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1.
Jane Remer 《Arts Education Policy Review》2013,114(3):81-96
This article explores the process of using lessons learned about high quality, effective arts education programs to help local educational leaders and practitioners create their own policy statements. It raises questions about policy implications from those lessons and connects them to the readers'own experience. It provides an intellectual framework and an action agenda for developing local policy at the classroom, school, or district level that supports high quality arts education for every student. It argues that effective arts education programs must be supported by responsive policy and ongoing tax levy funds to have a greater chance for providing quality arts teaching and learning that endures. 相似文献
2.
You Have to Be Your Own Doctor: Sociocultural Influences on Alternative Therapy Use among Gay Men with AIDS in West Hollywood 总被引:1,自引:0,他引:1
Jennifer J. Furin 《Medical anthropology quarterly》1997,11(4):498-504
This article considers the use of alternative therapies by gay men with AIDS in West Hollywood, California. In all, 89 different alternative therapies for HIV and AIDS treatment were uncovered during the course of the study. In addition to the high number of alternative therapies, a majority of the men in the study (69.2 percent) were currently using some type of alternative treatment. Sociocultural influences on the use of alternative therapies are explored, including AIDS activism. Because most of the men (92 percent) also use Western medicine as well, the interface of these two types of treatments is also explored, [alternative therapies, AIDS, gay men] 相似文献
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Multiple diversification rate shifts explain uneven clade richness in muroid rodents. Previous muroid studies have shown that extrinsic factors, notwithstanding ecological opportunity, are poor predictors of clade diversity. Here, we use a 297-muroid species chronogram that is sampled proportional to total clade diversity, along with various trait-dependent diversification approaches to investigate the association between diversification rates with intrinsic attributes—diet, habitat, body mass, and relative tail length. We found some association between both dietary specialization and body mass, as well as between habitat specialization with relative tail lengths using phylogenetic analyses of variance. However, there was no significant association between diversification rates with the evolution of these traits in muroid rodents. We also show that several of the state-dependent diversification approaches are highly susceptible to Type I error—a result that is in accordance with recent criticisms of these methods. Finally, we discuss several potential causes for the lack of association between the examined trait data with diversification rates, ranging from methodological biases (e.g. method conservativism) to biology (e.g. behavioral plasticity and ecological opportunism of muroid rodents). 相似文献
6.
In a series of experiments we examined heterosexuals’ reactions to the timing of disclosure of a gender-matched confederate’s same-sex dating partner. Disclosure occurred in a naturalistic context–that is, it occurred when meeting, or expecting to soon meet, a same-sex attracted individual, who voluntarily shared this information with the participant as a natural part of a broader topic of discussion. The confederate, when disclosing early rather than later, was approached more closely (Prestudy) and liked more (Studies 1–2). Those experiencing early disclosure, compared with later, were less drawn to topics of lower intimacy (Study 1), were happier and more excited about meeting the confederate, and more likely to choose to be alone with the confederate for a one-on-one discussion (Study 2). Further, women experiencing early disclosure were more willing to introduce the same-gender confederate to their friends (Study 2). The benefits of knowing sooner, rather than later, continued to apply even when participants were given further time to process the disclosure. To explore the underlying reasons for the more favorable experiences of upfront disclosure, we examined participants’ memory of the information shared by the confederate (Study 3). Results revealed that those who experienced delayed disclosure were more likely to incorrectly recall and negatively embellish information related to the confederate’s sexual orientation, suggesting that early disclosure resulted in a reduced tendency to focus on the confederate’s sexuality as a defining feature. These positive findings for early timing are discussed in light of previous studies that have found benefits for delayed disclosure and those that have failed to investigate the effects of timing of ‘coming out’ under conditions of contact. 相似文献
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Janina Brakel Franziska Julie Werner Verena Tams Thorsten B. H. Reusch Anna-Christina Bockelmann 《PloS one》2014,9(4)
