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1.
Zlatko Janeba Noha Maklad Morris J. Robins 《Nucleosides, nucleotides & nucleic acids》2013,32(10-12):1729-1743
Copper(I)-catalyzed 5-endo-dig cyclizations of 5-(alkyn-1-yl)uracil derivatives had given poor yields of substituted furo[2, 3]pyrimidin-2-ones unless the uracil ring was substituted at N1 with alkyl or glycosyl groups. This limited flexibility for the synthesis of analogues with varied substituents at N3 and/or C6 of the furo[2, 3]pyrimidin-2-one core has been overcome with 5-(3-hydroxyalkyn-1-yl)uracil compounds with no substituent at N1. Manipulation of the side-chain hydroxyl group gives access to additional furo[2,3-d]pyrimidin-2-one analogues. 相似文献
2.
《Journal of biological dynamics》2013,7(2):117-130
We address several conjectures raised in Cantrell et al. [Evolution of dispersal and ideal free distribution, Math. Biosci. Eng. 7 (2010), pp. 17–36 [9]] concerning the dynamics of a diffusion–advection–competition model for two competing species. A conditional dispersal strategy, which results in the ideal free distribution of a single population at equilibrium, was found in Cantrell et al. [9]. It was shown in [9] that this special dispersal strategy is a local evolutionarily stable strategy (ESS) when the random diffusion rates of the two species are equal, and here we show that it is a global ESS for arbitrary random diffusion rates. The conditions in [9] for the coexistence of two species are substantially improved. Finally, we show that this special dispersal strategy is not globally convergent stable for certain resource functions, in contrast with the result from [9], which roughly says that this dispersal strategy is globally convergent stable for any monotone resource function. 相似文献
3.
We investigated the morphology, morphogenesis and small subunit rRNA gene-based phylogeny of three marine urostylids, Uncinata gigantea Bullington, 1940, Holosticha heterofoissneri Hu & Song, 2001, and Holosticha cf. heterofoissneri. The dorsal morphogenesis of Uncinata gigantea shows de novo formation of two groups of anlagen near the marginal rows. Holosticha cf. heterofoissneri demonstrates fragmentation of the first dorsal kinety anlage as in Holosticha heterofoissneri. Our population of H. heterofoissneri corresponds well with previously described populations in terms of its general morphology and ciliary pattern. Uncinata gigantea can be recognized by its large and highly contractile body, yellowish to brownish cell colour, two types of cortical granules, and 20–30 transversely oriented and densely arranged cirri in the left marginal row, which often overlie the buccal vertex. Based on the new data, especially infraciliature, the genus Uncinata is here redefined. Both the morphology and phylogenetic analyses suggest that the genus Uncinata should be classified within the family Urostylidae. In addition, both morphological and morphogenetic data suggest that Holosticha bradburyae Gong et al., 2001 should be transferred to Uncinata as U. bradburyae (Gong et al., 2001) comb. nov., due to its possession of a characteristically prominent beak-like, leftwards curved projection and the developmental mode of the dorsal kineties. This assignment is supported by the phylogenetic analyses, which placed Uncinata gigantea in a clade with U. bradburyae (Gong et al., 2001) comb. nov., and revealed only 1.13% (19 bp) difference in their SSU-rDNA gene sequence. 相似文献
4.
In Disney/Pixar's phenomenally popular animated film Finding Nemo (Stanton, 2003), one of the central themes of fish welfare was highlighted when the moorish idol, Gill, commented, “Fish aren't meant to be kept in a box, kid. It does things to you.” The notion that fish might have the capacity to suffer in captivity (Chandroo, Duncan, & Moccia, 2004a, 2004b) links to the larger question of sentiency, which remains a fundamental tenet when justifying concerns for nonhuman animal welfare (Dawkins, 2006; Huntingford et al., 2006). Although terrestrial nonhuman-animal welfare has been discussed and explored for many years, the development of aquatic animal welfare concepts and approaches remains relatively new and beyond public awareness (Braastad, Damsgård, & Juell, 2006; Broom, 2007; Farmed Animal Welfare Council, 1996; Fisheries Society of the British Isles, 2002; Håstein, Scarfe, & Lund, 2005; Iwama, 2007; Schreck, 1981). 相似文献
5.
