Abstract:
:Solid-state cross-polarization/magic-angle sample-spinning (13)C NMR spectra have been recorded on chlorophyll a-water aggregates, methyl pyrochlorophyllide a, and methyl pyropheophorbide a (derivatives that lack a phytyl chain). Spectra have also been collected under a decoupling regime in which resonances of certain hydrogen-bearing carbon atoms are suppressed. These observations are used to assign the solid-state spectra.
journal_name
Proc Natl Acad Sci U S Aauthors
Brown CE,Spencer RB,Burger VT,Katz JJdoi
10.1073/pnas.81.2.641subject
Has Abstractpub_date
1984-01-01 00:00:00pages
641-4issue
2eissn
0027-8424issn
1091-6490journal_volume
81pub_type
杂志文章abstract::Cell type in Saccharomyces yeasts is regulated by two transposable blocks of DNA, the a and alpha cassettes. There are three loci where either cassette can exist. At the HML and HMR loci the cassettes are not expressed. The cassette at the MAT locus is expressed and controls the cell type. Changes of cell type involve...
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.77.5.2839
更新日期:1980-05-01 00:00:00
abstract::We previously developed a biological containment system using recombinant Salmonella Typhimurium strains that are attenuated yet capable of synthesizing protective antigens. The regulated delayed attenuation and programmed self-destructing features designed into these S. Typhimurium strains enable them to efficiently ...
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.1217554109
更新日期:2012-11-20 00:00:00
abstract::Recent studies have suggested that Paleozoic hyperoxia enabled animal gigantism, and the subsequent hypoxia drove a reduction in animal size. This evolutionary hypothesis depends on the argument that gas exchange in many invertebrates and skin-breathing vertebrates becomes compromised at large sizes because of distanc...
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.0611544104
更新日期:2007-08-07 00:00:00
abstract::Asexual freshwater planarians reproduce by tearing themselves into two pieces by a process called binary fission. The resulting head and tail pieces regenerate within about a week, forming two new worms. Understanding this process of ripping oneself into two parts poses a challenging biomechanical problem. Because pla...
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.1700762114
更新日期:2017-10-10 00:00:00
abstract::The capacity of a so-called male recombination (MR) chromosome in Drosophila melanogaster to generate mutations at 14 X-chromosome loci specifying visible phenotypes was investigated. Appreciable increases in mutation were found at three loci y, sn, and ras. Tests of represnetative mutants generated at each locus esta...
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.74.8.3490
更新日期:1977-08-01 00:00:00
abstract::Although the Austronesian expansion had a major impact on the languages of Island Southeast Asia, controversy still exists over the genetic impact of this expansion. The coexistence of both Asian and Papuan genetic ancestry in Eastern Indonesia provides a unique opportunity to address this issue. Here, we estimate rec...
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.1118892109
更新日期:2012-03-20 00:00:00
abstract::Many bacterial pathogens of plants and animals have evolved a specialized protein-secretion system termed type III to deliver bacterial proteins into host cells. These proteins stimulate or interfere with host cellular functions for the pathogen's benefit. The Salmonella typhimurium pathogenicity island 1 encodes one ...
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.170128997
更新日期:2000-08-29 00:00:00
abstract::Microviscosity (n) of the cell membrane lipid layer was determined in synchronized C1300 mouse neuroblastoma cells (clone Neuro-2A) by fluorescence polarization of 1,6-diphenystratum. The determined n value was maximal in mitosis, decreased markedly in the G1 phase, remained constant at a low level during the S phase,...
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.74.10.4458
更新日期:1977-10-01 00:00:00
abstract::Epstein-Barr nuclear antigen 1 (EBNA1) plays a vital role in the maintenance of the viral genome and is the only viral protein expressed in nearly all forms of Epstein-Barr virus (EBV) latency and EBV-associated diseases, including numerous cancer types. To our knowledge, no specific agent against EBV genes or protein...
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.1915372116
更新日期:2019-12-10 00:00:00
abstract::The [A] allele of SNP rs965513 in 9q22 has been consistently shown to be highly associated with increased papillary thyroid cancer (PTC) risk with an odds ratio of ∼1.8 as determined by genome-wide association studies, yet the molecular mechanisms remain poorly understood. Previously, we noted that the expression of 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.1506255112
更新日期:2015-05-12 00:00:00
abstract::Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the dri...
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.1613044113
更新日期:2016-11-22 00:00:00
abstract::MicroRNAs (miRNAs) are small, 18-22 nt long, noncoding RNAs that act as potent negative gene regulators in a variety of physiological and pathological processes. To repress gene expression, miRNAs are packaged into RNA-induced silencing complexes (RISCs) that target mRNAs for degradation and/or translational repressio...
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.1408037111
更新日期:2014-07-01 00:00:00
abstract::Genetic analysis for group selection is developed for the case of a biallelic locus (A, a) undergoing group selection of founder populations only. By contrast to R. Levins"E = E(x) models, extinction now depends on genetics at the propagule stage but acts uniformly on larger populations. Biological evidence supports 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.75.4.1909
更新日期:1978-04-01 00:00:00
abstract::Sonic hedgehog (Shh) plays an integral role in both the anterior-posterior (A-P) patterning and expansion of developing vertebrate limbs through a feedback loop involving Fgfs, Bmps, and Gremlin. In bat limbs A-P patterning and the size of the digital field are unique. The posterior digits of the forelimb are elongate...
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.0805308105
更新日期:2008-11-04 00:00:00
abstract::Analysis, by the recovery of specific genetic "markers," of the effects of DNase I, physical shear, and temperature shock on DNA-cell complexes demonstrates that sequential attachment of both ends of bacteriophage SP82G DNA to Bacillus subtilis precedes entry of the DNA molecule into the cell, and that each attachment...
