bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuous Blood Purification Ameliorates RhoA-Mediated Endothelial Permeability in Severe Acute Pancreatitis Patients with Lung Injury
Authors: Du Xiao-Gang , Chen Xue-Mei , Gan Hua , Li Zheng-Rong , Wen Yu-Jun , Wang Xi-Chao
Published: April 2011

Background

In the early phase of severe acute pancreatitis (SAP), serious pulmonary complications which are directly correlated with mortality are very common. Endothelial injury has been shown to play a key role in the pathogenesis of ALI/ARDS. Continuous blood purification (CBP) has been widely used in treating patients with multiple organ dysfunction syndrome (MODS) including ARDS. However, the impact of CBP on endothelial function has been little studied.

Methods

Human umbilical vein endothelial cells (HUVECs) were exposed to serum samples or replacement fluid taken from patients at specific time points during CBP, or pretreated with Y-27632 followed by treatment with serum, then, changes in cytoskeletal configuration, endothelial monolayer permeability, and RhoA activation were studied.

Results

Endothelial permeability, RhoA activity, and stress fiber reorganization increased in HUVECs treated with serum from patients before CBP initiation, and lessened in HUVECs treated with serum from patients after CBP initiation. Endothelial hyperpermeability and stress fiber reorganization reduced in HUVECs pretreated with Rho-kinase inhibitor, Y-27632, and in a dose-dependent fashion. Endothelial permeability and RhoA activity increased in HUVECs treated with waste replacement fluid collected 2 h after CBP initiation.

Conclusions

After CBP treatment, endothelial hyperpermeability induced by serum from SAP patients with lung injury was reduced. The inhibition of RhoA-mediated F-actin remodeling might be the mechanism.
Differences in Chemical Composition and Internal Structure Influence Systemic Host Response to Implants of Biomaterials
Authors: Scaglione Silvia , Cilli Michele , Fiorini Mauro , Quarto Rodolfo , Pennesi Giuseppina
Published: April 2011

In reconstructive surgery, implantable devices are used to supply a missing function. In tissue engineering, biomaterials serve to guide and eventually deliver cells and/or molecules where a tissue regenerative response is needed. The host organism always reacts to implants of any biomaterial, in some instances even triggering a local cascade of events called the foreign body response (FBR), whose mechanisms are well defined. What has yet to be completely unraveled are the biomarkers systemically mirroring the FBR and the regeneration processes, which would be helpful for assessing the therapeutic efficacy of the bioscaffold. Our goal was to identify a biomarker fingerprint of the systemic reaction of host response to bioscaffold implants.

Different biomaterials chosen for their osteoconductive properties, including collagen, hydroxyapatite, in foam or granules, and poly-ɛ-caprolactone, were implanted in immunocompetent mice. We analyzed serum concentrations of cells and cytokines involved in the inflammatory/immune response, and the histological features of grafts.

Within two weeks after implantation, a wave of proinflammatory cytokines was flowing in the blood stream and the concentration of blood cells changed, revealing specific patterns depending on the chemistry and structure of the implanted biomaterials. Cells secreting pro-inflammatory, chemoactractant, and pro-angiogenic cytokines required for the early events in tissue repair were locally recruited because of the presence of a bioscaffold.
Generalized Homogeneity of Means
Authors: Pałys Małgorzata , Sablik Maciej
Published: April 2011

We extend the classical notions of translativity and homogeneity of means to -homogeneity, that is, invariance with respect to an operation
We find the shape of for the arithmetic weighted mean and then the general form of
for quasi-linear means. Also, we are interested in characterizations of means. It turns out that no quasi-arithmetic mean can be characterized by -homogeneity with respect to a single operation
, one needs to take two of such operations in order to characterize a mean.
The Association of Tree Pollen Concentration Peaks and Allergy Medication Sales in New York City: 2003–2008
Authors: Sheffield Perry E. , Weinberger Kate R. , Ito Kazuhiko , Matte Thomas D. , Mathes Robert W. , Robinson Guy S. , Kinney Patrick L.
Published: April 2011

The impact of pollen exposure on population allergic illness is poorly characterized. We explore the association of tree pollen and over-the-counter daily allergy medication sales in the New York City metropolitan area. Dates of peak tree pollen (maple, oak, and birch) concentrations were identified from 2003 to 2008. Daily allergy medication sales reported to the city health department were analyzed as a function of the same-day and lagged tree pollen peak indicators, adjusting for season, year, temperature, and day of week. Significant associations were found between tree pollen peaks and allergy medication sales, with the strongest association at 2-day lag (excess sales of 28.7% (95% CI: 17.4–41.2) over the average sales during the study period). The cumulative effect over the 7-day period on and after the tree pollen peak dates was estimated to be 141.1% (95% CI: 79.4–224.1). In conclusion, tree pollen concentration peaks were followed by large increases in over-the-counter allergy medication sales.
Linear and Angular Distyrylpyrazines with Terminal Donor Groups: Synthesis, Solvatochromism, and Acidochromism of the Electronic Spectra
Authors: Schmitt Volker , Fischer Janina , Detert Heiner
Published: April 2011