The natural remobilization of an initially static mixed dense non-aqueous phase liquid (DNAPL) pool due to dissolution was demonstrated by (Roy et al. 2002, 2004) using a compositional mathematical model and laboratory experiments with open pools over a porous medium. The purposes of this study were to: a) demonstrate natural remobilization for a pool within porous media (as opposed to an open pool); and b) analyze the capillary effects associated with residual formation, a changing saturation profile, hysteresis, and aging, as these processes may reduce the potential for natural remobilization of pools in porous media. DNAPL pools comprised of tetrachloroethene and benzene were created within a zone of larger glass beads overlying smaller glass beads, in a water-saturated 2-D flow cell. In one case, remobilization occurred in the form of a DNAPL finger, after 56 days of flushing. In another case, no remobilization had occurred after 64 days of flushing, though the density increased by 430 kg m ?3 and remobilization was predicted by the compositional model. Comparison of observations with model predictions suggest that contact angle hysteresis, related to an observed change in wettability, was the most significant contributing factor causing overprediction of the potential for natural remobilization. 相似文献
6.
《Biodemography and social biology》2013,59(1):42-66
Recent adaptationist accounts of human mental and physical health have reinvigorated the debate over the evolution of human intelligence. In the tradition of strong inference the current study was developed to determine whether either Miller's (1998, 2000a) Fitness Indicator Theory or Rushton's (1985, 2000) Differential-K Theory better accounts for general intelligence (“g”) in an undergraduate university population (N = 192). Owing to the lengthy administration time of the test materials, a newly developed 18-item short form of the Ravens Advanced Progressive Matrices (APM-18; Sefcek, Miller, and Figueredo 2007) was used. A significant, positive relationship between K and F (r = .31, p < .001) emerged. Contrary to predictions, no significant relationships were found between “g” and either K or F (r = –.09, p ≥ .05 and r = .11, p ≥ .05, respectively). Though generally contrary to both hypotheses, these results may be explained in relation to antagonistic pleiotropy and a potential failure to derive correct predictions for within-species comparisons directly from the results of between-species comparisons. 相似文献
7.
Tad W. Patzek 《植物科学评论》2008,27(4):272-293
This paper considers the local, field-scale sustainability of a productive industrial maize agrosystem that has replaced a fertile grassland ecosystem.
Using the revised thermodynamic approach of Svirezhev (1998, 2000) and Steinborn and Svirezhev (2000), it is shown that currently this agrosystem is unsustainable in the U.S., with or without tilling the soil. The calculated average erosion rates of soil necessary to dissipate the entropy produced by U.S. maize agriculture, 23–45 t ha?1 yr?1, are bounded from above by an experimental estimate of mean soil erosion by conventional agriculture worldwide, 47 t ha?1 yr?1, (Montgomery, 2007). Between 1982 and 1997, US agriculture caused an estimated 7–23 t ha?1 yr?1 of average erosion with the mean of 15 t ha?1 yr?1 (USDA-NRCS Database). The lower mean erosion rate of no till agriculture, 1.5 t ha?1 yr?1 (Montgomery, 2007), necessitates the elimination of weeds and pests with field chemicals—with the ensuing chemical and biological soil degradation, and chemical runoff—to dissipate the produced entropy. The increased use of field chemicals that replace tillers is equivalent to the killing or injuring of up to 300 kg ha?1 yr?1 of soil flora and fauna. Additional soil degradation, not calculated here, occurs by acidification, buildup of insoluble metal compounds, and buildup of toxic residues from field chemicals. The degree of unsustainability of an average U.S. maize field is high, requiring 6–13 times more energy to reverse soil erosion and degradation, etc., than the direct energy inputs to maize agriculture. This additional energy, if spent, would not increase maize yields. The calculated “critical yield” of “organic” maize agriculture that does not use field chemicals and fossil fuels is only 30 percent lower than the average maize yield of 8.7 tons per hectare (～140 bu/acre) assumed here. This critical yield would not likely be achieved and sustained by large monocultures, but might be achieved by more balanced organic polycultures (Baum et al., 2008). 相似文献
8.
