Abstract:
:In an autoshaping experiment, food-deprived pigeons pecked rapidly at a moving dot that preceded the delivery of food. When the moving dot and food were no longer correlated, the rate of pecking dropped nearly to zero. When, subsequently, no food was given, pecking reappeared at a high rate (nearly 200 pecks per min for each subject), the rate dropping again in subsequent sessions. In two other experiments, designed to clarify relevant variables, the effect was replicated. The data suggest that although response-independent reinforcement produces a decrement in responding, it does not reduce a tendency to respond under other conditions.
journal_name
Proc Natl Acad Sci U S Aauthors
Epstein R,Skinner BFdoi
10.1073/pnas.77.10.6251subject
Has Abstractpub_date
1980-10-01 00:00:00pages
6251-3issue
10eissn
0027-8424issn
1091-6490journal_volume
77pub_type
杂志文章abstract::Our previous work [Levinger, L. & Varshavsky, A. (1982) Cell 28, 375-385] has shown that D1, a 50-kilodalton chromosomal protein of Drosophila melanogaster, is specifically associated with isolated nucleosomes that contain a complex A + T-rich satellite DNA with buoyant density of 1.688 g/ml. We show here that D1 is 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.79.23.7152
更新日期:1982-12-01 00:00:00
abstract::Heat shock locus V (HslV; also called ClpQ) is the proteolytic core of the ATP-dependent protease HslVU in Escherichia coli. It has sequence similarity with the beta-type subunits of the eukaryotic and archaebacterial proteasomes. Unlike these particles, which display 72-point symmetry, it is a dimer of hexamers 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.94.12.6070
更新日期:1997-06-10 00:00:00
abstract::The primary structure of the precursor of urotensin I, a neuropeptide hormone from the caudal neurosecretory system of the carp Cyprinus carpio, has been determined by analyzing the nucleotide sequence of cloned DNA complementary to the mRNA encoding it. The precursor consists of 145 amino acid residues and the carbox...
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.83.2.308
更新日期:1986-01-01 00:00:00
abstract::Time series data on arthropod populations are critical for understanding the magnitude, direction, and drivers of change. However, most arthropod monitoring programs are short-lived and restricted in taxonomic resolution. Monitoring data from the Arctic are especially underrepresented, yet critical to uncovering and u...
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.2002557117
更新日期:2021-01-12 00:00:00
abstract::The gene EPXH2 encodes for the soluble epoxide hydrolase (sEH), an enzyme involved in the regulation of cardiovascular and renal physiology containing two distinct domains connected via a proline-rich linker. The C-terminal domain containing the EH catalytic activity has been well studied. In contrast, a function for ...
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.0437724100
更新日期:2003-02-18 00:00:00
abstract::Duplexes constituted by closed or open RNA circles paired to single-stranded oligonucleotides terminating with 3'-CCAOH form resected pseudoknots that are substrates of yeast histidyl-tRNA synthetase. Design of this RNA fold is linked to the mimicry of the pseudoknotted amino acid accepting branch of the tRNA-like dom...
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.95.18.10431
更新日期:1998-09-01 00:00:00
abstract::The error frequency of in vitro DNA synthesis using a natural DNA template has been measured with a biological assay for nucleotide substitutions. phiX174 DNA containing an amber mutation was copied in vitro by Escherichia coli DNA polymerase I, and the reversion frequency of the progeny DNA was determined by transfec...
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.75.4.1924
更新日期:1978-04-01 00:00:00
abstract::Several significant steps have been completed toward a general method for the site-specific incorporation of unnatural amino acids into proteins in vivo. An "orthogonal" suppressor tRNA was derived from Saccharomyces cerevisiae tRNA2Gln. This yeast orthogonal tRNA is not a substrate in vitro or in vivo for any Escheri...
