Abstract:
:Most organisms are evolutionary conservatives; they may subdivide their niches but tend to remain within them. Yet the fossil record shows many cases of breakthrough to a new mode of life. How may such evolutionary innovation be recognized at this time level? Three species of Drosophila have accomplished an innovation in that they breed as obligate commensals on tropical land crabs. This could be dismissed as a curious aberration were it not for the fact that the three flies concerned represent three different phyletic lines of the family. Although Drosophila is abundant on the continents, these three parallel innovative evolutions have occurred on islands. The proposal is made that the genetic systems of many conservative groups of organisms carry variability that would permit them to evolve in a novel direction. The realization of this capacity, however, is possible only under special environmental conditions.
journal_name
Proc Natl Acad Sci U S Aauthors
Carson HLdoi
10.1073/pnas.71.9.3517subject
Has Abstractpub_date
1974-09-01 00:00:00pages
3517-21issue
9eissn
0027-8424issn
1091-6490journal_volume
71pub_type
杂志文章abstract::The emergence of multidrug-resistant (MDR) tuberculosis (TB) highlights the urgent need to understand the mechanisms of resistance to the drugs used to treat this disease. The aminoglycosides kanamycin and amikacin are important bactericidal drugs used to treat MDR TB, and resistance to one or both of these drugs is a...
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doi:10.1073/pnas.0907925106
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.94.10.5290
更新日期:1997-05-13 00:00:00
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更新日期:1997-08-05 00:00:00
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更新日期:1971-05-01 00:00:00
abstract::A cDNA, cRKIN1, encoding a putative homologue of the yeast (Saccharomyces cerevisiae) SNF1-encoded protein-serine/threonine kinase, has been isolated from a library prepared from rye endosperm mRNA. Northern blot analysis demonstrated the presence of cRKIN1-related transcripts in developing endosperms but not in shoot...
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:1991-10-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2013-07-09 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:2009-06-09 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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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:2005-03-15 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.95.23.13507
更新日期:1998-11-10 00:00:00
abstract::Nonesterified fatty acids accumulate at sites of tissue injury and necrosis. In cardiac tissue the concentrations of oleic acid, arachidonic acid, leukotrienes, and other fatty acids increase greatly during ischemia due to receptor or nonreceptor-mediated activation of phospholipases and/or diminished reacylation. 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.89.14.6452
更新日期:1992-07-15 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2001-07-17 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1995-05-23 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:2014-10-21 00:00:00
abstract::The attachment of human polymorphonuclear leukocytes (PMN) to bovine endothelial monolayers is increased by pretreatment of the endothelial cells with leukotriene B4 (LTB4). The response is dose dependent with a maximum at 10(-6) M, requires no more than 1 min of preincubation for the maximal effect, and decays linear...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1984-04-01 00:00:00
abstract::In a medium without Na+, gamma-aminobutyric acid (GABA) binds at 0 degrees to freshly prepared crude synaptic membranes from rat cerebral cortex with an apparent dissociation constant of 218 nM. An endogenous inhibitor of the Na+-independent GABA binding was removed from these membranes by freezing and thawing and by ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1978-08-01 00:00:00
abstract::India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO(2) concentration (pCO(2)) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-pro...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2008-10-21 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2009-12-15 00:00:00
abstract::Feasting is one of humanity's most universal and unique social behaviors. Although evidence for feasting is common in the early agricultural societies of the Neolithic, evidence in pre-Neolithic contexts is more elusive. We found clear evidence for feasting on wild cattle and tortoises at Hilazon Tachtit cave, a Late ...
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.1001809107
更新日期:2010-08-31 00:00:00
abstract::The plant hormones abscisic acid (ABA) and gibberellic acid (GA) are important regulators of the dormancy and germination of seeds. In cereals, GA enhances the synthesis and secretion of enzymes (principally alpha-amylases) in the aleurone cells of the endosperm, which then mobilize the storage reserves that fuel germ...
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.95.5.2697
更新日期:1998-03-03 00:00:00
abstract::CTCF sites are abundant in the genomes of diverse species but their function is enigmatic. We used chromosome conformation capture to determine long-range interactions among CTCF/cohesin sites over 2 Mb on human chromosome 11 encompassing the beta-globin locus and flanking olfactory receptor genes. Although CTCF occup...
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:2010-02-23 00:00:00