Pro- and eukaryotic microbes associated with multi-cellular organisms are receiving increasing attention as a driving factor in ecosystems. Endophytes in plants can change host performance by altering nutrient uptake, secondary metabolite production or defense mechanisms. Recent studies detected widespread prevalence of Labyrinthula zosterae in European Zostera marina meadows, a protist that allegedly caused a massive amphi-Atlantic seagrass die-off event in the 1930''s, while showing only limited virulence today. As a limiting factor for pathogenicity, we investigated genotype×genotype interactions of host and pathogen from different regions (10–100 km-scale) through reciprocal infection. Although the endophyte rapidly infected Z. marina, we found little evidence that Z. marina was negatively impacted by L. zosterae. Instead Z. marina showed enhanced leaf growth and kept endophyte abundance low. Moreover, we found almost no interaction of protist×eelgrass-origin on different parameters of L. zosterae virulence/Z. marina performance, and also no increase in mortality after experimental infection. In a target gene approach, we identified a significant down-regulation in the expression of 6/11 genes from the defense cascade of Z. marina after real-time quantitative PCR, revealing strong immune modulation of the host''s defense by a potential parasite for the first time in a marine plant. Nevertheless, one gene involved in phenol synthesis was strongly up-regulated, indicating that Z. marina plants were probably able to control the level of infection. There was no change in expression in a general stress indicator gene (HSP70). Mean L. zosterae abundances decreased below 10% after 16 days of experimental runtime. We conclude that under non-stress conditions L. zosterae infection in the study region is not associated with substantial virulence. 相似文献
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Christine M. Fennessey Morris E. Jones Martial Taillefert Thomas J. DiChristina 《Applied and environmental microbiology》2010,76(8):2425-2432
Shewanella oneidensis MR-1 respires a wide range of anaerobic electron acceptors, including sparingly soluble Fe(III) oxides. In the present study, S. oneidensis was found to produce Fe(III)-solubilizing organic ligands during anaerobic Fe(III) oxide respiration, a respiratory strategy postulated to destabilize Fe(III) and produce more readily reducible soluble organic Fe(III). In-frame gene deletion mutagenesis, siderophore detection assays, and voltammetric techniques were combined to determine (i) if the Fe(III)-solubilizing organic ligands produced by S. oneidensis during anaerobic Fe(III) oxide respiration were synthesized via siderophore biosynthesis systems and (ii) if the Fe(III)-siderophore reductase was required for respiration of soluble organic Fe(III) as an anaerobic electron acceptor. Genes predicted to encode the siderophore (hydroxamate) biosynthesis system (SO3030 to SO3032), the Fe(III)-hydroxamate receptor (SO3033), and the Fe(III)-hydroxamate reductase (SO3034) were identified in the S. oneidensis genome, and corresponding in-frame gene deletion mutants were constructed. ΔSO3031 was unable to synthesize siderophores or produce soluble organic Fe(III) during aerobic respiration yet retained the ability to solubilize and respire Fe(III) at wild-type rates during anaerobic Fe(III) oxide respiration. ΔSO3034 retained the ability to synthesize siderophores during aerobic respiration and to solubilize and respire Fe(III) at wild-type rates during anaerobic Fe(III) oxide respiration. These findings indicate that the Fe(III)-solubilizing organic ligands produced by S. oneidensis during anaerobic Fe(III) oxide respiration are not synthesized via the hydroxamate biosynthesis system and that the Fe(III)-hydroxamate reductase is not essential for respiration of Fe(III)-citrate or Fe(III)-nitrilotriacetic acid (NTA) as an anaerobic electron acceptor.Bacterial electron transfer to sparingly soluble electron acceptors is a critical component of a wide variety of environmental and energy-generating processes, including biogeochemical cycling of metals, degradation of natural and contaminant organic matter, weathering of clays and minerals, biomineralization of Fe-bearing minerals, reductive precipitation of toxic metals and radionuclides, and electricity generation in microbial fuel cells (17, 33, 34). Anaerobic and facultatively anaerobic bacteria capable of respiring sparingly soluble (<10−25 M at pH 7) Fe(III) oxides are ubiquitous in nature and may be found in marine, freshwater, and terrestrial environments, including metal- and radionuclide-contaminated subsurface aquifers (25, 34). Fe(III)-respiring prokaryotes are also deeply rooted and scattered throughout the domains Bacteria and Archaea (possibly indicating an ancient metabolic process) and include hyperthermophiles, psychrophiles, acidophiles, and extreme barophiles (34). Despite their potential environmental, energy-generating, and evolutionary significance, the molecular details of microbial Fe(III) respiration remain unclear.Fe(III)-respiring, neutrophilic bacteria are presented with a unique physiological challenge: they are required to respire anaerobically on electron acceptors found largely as sparingly soluble Fe(III) oxides presumably unable to contact periplasm- or inner membrane (IM)-localized electron transport systems. To overcome this problem, Fe(III)-respiring bacteria are postulated to