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.96.9.4780
更新日期:1999-04-27 00:00:00
abstract::Ubiquitylation of proteins can be a signal for a variety of cellular processes beyond the classical role in proteolysis. The different signaling functions of ubiquitylation are thought to rely on ubiquitin-binding domains (UBDs). Several distinct UBD families are known, but their functions are not understood in detail...
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.1010648107
更新日期:2010-11-16 00:00:00
abstract::Cyclin E is an important regulator of cell cycle progression that together with cyclin-dependent kinase (cdk) 2 is crucial for the G1/S transition during the mammalian cell cycle. Previously, we showed that severe overexpression of cyclin E protein in tumor cells and tissues results in the appearance of lower molecula...
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.93.26.15215
更新日期:1996-12-24 00:00:00
abstract::Immunoprecipitation followed by mass spectrometry (IP/MS) has recently emerged as a preferred method in the analysis of protein complex components and cellular protein networks. Targeting endogenous protein complexes of higher eukaryotes, particularly in large-scale efforts, has been challenging due to cellular hetero...
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.0912599106
更新日期:2010-02-09 00:00:00
abstract::Graphene superlattices were shown to exhibit high-temperature quantum oscillations due to periodic emergence of delocalized Bloch states in high magnetic fields such that unit fractions of the flux quantum pierce a superlattice unit cell. Under these conditions, semiclassical electron trajectories become straight agai...
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.1804572115
更新日期:2018-05-15 00:00:00
abstract::Alcoholism causes serious neurologic disease that may be due, in part, to the ability of ethanol to interact with neural cell membranes and change neuronal function. Adenosine receptors are membrane-bound proteins that appear to mediate some of the effects of ethanol in the brain. Human lymphocytes also have adenosine...
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.84.5.1413
更新日期:1987-03-01 00:00:00
abstract::Current theory indicates that mitochondria were obtained 1.5 billion years ago from an ancient prokaryote. The mitochondria provided the capacity for aerobic respiration, the creation of the eukaryotic cell, and eventually complex multicellular organisms. Recent reports have found that mitochondria play essential role...
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.0510511103
更新日期:2006-01-31 00:00:00
abstract::Addition of a 0.5 M KCl wash fraction from rabbit reticulocyte ribosomes causes a 3- to 10-fold increase in the extent of translation of natural mRNAs by Krebs-cell lysates. In the presence of the wash fraction, 1 pmol of rabbit or mouse 10S RNA directs the incorporation of 80 pmol of leucine into rabbit globin. 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.69.5.1299
更新日期:1972-05-01 00:00:00
abstract::Both activated and resting CD4(+) T cells in mucosal tissues play important roles in the earliest phases of infection after sexual transmission of HIV-1, a process that is inefficient. HIV-1 gp120 binds to integrin alpha(4)beta(7) (alpha(4)beta(7)), the gut mucosal homing receptor. We find that alpha(4)beta(7)(high) 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.0911796106
更新日期:2009-12-08 00:00:00
abstract::Proteins of ribosomes from various stages of development in Dictyostelium discoideum were analyzed by two-dimensional polyacrylamide gel electrophoresis. Significant changes in protein composition were observed; the data demonstrate that cell differentiation in a eukaryotic system is accompanied by ribosome heterogene...
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.78.5.3083
更新日期:1981-05-01 00:00:00
abstract::During or immediately after synthesis in vertebrate cells, the oncogenic protein-tyrosine kinase pp60v-src associates with the approximately 90-kDa heat-shock protein (hsp90). In this complex, pp60v-src is not functional as a kinase. When pp60v-src is subsequently found inserted into the plasma membrane, it is active ...
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.90.15.7074
更新日期:1993-08-01 00:00:00
abstract::Electrogenic sodium- and chloride-dependent gamma-aminobutyric acid (GABA) transport in crude synaptosomal membrane vesicles is partly inhibited by saturating levels of either of the substrate analogues cis-3-aminocyclohexanecarboxylic acid (ACHC) or beta-alanine. However, both of them together potently and fully inhi...
