Abstract:
:A general model for the contractility of cells is presented that accounts for the dynamic reorganization of the cytoskeleton. The model is motivated by three key biochemical processes: (i) an activation signal that triggers actin polymerization and myosin phosphorylation, (ii) the tension-dependent assembly of the actin and myosin into stress fibers, and (iii) the cross-bridge cycling between the actin and myosin filaments that generates the tension. Simple relations are proposed to model these coupled phenomena and a continuum model developed for simulating cell contractility. The model is capable of predicting key experimentally established characteristics including: (i) the decrease in the forces generated by the cell with increasing substrate compliance, (ii) the influence of cell shape and boundary conditions on the development of structural anisotropy, and (iii) the high concentration of the stress fibers at the focal adhesions. We present numerical examples of a square cell on four supports to demonstrate these capabilities.
journal_name
Proc Natl Acad Sci U S Aauthors
Deshpande VS,McMeeking RM,Evans AGdoi
10.1073/pnas.0605837103subject
Has Abstractpub_date
2006-09-19 00:00:00pages
14015-20issue
38eissn
0027-8424issn
1091-6490pii
0605837103journal_volume
103pub_type
杂志文章abstract::Chronic fatigue immune dysfunction syndrome (CFIDS) is a recently recognized illness characterized by debilitating fatigue as well as immunological and neurological abnormalities [Straus, S.E. (1988) J. Inf. Dis. 157, 405-412]. Once thought to be caused by Epstein-Barr virus, it is now thought to have a different 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.88.7.2922
更新日期:1991-04-01 00:00:00
abstract::Activation-induced cytidine deaminase (AID) is essential to class-switch recombination (CSR) and somatic hypermutation (SHM) in both V region SHM and S region SHM (s-SHM). Uracil DNA glycosylase (UNG), a member of the base excision repair (BER) complex, is required for CSR. Strikingly, however, UNG deficiency causes 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.1402391111
更新日期:2014-03-18 00:00:00
abstract::RNA of a common strain of tobacco mosaic virus was sequentially reconstituted first with protein of the same strain and then with protein of a tomato strain. The reconstituted particles were treated with specific antibodies against the two strain particles and were examined electron microscopically to locate the regio...
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.74.5.1913
更新日期:1977-05-01 00:00:00
abstract::The extensive refolding of the membrane-anchoring chain of hemagglutinin (HA) of influenza virus (termed HA2) in cellular endosomes, which initiates viral entry by membrane fusion, suggests that viral HA is meta-stable. HA2 polypeptide residues 38-175 expressed in Escherichia coli are reported here to fold in vivo int...
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.92.26.12205
更新日期:1995-12-19 00:00:00
abstract::The chromophore of photoactive yellow protein (PYP) (i.e., 4-hydroxycinnamic acid) has been replaced by an analogue with a triple bond, rather than a double bond (by using 4-hydroxyphenylpropiolic acid in the reconstitution, yielding hybrid I) and by a "locked" chromophore (through reconstitution with 7-hydroxycoumari...
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.95.13.7396
更新日期:1998-06-23 00:00:00
abstract::Cointegrate DNA molecules containing two copies of a transposable element appear to be intermediates in the transposition process. These structures are resolved by site-specific recombination to yield the normal end products of transposition. The transposable element gamma delta (Tn1000) synthesizes a product intercha...
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.79.1.46
更新日期:1982-01-01 00:00:00
abstract::Smooth muscle cells (SMCs) have been shown to migrate in response to insulin-like growth factor I (IGF-I). However, the mechanism mediating this response has not been determined. The migration rates of porcine and human vascular SMCs were assessed in a monolayer wounding assay. IGF-I and IGF-II induced increases of 14...
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.93.6.2482
更新日期:1996-03-19 00:00:00
abstract::The COVID-19 pandemic is a shocking reminder of how our world would look in the absence of vaccination. Fortunately, new technologies, the pace of understanding new and existing pathogens, and the increased knowledge of the immune system allow us today to develop vaccines at an unprecedented speed. Some of the vaccine...