A series of linear and angular distyrylpyrazines and lateral donor groups has been prepared by aldol condensation between dimethylpyrazines and the appropriate aromatic aldehyde. The optical absorption and emission properties of these systems were studied in different solvents and media. The materials display a strong solvatochromism of the emission that is reflected by large red shifts of their fluorescence emission maxima on increasing the solvent polarity. This behaviour suggests a highly polar emitting state, which is characteristic of compounds that undergo an internal charge transfer upon excitation. Upon protonation, the UV-vis spectra are altered, and the fluorescence intensity of the neutral compound vanishes. These molecules can be used as colorimetric and luminescence polarity and pH sensors.
Orthotropic Models of Corrugated Sheets in Finite Element Analysis
Authors: Wennberg David , Wennhage Per , Stichel Sebastian
Published: April 2011

To reduce computational effort of finite element (FE) calculations a corrugated sheet is replaced with an orthotropic plate. Analytical expressions for the mechanical properties are studied and compared to finite Element calculations in extension, free vibration, and buckling. Good similarity is shown in the stiffened and transverse direction of the corrugated sheet; however, the orthotropic models do not give an accurate twisting behavior. The stiffened direction of the corrugated sheet best matches the analytical expressions. Keeping in mind the presented limitation, the orthotropic model presented herein can be used to drastically reduce the number of elements needed when modelling corrugated sheet with finite elements.
Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries
Authors: Ainsworth C. H. , Samhouri J. F. , Busch D. S. , Cheung W. W. L. , Dunne J. , Okey T. A.
Published: April 2011

Ainsworth, C. H., Samhouri, J. F., Busch, D. S., Cheung, W. W. L., Dunne, J., and Okey, T. A. 2011. Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries. – ICES Journal of Marine Science, 68: 1217–1229. Although there has been considerable research on the impacts of individual changes in water temperature, carbonate chemistry, and other variables on species, cumulative impacts of these effects have rarely been studied. Here, we simulate changes in (i) primary productivity, (ii) species range shifts, (iii) zooplankton community size structure, (iv) ocean acidification, and (v) ocean deoxygenation both individually and together using five Ecopath with Ecosim models of the northeast Pacific Ocean. We used a standardized method to represent climate effects that relied on time-series forcing functions: annual multipliers of species productivity. We focused on changes in fisheries landings, biomass, and ecosystem characteristics (diversity and trophic indices). Fisheries landings generally declined in response to cumulative effects and often to a greater degree than would have been predicted based on individual climate effects, indicating possible synergies. Total biomass of fished and unfished functional groups displayed a decline, though unfished groups were affected less negatively. Some functional groups (e.g. pelagic and demersal invertebrates) were predicted to respond favourably under cumulative effects in some regions. The challenge of predicting climate change impacts must be met if we are to adapt and manage rapidly changing marine ecosystems in the 21st century.
Massilia flava sp. nov., isolated from soil
Authors: Wang Jiewei , Zhang Jianli , Pang Huancheng , Zhang Yabo , Li Yuyi , Fan Jinping
Published: April 2011

A Gram-stain-negative, rod-shaped bacterium, designated strain Y9T, was isolated from a soil sample collected in Ningxia Province in China and was characterized to determine its taxonomic position. Strain Y9T contained Q-8 as the predominant ubiquinone. Major fatty acid components were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) and C16 : 0. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The G+C content of the genomic DNA of strain Y9T was 68.7 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that the strain fell within the evolutionary radiation encompassed by the genus Massilia. Levels of 16S rRNA gene sequence similarity between strain Y9T and the type strains of recognized Massilia species ranged from 95.2 to 98.2 %, the highest values being with Massilia albidiflava 45T (98.2 %) and Massilia lutea 101T (98.0 %). However, levels of DNA–DNA relatedness between strain Y9T and M. albidiflava KCTC 12343T and M. lutea KCTC 12345T were 37 and 26 %, respectively. Strain Y9T was clearly differentiated from its nearest phylogenetic relatives in the genus Massilia based on phenotypic, chemotaxonomic and phylogenetic properties. Therefore, strain Y9T is considered to represent a novel species of the genus Massilia, for which the name Massilia flava sp. nov. is proposed. The type strain is Y9T ( = CGMCC 1.10685T  = KCTC 23585T).
New Motion Analysis System for Characterization of the Chemosensory Response Kinetics of Rhodobacter sphaeroides under Different Growth Conditions
Authors: Kojadinovic Mila , Sirinelli Antoine , Wadhams George H. , Armitage Judith P.
Published: April 2011

We developed a new set of software tools that enable the speed and response kinetics of large numbers of tethered bacterial cells to be rapidly measured and analyzed. The software provides precision, accuracy, and a good signal-to-noise ratio combined with ease of data handling and processing. The software was tested on the single-cell chemosensory response kinetics of large numbers of
Rhodobacter sphaeroides
cells grown under either aerobic or photoheterotrophic conditions and either in chemostats or in batch cultures, allowing the effects of growth conditions on responses to be accurately measured. Aerobically and photoheterotrophically grown
R. sphaeroides
exhibited significantly different chemosensory response kinetics and cell-to-cell variability in their responses to 100 μM propionate. A greater proportion of the population of aerobically grown cells responded to a 100 μM step decrease in propionate; they adapted faster and showed less cell-to-cell variability than photosynthetic populations. Growth in chemostats did not significantly reduce the measured cell to cell variability but did change the adaptation kinetics for photoheterotrophically grown cells.
13,16-Dimethyl Octacosanedioic Acid (
iso
-Diabolic Acid), a Common Membrane-Spanning Lipid of Acidobacteria Subdivisions 1 and 3
Authors: Sinninghe Damsté Jaap S. , Rijpstra W. Irene C. , Hopmans Ellen C. , Weijers Johan W. H. , Foesel Bärbel U. , Overmann Jörg , Dedysh Svetlana N.
Published: April 2011

