Abstract:
:Formulas are derived for the effect of size on a free-swimming microbe's ability to follow chemical, light, or temperature stimuli or to disperse in random directions. The four main assumptions are as follows: (i) the organisms can be modeled as spheres, (ii) the power available to the organism for swimming is proportional to its volume, (iii) the noise in measuring a signal limits determination of the direction of a stimulus, and (iv) the time available to determine stimulus direction or to swim a straight path is limited by rotational diffusion caused by Brownian motion. In all cases, it is found that there is a sharp size limit below which locomotion has no apparent benefit. This size limit is estimated to most probably be about 0.6 micron diameter and is relatively insensitive to assumed values of the other parameters. A review of existing descriptions of free-floating bacteria reveals that the smallest of 97 motile genera has a mean length of 0.8 micron, whereas 18 of 94 nonmotile genera are smaller. Similar calculations have led to the conclusion that a minimum size also exists for use of pheromones in mate location, although this size limit is about three orders of magnitude larger. In both cases, the application of well-established physical laws and biological generalities has demonstrated that a common feature of animal behavior is of no use to small free-swimming organisms.
journal_name
Proc Natl Acad Sci U S Aauthors
Dusenbery DBdoi
10.1073/pnas.94.20.10949subject
Has Abstractpub_date
1997-09-30 00:00:00pages
10949-54issue
20eissn
0027-8424issn
1091-6490journal_volume
94pub_type
杂志文章abstract::Four monoclonal anti-parathyroid antibodies were generated after immunization of mice with intact cells from human parathyroid tissue. All four monoclonal antibodies reacted in immunohistochemistry with structures present on parathyroid epithelial cells and proximal-tubule cells of the kidney but were unreactive with ...
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.84.9.2990
更新日期:1987-05-01 00:00:00
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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:2009-02-24 00:00:00
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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.0703071104
更新日期:2007-06-19 00:00:00
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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.81.11.3433
更新日期:1984-06-01 00:00:00
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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.0504949102
更新日期:2005-08-09 00:00:00
abstract::The plasma concentration of the major vitamin D metabolites; 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D were measured during pregnancy and lactation in the adult female rat. The concentrations of these metabolites were also measured in rat pups during lactation and after weaning. The pl...
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.76.11.5549
更新日期:1979-11-01 00:00:00
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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:2006-07-11 00:00:00
abstract::Oligomerization of members of the p53 family of transcription factors (p53, p63, and p73) is essential for their distinct functions in cell-cycle control and development. To elucidate the molecular basis for tetramer formation of the various family members, we solved the crystal structure of the human p73 tetramerizat...
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.0905867106
更新日期:2009-10-20 00:00:00
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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.1716861115
更新日期:2018-01-16 00:00:00
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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.1818668116
更新日期:2019-06-18 00:00:00
abstract::Entamoeba histolytica is a single cell eukaryote that is the etiologic agent of amoebic colitis. Core promoter elements of E. histolytica protein encoding genes include a TATA-like sequence (GTATTTAAAG/C) at -30, a novel element designated GAAC (GAACT) that has a variable location between TATA and the site of transcri...
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.94.16.8812
更新日期:1997-08-05 00:00:00
abstract::Amorphous silicon oxycarbide polymer-derived ceramics (PDCs), synthesized from organometallic precursors, contain carbon- and silica-rich nanodomains, the latter with extensive substitution of carbon for oxygen, linking Si-centered SiO(x)C(4-x) tetrahedra. Calorimetric studies demonstrated these PDCs to be thermodynam...
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.1312771110
更新日期:2013-10-01 00:00:00
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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.1700138114
更新日期:2017-03-28 00:00:00
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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.1722020115
更新日期:2018-05-01 00:00:00
abstract::The super-enhancers (SEs) of lineage-specific genes in B cells are off-target sites of somatic hypermutation. However, the inability to detect sufficient numbers of mutations in normal human B cells has precluded the generation of a high-resolution mutational landscape of SEs. Here we captured and sequenced 12 B cell ...
