Abstract:
:The density of benzodiazepine/gamma-aminobutyric acid receptor binding sites was lower in the midbrain of seizure-susceptible gerbils compared to control seizure-resistant gerbils. Binding of [3H]diazepam to high-affinity brain-specific sites in membrane homogenates of gerbil brain showed a 20-30% lower binding in midbrain (but not other regions) in adult seizure-susceptible gerbils than in controls. This binding deficit was localized by tissue slice autoradiography with [3H]flunitrazepam to the substantia nigra and mesencephalic periaqueductal gray regions, while higher binding was observed in the interpeduncular nucleus. These differences were also seen in animals sacrificed immediately after a seizure. A parallel deficit of [3H]bicuculline methochloride binding to low-affinity gamma-aminobutyric acid receptors also was seen in the same midbrain regions. Scatchard plot analysis showed that the benzodiazepine binding deficit in the nigra was due to a lower number of binding sites with not significant difference in affinity. Lower [3H]flunitrazepam binding was likewise seen in younger animals (29% lower at 30 days of age, 38% at 60 days, and 21% at 90 days), indicating that the midbrain receptor deficit is present in the seizure-susceptible gerbil prior to the age of onset of seizures at 50-100 days. Therefore, these changes are not likely to result from seizures but reflect genetically determined biochemical differences that could play a role in the expression of seizure susceptibility. The deficit in midbrain benzodiazepine/gamma-aminobutyric acid receptors in the seizure-susceptible gerbil would be consistent with the hypothesis that a deficit of gamma-aminobutyric acid-mediated inhibition might contribute to some kinds of epilepsy.
journal_name
Proc Natl Acad Sci U S Aauthors
Olsen RW,Wamsley JK,McCabe RT,Lee RJ,Lomax Pdoi
10.1073/pnas.82.19.6701subject
Has Abstractpub_date
1985-10-01 00:00:00pages
6701-5issue
19eissn
0027-8424issn
1091-6490journal_volume
82pub_type
杂志文章abstract::High-resolution analyses of a late Holocene core from Kettle Lake in North Dakota reveal coeval fluctuations in loss-on-ignition carbonate content, percentage of grass pollen, and charcoal flux. These oscillations are indicative of climate-fuel-fire cycles that have prevailed on the Northern Great Plains (NGP) for mos...
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.0503621102
更新日期:2005-06-21 00:00:00
abstract::The in vivo production of frameshift and base-substitution mutations predicted as a consequence of the metabolic processing of misaligned quasipalindromic DNA sequences has been confirmed. Spontaneous frameshift mutations of the T4 rII gene that had been genetically mapped to quasipalindromic DNA sequences were sequen...
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.81.17.5528
更新日期:1984-09-01 00:00:00
abstract::Regulated exocytosis requires tight coupling of the membrane fusion machinery to a triggering signal and a fast response time. Complexins are part of this regulation and, together with synaptotagmins, control calcium-dependent exocytosis. Stimulatory and inhibitory functions have been reported for complexins. To test ...
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.0812813106
更新日期:2009-02-10 00:00:00
abstract::Behavioral models indicate that persistent small afferent input, as generated by tissue injury, results in a hyperalgesia at the site of injury and a tactile allodynia in areas adjacent to the injury site. Hyperalgesia reflects a sensitization of the peripheral terminal and a central facilitation evoked by the persist...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章,评审
doi:10.1073/pnas.96.14.7680
更新日期:1999-07-06 00:00:00
abstract::Ammonium sulfate fractionation of crude extracts of E. coli yields a soluble enzyme fraction (about 25-fold purification) that catalyzes the conversion of phiX174 single-stranded DNA to duplex DNA. The reaction is rifampicin-resistant, requires single-stranded DNA, Mg++, deoxynucleoside triphosphates, and ATP, and is ...
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.72.10.3907
更新日期:1975-10-01 00:00:00
abstract::Understanding the genetic networks that operate inside cells will require the dissection of interactions among network members. Here we describe a peptide aptamer isolated from a combinatorial library that distinguishes among such interactions. This aptamer binds to cyclin-dependent kinase 2 (Cdk2) and inhibits its ki...
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.95.24.14272
更新日期:1998-11-24 00:00:00
abstract::Populations of isogenic embryonic stem cells or clonal bacteria often exhibit extensive phenotypic heterogeneity that arises from intrinsic stochastic dynamics of cells. The phenotypic state of a cell can be transmitted epigenetically in cell division, leading to correlations in the states of cells related by descent....
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.1504407112
更新日期:2015-05-05 00:00:00
abstract::Ecosystem services are supplied by nature but, by definition, are received by people. Ecosystem service assessments, intended to influence the decisions people make regarding their interactions with nature, need to understand how people benefit from different ecosystem services. A critical question is therefore, What ...
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.1413473111
更新日期:2014-12-16 00:00:00
abstract::Sulfated glycosaminoglycans (GAGs) such as heparan sulfate (HS) are heteropolysaccharides implicated in the pathology of protein aggregation diseases including localized and systemic forms of amyloidosis. Among subdomains of sulfated GAGs, highly sulfated domains of HS, called HS S-domains, have been highlighted as be...