The distribution of membrane lipids of 17 different strains representing 13 species of subdivisions 1 and 3 of the phylum
Acidobacteria
, a highly diverse phylum of the
Bacteria
, were examined by hydrolysis and gas chromatography-mass spectrometry (MS) and by high-performance liquid chromatography-MS of intact polar lipids. Upon both acid and base hydrolyses of total cell material, the uncommon membrane-spanning lipid 13,16-dimethyl octacosanedioic acid (
iso
-diabolic acid) was released in substantial amounts (22 to 43% of the total fatty acids) from all of the acidobacteria studied. This lipid has previously been encountered only in thermophilic
Thermoanaerobacter
species but bears a structural resemblance to the alkyl chains of bacterial glycerol dialkyl glycerol tetraethers (GDGTs) that occur ubiquitously in peat and soil and are suspected to be produced by acidobacteria. As reported previously, most species also contained
iso
-C
15
and C
16:1ω7C
as major fatty acids but the presence of
iso
-diabolic acid was unnoticed in previous studies, most probably because the complex lipid that contained this moiety was not extractable from the cells; it could only be released by hydrolysis. Direct analysis of intact polar lipids in the Bligh-Dyer extract of three acidobacterial strains, indeed, did not reveal any membrane-spanning lipids containing
iso
-diabolic acid. In 3 of the 17 strains, ether-bound
iso
-diabolic acid was detected after hydrolysis of the cells, including one branched GDGT containing
iso
-diabolic acid-derived alkyl chains. Since the GDGT distribution in soils is much more complex, branched GDGTs in soil likely also originate from other (acido)bacteria capable of biosynthesizing these components.
Predatory Bdellovibrio Bacteria Use Gliding Motility To Scout for Prey on Surfaces
Authors: Lambert Carey , Fenton Andrew K. , Hobley Laura , Sockett R. Elizabeth
Published: April 2011

Bdellovibrio bacteriovorus
is a famously fast, flagellate predatory bacterium, preying upon Gram-negative bacteria in liquids; how it interacts with prey on surfaces such as in medical biofilms is unknown. Here we report that
Bdellovibrio
bacteria “scout” for prey bacteria on solid surfaces, using slow gliding motility that is present in flagellum-negative and pilus-negative strains.
The Proteome and Interactome of Streptococcus pneumoniae Phage Cp-1
Authors: Häuser Roman , Sabri Mourad , Moineau Sylvain , Uetz Peter
Published: April 2011

Mass spectrometry analysis of
Streptococcus pneumoniae
bacteriophage Cp-1 identified a total of 12 proteins, and proteome-wide yeast two-hybrid screens revealed 17 binary interactions mainly among these structural proteins. On the basis of the resulting linkage map, we suggest an improved structural model of the Cp-1 virion.
Moral experience: a framework for bioethics research
Authors: Hunt Matthew R , Carnevale Franco A
Published: April 2011

Theoretical and empirical research in bioethics frequently focuses on ethical dilemmas or problems. This paper draws on anthropological and phenomenological sources to develop an alternative framework for bioethical enquiry that allows examination of a broader range of how the moral is experienced in the everyday lives of individuals and groups. Our account of moral experience is subjective and hermeneutic. We define moral experience as “Encompassing a person's sense that values that he or she deem important are being realised or thwarted in everyday life. This includes a person's interpretations of a lived encounter, or a set of lived encounters, that fall on spectrums of right-wrong, good-bad or just-unjust”. In our conceptualisation, moral experience is not limited to situations that are heavily freighted with ethically-troubling ramifications or are sources of debate and disagreement. Important aspects of moral experience are played out in mundane and everyday settings. Moral experience provides a research framework, the scope of which extends beyond the evaluation of ethical dilemmas, processes of moral justification and decision-making, and moral distress. This broad research focus is consistent with views expressed by commentators within and beyond bioethics who have called for deeper and more sustained attention in bioethics scholarship to a wider set of concerns, experiences and issues that better captures what is ethically at stake for individuals and communities. In this paper we present our conceptualisation of moral experience, articulate its epistemological and ontological foundations and discuss opportunities for empirical bioethics research using this framework.
Microcystin class of toxins: health effects and safety of drinking water supplies
Authors: Lambert T. W. , Holmes C. F. B. , Hrudey S. E.
Published: April 2011