9.
Christopher J. Derrick 《Cell cycle (Georgetown, Tex.)》2017,16(1):23-32
Localized mRNA translation is a widespread mechanism for targeting protein synthesis, important for cell fate, motility and pathogenesis. In Drosophila, the spatiotemporal control of gurken/TGF-α mRNA translation is required for establishing the embryonic body axes. A number of recent studies have highlighted key aspects of the mechanism of gurken mRNA translational control at the dorsoanterior corner of the mid-stage oocyte. Orb/CPEB and Wispy/GLD-2 are required for polyadenylation of gurken mRNA, but unlocalized gurken mRNA in the oocyte is not fully polyadenylated.1 At the dorsoanterior corner, Orb and gurken mRNA have been shown to be enriched at the edge of Processing bodies, where translation occurs.2 Over-expression of Orb in the adjacent nurse cells, where gurken mRNA is transcribed, is sufficient to cause mis-expression of Gurken protein.3 In orb mutant egg chambers, reducing the activity of CK2, a Serine/Threonine protein kinase, enhances the ventralized phenotype, consistent with perturbation of gurken translation.4 Here we show that sites phosphorylated by CK2 overlap with active Orb and with Gurken protein expression. Together with our new findings we consolidate the literature into a working model for gurken mRNA translational control and review the role of kinases, cell cycle factors and polyadenylation machinery highlighting a multitude of conserved factors and mechanisms in the Drosophila egg chamber. 相似文献
10.
《Cell Adhesion & Migration》2013,7(4):378-383
Cell migration is a highly integrated, multistep process that plays an important role in physiological and pathological processes. The migrating cell is highly polarized, with complex regulatory pathways that integrate its component processes spatially and temporally.1 The Drosophila tumor suppressor, Lethal (2) giant larvae (Lgl), regulates apical-basal polarity in epithelia and asymmetric cell division.2 But little is known about the role of Lgl in establishing cell polarity in migrating cells. Recently, we showed that the mammalian Lgl1 interacts directly with non-muscle myosin IIA (NMIIA), inhibiting its ability to assemble into filaments in vitro.3 Lgl1 also regulates the cellular localization of NMIIA, the maturation of focal adhesions, and cell migration.3 We further showed that phosphorylation of Lgl1 by aPKCζ prevents its interaction with NMIIA and is important for Lgl1 and acto-NMII cytoskeleton cellular organization.4 Lgl is a critical downstream target of the Par6-aPKC cell polarity complex; we showed that Lgl1 forms two distinct complexes in vivo, Lgl1-NMIIA and Lgl1-Par6-aPKCζ in different cellular compartments.4 We further showed that aPKCζ and NMIIA compete to bind directly to Lgl1 through the same domain. These data provide new insights into the role of Lgl1, NMIIA, and Par6-aPKCζ in establishing front-rear polarity in migrating cells. In this commentary, I discuss the role of Lgl1 in the regulation of the acto-NMII cytoskeleton and its regulation by the Par6-aPKCζ polarity complex, and how Lgl1 activity may contribute to the establishment of front-rear polarity in migrating cells. 相似文献
11.