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.2020368118
更新日期:2021-01-19 00:00:00
abstract::Human activities have increased N availability dramatically in terrestrial and aquatic ecosystems. Extensive research demonstrates that local plant species diversity generally declines in response to nutrient enrichment, yet the mechanisms for this decline remain unclear. Based on an analysis of >900 species responses...
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.0408648102
更新日期:2005-03-22 00:00:00
abstract::In adult rodents, neurons are continually generated in the subventricular zone of the forebrain, from where they migrate tangentially toward the olfactory bulb, the only known target for these neuronal precursors. Within the main olfactory bulb, they ascend radially into the granule and periglomerular cell layers, whe...
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.97.4.1823
更新日期:2000-02-15 00:00:00
abstract::To investigate protein folding dynamics in terms of compactness, we developed a continuous-flow mixing device to make small-angle x-ray scattering measurements with the time resolution of 160 micros and characterized the radius of gyration (R(g)) of two folding intermediates of cytochrome c (cyt c). The early intermed...
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.012458999
更新日期:2002-02-05 00:00:00
abstract::Genetic variants underlying life-threatening diseases, being unlikely to be transmitted to the next generation, are gradually and selectively eliminated from the population through negative selection. We study the determinants of this evolutionary process in human genes underlying monogenic diseases by comparing vario...
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.2001248118
更新日期:2021-01-19 00:00:00
abstract::2-[4-(3,4-Dichlorophenylureido)phenoxy]-2-methylpropionic acid, LR16, combines with two symmetrically related sites in the central cavity of deoxyhemoglobin, 20 A away from the binding site of 2,3-bisphosphoglycerate, and acts as an allosteric effector synergistic with 2,3-bisphosphoglycerate. LR16 (1 mM) raises P50, ...
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.85.16.6117
更新日期:1988-08-01 00:00:00
abstract::Calendar date of the beginning of the growing season at high altitude in the Colorado Rocky Mountains is variable but has not changed significantly over the past 25 years. This result differs from growing evidence from low altitudes that climate change is resulting in a longer growing season, earlier migrations, and e...
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.97.4.1630
更新日期:2000-02-15 00:00:00
abstract::l-tryptophan (Trp), an essential amino acid for mammals, is the precursor of a wide array of immunomodulatory metabolites produced by the kynurenine and serotonin pathways. The kynurenine pathway is a paramount source of several immunoregulatory metabolites, including l-kynurenine (Kyn), the main product of indoleamin...
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.1918215117
更新日期:2020-02-18 00:00:00
abstract::High magnetic fields have revealed a surprisingly small Fermi surface in underdoped cuprates, possibly resulting from Fermi-surface reconstruction due to an order parameter that breaks translational symmetry of the crystal lattice. A crucial issue concerns the doping extent of such a state and its relationship to the ...
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.1914166117
更新日期:2020-05-05 00:00:00
abstract::The Arabidopsis HYL1 gene encodes a nuclear double-stranded RNA-binding protein. A knockout mutation of the hyl1 gene is recessive and pleiotropic, causing developmental abnormalities, increasing sensitivity to abscisic acid, and reducing sensitivity to auxin and cytokinin. We report that levels of several microRNAs (...
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.0307969100
更新日期:2004-01-27 00:00:00
abstract::In contrast to the Hox genes in arthropods and vertebrates, those in molluscs show diverse expression patterns with differences reported among lineages. Here, we investigate 2 phylogenetically distant molluscs, a gastropod and a polyplacophoran, and show that the Hox expression in both species can be divided into 2 ca...
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.1907328117
更新日期:2020-01-07 00:00:00
abstract::IFN-gamma is well known as the signature cytokine of CD4+ T helper 1, CD8+, and natural killer cells, but recent studies demonstrate that antigen-presenting cells, in particular dendritic cells (DCs), are another potent source for this proinflammatory cytokine. T-bet, a transcription factor that controls IFN-gamma exp...