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.1914163116
更新日期:2019-12-03 00:00:00
abstract::The Zika virus (ZIKV) causes microcephaly and the Guillain-Barré syndrome. Little is known about how ZIKV causes these conditions or which ZIKV viral protein(s) is responsible for the associated ZIKV-induced cytopathic effects, including cell hypertrophy, growth restriction, cell-cycle dysregulation, and cell death. 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.1619735114
更新日期:2017-01-17 00:00:00
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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.0905825106
更新日期:2009-08-11 00:00:00
abstract::The reactivities of N-iodosuccinimide and iodine with various goitrogenic compounds were studied with dimethylsulfoxide through which nitrogen had been bubbled as a solvent. Although iodine does not react with all of the compounds, N-iodosuccinimide does react with all of them. N-Iodosuccinimide may, therefore, serve ...
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.70.5.1401
更新日期:1973-05-01 00:00:00
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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.85.20.7612
更新日期:1988-10-01 00:00:00
abstract::Male chickens with the henny feathering trait have a female feathering pattern. In two henny-feathered breeds, the Sebright bantam and the Golden Campine, the synthesis of estrogen is increased as a consequence of increased activity of aromatase, a cytochrome P-450 enzyme that converts androgen to estrogen. The activi...
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.82.9.3005
更新日期:1985-05-01 00:00:00
abstract::G protein-coupled receptors (GPCRs) have been found as monomers but also as dimers or higher-order oligomers in cells. The relevance of the monomeric or dimeric receptor state for G protein activation is currently under debate for class A rhodopsin-like GPCRs. Clarification of this issue requires the availability of 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.0705312104
更新日期:2007-07-17 00:00:00
abstract::Cyclonic atmospheric vortices of varying intensity, collectively known as low-pressure systems (LPS), travel northwest across central India and produce more than half of the precipitation received by that fertile region and its ∼600 million inhabitants. Yet, future changes in LPS activity are poorly understood, due 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.1709031115
更新日期:2018-03-13 00:00:00
abstract::Genes carried by EcoRI endonuclease-generated fragments of Staphylococcus plasmid DNA have been covalently joined to the E. coli antibiotic-resistance plasmid pSC101, and the resulting hybrid molecules have been introduced into E. coli by transformation. The newly constructed plasmids replicate as biologically functio...
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.71.4.1030
更新日期:1974-04-01 00:00:00
abstract::A class II (B) general transcription factor of 34 kDa has been purified from HeLa cells to apparent homogeneity. This factor appears to be transcription factor IIB (TFIIB), since it binds in vitro to template-committed preinitiation complexes formed between a template containing the TATA box/cap-site elements of the 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.89.1.397
更新日期:1992-01-01 00:00:00
abstract::An artificial charge pair buried in the hydrophobic core of staphylococcal nuclease was engineered by making the V23E and L36K substitutions. Buried individually, Glu-23 and Lys-36 both titrate with pKa values near 7. When buried together their pKa values appear to be normal. The ionizable moieties of the buried Glu-L...
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.1402900111
更新日期:2014-08-12 00:00:00
abstract::Modern European genetic structure demonstrates strong correlations with geography, while genetic analysis of prehistoric humans has indicated at least two major waves of immigration from outside the continent during periods of cultural change. However, population-level genome data that could shed light on the demograp...
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.1719880115
更新日期:2018-03-27 00:00:00
abstract::All classes of antidepressants increase hippocampal cell proliferation and neurogenesis, which contributes, in part, to the behavioral actions of these treatments. Among antidepressant treatments, electroconvulsive seizure (ECS) is the most robust stimulator of hippocampal cell proliferation and the most efficacious t...
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.0710858105
更新日期:2008-08-12 00:00:00
abstract::On a planet experiencing global environmental change, the governance of natural resources depends on sustained collective action by diverse populations. Engaging in such collective action can only build upon the foundation of human cognition in social-ecological settings. To help understand this foundation, we assess ...
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.1915824117
更新日期:2020-04-07 00:00:00
abstract::O-GlcNAc is an intracellular posttranslational modification that governs myriad cell biological processes and is dysregulated in human diseases. Despite this broad pathophysiological significance, the biochemical effects of most O-GlcNAcylation events remain uncharacterized. One prevalent hypothesis is that O-GlcNAc m...
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.1722437115
更新日期:2018-06-05 00:00:00