《朊病毒》2013,7(5):433-436
Mutations in the gene encoding the amyloid precursor protein (APP) or the enzymes that process APP are correlated with familial Alzheimer disease. Alzheimer disease is also associated with insulin resistance (type 2 diabetes). In our recently published study,1 we obtained genetic evidence that the extracellular fragment of APL-1, the C. elegans ortholog of human APP, may act as a signaling molecule to modulate insulin and nuclear hormone pathways in C. elegans development. In addition, independent of insulin and nuclear hormone signaling, high levels of the extracellular fragment of APL-1 (sAPL-1) leads to a temperature-sensitive embryonic lethality, which is dependent on activity of a predicted receptor protein tyrosine phosphatase (MOA-1/R155.2). Furthermore, this embryonic lethality is enhanced by knockdown of a predicted prion-like protein (pqn-29). The precise molecular mechanisms underlying these processes remain to be determined. Here, we present hypothetical models as to how sAPL-1 signaling influences metabolic and developmental pathways. Together, with previous findings in mammals that the extracellular domain of mammalian APP (sAPP) binds to a death-receptor,2 our findings support the model that sAPP signaling affects critical biological processes. 相似文献
12.
An automated, iterative approach to finding the lowest energy, ionic diffusion paths through a periodic structure has been developed within our new code (written in FORTRAN 77 and named Bubble). The approach is quite general in that it can be applied to find, at a chosen temperature, the accessible (ergodic) regions of a hyper-surface, which is defined across a uniform grid [1]. We describe both our implementation within the Bubble code and its application to locating the approximate transition states for Mg interstitial diffusion in forsterite, which can then be refined using standard transition state searching [2]. 相似文献
13.
Gobies (Gobiidae sensu Gill & Mooi, 2012) are one of the most diverse families of vertebrates, and comprise over 1700 species of marine, brackish and freshwater fishes. Phylogenetic studies based on morphological characters and mtDNA have suggested that goby diversity is asymmetrically split between a speciose clade of predominantly marine species, and a less rich, but ecologically diverse, clade comprising predominantly freshwater and brackish species. This study is the first to explore this deep divide in gobies and their relationships at the family level using phylogenetic data from nuclear genes (RAG1, rhodopsin). Our results confirm the split within the Gobiidae, and agree with prior molecular studies on the inclusion of the following taxa within the two goby clades: (i) the more diverse of the two clades of gobies (the ‘Gobiidae’ sensu stricto of Thacker 2009) comprises the gobiines, microdesmines, ptereleotrines and kraemeriines; (ii) the less diverse of the two gobiid clades (‘Gobionellidae’ sensu Thacker 2009) includes the gobionellines, oxudercines, amblyopines, sicydiines, as well as the European sand gobies. Some relationships within the two major gobiid clades remain unclear. Specifically, there remains confusion regarding the monophyly and interrelationships between the northern Pacific gobionellines, the Mugilogobius group gobionellines, and the European sand gobies. Additionally, within Thacker's (2009) Gobiidae sensu stricto, there are several well-supported groups (e.g. the wormfishes and dartfishes, the Coral Gobies, the Gobiosomatini), yet relationships among these groups are still poorly resolved despite the use of data from two conserved nuclear genes. Future phylogenetic analyses of gobies will benefit greatly from taxon sampling that includes groups that have been historically under-represented in molecular studies (e.g. European sand gobies, northern Pacific gobionellines, African species), as well as deeper genetic sampling including large numbers of independent loci from throughout the genome (i.e. a phylogenomic approach). 相似文献
14.
James E. Côté 《应用发育科学》2013,17(4):177-188
This article examines the theory of emerging adulthood, introduced into the literature by Arnett (2000), in terms of its methodological and evidential basis, and finds it to be unsubstantiated on numerous grounds. Other, more convincing, formulations of variations in the transition to adulthood are examined. Most flawed academic theories are simply ignored by scientists. However, Arnett's unsubstantiated formulations have found their way to journalists, who are influencing public opinion, and policymakers, who are determining the fate of youth populations. As such, the article argues that an academic myth is being created that has serious economic and emotional repercussions for the many young people facing difficult circumstances in their transition to adulthood. Consequently, this myth requires corrections from the scientific community, one of which is provided here. 相似文献
15.