employ novel respiratory strategies not found in other bacteria (e.g., aerobes, denitrifiers, sulfate-reducing bacteria, and methanogens) that respire soluble electron acceptors (17, 38). The novel respiratory strategies include (i) a direct-contact pathway in which terminal Fe(III) reductases are secreted to the cell outer membrane (OM), where they contact and deliver electrons directly to external Fe(III) oxides (18, 23, 40, 42, 48, 57, 64, 67), (ii) a two-step electron shuttling pathway in which bacterially reduced endogenous or exogenous electron shuttles deliver electrons to external Fe(III) oxides in a second (abiotic) electron transfer reaction (11, 26, 39, 45), and (iii) a two-step Fe(III) chelation (solubilization) pathway in which Fe(III) oxides are first nonreductively dissolved by endogenously synthesized organic ligands prior to reduction of the resulting soluble organic Fe(III) [Fe(III) bound to an organic molecule] complexes (36, 59).Candidate organic ligands for production of soluble organic Fe(III) during anaerobic Fe(III) oxide respiration include siderophores, the Fe(III)-chelating compounds synthesized and secreted by a wide variety of bacteria and fungi for solubilization and subsequent assimilation of otherwise inaccessible Fe(III) substrates (12, 44, 49, 63). Hydroxamate-type siderophores are produced via N6 hydroxylation and N6 acylation of l-ornithine and, in some cases, cyclization to macrocyclic ring structures (13). The macrocyclic siderophores bisucaberin and putrebactin, for example, are two structural analogs of the cyclic bis(hydroxamate) siderophore alcaligin, synthesized by Aliivibrio salmonicida and Shewanella putrefaciens strain 200, respectively (27, 32, 65). After transport across the cell envelope via a TonB-dependent pathway, Fe(III) is subsequently released from the Fe(III)-siderophore complex by ligand exchange reactions promoted by siderophore ligand hydrolysis and/or protonation or by Fe(III)-siderophore reduction and release of Fe(II) to acceptor ligands (9, 66).The main objectives of the present study were to determine (i) if the Fe(III)-solubilizing organic ligands produced by S. oneidensis during anaerobic Fe(III) oxide respiration are synthesized by Fe(III)-siderophore biosynthesis systems and (ii) if Fe(III)-siderophore reductases are required for respiration of soluble organic Fe(III) as an anaerobic electron acceptor. The experimental strategy for this study included (i) identification of genes encoding the siderophore biosynthesis and Fe(III)-siderophore reductase systems in the S. oneidensis genome, (ii) generation of in-frame deletions in the corresponding siderophore biosynthesis and Fe(III)-siderophore reductase genes, (iii) tests of the resulting siderophore biosynthesis mutants for production of siderophores and soluble organic Fe(III) during aerobic and anaerobic Fe(III) oxide respiration, and (iv) tests of the resulting Fe(III)-siderophore reductase mutants for respiration of soluble organic Fe(III) as an anaerobic electron acceptor. 相似文献
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Sequences from the ribosomal nuclear internal transcribed spacers (ITS) have been widely used to infer evolutionary hypotheses
across a broad range of living organisms. Intraspecific sequence variation is assumed to be absent or negliable in most species,
but few detailed studies have been conducted to assess the apportionment of ITS sequence variation within and between plant
populations. Buxus balearica was chosen as a model species to assess the levels of infraspecific and intragenomic ITS variation in rare and endangered
species occurring in disjunct populations around the Mediterranean basin. Intragenomic polymorphic sites were detected for
western and eastern accessions of B. balearica and in two accessions of the sister species B. sempervirens. Overall, 19 different ribotypes were found in B. balearica after sequencing 48 clones, whereas 15 ribotypes were detected in 19 clones of B. sempervirens. The integrity and secondary structure stability of the ribosomal sequences suggest that they are not pseudogenes. The high
number of ribotypes recovered through cloning suggested that some sequences could be chimeric or generated in vivo by partial
homogenization through gene conversion or unequal crossing-over. Average sequence divergence among B. balearica clones was 0.768%, and the most divergent sequences differed by 1.62%. Available evidence does not suggest that B. balearica paralogues have been obtained from other extant Buxus species through interspecific hybridization. The presence of several ribosomal sequences in box implies that the molecular forces
driving the concerted evolution of this multigene family are not fully operational in this genus. Phylogenetic analyses of
cloned ITS sequences from B. balearica displayed very poor resolution and only two clades received moderate bootstrap support. Despite the marked intragenomic sequence
divergence found, ribosomal data suggest a clear phylogeographic split in B. balearica between western and eastern accessions. The distinct, nonchimeric sequences that are postulated as being present in each
biogeographic group suggest that box populations from Anatolia (eastern Mediterranean) are relict.