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.1332767100
更新日期:2003-06-24 00:00:00
abstract::We partially purified a preparation from Escherichia coli that proteolytically degrades the enzyme glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2]. The degradation is at least a two-step process. First, the glutamine synthetase undergoes an oxidative modification. This modification leads to...
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.78.4.2120
更新日期:1981-04-01 00:00:00
abstract::The rate of leucine incorporation into a specific estrogen-induced protein of immature rat isolated by gel electrophoresis declines rapidly between 2-4 hr after estrogen stimulation in vivo followed by incubation in vitro. Actinomycin D present during the in vitro phase prevents this decline, and elicits a "superinduc...
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.70.1.18
更新日期:1973-01-01 00:00:00
abstract::The vaccinia virus early transcription factor (VETF), a heterodimeric protein composed of 82- and 70-kDa subunits, interacts with viral early promoters at both a sequence-specific core region upstream and a sequence-independent region downstream of the RNA start site. To determine the VETF subunit-promoter interaction...
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.93.15.7540
更新日期:1996-07-23 00:00:00
abstract::We present a physical and molecular genetic characterization of Drosophila melanogaster TFIIE (dTFIIE), a component of the basal RNA polymerase II transcription apparatus. We have purified dTFIIE to near homogeneity from nuclear extracts of Drosophila embryos and found that it is composed of two subunits with apparent...
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.94.2.433
更新日期:1997-01-21 00:00:00
abstract::Identifying the drivers and processes that determine globally the geographic range size of species is crucial to understanding the geographic distribution of biodiversity and further predicting the response of species to current global changes. However, these drivers and processes are still poorly understood, and no e...
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.1902484116
更新日期:2019-07-02 00:00:00
abstract::Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) plays a vital role in immune signal transduction pathways by acting as a ubiquitin ligase (E3) for Lys63-linked polyubiquitin chain synthesis. However, the detailed mechanism by which the TRAF6 RING dimer promotes ubiquitin transfer was unknown. Through ...
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.1721788115
更新日期:2018-02-20 00:00:00
abstract::After primary infection, human cytomegalovirus (HCMV) persists as a life-long latent infection, with host immunosuppression often resulting in clinical reactivation. During lytic infection, major changes in the expression of secreted cellular proteins (the secretome) occur that have profound effects on host-cell inter...
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.1204836109
更新日期:2012-09-04 00:00:00
abstract::If X(1), X(2),... are independent random variables with zero expectation and finite variances, the cumulative sums S(n) are, on the average, of the order of magnitude S(n), where S(n) (2) = E(S(n) (2)). The occasional maxima of the ratios S(n)/S(n) are surprisingly large and the problem is to estimate the extent of th...
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.63.3.637
更新日期:1969-07-01 00:00:00
abstract::Murine endothelial cells are readily transformed in a single step by the polyomavirus oncogene encoding middle-sized tumor antigen. These cells (bEND.3) form tumors (hemangiomas) in mice which are lethal in newborn animals. The bEND.3 cells rapidly proliferate in culture and express little or no thrombospondin 1 (TS1)...
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.92.15.6788
更新日期:1995-07-18 00:00:00
abstract::Cells obtained from normal human skin synthesize predominantly type I collogen in culture. Cells obtained from the skin of an infant with a severe form of osteogenesis imperfecta were found to synthesize as much type III as type I collagen. Decreased synthesis of type I collagen could explain the tissue fragility obse...
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.72.2.586
更新日期:1975-02-01 00:00:00
abstract::We find that the transcription of various ribosomal proteins can be differentially affected by polyamines and by changes in growth rates. Using strain MG1655 of Escherichia coli K-12 (F-, lambda-), we have determined the effects of polyamines and changes in growth rate on the transcription of several ribosomal genes 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.87.9.3464
更新日期:1990-05-01 00:00:00