《Cell cycle (Georgetown, Tex.)》2013,12(19):3555-3558
CEP192 is a centrosome protein that plays a critical role in centrosome biogenesis and function in mammals, Drosophila and C. elegans.1-6 Moreover, CEP192-depleted cells arrest in mitosis with disorganized microtubules, suggesting that CEP192’s function in spindle assembly goes beyond its role in centrosome activity and pointing to a potentially more direct role in the regulation of the mitotic microtubule landscape.7 To better understand CEP192 function in mitosis, we used mass spectrometry to identify CEP192-interacting proteins. We previously reported that CEP192 interacts with NEDD1, a protein that associates with the γ-tubulin ring complex (γ-TuRC) and regulates its phosphorylation status during mitosis.8 Additionally, within the array of proteins that interact with CEP192, we identified the microtubule binding K63-deubiquitinase CYLD. Further analyses show that co-depletion of CYLD alleviates the bipolar spindle assembly defects observed in CEP192-depleted cells. This functional relationship exposes an intriguing role for CYLD in spindle formation and raises the tantalizing possibility that CEP192 promotes robust mitotic spindle assembly by regulating K63-polyubiquitin-mediated signaling through CYLD. 相似文献
16.
Public familiarity with basic scientific concepts and principles has been proposed as essential for effective democratic decision-making (Miller, 1998). Empirical research, however, finds that public ‘scientific literacy’ is generally low, falling well short of what normative criteria would consider ‘acceptable’. This has prompted calls to better engage, educate and inform the public on scientific matters, with the additional, usually implicit assumption that a knowledgeable citizenry should express more supportive and favourable attitudes toward science. Research investigating the notion that ‘to know science is to love it’ has provided only weak empirical support and has itself been criticised for representing science and technology as a unified and homogenous entity. In practice, it is argued, how knowledge impacts on the favourability of attitudes will depend on a multiplicity of factors, not least of which is the particular area of science in question and the technologies to which it gives rise (Evans & Durant, 1992). This article uses a new method for examining the knowledge-attitude nexus on a prominent area of 21st century science—biotechnology. The idea that greater scientific knowledge can engender change in the favourability of attitudes toward specific areas of science is investigated using data from the 2000 British Social Attitudes Survey and the 1999 Wellcome Consultative Panel on Gene Therapy. Together the surveys measure public opinion on particular applications of genetic technologies, including gene therapy and the use of genetic data, as well as more general attitudes towards genetic research. We focus our analysis on how two different measures of knowledge impact on these attitudes; one a general measure of scientific knowledge, the other relating specifically to knowledge of modern genetic science. We investigate what impact these knowledge domains have on attitudes towards biotechnology using a regression-based modelling technique (Bartels, 1996; Althaus, 1998; Sturgis, 2003). Controlling for a range of socio-demographic characteristics, we provide estimates of what collective and individual opinion would look like if everyone were as knowledgeable as the currently best-informed members of the general public on the knowledge domains in question. Our findings demonstrate that scientific knowledge does appear to have an important role in determining individual and group attitudes to genetic science. However, we find no support for a simple ‘deficit model’ of public understanding, as the nature of the relationship itself depends on the application of biotechnology in question and the social location of the individual. 相似文献
17.
The enzymatic oxidization of dissolved Fe(II) to Fe(III) by neutrophilic Fe-oxidizing bacteria plays a significant role in biological cycling of iron by inducing the precipitation of Fe(III) oxyhydroxide in aqueous environments. Among the diverse neutrophilic Fe-oxidizing bacteria, the genus Gallionella has received wide attention for its production of unique twisted extracellular stalks. Hallberg and Tai (2014) recently reported the detection of multi-wall carbon nanotubes on the twisted-stalks, and they viewed those carbon nanotubes as being biologically produced by Gallionella. We scrutinized Gallionella-produced biofilms collected from natural environments by scanning electron microscopy and high-resolution transmission electron microscopy. Ferrihydrite and lepidocrocite were the only nano-scaled minerals observed on the stalk, while there were nanometer-sized sheet-like graphitic contaminants on the grid in the vicinity of the sample which showed the same morphology as Hallberg and Tai (2014) observed. Moreover, similar materials on an empty grid and a grid loaded with randomly selected synthesized materials were also observed. Based on the current knowledge of carbon nanotube syntheses, none of the three known synthesizing methods including root-growth, rolling-up and bottom-up could be biochemically produced by any life because of the significant kinetic and energy obstacles. The carbon nanomaterials reported by Hallberg and Tai (2014) were clearly contaminations from amorphous carbon film on the grids for holding samples for transmission electron microscopic observations. 相似文献
18.
