, however, birch was the only species affected by Cd, i.e., the most sensitive species. Pine and birch had similar Cd uptake, while spruce had lower uptake and translocation of Cd compared with the others. There were also differences in sensitivity within the species. The central ecotype of all species tended to be the most Cd resistant. The central ecotype of spruce and birch had the lowest Cd uptake, whereas the central ecotype of spruce and pine had the lowest translocation of Cd to the shoot.Key words: birch, cadmium, pine, sensitivity, spruce, uptake.
Evolutionary analysis of subsection Magnicellulatae of Podosphaera section Sphaerotheca (Erysiphales) based on the rDNA internal transcribed spacer sequences with special reference to host plants
Authors: Hirata Tetsuya , Cunnington James H , Paksiri Urailak , Limkaisang Saranya , Shishkoff Nina , Grigaliunaite Banga , Sato Yukio , Takamatsu Susumu
Published: April 2011

To understand the evolutionary history of subsection Magnicellulatae of Podosphaera section Sphaerotheca, nucleotide sequences of the rDNA internal transcribed spacer region were determined for 79 isolates from 60 host species. With the exception of two species occurring on the Scrophulariaceae, all isolates formed a large, well-defined clade. Genetic diversity among species on the Scrophulariaceae was much larger than the diversity among all other taxa, and the first split of the Magnicellulatae clade was shared by these species. This suggests that the Scrophulariaceae is the earliest host of subsection Magnicellulatae. Isolates from the Asteraceae shared the largest sequence diversity and were represented in all major groups. Most members of the basal groups consisted of isolates from the Asteraceae. This suggests that an early radiation in the large clade occurred on the Asteraceae. Based on the small sequence diversity and placement at the terminal end of the phylogenetic tree of isolates from the Cucurbitaceae and the Fabaceae, it is suggested that the ability of subsection Magnicellulatae to infect these families was acquired more recently. The groupings of fungal taxa by molecular phylogeny showed general agreement with groupings by infectivity, which suggests niche separation caused by host specialization triggers genetic divergence in these fungi.Key words: Ascomycetes, Erysiphaceae, host range, phylogeny, Podosphaera, Sphaerotheca.