[Reviewing Editor: Dr. Rafael Zardoya] 相似文献
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Though salmonid fishes are a well-studied group, phylogenetic questions remain, especially with respect to genus-level relationships. These questions were addressed with duplicate growth hormone (GH) introns. Intron sequences from each duplicate gene yielded phylogenetic trees that were not significantly different from each other in topology. Statistical tests supported validity of the controversial monotypic genusParahucho,monophyly ofOncorhynchus,and inclusion ofAcantholingua ohridanawithinSalmo.Suprisingly, GH1 intron C (GH1C) did not support the widely accepted hypothesis thatOncorhynchus(Pacific salmon and trout) andSalmo(Atlantic salmon and trout) are sibling genera; GH2C was ambiguous at this node. Previously published data were also examined for support ofSalmoandOncorhynchusas sister taxa and only morphology showed significant support. If not sister taxa, the independent evolution of anadromy—the migration to sea and return to freshwater for spawning—is most parsimonious. While there was incongruence with and among published data sets, the GH1C intron phylogeny was the best hypothesis, based on currently available molecular data. 相似文献
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Hylema sp.5females oviposit on the undersides of sepals of developing buds of both Ipomopsis aggregata and Polemonium foliosissimum. Eggs deposited on the latter are significantly more likely to be fully protected by the sepal than are eggs deposited on the former. Unexposed eggs have a significantly greater likelihood of successfully developing to the larval stage than do exposed eggs. The difference in frequency of egg exposure on the two plant species can be attributed to differences in sepal morphology: I. aggregata sepals are significantly narrower than those of P. foliosissimum. The hypothesis that females preferentially oviposit on larger flowers was unconfirmed by a manipulative choice experiment. Plants differing in the size of their flowers were potted together and presented to Hylemya in arrays in the field. Flowers of the larger-flowered pair were no more likely to be oviposited on than flowers of the smaller-flowered pair. However, there were significant negative correlations between the corolla length and the percentage of flowers laid on per day at each of two sites. There was also a significant positive correlation between the corolla width and the percentage of flowers laid on at one site. Thus females appear to be using some measure of flower morphology, or a correlated trait, in making oviposition decisions. The degree to which Hylemya is making suboptimal choices between host plant species is discussed and requires further examination. 相似文献
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Joshua M. Plotnik Jennifer J. Pokorny Titiporn Keratimanochaya Christine Webb Hana F. Beronja Alice Hennessy James Hill Virginia J. Hill Rebecca Kiss Caitlin Maguire Beckett L. Melville Violet M. B. Morrison Dannah Seecoomar Benjamin Singer Jehona Ukehaxhaj Sophia K. Vlahakis Dora Ylli Nicola S. Clayton John Roberts Emilie L. Fure Alicia P. Duchatelier David Getz 《PloS one》2013,8(4)
Recent research suggests that domesticated species – due to artificial selection by humans for specific, preferred behavioral traits – are better than wild animals at responding to visual cues given by humans about the location of hidden food. \Although this seems to be supported by studies on a range of domesticated (including dogs, goats and horses) and wild (including wolves and chimpanzees) animals, there is also evidence that exposure to humans positively influences the ability of both wild and domesticated animals to follow these same cues. Here, we test the performance of Asian elephants (Elephas maximus) on an object choice task that provides them with visual-only cues given by humans about the location of hidden food. Captive elephants are interesting candidates for investigating how both domestication and human exposure may impact cue-following as they represent a non-domesticated species with almost constant human interaction. As a group, the elephants (n = 7) in our study were unable to follow pointing, body orientation or a combination of both as honest signals of food location. They were, however, able to follow vocal commands with which they were already familiar in a novel context, suggesting the elephants are able to follow cues if they are sufficiently salient. Although the elephants’ inability to follow the visual cues provides partial support for the domestication hypothesis, an alternative explanation is that elephants may rely more heavily on other sensory modalities, specifically olfaction and audition. Further research will be needed to rule out this alternative explanation. 相似文献
