Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Native

  • alaska native
  • digital native
  • species native

  • Terms modified by Native

  • native american
  • native american grave protection
  • native american population
  • native ant
  • native artery
  • native articular cartilage
  • native bee
  • native biodiversity
  • native biota
  • native bird
  • native bone
  • native cartilage
  • native cattle
  • native cell
  • native chemical ligation
  • native child
  • native coarctation
  • native collagen
  • native community
  • native condition
  • native conformation
  • native congener
  • native counterpart
  • native country
  • native crystal
  • native data
  • native data set
  • native diffraction data
  • native distribution
  • native distribution range
  • native ecosystem
  • native english speakers
  • native environment
  • native enzyme
  • native fauna
  • native fish
  • native fish community
  • native fish species
  • native flora
  • native forb
  • native forest
  • native form
  • native freshwater fish
  • native frog
  • native gel
  • native gel electrophoresis
  • native glp-1
  • native grass
  • native grassland
  • native habitat
  • native heart
  • native herbivore
  • native host
  • native hosts
  • native insect
  • native kidney
  • native language
  • native liver
  • native macrophyte
  • native membrane
  • native microflora
  • native minnow
  • native north america
  • native oxide
  • native page
  • native people
  • native peptide
  • native perennial grass
  • native pig
  • native plant
  • native plant community
  • native plant diversity
  • native plant population
  • native plant species
  • native polyacrylamide gel electrophoresis
  • native population
  • native predator
  • native protein
  • native protein structure
  • native range
  • native richness
  • native secondary structure
  • native shrub
  • native site
  • native space
  • native speaker
  • native speakers
  • native species
  • native species richness
  • native starch
  • native state
  • native strain
  • native structure
  • native substrate
  • native taxa
  • native tissue
  • native tree
  • native tree species
  • native valve endocarditis
  • native vegetation
  • native vessel
  • native woody species

  • Selected Abstracts


    EVOLUTION, Issue 8 2007
    John L. Maron
    How introduced plants, which may be locally adapted to specific climatic conditions in their native range, cope with the new abiotic conditions that they encounter as exotics is not well understood. In particular, it is unclear what role plasticity versus adaptive evolution plays in enabling exotics to persist under new environmental circumstances in the introduced range. We determined the extent to which native and introduced populations of St. John's Wort (Hypericum perforatum) are genetically differentiated with respect to leaf-level morphological and physiological traits that allow plants to tolerate different climatic conditions. In common gardens in Washington and Spain, and in a greenhouse, we examined clinal variation in percent leaf nitrogen and carbon, leaf ,13C values (as an integrative measure of water use efficiency), specific leaf area (SLA), root and shoot biomass, root/shoot ratio, total leaf area, and leaf area ratio (LAR). As well, we determined whether native European H. perforatum experienced directional selection on leaf-level traits in the introduced range and we compared, across gardens, levels of plasticity in these traits. In field gardens in both Washington and Spain, native populations formed latitudinal clines in percent leaf N. In the greenhouse, native populations formed latitudinal clines in root and shoot biomass and total leaf area, and in the Washington garden only, native populations also exhibited latitudinal clines in percent leaf C and leaf ,13C. Traits that failed to show consistent latitudinal clines instead exhibited significant phenotypic plasticity. Introduced St. John's Wort populations also formed significant or marginally significant latitudinal clines in percent leaf N in Washington and Spain, percent leaf C in Washington, and in root biomass and total leaf area in the greenhouse. In the Washington common garden, there was strong directional selection among European populations for higher percent leaf N and leaf ,13C, but no selection on any other measured trait. The presence of convergent, genetically based latitudinal clines between native and introduced H. perforatum, together with previously published molecular data, suggest that native and exotic genotypes have independently adapted to a broad-scale variation in climate that varies with latitude. [source]


    ABSTRACT Conformational changes of ewe's ,-lactalbumin (ALA) upon removal of Ca2+ were determined by surface hydrophobicity, calorimetry and circular dichroism. Native ewe's ALA resisted trypsinolysis, showing 4% maximum degradation after 20 h of hydrolysis. Removal of bound calcium by addition of either ethylenediaminetetraacetic acid or ethylene glycol bis ,-aminoethyl ether-N,N,N,N-tetraacetic acid induced major protein conformational changes, enhancing its susceptibility to trypsinolysis, and leading to complete degradation of the protein. Reversed-phase high-performance liquid chromatography profiles of tryptic hydrolysate of Ca2+ -free ALA were nearly the same through the whole enzymatic incubation period (24 h) showing the absence of sequential hydrolytic mechanism. They were characterized by the presence of five main peaks representing hydrophobic large-sized peptides. Cleaving the S-S bonds in the resulting hydrolysates with 2-mercaptoethanol gave rise to new peaks representing more hydrophilic and hydrophobic peptides. [source]


    Alberto Dávila
    ABSTRACT Using 1990 and 2000 U.S. census data, this study investigates changes in immigrant/native earnings disparities for workers in U.S. cities along the international border with Mexico vis-à-vis the U.S. interior during the 1990s. Our findings,based on estimating earnings functions and employing the Juhn-Murphy-Pierce (1993, JPE) wage decomposition technique,indicate that the average earnings of Mexican immigrants along the U.S.-Mexico border improved relative to those accrued by their counterparts in the U.S. interior and by otherwise similar U.S.-born Mexican Americans between 1990 and 2000. However, when comparing Mexican-born workers to U.S.-born non-Hispanic whites, the immigrant border-earnings penalty remained statistically unchanged. [source]

    Endangered Native or Alien Invader?

