Abstract:
:Species competing exclusively for renewing resources are shown to obey simultaneous differential equations equivalent to the conditions for minimizing a certain quadratic form. In this sense competition acts to select species abundances giving the best least-squares fit in an expression [Formula: see text] Thus the number of species which can coexist competitively is limited mostly by the inequality of the interspecies competition coefficients and not appreciably by their magnitude. Seasonality and number of resources become the main factors limiting the number of coexisting species.
journal_name
Proc Natl Acad Sci U S Aauthors
Arthur RMdoi
10.1073/pnas.64.4.1369subject
Has Abstractpub_date
1969-12-01 00:00:00pages
1369-71issue
4eissn
0027-8424issn
1091-6490journal_volume
64pub_type
杂志文章abstract::Fetal cerebral neurons at the initiation of active neurite outgrowth in culture incorporate 4-fold more [3H]glucosamine into glycoproteins than into the cellular lipid fraction. After 8 days or longer, when a well-developed fiber network is apparent, lipids are labeled more extensively than the glycoproteins. Labeling...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.18.5638
更新日期:1984-09-01 00:00:00
abstract::Allostery, the coupling between ligand binding and protein conformational change, is the heart of biological network and it has often been explained by two representative models, the induced-fit and the population-shift models. Here, we clarified for what systems one model fits better than the other by performing mole...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0802524105
更新日期:2008-08-12 00:00:00
abstract::The incidence of pediatric adrenal cortical carcinoma (ACC) in southern Brazil is 10-15 times higher than that of pediatric ACC worldwide. Because childhood ACC is associated with Li-Fraumeni syndrome, we examined the cancer history and p53 status of 36 Brazilian patients and their families. Remarkably, 35 of 36 patie...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.161479898
更新日期:2001-07-31 00:00:00
abstract::Scientific cinematography using ultrafast optical imaging is a common tool to study motion. In opaque organisms or structures, X-ray radiography captures sequences of 2D projections to visualize morphological dynamics, but for many applications full four-dimensional (4D) spatiotemporal information is highly desirable....
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1308650111
更新日期:2014-03-18 00:00:00
abstract::Unlike tailed bacteriophages, which use a preformed tail for transporting their genomes into a host bacterium, the ssDNA bacteriophage ΦX174 is tailless. Using cryo-electron microscopy and time-resolved small-angle X-ray scattering, we show that lipopolysaccharides (LPS) form bilayers that interact with ΦX174 at an ic...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1716614114
更新日期:2017-12-26 00:00:00
abstract::Retrotransposons and retroviruses integrate nonrandomly into eukaryotic genomes. For the yeast retrotransposon Ty5, integration preferentially occurs within domains of heterochromatin. Targeting to these locations is determined by interactions between an amino acid sequence motif at the C terminus of Ty5 integrase (IN...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1036705100
更新日期:2003-05-13 00:00:00
abstract::The ATM gene is mutated in the syndrome of ataxia telangiectasia (AT), associated with neurologic dysfunction, growth abnormalities, and extreme radiosensitivity. Insulin-like growth factor-I receptor (IGF-IR) is a cell surface receptor with tyrosine kinase activity that can mediate mitogenesis, cell transformation, a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2001-02-13 00:00:00
abstract::Archaeological evidence indicates that pig domestication had begun by ∼10,500 y before the present (BP) in the Near East, and mitochondrial DNA (mtDNA) suggests that pigs arrived in Europe alongside farmers ∼8,500 y BP. A few thousand years after the introduction of Near Eastern pigs into Europe, however, their charac...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 历史文章,杂志文章
doi:10.1073/pnas.1901169116
更新日期:2019-08-27 00:00:00
abstract::Choroideremia is an X-linked hereditary retinal degeneration resulting from mutations in the Rab escort protein-1 (REP1). The Rep1 protein facilitates posttranslational modification of Rab proteins, which regulate intracellular trafficking in the retinal pigment epithelium (RPE) and photoreceptors and are likely invol...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0605818104
更新日期:2007-03-13 00:00:00
abstract::The cDNA sequences encoding the adult alpha- and beta-globin polypeptides of a marsupial, the native cat Dasyurus viverrinus, have been cloned and their nucleotide sequences have been determined. Using these cDNA clones we have determined the chromosomal location of the native cat alpha- and beta-globin genes by in si...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.23.8105
更新日期:1985-12-01 00:00:00
abstract::The density of cells and neurons in the neocortex of many mammals varies across cortical areas and regions. This variability is, perhaps, most pronounced in primates. Nonuniformity in the composition of cortex suggests regions of the cortex have different specializations. Specifically, regions with densely packed neur...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1524208113
更新日期:2016-01-19 00:00:00
abstract::Insects impact human health through vector-borne diseases and cause major economic losses by damaging crops and stored agricultural products. Insect-specific growth regulators represent attractive control agents because of their safety to the environment and humans. We identified plant compounds that serve as juvenile...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1424386112
更新日期:2015-02-10 00:00:00
abstract::Lactobacillus acidophilus NCFM is a probiotic bacterium that has been produced commercially since 1972. The complete genome is 1,993,564 nt and devoid of plasmids. The average GC content is 34.71% with 1,864 predicted ORFs, of which 72.5% were functionally classified. Nine phage-related integrases were predicted, but ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0409188102
更新日期:2005-03-15 00:00:00
abstract::The T cell alphabeta receptor (TCR) recognizes foreign peptide antigens bound to proteins encoded in the MHC. The MHC portion of this complex contributes much to the footprint of the TCR on the ligand, yet T cells are usually very specific for individual foreign peptides. Here, we show that the development of peptide-...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1934636100
更新日期:2003-09-30 00:00:00
