Abstract:
:Shell shape and shell thickness of the intertidal snail Littorina obtusata changed markedly between 1871 and 1984 in northern New England. Shells collected prior to 1900 were high-spired with thin walls, whereas shells collected in 1982-84 were low-spired with thick walls. An intertidal crab (Carcinus maenas) which preys on L. obtusata expanded its range into northern New England around 1900. This suggests that the change in snail shell form was a response to predation by Carcinus. Field and laboratory experiments demonstrated that the high-spired form of L. obtusata, which can still be found in some Maine localities, is more vulnerable to predation by Carcinus than is the low-spired form of L. obtusata. Electrophoretic comparisons of high- and low-spired populations of L. obtusata confirmed that these populations represent different morphological forms of L. obtusata rather than different species [Nei's D (unbiased measure of genetic distance) = 0.003]. These data demonstrate that classical Darwinian selection can produce a rapid morphological transition without speciation.
journal_name
Proc Natl Acad Sci U S Aauthors
Seeley RHdoi
10.1073/pnas.83.18.6897subject
Has Abstractpub_date
1986-09-01 00:00:00pages
6897-901issue
18eissn
0027-8424issn
1091-6490journal_volume
83pub_type
杂志文章abstract::Mechanisms for controlling symbiont populations are critical for maintaining the associations that exist between a host and its microbial partners. We describe here the transcriptional, metabolic, and ultrastructural characteristics of a diel rhythm that occurs in the symbiosis between the squid Euprymna scolopes and ...
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.0909712107
更新日期:2010-02-02 00:00:00
abstract::Hitherto it has not been possible to obtain spore and stalk cell differentiation of the cellular slime molds in submerged cultures. It is shown here that cells, when placed in roller tubes under an atmosphere of oxygen, will form clumps and differentiate in 48-72 hr into mature spores and stalk cells. Although differe...
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.74.1.268
更新日期:1977-01-01 00:00:00
abstract::Contact-dependent growth inhibition (CDI) is a mechanism by which bacteria exchange toxins via direct cell-to-cell contact. CDI systems are distributed widely among Gram-negative pathogens and are thought to mediate interstrain competition. Here, we describe tsf mutations that alter the coiled-coil domain of elongatio...
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.1619273114
更新日期:2017-03-07 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.1705060114
更新日期:2017-08-08 00:00:00
abstract::Mutant I1A cells, lacking IL-1 receptor-associated kinase (IRAK) mRNA and protein, have been used to study the involvement of IRAK in NFkappaB and c-Jun N-terminal kinase (JNK) activation. A series of IRAK deletion constructs were expressed in I1A cells, which were then tested for their ability to respond to IL-1. Bot...
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.071054198
更新日期:2001-04-10 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.0406798102
更新日期:2005-01-25 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.1917597117
更新日期:2020-05-26 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.1104969108
更新日期:2011-10-25 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:2018-12-18 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.1412897111
更新日期:2014-08-19 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.0904942106
更新日期:2009-09-22 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.78.12.7707
更新日期:1981-12-01 00:00:00
abstract::The crystal structure of the decanucleotide d(CGCAATTGCG)2 has been solved by a combination of molecular replacement and heavy-atom procedures and has been refined to an R factor of 20.2% at 2.7 A. It is not a fully base-paired duplex but has a central core of eight Watson-Crick base pairs flanked by unpaired terminal...
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.92.23.10767
更新日期:1995-11-07 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.142310499
更新日期:2002-07-23 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
doi:10.1073/pnas.86.2.641
更新日期:1989-01-01 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.82.12.4127
更新日期:1985-06-01 00:00:00
abstract::Inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs) are IP(3)-gated Ca(2+) channels that are located on intracellular Ca(2+) stores. We previously identified an IP(3)R binding protein, termed IP(3)R binding protein released with IP(3) (IRBIT). Because IRBIT is released from IP(3)R by physiological concentrations ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.0602250103
更新日期:2006-06-20 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
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更新日期:2007-11-13 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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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.73.5.1523
更新日期:1976-05-01 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.94.21.11168
更新日期:1997-10-14 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.1116590109
更新日期:2012-06-26 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.1207040109
更新日期:2012-07-31 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.0702451104
更新日期:2007-10-09 00:00:00
abstract::We have isolated and characterized cDNA and genomic clones that specify a Paracentrotus lividus procollagen chain. The cDNAs code for 160 uninterrupted Gly-Xaa-Yaa triplets and a 252-amino acid carboxyl propeptide. Analysis of the deduced amino acid sequences indicated that the sea urchin polypeptide exhibits structur...
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.86.23.9303
更新日期:1989-12-01 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.93.14.6924
更新日期:1996-07-09 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
doi:10.1073/pnas.0308478100
更新日期:2004-02-17 00:00:00
abstract::Regulated changes in gene expression underlie many biological processes, but globally profiling cell-to-cell variations in transcriptional regulation is problematic when measuring single cells. Transcriptome-wide identification of regulatory heterogeneities can be robustly achieved by randomly collecting small numbers...
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.1311647111
更新日期:2014-02-04 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.1102999108
更新日期:2011-09-20 00:00:00
abstract::What are the origins of humans' capacity to represent social relations? We approached this question by studying human infants' understanding of social dominance as a stable relation. We presented infants with interactions between animated agents in conflict situations. Studies 1 and 2 targeted expectations of stabilit...
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.1113194109
更新日期:2012-05-01 00:00:00