The microcystins are produced by several species of common planktonic cyanobacteria found in surface waters, but their biological function remains unknown. The microcystins have been shown to be extremely potent hepatotoxins in a variety of experimental animals and they are lethal at low doses. Microcystin-LR, one of over 40 microcystin analogues, has also been shown to be a potent tumor promoter. The toxic effects of the microcystins have been attributed to the inhibition of protein phosphatases. This inhibition causes collapse of the cytoskeleton and interferes with a general signal transduction mechanism in cells. The presence of toxic cyanobacteria in surface water has been documented in all parts of the world. The microcystins have been related to a few incidents of human illness and several incidents of animal poisoning in Canada, United States, Australia, Europe, and Africa. Therefore, exposure to the microcystins is a potentially significant health risk and toxin removal from drinking water is becoming a concern worldwide. Conventional water treatment processes (coagulation/sedimentation, chlorination) have generally proven ineffective at removing microcystin toxins from drinking water. Activated carbon, ozone, and free chlorine have been effective in removing microcystins below detectable concentrations in laboratory experiments. Considering these factors, the occurrence of microcystins in drinking water supplies deserves serious attention to insure that adverse health effects are prevented.Key words: microcystins, hepatotoxins, cyanobacteria, blue-green algae, water treatment, health risk.
Structural changes of spores of tree fungal pathogens after treatment with the designed antimicrobial peptide D2A21
Authors: Rioux D , Jacobi V , Simard M , Hamelin R C
Published: April 2011

In vitro effects of the antimicrobial synthetic D2A21 peptide on the structure of spores of four fungal pathogens causing important tree diseases were examined by microscopy in parallel with tests to measure inhibition of spore germination. With light microscopy, the use of SYTOX®green stain indicated that the peptide rapidly altered the plasma membrane of conidia of three Ascomycetes: Gremmeniella abietina (Lagerberg) Morelet var. abietina Petrini et al., Ophiostoma ulmi (Buism.) Nannf., and Nectria galligena Bres. With basidiospores of Cronartium ribicola J.C. Fisch., a difference between control and treated spores was also found, but it was less pronounced than with conidia of the Ascomycetes. In transmission electron microscopy, untreated conidia showed typical cytoplasmic contents with the regular presence of mitochondria, ribosomes, and nuclei, at times accompanied by vacuoles of various sizes. At concentrations of the peptide inhibitory to spore germination, plasma membranes, as well as nuclear and mitochondrial envelopes, were either generally difficult to discern or were distorted and swollen. At more advanced stages, the cytoplasm of treated spores contained numerous vesicles and was in places more electron-dense than in controls. Cytoplasm leakage was also regularly observed. Present observations strongly suggest that the primary site of action of this peptide is located at the plasma membrane level.Key words: Cronartium ribicola, Gremmeniella abietina, Nectria galligena, Ophiostoma ulmi, D2A21, peptide.
Molecular phylogenetics of the Chytridiomycota supports the utility of ultrastructural data in chytrid systematics
Authors: James Timothy Y , Porter David , Leander Celeste A , Vilgalys Rytas , Longcore Joyce E
Published: April 2011

The chytrids (Chytridiomycota) are morphologically simple aquatic fungi that are unified by their possession of zoospores that typically have a single, posteriorly directed flagellum. This study addresses the systematics of the chytrids by generating a phylogeny of ribosomal DNA sequences coding for the small subunit gene of 54 chytrids, with emphasis on sampling the largest order, the Chytridiales. Selected chytrid sequences were also compared with sequences from Zygomycota, Ascomycota, and Basidiomycota to derive an overall fungal phylogeny. These analyses show that the Chytridiomycota is probably not a monophyletic group; the Blastocladiales cluster with the Zygomycota. Analyses did not resolve relationships among chytrid orders, or among clades within the Chytridiales, which suggests that the divergence times of these groups may be ancient. Four clades were well supported within the Chytridiales, and each of these clades was coincident with a group previously identified by possession of a common subtype of zoospore ultrastructure. In contrast, the analyses revealed homoplasy in several developmental and zoosporangial characters.Key words: zoospore ultrastructure, Chytridiales, molecular phylogeny, Chytridiomycota, operculum.
New cuticular morphotypes of Cordaites principalis from the Canadian Carboniferous Maritimes Basin
Authors: Zodrow Erwin L , imunek Zbynek , Bashforth Arden R
Published: April 2011

Fossil cuticles were extracted from leaves attributed to Cordaites principalis (Germar) Geinitz (Cordaitales) that were collected from Upper Carboniferous strata in Nova Scotia (Sydney and Stellarton sub-basins) and in Newfoundland (Bay St. George sub-basin). The quality of the cuticular preservation is directly related to the thermal maturity and the grain size and angularity of sediments entombing the fossil leaves. Detailed transmitted light and scanning electron microscopy of the cuticles revealed that five distinct cuticular morphotypes could be recognized, demonstrating the variability in epidermal morphology of leaves belonging to one taxon. Two morphotypes show dissimilar and discrete epidermal characteristics, whereas three morphotypes form, more or less, a morphological continuum. Comparison with cuticles from Euramerican and Angaran floral provinces suggests that only one morphotype is in common with cuticles described from Europe, while four morphotypes are new for the Carboniferous.Key words: cuticle, Cordaites, Carboniferous, Canada.
Ultrastructural effects of thaxtomin A produced by Streptomyces scabies on mature potato tuber tissues
Authors: Goyer Claudia , Charest Pierre-Mathieu , Toussaint Vicky , Beaulieu Carole
Published: April 2011