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.69.6.1545
更新日期:1972-06-01 00:00:00
abstract::DNA fragments encoding the mouse steroid 21-hydroxylase (C21 or Cyp21A1) gene are de novo methylated when introduced into the mouse adrenocortical tumor cell line Y1 by DNA-mediated gene transfer. Although CCGG sequences within the C21 gene are de novo methylated, CCGG sites within flanking vector sequences, other mam...
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.86.18.6853
更新日期:1989-09-01 00:00:00
abstract::Micro-RNAs (miR genes) are a large family of highly conserved noncoding genes thought to be involved in temporal and tissue-specific gene regulation. MiRs are transcribed as short hairpin precursors ( approximately 70 nt) and are processed into active 21- to 22-nt RNAs by Dicer, a ribonuclease that recognizes target 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.242606799
更新日期:2002-11-26 00:00:00
abstract::This study demonstrates the presence of an N-acetyl-D-galactosaminyltransferase in human serum and in erythrocyte membranes. This enzyme catalyzes the transfer of N-acetyl-D-galactosamine from UDP-N-acetyl-D-galactosamine to a mucin receptor and 2'-fucosyllactose that have blood group H activity and may be responsible...
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.68.8.1753
更新日期:1971-08-01 00:00:00
abstract::Merkel cell polyomavirus (MCV) contributes to approximately 80% of all Merkel cell carcinomas (MCCs), a highly aggressive neuroendocrine carcinoma of the skin. MCV-positive MCC expresses small T antigen (ST) and a truncated form of large T antigen (LT) and usually contains wild-type p53 (TP53) and RB (RB1). In contras...
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.1818798116
更新日期:2019-01-15 00:00:00
abstract::DNA delivery of IL-12 has shown promise in reducing the toxic side effects associated with administration of recombinant human (h)IL-12 protein while maintaining the ability to inhibit tumor growth and abolish tumor metastases in animal models. We have developed a more potent version of IL-12 by using DNA shuffling an...
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.0237327100
更新日期:2003-02-04 00:00:00
abstract::A significant improvement in molecular hydrogen uptake properties is revealed by our ab initio calculations for Li-decorated metal-organic framework 5. We have found that two Li atoms are strongly adsorbed on the surfaces of the six-carbon rings, one on each side, carrying a charge of +0.9e per Li atom. Each Li can cl...
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.0708603104
更新日期:2007-12-18 00:00:00
abstract::A variety of agricultural plant species, including corn, respond to insect herbivore damage by releasing large quantities of volatile compounds and, as a result, become highly attractive to parasitic wasps that attack the herbivores. An elicitor of plant volatiles, N-(17-hydroxylinolenoyl)-L-glutamine, named volicitin...
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.95.23.13971
更新日期:1998-11-10 00:00:00
abstract::Citrus bacterial canker (CBC) caused by Xanthomonas axonopodis pv. citri (Xac) was first documented in India and Java in the mid 19th century. Since that time, the known distribution of the disease has steadily increased. Concurrent with the dispersion of the pathogen, the diversity of described strains continues to i...
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.0705590104
更新日期:2007-11-20 00:00:00
abstract::Geckos can run rapidly on walls and ceilings, requiring high friction forces (on walls) and adhesion forces (on ceilings), with typical step intervals of approximately 20 ms. The rapid switching between gecko foot attachment and detachment is analyzed theoretically based on a tape model that incorporates the adhesion ...
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.0608841103
更新日期:2006-12-19 00:00:00
abstract::New Zealand black x New Zealand white (NZB/W) F1 mice spontaneously develop an autoimmune syndrome with notable similarities to human systemic lupus erythematosus. Female NZB/WF1 mice produce high titers of antinuclear antibodies and invariably succumb to severe glomerulonephritis by 12 months of age. Although the dev...
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.93.16.8563
更新日期:1996-08-06 00:00:00
abstract::Organic reaction networks are formalized by representing chemical species as points in a space and representing reactions by connectivity rules. Using the generalized network, the behavior of the system is investigated under conditions of electronically exciting input and output to a thermal reservoir. Under steady-st...
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.71.6.2335
更新日期:1974-06-01 00:00:00
abstract::In Saccharomyces cerevisiae cells harboring a GAL1 promoter-linked beta-galactosidase gene, the simultaneous expression of Escherichia coli DNA topoisomerase I and inactivation of yeast DNA topoisomerases I and II reduces the cellular level of beta-galactosidase to an undetectable level. Analysis of intracellular mRNA...
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.89.23.11461
更新日期:1992-12-01 00:00:00
abstract::The translocation of lipids from the inner to the outer membrane of Escherichia coli has been investigated by pulse-chase experiments. After a pulse with [2-3H]glycerol, the specific activity of the newly synthesized [3H]phosphatidylethanolamine was 5 times greater in the inner than in the outer membrane. During the c...
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.77.4.1867
更新日期:1980-04-01 00:00:00
abstract::E2A helix-loop-helix proteins are involved in the control of various developmental pathways. We show here by in situ hybridization that E2A transcripts are present in most embryonic and adult tissues. However, no E2A expression is detectable in heart and nonproliferative regions of the brain and spinal cord. Highest 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.90.16.7583
更新日期:1993-08-15 00:00:00
abstract::The results of physicochemical studies of mammalian metallothioneins are summarized and used to propose a model of the protein. The primary structures of all mammalian metallothioneins are very homologous; there are 38 invariant residues and 20 of them are cysteines. The results of UV and CD optical studies indicated ...
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.80.6.1501
更新日期:1983-03-01 00:00:00