《Fly》2013,7(4):155-159
ABSTRACTAnimals have modular cis-regulatory regions in their genomes, and expression of a single gene is often regulated by multiple enhancers residing in such a region. In the laboratory, and also in natural populations, loss of an enhancer can result in a loss of gene expression. Although only a few examples have been well characterized to date, some studies have suggested that an evolutionary gain of a new enhancer function can establish a new gene expression domain. Our recent study showed that Drosophila guttifera has more enhancers and additional expression domains of the wingless gene during the pupal stage, compared to D. melanogaster, and that these new features appear to have evolved in the ancestral lineage leading to D. guttifera.1 Gain of a new expression domain of a developmental regulatory gene (toolkit gene), such as wingless, can cause co-option of the expression of its downstream genes to the new domain, resulting in duplication of a preexisting structure at this new body position. Recently, with the advancement of evo-devo studies, we have learned that the developmental regulatory systems are strikingly similar across various animal taxa, in spite of the great diversity of the animals' morphology. Even behind “new” traits, co-options of essential developmental genes from known systems are very common. We previously provided concrete evidence of gains of enhancer activities of a developmental regulatory gene underlying gains of new traits.1 Broad occurrence of this scenario is testable and should be validated in the future. 相似文献
19.
The influence of the geometry of the porcine cornea on the biomechanical response of inflation tests
Anna Pandolfi Federica Boschetti 《Computer methods in biomechanics and biomedical engineering》2013,16(1):64-77
To withstand the high probability of success, the growing diffusion of laser surgery for the correction of visual defects, corneal surgeons are regarding with interest numerical tools able to provide reliable predictions of the intervention outcomes. The main obstacle to the definition of a predictive numerical instrument is the objective difficulty in evaluating the in vivo mechanical properties of the human cornea. In this study, we assess the ability of a parametrised numerical model of the cornea (Pandolfi and Manganiello 2006) to describe individual pressurisation tests on whole porcine corneas once the mechanical parameters of the model have been calibrated over average data. We also aim at estimating the sensitivity of the mechanical response with the variation of basic geometrical parameters, such as the central corneal thickness, the curvature and the in-plane diameter. We conclude that the actual geometry of a cornea has a minor role in the overall mechanical response, and therefore the material properties must be considered carefully and individually in any numerical application. This study makes use of the data obtained from a wide experimental program, where a set of 21 porcine corneas has been fully characterised in terms of mechanical and geometrical properties (Boschetti et al. 2012). 相似文献
20.
Guillermo F. Aceñolaza 《Ichnos》2013,20(1):59-63
Abstract A new ichnofossiliferous locality in Salta Province (northwest Argentina) contains an association with numerous irregular spiral traces assigned to Spirodesmos milanai n. isp., in mature sandstones and quartzites with rippled bedding surfaces, rare wavy lamination and cross-bedded stratification. This record of early spiral behavior is interpreted as a primitive grazing method formed on muddy laminae above sand layers, and is related to a feeding strategy of an annelid-type of organism. Associated traces are Cruziana cf. semiplicata, Diplocraterion isp., Monocraterion isp., Rusophycus isp., Skolithos linearis Haldeman and Skolithos magnus Howell. The ichnoassemblage is similar to a shallow-water ichnoassociation from the Permian Ecca Group of South Africa (Mason et al., 1983). 相似文献