Abstract:
:Recommended Daily Allowances (US RDA) of the Food and Drug Administration for ascorbic acid are higher than Recommended Dietary Allowances (set by the Food and Nutrition Board) for adults. There is a 6-fold margin between the requirement to prevent scurvy and the US RDA. The high requirement reported for the rhesus monkey may be needed to compensate for oxidative catabolism of ascorbic acid in this species. The rate of production of ascorbic acid, in mammals that synthesize it has been listed as 3-19 g/70 kg per day. If this high rate of synthesis represents the requirement of such animals, mutations that caused a loss of ascorbic-acid-synthesizing ability would be eliminated by natural selection on diets that failed to supply these large quantities. The loss of ascorbic-acid-synthesizing ability by human beings could indicate a low requirement, which has enabled our species to spread to regions of the earth where dietary sources of ascorbic acid are poor.
journal_name
Proc Natl Acad Sci U S Aauthors
Jukes THdoi
10.1073/pnas.72.10.4151subject
Has Abstractpub_date
1975-10-01 00:00:00pages
4151-2issue
10eissn
0027-8424issn
1091-6490journal_volume
72pub_type
杂志文章abstract::The requirement for protein synthesis in the mechanism of a circadian pacemaker was investigated by using inhibitors of protein synthesis. Continuous treatment of the ocular circadian pacemaker of the mollusc Bulla gouldiana with anisomycin or cycloheximide substantially lengthened (up to 39 and 52 hr, respectively) 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.89.22.10862
更新日期:1992-11-15 00:00:00
abstract::Previous research and theory suggest that two stable personality dimensions, extroversion and neuroticism, differentially influence emotional reactivity to a variety of pleasurable phenomena. Here, we use event-related functional MRI to address the putative neural and behavioral associations between humor appreciation...
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.0408457102
更新日期:2005-11-08 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.0906851106
更新日期:2009-08-11 00:00:00
abstract::The strikingly high incidence of obstructed labor due to the disproportion of fetal size and the mother's pelvic dimensions has puzzled evolutionary scientists for decades. Here we propose that these high rates are a direct consequence of the distinct characteristics of human obstetric selection. Neonatal size relativ...
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.1612410113
更新日期:2016-12-20 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.1214809110
更新日期:2013-06-04 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.89.14.6452
更新日期:1992-07-15 00:00:00
abstract::In autotrophically grown Chlorella cells, glucose induces a hexose transport system but, at the same time, the synthesis of two amino acid transport systems is also induced. Thus, the rates of uptake of glycine, L-alanine, L-proline, and L-serine, all of which compete with each other for entry into the cells, increase...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.78.6.3591
更新日期:1981-06-01 00:00:00
abstract::Recent evidence suggests that the Myc and Mad1 proteins are implicated in the regulation of the gene encoding the human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase. We have analyzed the in vivo interaction between endogenous c-Myc and Mad1 proteins and the hTERT promoter in HL60 cells...
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.071043198
更新日期:2001-03-27 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.90.10.4758
更新日期:1993-05-15 00:00:00
abstract::Homeodomain-interacting protein kinase-2 (HIPK2) is a serine/threonine kinase involved in transcriptional regulation and apoptosis. The transcriptional corepressor CtBP (carboxyl-terminal binding protein) also plays a fundamental role in these processes. Our previous studies indicate that HIPK2 participates in a pathw...
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.0409373102
更新日期:2005-02-22 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.1720475115
更新日期:2018-02-13 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
doi:10.1073/pnas.96.22.12379
更新日期:1999-10-26 00:00:00
abstract::In extracts of interferon-treated HeLa cells, RNA covalently linked to double-stranded RNA (dsRNA) is preferentially degraded compared with mRNA not linked in dsRNA. This was established by following the degradation of poly(A)-containing mRNA annealed with poly(U), of poly(C)-containing encephalomyocarditis virus RNA ...
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.76.6.2600
更新日期:1979-06-01 00:00:00
abstract::Cyclophilins are a family of ubiquitous proteins that are the intracellular target of the immunosuppressant drug cyclosporin A. Although cyclophilins catalyze peptidylprolyl cis-trans isomerization in vitro, it has remained open whether they also perform this function in vivo. Here we show that Cpr3p, a cyclophilin 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.92.14.6319
更新日期:1995-07-03 00:00:00
abstract::We have identified the mutation responsible for the autosomal recessive wasted (wst) mutation of the mouse. Wasted mice are characterized by wasting and neurological and immunological abnormalities starting at 21 days after birth; they die by 28 days. A deletion of 15.8 kb in wasted mice abolishes expression of a gene...