abstract::L203 and L227 are mouse monoclonal antibodies specific for human HLA-DR antigens. Their reactivity with multiple, structurally different, HLA-DR antigens was examined by using radioiodinated human lymphoblastoid cells and cell lines, heterozygous or homozygous at the HLA-D locus. Antibody L203 precipitates DR antigens...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.8.2658
更新日期:1982-04-01 00:00:00
abstract::To explore protein space from a global perspective, we consider 9,710 SCOP (Structural Classification of Proteins) domains with up to 70% sequence identity and present all similarities among them as networks: In the "domain network," nodes represent domains, and edges connect domains that share "motifs," i.e., signifi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1403395111
更新日期:2014-08-12 00:00:00
abstract::We examined the contributions of the human pulvinar to goal directed selection of visual targets in 3 patients with chronic, unilateral lesions involving topographic maps in the ventral pulvinar. Observers completed 2 psychophysical tasks in which they discriminated the orientation of a lateralized target grating in t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 临床试验,杂志文章
doi:10.1073/pnas.0810086106
更新日期:2009-03-10 00:00:00
abstract::The recent intensification of agriculture, and the prospects of future intensification, will have major detrimental impacts on the nonagricultural terrestrial and aquatic ecosystems of the world. The doubling of agricultural food production during the past 35 years was associated with a 6.87-fold increase in nitrogen ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.11.5995
更新日期:1999-05-25 00:00:00
abstract::A TL+ leukemia of a (B6 X A)F1 hybrid mouse (H-2b/H-2a) was previously subjected to immunoselection against H-2a by passage in (B6 X A.SW)F1 mice (H-2b/H-2s). A variant leukemia line was obtained that serologically lacked not only the H-2a phenotype but also the TL phenotype determined by the linked cis Tlaa allele of...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.20.6447
更新日期:1984-10-01 00:00:00
abstract::We use a three-dimensional, higher-order ice flow model and a realistic initial condition to simulate dynamic perturbations to the Greenland ice sheet during the last decade and to assess their contribution to sea level by 2100. Starting from our initial condition, we apply a time series of observationally constrained...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1017313108
更新日期:2011-05-31 00:00:00
abstract::The epidermal growth factor (EGF) receptor gene is the cellular homolog of the avian erythroblastosis virus erbB oncogene. Control of EGF receptor expression determines cellular responsiveness to EGF and might play an important role in neoplastic development. Using RNA blot hybridization, we have found that exposure o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.24.8374
更新日期:1985-12-01 00:00:00
abstract::The epithelial-derived cytokine thymic stromal lymphopoietin (TSLP) is important for the initiation of allergic airway inflammation through a dendritic cell-mediated T helper 2 response. To identify the factors that control TSLP expression, we examined the ability of inflammatory mediators to regulate TSLP production ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0607305104
更新日期:2007-01-16 00:00:00
abstract::In insulin resistant states such as type 2 diabetes, there is a high demand on the β-cell to synthesize and secrete insulin, which challenges the ability of the endoplasmic reticulum (ER) to synthesize and fold nascent proteins. This creates a state of ER stress that triggers a coordinated program referred to as the u...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1322564111
更新日期:2014-01-21 00:00:00
abstract::Nitric oxide (NO) is an antiviral effector of the innate immune system. Viruses that can interfere with NO synthesis may be able to replicate more rapidly than viruses that cannot limit NO synthesis. We show that the adenovirus E1A protein inhibits NO production by decreasing expression of the inducible NO synthase (N...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1337185100
更新日期:2003-06-24 00:00:00
abstract::Acute injury to the intestinal mucosa is a major dose-limiting complication of abdominal radiation therapy. We studied the role of the transcription factor NF-kappaB in protection against radiation-induced apoptosis in the intestinal epithelium in vivo. We use mice in which NF-kappaB signaling through IkappaB-kinase (...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0306734101
更新日期:2004-02-24 00:00:00
abstract::When Drosophila melanogaster embryos were ligated at very early stages of nuclear multiplication (45-60 min after egg deposition) for the entire period of embryogenesis, egg fragments of variable sizes were able to continue development up to the hatching stage. These ligated embryos differentiated larval structures; a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.5.2050
更新日期:1977-05-01 00:00:00
abstract::Rod-like colloids distort fluid interfaces and interact by capillarity. We explore this interaction at the free surface of aligned nematic liquid crystal films. Naive comparison of capillary and elastic energies suggests that particle assembly would be determined solely by surface tension. Here, we demonstrate that, u...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1504817112
更新日期:2015-05-19 00:00:00
abstract::Parts of the primary structure of the NAD-specific glutamate dehydrogenase [L-glutamate:NAD oxidoreductase (deaminating), EC 1.4.1.2] from Neurospora crassa are presented. Segments of the sequence representing 886 unique amino-acid residues have been determined; the largest contains 267 residues. There are only short ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.72.12.4891
更新日期:1975-12-01 00:00:00
abstract::An oligoribonucleotide (a 27-mer) that mimics the sarcin/ricin (S/R) domain of Escherichia coli 23S rRNA binds elongation factor EF-G; the Kd is 6.9 microM, whereas for binding to ribosomes it is 0.7 microM. Binding saturates when EF-G and the S/R RNA are equimolar; at saturation 70% of the input RNA is in complexes w...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.23.12280
更新日期:1997-11-11 00:00:00
abstract::Recent studies have shown that phytoliths are softer than dental enamel but still act as abrasive agents. Thus, phytolith content should be reflected in dental wear. Because native phytoliths show lower indentation hardness than phytoliths extracted by dry ashing, we propose that the hydration state of plant tissue wi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1814081116
更新日期:2019-01-22 00:00:00