    CONSERVATION, Issue 4 2005
    Article first published online: 8 MAR 200

    Countryside Biogeography of Moths in a Fragmented Landscape: Biodiversity in Native and Agricultural Habitats

    Taylor H. Ricketts
    We sampled moth species richness within a 227-ha forest fragment and in four surrounding agricultural habitats (coffee, shade coffee, pasture, and mixed farms) in southern Costa Rica. We found no significant difference in moth species richness or abundance among agricultural habitats, but agricultural sites within 1 km of the forest fragment had significantly higher richness and abundance than sites farther than 3.5 km from the fragment. In addition, species composition differed significantly between distance classes ( but not among agricultural habitats), with near sites more similar to forest than far sites. These results suggest that (1) different agricultural production regimes in this region may offer similar habitat elements and thus may not differ substantially in their capacities to support native moth populations and (2) that the majority of moths may utilize both native and agricultural habitats and move frequently between them, forming "halos" of relatively high species richness and abundance around forest fragments. Correlations between species richness and the amount of nearby forest cover, measured over circles of various radii around the sites, suggest that halos extend approximately 1.0,1.4 km from the forest edge. The extent of these halos likely differs among taxa and may influence their ability to survive in fragmented landscapes. Resumen: Los estudios de paisajes fragmentados, especialmente en los trópicos, tradicionalmente se han enfocado en los fragmentos nativos per se, ignorando las distribuciones de especies en áreas agrícolas circundantes o en otras áreas dominadas por humanos. Muestreamos la riqueza de polillas dentro de un fragmento de bosque de 227 hectáreas y en cuatro hábitats agrícolas (café, café con sombra, pastizal y campos mixtos) en el Sur de Costa Rica. Encontramos que no hubo diferencias significativas en la riqueza de especies o en la abundancia de polillas entre los hábitats agrícolas, sin embargo, los sitios agrícolas cercanos (<1 km) al fragmento de bosque tuvieron una riqueza de especies y abundancia significativamente mayor que las de los sitios lejanos (>3.5 km) al fragmento. Además, la composición de especies fue significativamente diferente entre las clases de distancia ( pero no entre los hábitats agrícolas), siendo los sitios cercanos más similares al bosque que los sitios retirados. Estos resultados sugieren que (1) los diferentes regímenes de producción agrícola en esta región pueden ofrecer elementos de hábitat similares y por lo tanto pueden no diferir substancialmente en lo que se refiere a su capacidad para sostener poblaciones de polillas nativas y (2) que la mayoría de las polillas pueden utilizar tanto hábitatsnativos como agrícolas y mover frecuentemente entre ellos, formando "halos" con una riqueza de especies y una abundancia relativamente altas alrededor de los fragmentos del bosque. Las correlaciones entre la riqueza de especies y la cantidad de cobertura forestal circundante, medida en círculos de diferente radio alrededor de los sitios de estudio, sugiere que los halos se extienden aproximadamente 1.0,1.4 km del borde del bosque. La extension de estos halos posiblemente difiere entre taxones y puede influenciar sus habilidades para sobrevivir en paisajes fragmentados. [source]

    Disentangling the relative effects of environmental versus human factors on the abundance of native and alien plant species in Mediterranean sandy shores

    Marta Carboni
    Abstract Aim, Mediterranean coastal sand dunes are characterized by both very stressful environmental conditions and intense human pressure. This work aims to separate the relative contributions of environmental and human factors in determining the presence/abundance of native and alien plant species in such an extreme environment at a regional scale. Location, 250 km of the Italian Tyrrhenian coast (Region Lazio). Methods, We analysed alien and native plant richness and fitted generalized additive models in a multimodel-inference framework with comprehensive randomizations to evaluate the relative contribution of environmental and human correlates in explaining the observed patterns. Results, Native and alien richness are positively correlated, but different variables influence their spatial patterns. For natives, human population density is the most important factor and is negatively related to richness. Numbers of natives are unexpectedly lower in areas with a high proportion of natural land cover (probably attributable to local farming practices) and, to a lesser degree, affected by the movement of the coastline. On the other hand, alien species richness is strongly related to climatic factors, and more aliens are found in sectors with high rainfall. Secondarily, alien introductions appear to be related to recent urban sprawl and associated gardening. Main conclusions, Well-adapted native species in a fragile equilibrium with their natural environment are extremely sensitive to human-driven modifications. On the contrary, for more generalist alien species, the availability of limited resources plays a predominant role. [source]

    Sensitive Electrochemical Detection of Native and Aggregated ,-Synuclein Protein Involved in Parkinson's Disease