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Understanding how enzyme specificity evolves will provide guiding principles for protein engineering and function prediction. The o-succinylbenzoate synthase (OSBS) family is an excellent model system for elucidating these principles because it has many highly divergent amino acid sequences that are <20% identical, and some members have evolved a second function. The OSBS family belongs to the enolase superfamily, members of which use a set of conserved residues to catalyze a wide variety of reactions. These residues are the only conserved residues in the OSBS family, so they are not sufficient to determine reaction specificity. Some enzymes in the OSBS family catalyze another reaction, N-succinylamino acid racemization (NSAR). NSARs cannot be segregated into a separate family because their sequences are highly similar to those of known OSBSs, and many of them have both OSBS and NSAR activities. To determine how such divergent enzymes can catalyze the same reaction and how NSAR activity evolved, we divided the OSBS family into subfamilies and compared the divergence of their active site residues. Correlating sequence conservation with the effects of mutations in Escherichia coli OSBS identified two nonconserved residues (R159 and G288) at which mutations decrease efficiency ≥200-fold. These residues are not conserved in the subfamily that includes NSAR enzymes. The OSBS/NSAR subfamily binds the substrate in a different orientation, eliminating selective pressure to retain arginine and glycine at these positions. This supports the hypothesis that specificity-determining residues have diverged in the OSBS family and provides insight into the sequence changes required for the evolution of NSAR activity. 相似文献
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Sorption of Fe (Hydr)Oxides to the Surface of Shewanella putrefaciens: Cell-Bound Fine-Grained Minerals Are Not Always Formed De Novo 总被引:1,自引:0,他引:1
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Shewanella putrefaciens, a gram-negative, facultative anaerobe, is active in the cycling of iron through its interaction with Fe (hydr)oxides in natural environments. Fine-grained Fe precipitates that are attached to the outer membranes of many gram-negative bacteria have most often been attributed to precipitation and growth of the mineral at the cell surface. Our study of the sorption of nonbiogenic Fe (hydr)oxides revealed, however, that large quantities of nanometer-scale ferrihydrite (hydrous ferric oxide), goethite (α-FeOOH), and hematite (α-Fe2O3) adhered to the cell surface. Attempts to separate suspensions of cells and minerals with an 80% glycerin cushion proved that the sorbed minerals were tightly attached to the bacteria. The interaction between minerals and cells resulted in the formation of mineral-cell aggregates, which increased biomass density and provided better sedimentation of mineral Fe compared to suspensions of minerals alone. Transmission electron microscopy observations of cells prepared by whole-mount, conventional embedding, and freeze-substitution methods confirmed the close association between cells and minerals and suggested that in some instances, the mineral crystals had even penetrated the outer membrane and peptidoglycan layers. Given the abundance of these mineral types in natural environments, the data suggest that not all naturally occurring cell surface-associated minerals are necessarily formed de novo on the cell wall. 相似文献
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Ian C. W. Hardy Stinne Stokkebo Jesper Bønløkke-Pedersen & Mikael K. Sejr 《Ethology : formerly Zeitschrift fur Tierpsychologie》2000,106(11):1021-1032
Models considering sex ratio optima under single foundress strict local mate competition predict that female bias will be reduced by stochasticity in sex allocation, developmental mortality of males and limited insemination capacity of males. In all three cases the number of males per brood is expected to increase with brood size. Sex ratio optima may also be less female biased when several mothers contribute offspring to local mating groups or if non‐local mating occurs between members of different broods; again more males are expected in larger broods. In the parasitoid wasp Goniozus legneri (Hymenoptera: Bethylidae), sex allocation has only a small stochastic component, developmental mortality is low and non‐siblings are unlikely to develop in the same brood. However, the number of males per brood increases with the size of the brood (produced by a single mother). We investigated the further possibilities of limited insemination capacity and non‐local mating using a naturalistic experimental protocol. We found that limited insemination capacity is an unlikely general explanation for the increase in number of males with brood size. All males and females dispersed from both mixed and single sex broods. Although most females in mixed sex broods mated prior to dispersal, these data suggest that non‐local mating is possible, for instance via male immigration to broods containing virgin females. This may influence sex ratio optima and account for the trend in male number. 相似文献
18.