The cytological and ultrastructural modifications induced by thaxtomin A, a phytotoxin produced by Streptomyces scabies, were analyzed on mature field-grown potato tuber tissues. In tissue sampled during the first 12 h after treatment with thaxtomin A, the plasmalemma of parenchyma cells was detached from the cell wall in several places. However, the plasmalemma did not appear ruptured. The intercellular spaces between the retracted plasmalemma and the cell wall often contained fibrillar material. After a longer period of time, cells from tissues treated with thaxtomin A showed significant disorganization, such as detachment and invagination of the plasmalemma, the presence of a fibrillar-like material in the cytoplasm, and electron-dense material associated with moribund cellular features.Key words: common scab, potato, phytotoxin, Solanum tuberosum.
Stigma form and surface in the tribe Boragineae (Boraginaceae): micromorphological diversity, relationships with pollen, and systematic relevance
Authors: Bigazzi Massimo , Selvi Federico
Published: April 2011

A comparative analysis of stigma form in 62 species representing 15 genera of the tribe Boragineae by means of light and electron (transmission and scanning) microscopy highlighted the structural diversity, peculiarity, and functional specialization of the receptive surface of the boraginaceous stigma. Cluster analysis identified 13 stigma morphotypes, 6 of which were peculiar to the genera Anchusella, Brunnera, Cynoglottis, Gastrocotyle, Pentaglottis, and Trachystemon. Nonea showed the broadest intrageneric stigma polymorphism, with 6 types differing in terms of stigma form and papillar structure. Stigma and pollen variations were poorly associated in this complex genus, while in other groups, the pollen-stigma typological correspondence indicated the taxonomic distinctiveness of some critical species, such as Gastrocotyle hispida (Forssk.) C.B. Clarke and Anchusella spp. Positive correlations were found between pollen and papillar size, between interpapillar distance and pollen equatorial diameter, and between pollen volume and style length. Qualitative and quantitative pollen-stigma relationships suggested functional implications of an adaptive nature that were interpreted through the recognition of three distinct stages of early interaction, i.e., capture, lodging, and hydration of the grains.Key words: Boragineae, electron microscopy, micromorphology, pollen-stigma, receptive surface, systematics.
Epiphytic bryophytes on European aspenPopulus tremulain old-growth forests in northeastern Finland and in adjacent sites in Russia
Authors: Ojala E , Mönkkönen M , Inkeröinen. J
Published: April 2011

We studied the occurrence and cover of epiphytic bryophytes and one lichen species (Lobaria pulmonaria (L.) Hoffm.) growing on Populus tremula L. trunks. Our aim was to explore the spatial scales where epiphyte species respond to their environment. At the landscape scale, fragmented Finnish old-growth forests close to the Russian border and farther west in a heavily fragmented landscape were compared with Russian sites with more continuous old-growth forest landscapes to assess the effect of landscape structure on epiphyte assemblages. We studied factors affecting populations at the level of individual sites and local habitat patches within the forests. Twelve sites were surveyed for epiphytes. We estimated epiphyte occurrence from 353 Populus tremula trunks. There seemed to be only minor differences in the structure of epiphyte assemblages between the three landscapes surveyed. Species richness varied also independently of the landscape structure but was positively related to regional Populus tremula abundance (alpha diversity) and the size of the substrate trunk (point diversity). At the regional scale, the most important factor affecting the occurrence of epiphytes was the abundance of Populus tremula. At the local scale, the size of the Populus tremula surveyed and tree density around the trunk surveyed correlated positively with the occurrence of some species. The size and abundance of Populus tremula as well as tree density are the most important factors for maintaining viable populations of the studied species.Key words: biodiversity, boreal forest, Bryophyte, forest management, landscape structure, Lobaria pulmonaria.
Development of the inflorescence and flower ofPhilodendron fragrantissimum(Araceae): a qualitative and quantitative study
Authors: Barabé Denis , Lacroix Christian , Jeune Bernard
Published: April 2011

The early stages of inflorescence development in Philodendron fragrantissimum (Hook.) G. Don are examined using scanning electron microscopy. Pistillate flowers are initiated on the lower portion of the inflorescence and staminate flowers are initiated on the distal portion. Male flowers have 6-8 stamens (sometimes 5) and female flowers have a multilocular ovary consisting of 6-10 locules. A transition zone consisting of sterile male flowers and bisexual flowers with fused or free carpels and staminodes is also present. This zone is located between the male- and female- flower zones. Generally, the portion of the bisexual flower adjacent to the male zone forms staminodes and the portion bordering the female zone develops an incomplete gynoecium with few carpels. The different floral organs of the bisexual flowers are all inserted in the same whorl. Pistillate and staminate flowers are inserted on the same contact parastichies along the inflorescence; there is no spatial discontinuity between the female zone, the bisexual zone, and the male zone. The presence of bisexual flowers is believed to correspond to a morphogenetic gradient at the level of the inflorescence as a whole. A quantitative analysis of a series of parameters (i.e., length and width of flower types and inflorescence zones) indicates that each zone of the inflorescence has its own particular nature as far as rhythm of growth and geometry are concerned. There appears to be evidence for some form of partitioning in the global development of the inflorescence. The growth of a zone seems to be more variable in size and geometry than that of individual flowers. During later stages of development, the size of the flowers of the intermediate zone, especially the sterile male flowers, increases considerably, until it exceeds that of both male and female flowers.Key words: homeosis, morphogenesis, gradient, allometry, reproduction.
Characterization of changes in pectin methylesterase expression and pectin esterification during tomato fruit ripening
Authors: Blumer J M , Clay R P , Bergmann C W , Albersheim P , Darvill A
Published: April 2011