    ELECTROANALYSIS, Issue 13-14 2004
    Michal Masa
    Abstract The aggregation of ,-synuclein, a 14,kDa protein, is involved in several human neurodegenerative disorders, including Parkinson's disease. We studied native and in vitro aggregated ,-synuclein by circular dichroism (CD), atomic force microscopy (AFM) and electrochemical methods. We used constant current chronopotentiometric stripping analysis (CPSA) to measure hydrogen evolution catalyzed by ,-synuclein (peak H) at hanging mercury drop electrodes (HMDE) and square-wave stripping voltammetry (SWSV) to monitor tyrosine oxidation at carbon paste electrodes (CPE). To decrease the volume of the analyte, most of the electrochemical measurements were performed by adsorptive transfer (medium exchange) from 3,6,,L drops of ,-synuclein samples. With both CPE and HMDE we observed changes in electrochemical responses of ,-synuclein corresponding to protein fibrillization detectable by CD, fluorescence and AFM. Aggregation-induced changes in peak H at HMDE were relatively large in strongly aggregated samples, suggesting that this electrochemical signal may find use in the analysis of early stages of ,-synuclein aggregation. This assumption was documented by marked changes in the peak H potential and height in samples withdrawn at the end of the lag and the beginning of the elongation phase. Native ,-synuclein can be detected down to subnanomolar concentrations by CPSA. [source]

    ,-Cyclodextrin as novel chiral probe for enantiomeric separation by electromigration methods

    ELECTROPHORESIS, Issue 21 2006
    Dorothee Wistuba
    Abstract Native ,-CD has been employed as chiral selector in CE and MEKC. To investigate the potential of the enantiodiscriminating properties of ,-CD, negatively charged 5-dimethylamino-1-naphthalene-sulfonyl (dansyl)-, 2,4-dinitrophenyl (DNP)- and FMOC-derivatives of several amino acids, 1,1'-binaphthyl-2,2'-diylhydrogenphosphate, flavanones and three positively charged drugs have been selected as testing samples. Enantioresolution factors up to 4.82 have been observed. The results were compared with those achieved by the conventional running buffer additives ,-, ,- and ,-CDs. For several examples a steady increase of enantioresolution with increasing degree of oligomerization has been detected. [source]

    Determination of tryptamine derivatives in illicit synthetic drugs by capillary electrophoresis and ultraviolet laser-induced fluorescence detection

    ELECTROPHORESIS, Issue 12 2005
    Carolin Huhn
    Abstract A method based on separation by capillary electrophoresis combined with UV-laser-induced fluorescence detection (,ex,=,266,nm) was developed for the determination of nine tryptamine derivatives of forensic interest and potential matrix constituents. The composition of the separation electrolyte was optimized with respect to the resolution of solutes of interest and to the sensitivity of fluorescence detection. Native ,-cyclodextrin was employed as a complex forming modifier of the electrophoretic separation and fluorescence-enhancing agent. With the help of a stacking procedure, limits of detection of 0.1,6,µg/L for all analytes were obtained. The repeatability for the peak area (at a concentration of the analyte about 100 times the LOD) was less than 2.3%,RSD. A second HPLC method was developed, and its analytical parameters were evaluated for an estimation of the accuracy of the CE-LIF method and for method comparison. The results of the determination of tryptamine derivatives in the samples of forensic interest obtained with the two independent methods are in good agreement. [source]

    Native and subunit molecular mass and quarternary structure of the hemoglobin from the primitive branchiopod crustacean Triops cancriformis

    FEBS JOURNAL, Issue 17 2006
    Morgane Rousselot
    Many branchiopod crustaceans are endowed with extracellular, high-molecular-weight hemoglobins whose exact structural characteristics have remained a matter of conjecture. By using a broad spectrum of techniques, we provide precise and coherent information on the hemoglobin of one of the phylogenetically ,oldest' extant branchiopods, the tadpole shrimp Triops cancriformis. The hemoglobin dissociated under reducing conditions into two subunits, designated TcHbA and TcHbB, with masses of 35 775 ± 4 and 36 055 ± 4 Da, respectively, determined by ESI-MS. Nonreducing conditions showed only two disulfide-bridged dimers, a homodimer of TcHbA, designated D1 (71 548 ± 5 Da), and the heterodimer D2 (71 828 ± 5 Da). Carbamidomethylation of free SH groups revealed the presence of three cysteines per subunit and indicated one intrasubunit and one intersubunit disulfide bridge. Ultracentrifugation and light-scattering experiments under nondenaturating conditions yielded mass estimates that suggested an uneven number of 17 subunits forming the native hemoglobin. This unrealistic number resulted from the presence of two size classes (16-mer and 18-mer), which were recognized by native PAGE and Ferguson plot analysis. ESI-MS revealed three hemoglobin isoforms with masses of 588.1 kDa, 662.0 kDa, and 665.0 kDa. The 16-mer and the smaller 18-mer species are supposed to be composed of TcHbA only, given the dominance of this subunit type in SDS/PAGE. Transmission electron microscopy of negatively stained specimens showed a population of compact molecules with geometrical extensions of 14, 16 and 9 nm. The proposed stoichiometric model of quarternary structure provides the missing link to achieve a mechanistic understanding of the structure,function relationships among the multimeric arthropodan hemoglobins. [source]

    J.G. Granö and Edgar Kant: Teacher and Pupil, Colleagues and Friends

    Olavi Granö
    Abstract This paper is adapted from an address given at the plenary session of the conference 'From Native and Landscape Research to Urban and Regional Studies, held in Tartu on 23 August, 2002, to mark the birthdays of J.G. Granö (120 years.) and Edgar Kant (100 years). The Finnish geographer J.G. Granö was Professor of Geography at the University of Tartu from 1919 to 1923, a period during which that university became the birthplace of many original geographical ideas. Edgar Kant was beginning his studies at that time, and a link was forged between the two scholars which lasted until Granö's death in 1956. The nature of this interaction and its significance for the history of geographical studies are discussed. [source]