Despite inducing very low IFN-γ response and highly attenuated in vivo, infection of mice with phosphoglycan (PG) deficient Leishmania major (lpg2-) induces protection against virulent L. major challenge. Here, we show that mice infected with lpg2- L. major generate Leishmania-specific memory T cells. However, in vitro and in vivo proliferation, IL-10 and IFN-γ production by lpg2- induced memory cells were impaired in comparison to those induced by wild type (WT) parasites. Interestingly, TNF recall response was comparable to WT infected mice. Despite the impaired proliferation and IFN-γ response, lpg2- infected mice were protected against virulent L. major challenge and their T cells mediated efficient infection-induced immunity. In vivo depletion and neutralization studies with mAbs demonstrated that lpg2- L. major-induced resistance was strongly dependent on IFN-γ, but independent of TNF and CD8+ T cells. Collectively, these data show that the effectiveness of secondary anti-Leishmania immunity depends on the quality (and not the magnitude) of IFN-γ response. These observations provide further support for consideration of lpg2- L. major as a live-attenuated candidate for leishmanization in humans since it protects strongly against virulent challenge, without inducing pathology in infected animals. 相似文献
19.
Acidic Conditions Are Not Obligatory for Onset of Butanol Formation by Clostridium beijerinckii (Synonym, C. butylicum) 总被引:4,自引:6,他引:4
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Factors that may initiate the metabolic transition for butanol production were investigated in batch cultures of Clostridium beijerinckii (synonym, Clostridium butylicum) VPI 13436. Cultures maintained at pH 6.8 produced nearly as much butanol as those incubated without pH control, indicating that neither a change in the culture pH nor acid conditions per se are always required to initiate solvent formation. Acetate and butyrate levels at the onset of butanol production were dependent on the pH at which the cultures were maintained. Cultures maintained at pH 6.8 could be accelerated into solvent production by artificially lowering the pH to 5.0 or by the addition of acetate plus butyrate without a pH change (but neither acid alone was effective). Solvent production was associated with slower rates of growth and general metabolism, and it did not show a requirement for mature spore formation. We speculate that a slowdown in metabolism, which may be brought about by several conditions, is mechanistically related to the onset of butanol production. Extracts of solvent-producing cells contained acetoacetate decarboxylase activity as well as higher NADP+-linked butanol dehydrogenase and lower hydrogenase activities than extracts of acid-producing cells. Solvent production did not appear to involve an enhanced ability to catalyze H2 oxidation. 相似文献
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The key question in understanding how force and movement are produced in muscle concerns the nature of the cyclic interaction of myosin molecules with actin filaments. The lever arm of the globular head of each myosin molecule is thought in some way to swing axially on the actin-attached motor domain, thus propelling the actin filament past the myosin filament. Recent X-ray diffraction studies of vertebrate muscle, especially those involving the analysis of interference effects between myosin head arrays in the two halves of the thick filaments, have been claimed to prove that the lever arm moves at the same time as the sliding of actin and myosin filaments in response to muscle length or force steps. It was suggested that the sliding of myosin and actin filaments, the level of force produced and the lever arm angle are all directly coupled and that other models of lever arm movement will not fit the X-ray data. Here, we show that, in addition to interference across the A-band, which must be occurring, the observed meridional M3 and M6 X-ray intensity changes can all be explained very well by the changing diffraction effects during filament sliding caused by heads stereospecifically attached to actin moving axially relative to a population of detached or non-stereospecifically attached heads that remain fixed in position relative to the myosin filament backbone. Crucially, and contrary to previous interpretations, the X-ray interference results provide little direct information about the position of the myosin head lever arm; they are, in fact, reporting relative motor domain movements. The implications of the new interpretation are briefly assessed. 相似文献