The production, accumulation, and in situ location of pectin methylesterase (EC 3.1.11) was examined in ripening fruit of the processing tomato cv. UC82B. Pectin methylesterase detected with a monoclonal antibody (PME-1) first appeared adjacent to seeds in immature green fruit and was later detected only in tissue adjacent to the cuticle (i.e., exopericarp) during ripening. Enzyme-linked immunosorbant assay and Western blot analysis using PME-1 demonstrated that the fresh-market cultivars Celebrity and Better Boy accumulated lower levels of this immunologically detectable pectin methylesterase during maturation than did processing cv. UC82B, and that the immunologically detected pectin methylesterase and the total detectable pectin methylesterase activities of 'Celebrity' and 'Better Boy' increased throughout ripening. In contrast, processing cv. UC82B displayed a total detectable pectin methylesterase activity profile that peaked during the breaker stage, a finding supported immunologically by tissue-printing. To correlate pectin methylesterase expression during ripening to the degree of methylesterification of pectins in exopericarp cell walls, we subjected exopericarp tissue from 'UC82B' fruit to an immunocytochemical and ultrastructure study. Esterified pectin decreased in some regions of the exopericarp cell walls during fruit development but persisted in some regions as well. Less-esterified pectin was localized in the middle lamella of exopericarp cell walls during preripe stages, while in ripe fruit, this labeling was largely absent.Key words: pectin methylesterase (PME), immunocytochemistry, tissue-print, pectin esterification, Lycopersicon esculentum.
Seed rain and seed bank along an alpine altitudinal gradient in Swedish Lapland
Authors: Molau Ulf , Larsson Eva-Lena
Published: April 2011

We studied the seed flux, including seed rain and seed bank (germinable and total), at twelve sites along an altitudinal gradient in the Abisko area in northernmost Swedish Lapland during a period of 3 years with contrasting summer climates. The study sites were evenly spaced in altitude from the timberline at 700 m above sea level to the highest peaks in the area (1560 m). A subalpine birch forest site was included for comparison. Each site was equipped with seed traps, replaced and emptied directly upon snow-melt each summer. Soil samples for seed bank assessment were taken at all sites, and inventories of the vascular plant flora were carried out in the 10 m radius neighborhood of the traps. The results revealed high variation among years with regard to seed rain and its partitioning over various functional types of plants. Even though most of the seed rain could be attributed to species present in the plant community of the trap sites themselves, some more long-distance dispersal takes place every year. A number of extrazonal recoveries are reported, often several hundred m above the distributional limit of the species. Even though seed number and species diversity declined rapidly from seed rain over total seed bank to germinable seed bank, the correlation among all three aspects of the seed pool was high. The dominant species in the seed flux at moderate altitudes, Empetrum hermaphroditum Hagerup, has a persistent seed bank with an average turnover of more than 200 years.Key words: seed rain, seed bank, total seed bank, germinable seed bank, alpine, dispersal.
Decreased photosynthetic efficiency in plant species exposed to multiple airborne pollutants along the Russian-Norwegian border
Authors: Odasz-Albrigtsen Ann Marie , Tømmervik Hans , Murphy Patrick
Published: April 2011

Photosynthetic efficiency was estimated by chlorophyll fluorescence measurements (Fv/Fm) in 11 plant species growing along a steep gradient of airborne pollution along the Russian-Norwegian border (70°N, 30°E). Photosynthetic efficiency was positively correlated with environmental variables including annual temperature and a maritime gradient and was negatively correlated with the airborne concentrations of Cu, Ni, and SO2 from the Cu-Ni smelters. Photosynthetic efficiency in six plant species from the mixed forest, but not pine (Pinus sylvestris L.), and three species from the birch forest was inversely correlated with SO2 and the concentrations of Ni and Cu in lichens. Measurement of fluorescence in these species was a sensitive indicator of pollutant impact. Plant cover at the 16 study sites and the photosynthetic efficiency of five target species correlated with normalized difference vegetation index (NDVI) values. This study demonstrated that it is possible to detect relations among field-measured ecophysiological responses in plants, levels of airborne pollutants, and satellite remote-sensed data.Key words: chlorophyll fluorescence, smelters, sulfur dioxide, nickel, copper, normalized difference vegetation index (NDVI).
Tolerance of the arctic graminoid Luzula arcuata ssp. confusa to simulated grazing in two nitrogen environments
Authors: Bråthen Kari Anne , Odasz-Albrigtsen Ann Marie
Published: April 2011