    Stabilization of PbS Nanocrystals by Bovine Serum Albumin in its Native and Denatured States

    Mandeep Singh Bakshi
    Abstract PbS nanocrystals (NCs) are synthesized in aqueous phase within a temperature range of 40,80,°C in the presence of native and denatured states of bovine serum albumen (BSA) as the capping/stabilizing agent. The NCs are characterized with the help of field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. At 40,°C, large ball-shaped NCs (145,±,37,nm) with small surface protrusions are formed when 1,×,10,4,g mL,1 BSA is used. As the reaction temperature is increased towards 80,°C, the size of NCs decreases and they acquire somewhat cubic geometries (49.1,±,7.0,nm) due to a change in the capping behavior of BSA between its native and denatured states. The native and denatured states of BSA are simultaneously studied by fluorescence spectroscopy using tryptophan emission, and pH measurements with respect to time and temperature. Gel electrophoresis is used to determine the polarity of the BSA capped NCs. Only the small sized NCs conjugated with relatively larger amounts of BSA show a displacement towards the positively charged electrode in comparison to larger NCs with lower amounts of BSA capping. It was concluded that the denatured state of BSA is more effective in controlling the crystal growth of PbS than its native state especially in the low concentration range. [source]

    Conversation Orientation and Cognitive Processes: A Comparison of U.S. Students in Initial Interaction With Native- Versus Nonnative-Speaking Partners

    Ling Chen
    The present study compares thought patterns, perceptions of interaction (perceived interaction smoothness and interaction involvement), and conversation orientation of U.S. students (N = 60) in dyadic interaction with a partner who is either another American or a non-American nonnative speaker of English. As hypothesized, U.S. participants with nonnative-speaking partners perceived interaction as more difficult, or less smooth, than did their counterparts with native-speaking partners. U.S. participants with nonnative-speaking partners also displayed different thought patterns, having more thoughts showing confusion, as well as more thoughts focused on the partner and less on the content of the ongoing conversation, than those with fellow native-speaking partners. U.S. participants with a nonnative-speaking partner also exhibited a different conversation orientation pattern, focusing more on understanding of the other's message, less on clarifying their own message, and less on displaying their own involvement. Specific thought categories and perceived interaction smoothness were correlated with conversation orientation indices for participants in interactions between native and nonnative speakers. Finally, interaction involvement was found to contribute most to variation in perceived interaction smoothness for both U.S. and non-U.S. participants in interactions between native and nonnative speakers. Implications of the findings are discussed. [source]

    Strategies for developing multi-epitope, subunit-based, chemically synthesized anti-malarial vaccines

    M. E. Patarroyo
    ,,Introduction ,,P. falciparum invasion of RBCs ,,Merozoite proteins involved in invading erythrocytes ,,Erythrocyte proteins involved in merozoite invasion ,,The state of current worldwide anti-malarial vaccine approaches ,,A rational approach towards developing subunit-based synthetic vaccines ,,The immune response elicited by conserved HABPs ,,Structural analysis of native and modified HABPs ,,Secondary structure analysis ,,Native and modified HABP 3D structure explains some immunological phenomena ,,Supporting the haplotype , and allele-conscious TCR concept ,,Modified HABPs' 3D structure revealed a fit into HLA molecules ,,Conclusion Abstract An anti-malarial vaccine against the extremely lethal Plasmodium falciparum is desperately needed. Peptides from this parasite's proteins involved in invasion and having high red blood cell-binding ability were identified; these conserved peptides were not immun genic or protection-inducing when used for immunizing Aotus monkeys. Modifying some critical binding residues in these high-activi binding peptides' (HABPs') attachment to red blood cells (RBC) allowed them to induce immunogenicity and protection against expermental challenge and acquire the ability to bind to specific HLA-DRp1* alleles. These modified HABPs adopted certain characterist structural configurations as determined by circular dichroism (CD) and 1H nuclear magnetic resonance (NMR) associated with certain HLA-DR,1* haplotype binding activities and characteristics, such as a 2-Å-distance difference between amino acids fitting into HLA-DRp1 Pockets 1 to 9, residues participating in binding to HLA-DR pockets and residues making contact with the TCR, suggesting haplotyp and allele-conscious TCR. This has been demonstrated in HLA-DR-like genotyped monkeys and provides the basis for designing high effective, subunit-based, multi-antigen, multi-stage, synthetic vaccines, for immediate human use, malaria being one of them. [source]

    Honoring children, mending the circle: cultural adaptation of trauma-focused cognitive-behavioral therapy for American Indian and Alaska Native children

    Dolores Subia BigFoot
    Abstract American Indians and Alaska Natives are vulnerable populations with significant levels of trauma exposure. The Indian Country Child Trauma Center developed an American Indian and Alaska Native (AI/AN) adaptation of the evidence-based child trauma treatment, trauma-focused cognitive-behavioral therapy. Honoring Children, Mending the Circle (HC-MC) guides the therapeutic process through a blending of AI/AN traditional teachings with cognitive-behavioral methods. The authors introduced the HC-MC treatment and illustrated its therapeutic tools by way of a case illustration. © 2010 Wiley Periodicals, Inc. J Clin Psychol: In Session 66:1,10, 2010. [source]