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.87.7.2550
更新日期:1990-04-01 00:00:00
abstract::HIV infection leads to a state of chronic immune activation and progressive deterioration in immune function, manifested most recognizably by the progressive depletion of CD4+ T cells. A substantial percentage of natural killer (NK) cells from patients with HIV infection are activated and express the natural cytotoxic...
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.0504315102
更新日期:2005-08-02 00:00:00
abstract::We applied the directional tag PCR subtractive hybridization method to construct a rat hypothalamic cDNA library from which cerebellar and hippocampal sequences had been depleted, enriching 20-30-fold for sequences expressed selectively in the hypothalamus. We studied a sample of 94 clones selected for enrichment in 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.93.16.8733
更新日期:1996-08-06 00:00:00
abstract::Inorganic polyphosphate (polyP) is composed of linear chains of phosphate groups linked by high-energy phosphoanhydride bonds. However, this simple, ubiquitous molecule remains poorly understood. The use of nonstandardized analytical methods has contributed to this lack of clarity. By using improved polyacrylamide gel...
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.1519440113
更新日期:2016-01-26 00:00:00
abstract::In adipocytes, adenylate cyclase is positively regulated by beta-adrenergic agents and negatively regulated by adenosine. Incubation of adipocytes with adenosine deaminase relieves the inhibition of adenylate cyclase by destroying the adenosine that the cells release into the medium. When adipocytes are incubated 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.82.6.1614
更新日期:1985-03-01 00:00:00
abstract::Mouse teratocarcinoma cells induced to differentiate in vitro undergo a massive (30%) demethylation of DNA. A similar undermethylation is also observed in the mouse extraembryonic membranes, the yolk sac and placenta. In both cases, the decrease in methyl moieties occurs at a large number of CpG sites spread out over ...
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.81.8.2275
更新日期:1984-04-01 00:00:00
abstract::Tubulin cofactor B (TCoB) plays an important role in microtubule dynamics by facilitating the dimerization of alpha- and beta-tubulin. Recent evidence suggests that p21-activated kinase 1 (Pak1), a major signaling nodule in eukaryotic cells, phosphorylates TCoB on Ser-65 and Ser-128 and plays an essential role in micr...
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.0705149104
更新日期:2007-12-04 00:00:00
abstract::Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the concentration of an inhibitor such as Colcemid. Fibroblasts of high population do...
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.76.3.1274
更新日期:1979-03-01 00:00:00
abstract::Most new genes are thought to evolve from preexisting genes but duplications of entire genes or shuffling of preexisting exons provides only a limited repertoire of new sequences that can be presented to a cell. Only pieces that previously existed can be used in the construction and any further divergence depends on 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.91.16.7506
更新日期:1994-08-02 00:00:00
abstract::During clathrin-mediated endocytosis, adaptor proteins recognize specific internalization signals on cargo receptors, either recruiting cargos into clathrin-coated pits (CCPs) or initiating clathrin-coat assembly around the cargo molecules. Here, we identify epsin 1, a clathrin-, ubiquitin-, and phospholipid-interacti...
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.0803711105
更新日期:2008-08-19 00:00:00
abstract::Gold nanoparticles (NPs) wrapped in a membrane can be utilized as artificial virus nanoparticles (AVNs) that combine the large nonblinking or bleaching optical cross-section of the NP core with the biological surface properties and functionalities provided by a self-assembled lipid membrane. We used these hybrid nanom...
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.1804292115
更新日期:2018-09-25 00:00:00
abstract::Vasopressin's action in renal cells to regulate water transport depends on protein phosphorylation. Here we used mass spectrometry-based quantitative phosphoproteomics to identify signaling pathways involved in the short-term V2-receptor-mediated response in cultured collecting duct cells (mpkCCD) from mouse. Using 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.0910646107
更新日期:2010-02-23 00:00:00