We investigated the response of the important forage plant Luzula arcuata Swartz ssp. confusa (Lindeb.) Blytt to simulated grazing during two growing seasons in a phytotron. Plants were clipped at five levels of intensity and fertilized at two levels of nitrogen. There was no reduction in net primary production of clipped compared with unclipped plants after either of the two growing seasons. Such results indicate that L. arcuata ssp. confusa can compensate for defoliation. Plants overcompensated in net aboveground primary production (NAPP) in the first season and compensated in NAPP in the second season. Plant traits contributing to the compensation in NAPP were stimulation of tillering in clipped plants, increase in specific leaf area of the most heavily clipped plants, and a higher proportion of NAPP occurring below clipping height in frequently clipped plants. Sexual reproduction (number of flowering shoots) was enhanced in the second season in plants clipped at 6 cm above the soil and reduced in plants clipped 3 cm above the soil. The response to clipping was independent of nitrogen treatment, suggesting that nitrogen did not limit regrowth even in the low nitrogen environment. Luzula arcuata ssp. confusa is tolerant of dry, cold and windswept, low-nutrient habitats in the Arctic. This study shows that it also is tolerant of defoliation.Key words: forage, herbivory, compensation, grazing responses, Svalbard.
Lateral root development in a woody plant,Quercus suberL. (cork oak)
Authors: Verdaguer Dolors , Casero Pedro J , Molinas Marisa
Published: April 2011

The distribution and the ontogenesis of lateral roots have been investigated in the Mediterranean woody species Quercus suber L. (cork oak). Lateral roots arose in protoxylem-based ranks and a tendency to clumping was observed. Three stages are distinguished in lateral root primordium development. Lateral root primordia are derived mainly from pericycle cells. The endodermis contributed to the initial lateral root development, forming an endodermal cover that sloughs off with lateral root emergence. The unemerged lateral roots show an incipient layered root meristem; this meristem can be classified as a closed type meristem. Primary vascular connection takes place with the xylem strand opposite the lateral root primordium and the two adjacent phloem strands. Primary vascular connector elements are derived from pericyclic derivative cells. Vascular parenchyma cells contribute mainly in the development of the cambium and the subsequent secondary xylem and phloem connector elements. The secondary vascular elements of the lateral root and parent root differentiate in continuity. Vascular connection is discussed in relation to the root vascular plexus described in monocotyledonous and in some herbaceous dicotyledonous plants. An endodermis with suberized lamellae is continuous between the lateral and parent root in emerged lateral roots.Key words: lateral root, development pattern, apical lateral root meristem, root vascular connection, Quercus suber L.
Genetic variability and phytogeography ofMiscanthus sinensisvar.condensatus, an apomictic grass, based on RAPD fingerprints
Authors: Chou Chang-Hung , Chiang Yu-Chung , Chiang Tzen-Yuh
Published: April 2011

DNA fingerprinting using random amplified polymorphic DNA (RAPD) markers was employed to investigate the genetic variation within and among populations of Miscanthus Anderss. sinensis var. condensatus (Hack.) Makino, an apomictic grass distributed along the coasts of Taiwan and Ryukyu Islands. A total of 250 plants from three Taiwanese populations (Southeast Coast, Orchid Islet, and Green Islet) and two populations from Ryukyu (Ishigaki and Amami-O-Shima Islets) were sampled. The amplified products of 40 random primers showed monomorphic banding patterns within all populations as well as among the three populations from Taiwan. Low genetic variation (with only two polymorphic loci), but significant differentiation, was detected between populations from Taiwan and Ryukyu (ΦCT= 0.864) and between populations (ΦST= 1.0) from Ishigaki and Amami-O-Shima Islets. In contrast, a high level of variation was exhibited in the outcrossing Miscanthus sinensis var. glaber (Nakai) Li. In addition to apomictic reproduction, low genetic variation across populations of M. sinensis var. condensatus may be a result of high salinity acting as a selective agent. With the cost of reduced genetic heterogeneity, apomixis may have provided a mechanism for avoiding the transmission of endophytic fungi. The phytogeographic pattern of M. sinensis var. condensatus, as reflected by the RAPD data, likely represents isolation between Taiwan and Ryukyu since the mid-Pleistocene.Key words: apomixis, Miscanthus sinensis var. condensatus, phytogeography, population differentiation, RAPD, system of mating.
Stream biomonitoring at an agricultural test site using benthic algae
Authors: Winter Jennifer G , Duthie Hamish C
Published: April 2011

The percent cover and composition of benthic macroalgal growths and the structure of epilithic diatom communities were analyzed in 1995 at four sites in a stream flowing through a cultivated field near Kintore, Ontario, Canada. The dominant epilithic diatom taxa did not differ greatly among sites. However, a correspondence analysis of the diatoms sampled monthly between July and September separated an upstream site from those receiving agricultural runoff. Sites downstream of agricultural inputs showed an increase in the cover of Cladophora glomerata (L.) Kütz and other green algae, and in general a reduction in the cover of diatoms and crusts dominated by Oscillatoriaceae (aff. Oscillatoria sp.) and the red alga Audouinella violacea (Kütz.) Hamel. In particular, there was a positive correlation between the cover of Cladophora and nitrate concentration.Key words: biomonitoring, diatoms, periphyton, agriculture, correspondence analysis (CA).
Effect of embryo orientation on the developmental sequence of adventitious organogenesis in jack pine (Pinus banksiana Lamb.)
Authors: Pelletier Gervais , Laliberté Sylvie
Published: April 2011