    The Use of Potato and Sweet Potato Starches Affects White Salted Noodle Quality

    Z. CHEN
    ABSTRACT Potato and sweet potato starches and derivatives thereof were used to substitute part of the wheat flour in white salted noodle (WSN) manufacture. The quality of the WSN obtained was compared with the quality of WSN made from wheat flour only. When up to 20% of wheat flour was replaced by acetylated potato starch and acetylated sweet potato starches, the cooking loss of WSN decreased, while the softness, stretchability, and slipperiness increased significantly. Native and hydroxypropylated starches did not exhibit these effects. It can be concluded that the substitution of part of wheat flour with acetylated starches strongly affects noodle-making and final noodle quality, and starch substitution can be used to change the performance of a given wheat flour for noodle making in a desired way. [source]

    Genetic Analysis of Tolerance to Rice Tungro Bacilliform Virus in Rice (Oryza sativa L.) Through Agroinoculation

    N. S. Zenna
    Abstract Balimau Putih [an Indonesian cultivar tolerant to rice tungro bacilliform virus (RTBV)] was crossed with IR64 (RTBV, susceptible variety) to produce the three filial generations F1, F2 and F3. Agroinoculation was used to introduce RTBV into the test plants. RTBV tolerance was based on the RTBV level in plants by analysis of coat protein using enzyme-linked immunosorbent assay. The level of RTBV in cv. Balimau Putih was significantly lower than that of IR64 and the susceptible control, Taichung Native 1. Mean RTBV levels of the F1, F2 and F3 populations were comparable with one another and with the average of the parents. Results indicate that there was no dominance and an additive gene action may control the expression of tolerance to RTBV. Tolerance based on the level of RTBV coat protein was highly heritable (0.67) as estimated using the mean values of F3 lines, suggesting that selection for tolerance to RTBV can be performed in the early selfing generations using the technique employed in this study. The RTBV level had a negative correlation with plant height, but positive relationship with disease index value. [source]

    Phytogenic resources of halophytes of Central Asia and their role for rehabilitation of sandy desert degraded rangelands

    K. N. Toderich
    Abstract Based on soil characteristics, watertable level, mineral composition of plant biomass, morphological/reproductive traits and carbon discrimination values, a new concept for the classification of halophytes was developed. Six main groups of halophytes have been described within the desert flora of Central Asia. Significant changes on chemical contents of ions: Cl,, SO, HCO, Na+, K+, Ca2+ and Mg2+among 23 studied halophytic forage species were revealed. Alhagi pseudoalhagi, Poaceae spp., Artemisia diffusa containing minimum concentration of mineral ions were categorised as relatively more palatable and valuable feed for livestock on open grazing and as hay. Fresh biomass of forage species growing under highly saline soils sharply decreased with increasing of salinity gradient. Potassium concentration was found highest in Kochia scoparia, Agropyron desertorum, closely followed by Atriplex nitens, Suaeda salsa, while annuals Salsola spp., Bromus tectorum, Aeluropus littoralis, Tamarix hispida, Eremopyrum orientale, Agropyron desertorum contain low amount of mineral ions because excess of salts are exuded through salt glands present abundantly on the surface of the epidermis. Native and exotic, both C3 and C4, halophytes are suitable for reclamation of degraded lands have been proven very useful in demonstration trials. The fresh biomass of investigated C3 plants sharply decreased with the increasing of soil salinity gradient. An integrated Biosaline Agriculture model for sustainable and integrated use of marginal mineralised water resources and salt-affected soils through involvement of food,feed salt/drought tolerant crops and forage legumes to improve food security, alleviate poverty and enhance ecosystem health in smallholder crop,livestock systems has been demonstrated. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Establishing native plants on newly-constructed and older-reclaimed sites along West Virginia highways

    J.G. Skousen
    Abstract Many state highway departments in the USA must use native plants for revegetating roadsides. We conducted two field studies in West Virginia to assess native plant establishment under two different conditions. On newly-constructed sites, native species were seeded alone or combined with non-native species. On older roadsides, native species were seeded in disturbed existing vegetation. In the first study, we used four seed mixtures comprised of seeds of native and non-native species, and two N-P-K fertilizer treatments at three newly-constructed sites. Native, warm-season grasses were slow to establish and only contributed 25 per cent cover in some plots after three years. Indiangrass (Sorghastrum nutans [L.] Nash), big bluestem (Andropogon gerardii Vitman), Brown-Eyed Susan (Rudbeckia triloba L.), and wild senna (Cassia hebecarpa Fernald) were the only seeded native species found. Fertilizer at 150,kg,ha,1 of 10-20-10 showed little influence on increasing plant cover. In the second study, we disturbed three different-aged established stands of vegetation composed of tall fescue (Festuca arundinacea Screb.) and crownvetch (Coronilla varia L.) by mowing, herbicide, or tillage, and native plants were seeded with and without fertilizer. Native cover was <10 per cent in all plots during the first year, but greatly increased by the second year to as much as 45 per cent in tilled plots, indicating that disturbance was necessary for natives to become important contributors within 2 years. Only switchgrass (Panicum virgatum L.), little bluestem (Andropogon scoparius Vitman), partridge pea (Chamaecrista fasciculate Michx.), and Brown-Eyed Susan were observed in plots. Fertilizer at 300,kg,ha,1 of 10-20-10 did not increase native plant cover on these sites. Based on our results, introducing or increasing the cover of native species along roadsides requires (1) reducing competition from non-native species, and (2) longer time periods for these slower-establishing species to be observed. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Origin and genetic diversity of Western European populations of the potato cyst nematode (Globodera pallida) inferred from mitochondrial sequences and microsatellite loci