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.95.8.4463
更新日期:1998-04-14 00:00:00
abstract::Steroidogenic acute regulatory protein (StAR) appears to mediate the rapid increase in pregnenolone synthesis stimulated by tropic hormones. cDNAs encoding StAR were isolated from a human adrenal cortex library. Human StAR, coexpressed in COS-1 cells with cytochrome P450scc and adrenodoxin, increased pregnenolone synt...
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.92.11.4778
更新日期:1995-05-23 00:00:00
abstract::Systemic lupus erythematosus (SLE) is a multigenic autoimmune disease, and the major histocompatibility complex (MHC) class II polymorphism serves as a key genetic element. In SLE-prone (NZB x NZW)F(1) mice, the MHC H-2(d/z) heterozygosity (H-2(d) of NZB and H-2(z) of NZW) has a strong impact on disease; thus, congeni...
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.0405807101
更新日期:2004-09-21 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.1922189117
更新日期:2020-09-01 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.94.10.4836
更新日期:1997-05-13 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
doi:10.1073/pnas.96.4.1309
更新日期:1999-02-16 00:00:00
abstract::Human apolipoprotein E (apoE) was produced in Escherichia coli by transforming cells with an expression vector containing a reconstructed apoE cDNA, a lambda PL promoter regulated by the thermolabile cI repressor, and a ribosomal binding site derived from the lambda cII or the E. coli beta-lactamase gene. Transformed ...
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.82.24.8696
更新日期:1985-12-01 00:00:00
abstract::Volcanic eruptions caused major weather and climatic changes on timescales ranging from hours to centuries in the past. Volcanic particles are injected in the atmosphere both as primary particles rapidly deposited due to their large sizes on time scales of minutes to a few weeks in the troposphere, and secondary parti...
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.1104923108
更新日期:2011-07-26 00:00:00
abstract::I describe some recent observations of large-scale structure in the galaxy distribution. The best constraints come from two-dimensional galaxy surveys and studies of angular correlation functions. Results from galaxy redshift surveys are much less precise but are consistent with the angular correlations, provided 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.90.11.4859
更新日期:1993-06-01 00:00:00
abstract::A type of heritable cellular change, known as habituation, occurs spontaneously in plant tissue and cell culture. This phenomenon is characterized by a newly acquired capacity of plant cells to produce growth regulatory substances. Using cloned lines of tobacco pith parenchyma cells, we demonstrated that a newly acqui...
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.70.9.2660
更新日期:1973-09-01 00:00:00
abstract::Over the last two decades, the number of gene/protein sequences gleaned from sequencing projects of individual genomes and environmental DNA has grown exponentially. Only a tiny fraction of these predicted proteins has been experimentally characterized, and the function of most proteins remains hypothetical or only pr...
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.1815791116
更新日期:2019-03-26 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.1508990112
更新日期:2015-06-30 00:00:00
abstract::Superficial cells from early amphibian embryos display regional specializations of their cell surfaces. That portion of the plasma membrane facing the perivitelline space (apical surface) is nonadhesive, whereas, in the same cell, the lateral and basal portions of the plasma membrane will adhere to other cells. These ...
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.77.6.3460
更新日期:1980-06-01 00:00:00
abstract::Studies in vitro have established that free tryptophan induces tna operon expression by binding to the ribosome that has just completed synthesis of TnaC-tRNA(Pro), the peptidyl-tRNA precursor of the leader peptide of this operon. Tryptophan acts by inhibiting Release Factor 2-mediated cleavage of this peptidyl-tRNA 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.0600082103
更新日期:2006-03-07 00:00:00
abstract::We demonstrate that single interneurons can toggle the output neurons of the cerebellar cortex (the Purkinje cells) between their two states. The firing of Purkinje cells has previously been shown to alternate between an "up" state in which the cell fires spontaneous action potentials and a silent "down" state. We sho...
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.1002082107
更新日期:2010-07-20 00:00:00
abstract::It is generally believed that the old quantum theory, as presented by Niels Bohr in 1913, fails when applied to few electron systems, such as the H(2) molecule. Here, we find previously undescribed solutions within the Bohr theory that describe the potential energy curve for the lowest singlet and triplet states of H(...
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.0505778102
更新日期:2005-08-23 00:00:00