The developmental sequence of adventitious organogenesis in jack pine (Pinus banksiana Lamb.) embryos was analysed depending on two explant orientations. Embryos were placed vertically (cotyledons downward) or horizontally on half-strength Schenk and Hildebrandt medium containing 10 µM 6-benzylaminopurine. Samples were harvested at 2- to 3-day intervals for a 21-day period and observed using light and electron microscopy. In vertically placed embryos, cotyledons were inserted into the medium and became necrotic, while buds and phylloids developed on the upper part of the hypocotyl and in the apical area, 14 and 9 days after culture initiation respectively. In horizontally cultured embryos, organogenesis started in the intercotyledonary areas (day 11) and spread to the abaxial surface of cotyledonary margins outside the medium (day 14). A few buds also developed on the adaxial surface of cotyledons, starting on day 16. In the apical area, phylloid formation started on day 18. Nodules were induced in tissues in contact with the medium for both orientations, but in distinct sites. Embryo orientation influenced the localization of induction sites and the time sequence of organogenesis. The pattern for the mobilization of proteins, lipids, and polysaccharides prior to organogenesis was similar for both orientations. A depletion in proteins and polysaccharides did not occur in tissues in contact with the culture medium.Key words: adventitious organogenesis, embryo culture, explant orientation, jack pine, microscopy, Pinus banksiana.
A comparison of ITS and LSU nrDNA phylogenies of Fulgensia (Teloschistaceae, Lecanorales), a genus of lichenised ascomycetes
Authors: Kasalicky Thomas , Döring Heidi , Rambold Gerhard , Wedin Mats
Published: April 2011

The phylogeny of the lichen genus Fulgensia Massal. & De Not. (Teloschistaceae, Lecanorales) is analysed using maximum parsimony and neighbor joining analyses of nuclear ITS and partial large subunit nuclear ribosomal DNA (nrDNA) sequences. Three matrices were analysed with maximum parsimony; an internal transcribed spacer nrDNA matrix, a large subunit nrDNA matrix, and a combined data set. The internal transcribed spacer region contributes 70% of the informative sites to the combined data set. The topology of the trees resulting from the analysis of the internal transcribed spacer region is identical to the tree topology resulting from the combined analysis, but it shows less resolution at basal parts of the tree. Two sites for putative spliceosomal introns in the large subunit nrDNA, at position 808 and 914 (relative to Saccharomyces cerevisiae) are reported. Fulgensia, as currently understood, is polyphyletic and some species have to be excluded. The molecular analyses identified groups of species within the genus that are also supported by anatomical and morphological characters. The results of the analyses are compared with existing classification concepts based on morphological and anatomical data.Key words: LSU, ITS, nrDNA, introns, Fulgensia, phylogeny.
Defence reactions ofHordeum chilenseaccessions to three formae speciales of cereal powdery mildew fungi
Authors: Rubiales D , Carver T LW
Published: April 2011

The histology of resistance to infection by Blumeria graminis DC Speer f.sp. hordei, Blumeria graminis f.sp. tritici, and Blumeria graminis f.sp. avenae was studied in 15 accession lines of Hordeum chilense. All were highly resistant to all formae speciales. There were small differences in spore germination rates and the morphological normality of germlings formed on the different lines. Relatively large differences between accessions were detected in terms of penetration resistance and the frequency with which attacked epidermal cells died. Greater penetration resistance was expressed by epidermal cells of the seventh-formed leaves than by earlier leaves, indicating that penetration resistance is a component of adult plant resistance in H. chilense. Epidermal cells overlying vascular tissues (long epidermal cells) were more resistant to penetration than cells adjacent or close to stomatal complexes. In a limited examination involving two accession lines, epidermal cells on the abaxial leaf surface of one line were more penetration resistant than those on the adaxial surface; the other line was highly resistant on both surfaces. However, in the few cases where long cells and abaxial cells were penetrated, the frequency of associated cell death was lower than in short cells or on the adaxial leaf surface. This is consistent with the macroscopic observation that the few colonies formed on H. chilense were often close to the mid-rib and more frequent on the abaxial leaf surface. The data support the view that H. chilense offers a valuable source of powdery mildew resistance for cultivated cereals.Key words: Blumeria graminis, Erysiphe graminis, powdery mildew, disease resistance, histology, Hordeum chilense.
Ultrastructural characterization of male sterile33 (ms33) mutant in Arabidopsis affected in pollen desiccation and maturation
Authors: Fei Houman , Sawhney Vipen K
Published: April 2011

The MS33 gene in Arabidopsis is required for stamen filament growth and for pollen maturation. The objective of this study was to characterize the effects of ms33 mutation on pollen development at the ultrastructural level. There were no differences between the wild type and ms33 mutant pollen development before the first mitotic division of microspores. At the bicellular pollen stage, the first signs of abnormalities were observed in the ms33 tapetum, which started to degenerate early and released osmiophilic material in the anther locule. In ms33 pollen, the endintine was thicker, and exintine thinner, than in the wild type, and the mutant pollen had large vacuoles. Later in development, the mutant pollen underwent second mitosis and produced two normal-looking sperm cells; however, the intine was precociously formed, and there were abnormalities in tryphine deposition on the pollen wall, in the size of vacuoles, and in the formation of lipid bodies in the vegetative cell cytoplasm. Based on these observations it is suggested that mutation in the MS33 gene interferes with intine formation and tryphine deposition, both of which negatively affect pollen desiccation resulting in large, highly vacuolate pollen that are nonviable.Key words: Arabidopsis, male sterility, mutant, pollen, tapetum, ultrastructure.