    MOLECULAR ECOLOGY, Issue 9 2008
    Abstract Native to South America, the potato cyst nematode Globodera pallida is one of the principal pests of Andean potato crops and is also an important global pest following its introduction to Europe, Africa, North America, Asia and Oceania. Building on earlier work showing a clear south to north phylogeographic pattern in Peruvian populations, we have been able to identify the origin of Western European populations with high accuracy. They are all derived from a single restricted area in the extreme south of Peru, located between the north shore of the Lake Titicaca and Cusco. Only four cytochrome b haplotypes are found in Western Europe, one of them being also found in some populations of this area of southern Peru. The allelic richness at seven microsatellite loci observed in the Western European populations, although only one-third of that observed in this part of southern Peru, is comparable to the allelic richness observed in the northern region of Peru. This result could be explained by the fact that most of the genetic variability observed at the scale of a field or even of a region is already observed at the scale of a single plant within a field. Thus, even introduction via a single infected potato plant could result in the relatively high genetic variability observed in Western Europe. This finding has important consequences for the control of this pest and the development of quarantine measures. [source]

    The ruddy duck Oxyura jamaicensis in Europe: natural colonization or human introduction?

    MOLECULAR ECOLOGY, Issue 6 2006
    Abstract Native to North America, ruddy ducks Oxyura jamaicensis now occur in 21 countries in the western Palaearctic (including Iceland) and their expanding population threatens the native white-headed duck, Oxyura leucocephala, through hybridization and possibly competition for food and nest sites. We used mitochondrial DNA sequences and nuclear microsatellites to test whether the European ruddy duck population is descended solely from the captive population in the UK, which traces to seven individuals imported from the USA in 1948, or, alternatively, has been augmented by natural dispersal of birds from North America. Limited genetic diversity in the European population is consistent with a founder population as small as seven birds. In addition, shifts in allele frequencies at several loci, presumably due to genetic drift in the founding population, result in significant differentiation between the European and North American populations. Despite the recent separation of these populations, almost all individuals could be unambiguously assigned based on their composite genotypes, to one of two distinct populations, one comprising all of the European ruddy ducks we sampled (including those from Iceland and captive birds in the UK) and the other comprising all North American samples. Our results confirm that the European ruddy duck population is likely to derive solely from the captive population in the UK and we find no evidence of recent arrivals from North America or of admixture between ruddy ducks from Europe and North America. [source]

    Growth phase-dependent expression and degradation of histones in the thermophilic archaeon Thermococcus zilligii

    Marcel E. Dinger
    HTz is a member of the archaeal histone family. The archaeal histones have primary sequences and structural similarity to the eukaryal histone fold domain, and are thought to resemble the archetypal ancestor of the eukaryal nucleosome core histones. The effects of growth phase on the total soluble proteins from Thermococcus zilligii, isolated after various stages of growth from mid-logarithmic to late stationary phase, were examined by denaturing polyacrylamide gel electrophoresis. On entry into stationary phase, at least 11 proteins were detected that changed considerably in level. One of these proteins was identified by Western hybridization as HTz. The level of HTz decreased dramatically as cells entered stationary phase, and it could not be detected by late stationary phase. Unexpectedly, the Western hybridization detected a second protein, with an estimated molecular mass of approximately 14 kDa, which paralleled the decrease in level of HTz. Native purified HTz was shown to retain complete activity after prolonged incubation at the growth temperature of the organism, suggesting that the decrease in HTz was a specific cell-regulated process. Analysis of native purified HTz by electrospray ionization mass spectrometry revealed the molecular masses of HTz1 and HTz2 to be 7204 ± 3 Da and 7016 ± 3 Da respectively. The only non-covalent species that was detected corresponded to the molecular mass of an HTz1,HTz2 heterodimer. Northern analyses of T. zilligii total RNA with an htz1 gene probe indicated a rapid decrease in expression of htz1 with progression of the growth phase, and complete repression of htz1 transcript synthesis by late logarithmic phase. Three proteins that changed in level with growth phase were identified by N-terminal sequence analysis. The first was homologous to a hypothetical protein conserved in all Archaea sequenced to date, the second to the Sac10b family of archaeal DNA-binding proteins and the third to the C-terminal region of the leucine-responsive regulatory family of DNA-binding proteins (LRPs). [source]

    The Political Economy of the Ecological Native

    In Chimalapas, Mexico, nongovernmental actors attempted to integrate campesinos into the discourse and practices of the Western environmental movement. The political economy school of anthropology assumes that cultural identity and practice flow from historical experiences grounded in relevant national and institutional contexts. In this article, I argue that although the movement in Chimalapas drew from the well-developed symbolic toolkit of the environmental movement, it was not able to create a space for local concerns within a transnational agenda that was already fairly well established and inflexible. Political ecology was the hinge of this movement: a political-economic analysis that validated traditional agrarian concerns in Chimalapas but included an environmentalist discourse legible to international funders. In this way, environmentalists in Chimalapas attempted both to create new practices and to link old practices to new expressions of culture and identity. [source]

    The Praxis of Indigenism and Alaska Native Timber Politics

    Kirk Dombrowski
    This article addresses the most recent discourse on indigenism in Southeast Alaska that has emerged around the Alaska Native Claims Settlement Act of 1971 and its subsequent revisions. It argues that one must consider the "politics of recognition" in Southeast Alaska in terms of the larger political dynamics that shape state and industry access to resources, especially commercially valuable stands of timber. In Southeast Alaska, recognition of Native claims has allowed industrial timber and pulp producers to, in effect, circumvent environmental laws aimed at curbing production, thus allowing them to continue devastating the living conditions of many Natives. Among the local responses to the manipulation of Native claims and identity, the all,Native, radical Christian churches that have taken a strong stance against the recent, corporate,sponsored, cultural revitalization are unique in their resistance to indigenist politics. [Keywords: indigenism, Alaska Natives, development, Pentecostalism] [source]

    Native and nonnative conformational preferences in the urea-unfolded state of barstar

    PROTEIN SCIENCE, Issue 12 2004
    Neel S. Bhavesh
    NMR, nuclear magnetic resonance; HSQC, hetero-nuclear single-quantum coherence Abstract The refolding of barstar from its urea-unfolded state has been studied extensively using various spectroscopic probes and real-time NMR, which provide global and residue-specific information, respectively, about the folding process. Here, a preliminary structural characterization by NMR of barstar in 8 M urea has been carried out at pH 6.5 and 25°C. Complete backbone resonance assignments of the urea-unfolded protein were obtained using the recently developed three-dimensional NMR techniques of HNN and HN(C)N. The conformational propensities of the polypeptide backbone in the presence of 8 M urea have been estimated by examining deviations of secondary chemical shifts from random coil values. For some residues that belong to helices in native barstar, 13C, and 13CO secondary shifts show positive deviations in the urea-unfolded state, indicating that these residues have propensities toward helical conformations. These residues are, however, juxtaposed by residues that display negative deviations indicative of propensities toward extended conformations. Thus, segments that are helical in native barstar are unlikely to preferentially populate the helical conformation in the unfolded state. Similarly, residues belonging to ,-strands 1 and 2 of native barstar do not appear to show any conformational preferences in the unfolded state. On the other hand, residues belonging to the ,-strand 3 segment show weak nonnative helical conformational preferences in the unfolded state, indicating that this segment may possess a weak preference for populating a helical conformation in the unfolded state. [source]

    Integrity of thermus thermophilus cytochrome c552 Synthesized by escherichia coli cells expressing the host-specific cytochrome c maturation genes, ccmABCDEFGH: Biochemical, spectral, and structural characterization of the recombinant protein

    PROTEIN SCIENCE, Issue 11 2000
    James A. Fee
    Abstract We describe the design of Escherichia coli cells that synthesize a structurally perfect, recombinant cytochrome c from the Thermus thermophilus cytochrome c552 gene. Key features are (1) construction of a plasmid-borne, chimeric cycA gene encoding an Escherichia coli -compatible, N-terminal signal sequence (MetLysIleSerIleTyrAlaThrLeu AlaAlaLeuSerLeuAlaLeuProAlaGlyAla) followed by the amino acid sequence of mature Thermus cytochrome c552; and (2) coexpression of the chimeric cycA gene with plasmid-borne, host-specific cytochrome c maturation genes (ccmABCDEFGH). Approximately 1 mg of purified protein is obtained from 1 L of culture medium. The recombinant protein, cytochrome rsC552, and native cytochrome c552 have identical redox potentials and are equally active as electron transfer substrates toward cytochrome ba3, a Thermus heme-copper oxidase. Native and recombinant cytochromes c were compared and found to be identical using circular dichroism, optical absorption, resonance Raman, and 500 MHz 1H-NMR spectroscopies. The 1.7 Å resolution X-ray crystallographic structure of the recombinant protein was determined and is indistinguishable from that reported for the native protein (Than, ME, Hof P, Huber R, Bourenkov GP, Bartunik HD, Buse G, Soulimane T, 1997, J Mol Biol 271:629,644). This approach may be generally useful for expression of alien cytochrome c genes in E. coli. [source]

    Effects of Native and Non-Native Grassland Plant Communities on Breeding Passerine Birds: Implications for Restoration of Northwest Bunchgrass Prairie

    Patricia L. Kennedy
    Abstract One common problem encountered when restoring grasslands is the prominence of non-native plant species. It is unclear what effect non-native plants have on habitat quality of grassland passerines, which are among the most imperiled groups of birds. In 2004 and 2005, we compared patterns of avian reproduction and the mechanisms that might influence those patterns across a gradient of 13 grasslands in the Zumwalt Prairie in northeastern Oregon that vary in the degree of non-native plant cover (0.9,53.4%). We monitored the fate of 201 nests of all the breeding species in these pastures and found no association of percent non-native cover with nest densities, clutch size, productivity, nest survival, and nestling size. Regardless of the degree of non-native cover, birds primarily fed on Coleoptera, Orthoptera, and Araneae. But as percent non-native cover in the pastures increased, Orthoptera made up a greater proportion of diet and Coleoptera made up a smaller proportion. These diet switches were not the result of changes in terrestrial invertebrate abundance but may be related to decreases in percent bare ground associated with increasing cover of non-native vegetation. Measures of nest crypticity were not associated with cover of non-native vegetation, suggesting that predation risk may not increase with increased cover of non-native vegetation. Thus, the study results show that increased non-native cover is not associated with reduced food supplies or increased predation risk for nesting birds, supporting the growing body of evidence that grasslands with a mix of native and non-native vegetation can provide suitable habitat for native grassland breeding birds. [source]

    Effect of Hydrologic Restoration and Lonicera maackii Removal on Herbaceous Understory Vegetation in a Bottomland Hardwood Forest

    Rebecca M. Swab
    Abstract Amur honeysuckle (Lonicera maackii (Rupr.) Herder), a large deciduous shrub from China, has invaded many forests in eastern/central United States. The species was removed by cutting and herbicide application from a recently hydrologically restored section of a bottomland hardwood forest in central Ohio, and the response of understory plants, especially herbaceous species, was measured. Plots were established in uncleared and cleared sections, and percent cover of each herbaceous understory species was estimated monthly. One season after several years of Lonicera removal efforts, no significant association was discovered between percentage of Lonicera cover and total understory species abundance. There was, however, a direct correlation between elevation and honeysuckle abundance; L. maackii abundance was negatively associated with low elevations, likely due to hydrologic factors. Plant species diversity (H) and richness (s) increased with elevation but were not significantly different on plots with honeysuckle removal (H = 0.86 ± 0.08 vs. 0.78 ± 0.09 and s = 4.4 ± 0.19 vs. 4.2 ± 0.2 species/m2, respectively) despite the fact that understory light levels measured by densiometer were significantly higher (,= 0.003) in cleared versus uncleared sections. Native and invasive species were found in similar proportions in the two sections, and significant sprouting and regrowth of L. maackii were observed throughout the cleared section. Although the removal of L. maackii altered the characteristics of the plant species assemblage, the value of this management remains questionable in the years immediately following treatment. [source]

    Response of Native and Exotic Grasses to Increased Soil Nitrogen and Recovery in a Postfire Environment

    Molly E. Hunter
    Abstract Native plant recovery following wildfires is of great concern to managers because of the potential for increased water run-off and soil erosion associated with severely burned areas. Although postfire seeding with exotic grasses or cultivars of native grasses (seeded grasses) may mitigate the potential for increased run-off and erosion, such treatments may also be detrimental to long-term recovery of other native plant species. The degree to which seeded grasses dominate a site and reduce native plant diversity may be a function of the availability of resources such as nitrogen and light and differing abilities of native and seeded grasses to utilize available resources. We tested the hypothesis that seeded grasses have higher growth rates than native grasses when nitrogen and light availability is high in a greenhouse experiment. To determine how differing resource utilization strategies may affect distribution of native and seeded grasses across a burned landscape, we conducted botanical surveys after a wildfire in northern New Mexico, U.S.A., one and four years after the fire. In the greenhouse study we found seeded grasses to produce significantly more biomass than native grasses when nitrogen and light availability was high. Seeded grasses increased in cover from 1,4 years after the fire only in areas where total soil nitrogen was higher. Increased cover of seeded grasses did not affect recovery of native grasses, but it did lead to reduced native species richness at small scales. The potential negative long-term consequences of seeding with exotic grasses should be considered in postfire rehabilitation treatments. [source]

    Negotiating the production of space in Tl'azt,en territory, Northern British Columbia

    Societies produce the space in which they operate through social practices that visualize, administer, and use lands and resources. Because Native peoples have held relatively little political power, their ability to influence the production of space has received little attention. Yet the superimposition of Euro-Canadian social practices onto Native spaces rarely erased native spatiality, but rather created a territory made up of shared and hybrid spaces which resulted from the interaction of Native and Euro-Canadian societies. This paper suggests that the social processes involved in the production of space are perhaps most visible when two parties are negotiating the allocation and management of lands and resources. In the 1970s the Tl'azt'en engaged in negotiations over the construction of a railway through their territory. Through the negotiations Tl'azt'en social and economic goals were inscribed to a significant degree in the spatial organization of the territory. Like current treaty negotiations, the 1970s negotiations involved compromises by both parties, and resulted in the creation of new hybrid social spaces which reflected the goals and strategies of both groups. Les sociétés produisent l'espace dans lequel elles opèrent à travers des pratiques sociales qui visualisent, administrent et utilisent les terres et les ressources. Parceque les peuple Natifs ont eu relativement peu de pouvoir politique, leur capacitéà influencer la production de l'espace a reçu peu d'attention. Cependant, l'imposition de pratiques sociales Euro-Canadiennes sur les espaces Natfs a rarement effacé la spatialité indigené, mais a plutôt crée un territoire composé d'espaces partagés et hybrides, résultat de l'intéraction des sociétés indigènes et Euro-Canadiennes. Cet exposé suggère que les procédés sociaux impliqués dans lá production de l'espace sont peut-être plus visibles quand deux partis négocient l'allocation et la gestion des terres et des ressources. Dans les années 70, le peuple Tl'azt'en s'est engagé dans des négociations au sujet de la construction d'un chemin de fer à travers leur territoire. Dans ces négociations, les buts sociaux et économiques du Tl'azt'en furent inscrits à un degré significatif dans l'organisation spatiale du territoire. Comme les présentes négociations de traité, les négociations des années 1970 ont impliqué des compromis par les deux partis, et ont résultéà la création de nouveaux espaces sociaux hybrides qui reflétaient les buts et stratégies des deux groupes. [source]