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.2009931117
更新日期:2020-12-29 00:00:00
abstract::Blood viscosity decreases with shear stress, a property essential for an efficient perfusion of the vascular tree. Shear thinning is intimately related to the dynamics and mutual interactions of RBCs, the major component of blood. Because of the lack of knowledge about the behavior of RBCs under physiological conditio...
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.1608074113
更新日期:2016-11-22 00:00:00
abstract::We have determined the localization and orientation of two genetic probes within the human major histocompatibility complex by chromosomal in situ hybridization. Our data indicate that a cloned genomic probe cross-hybridizing to HLA-A, -B, and -C heavy chain loci is homologous to sequences located on chromosome 6 at b...
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.81.9.2816
更新日期:1984-05-01 00:00:00
abstract::The engineering of structures across different length scales is central to the design of novel materials with controlled macroscopic properties. Herein, we introduce a unique class of self-assembling materials, which are built upon shape- and volume-persistent molecular nanoparticles and other structural motifs, such ...
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.1302606110
更新日期:2013-06-18 00:00:00
abstract::Ca2+ is a powerful inhibitor (Ki is congruent to 16 muM) of basal and prostaglandin E1 (PGE1)-stimulated adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); EC 4.6.1.1] activity in membranes obtained from homogenized human platelets. Ca2+ (but not the ionophore A23,187) decreased V(max) of the reaction without 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.73.6.1829
更新日期:1976-06-01 00:00:00
abstract::Fluorescence of quinacrine in the presence of different polynucleotides was studied to attempt to identify the specific nucleotides responsible for the fluorescence of stained chromosome preparations. A marked enhancement of fluorescence was seen in the presence of bihelical polynucleotides, such as poly(dA-dT), poly(...
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.69.3.629
更新日期:1972-03-01 00:00:00
abstract::The thymus lacks self-renewing hematopoietic cells, and thymopoiesis fails rapidly when the migration of progenitor cells to the thymus ceases. Hence, the process of thymus homing is an essential step for T-cell development and cellular immunity. Despite decades of research, the molecular details of thymus homing have...
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.1016428108
更新日期:2011-05-03 00:00:00
abstract::Herpes simplex virus (HSV) is known to bud from the inner membrane of the nuclear envelope. The structural gene for the glycoprotein gB, which is essential for virus entry and cell fusion induced by HSV type 1, has been cloned in a transient expression vector containing the adenovirus major late promoter, tripartite 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.84.16.5675
更新日期:1987-08-01 00:00:00
abstract::Dominant mutations in the maize homeobox gene knotted1 (kn1) act nonautonomously during maize leaf development, indicating that Kn1 is involved in the generation or transmission of a developmental signal that passes from the inner layers of the leaf to epidermal cells. We previously found that this nonautonomous activ...
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.052484099
更新日期:2002-03-19 00:00:00
abstract::The exquisite selectivity and catalytic activity of enzymes have been shaped by the effects of positive and negative selection pressure during the course of evolution. In contrast, enzyme variants engineered by using in vitro screening techniques to accept novel substrates typically display a higher degree of catalyti...
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.0500063102
更新日期:2005-05-10 00:00:00
abstract::Human cytomegalovirus (HCMV) strains that have been passaged in vitro rapidly acquire mutations that impact viral growth. These laboratory-adapted strains of HCMV generally exhibit restricted tropism, produce high levels of cell-free virus, and develop susceptibility to natural killer cells. To permit experimentation ...
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.1704809114
更新日期:2017-06-06 00:00:00
abstract::Apomixis is a naturally occurring mode of reproduction that results in embryo formation without the involvement of meiosis or fertilization of the egg. Seed-derived progeny of an apomictic plant are genetically identical to the maternal parent. We are studying a form of apomixis called apospory that occurs in the genu...
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.95.9.5127
更新日期:1998-04-28 00:00:00
abstract::Synapsin I is a neuron-specific phosphoprotein associated with the membranes of small synaptic vesicles. Its function is not entirely clear, but evidence points to a possible role in the regulation of neurotransmitter release. Its biosynthesis is under developmental control. Assignment of the human synapsin I gene to ...
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.83.22.8679
更新日期:1986-11-01 00:00:00
abstract::The principal sequence feature responsible for intrinsic DNA curvature is generally assumed to be runs of adenines. However, according to the wedge model of DNA curvature, each dinucleotide step is associated with a characteristic deflection of the local helix axis. Thus, an important test of a more general view of se...
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.88.6.2312
更新日期:1991-03-15 00:00:00
abstract::An homologous in vitro assay for yeast nonsense suppressors was used to examine the effect of the cytoplasmically inherited genetic determinant [psi] on the efficiency of in vitro nonsense suppression. The efficiency of all three types of yeast tRNA-mediated nonsense suppressor (ochre, amber, and UGA) is much greater ...
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.80.10.2824
更新日期:1983-05-01 00:00:00
abstract::CCR5 (R5)-tropic, but not CXCR4 (X4)-tropic, HIV-1 is associated with primary HIV-1 infection and transmission. Recent studies have shown that IFN-induced transmembrane (IFITM) proteins, including IFITM1, IFITM2, and IFITM3, restrict a broad range of viruses. Here, we demonstrate that an IFITM2 isoform (Δ20 IFITM2) la...
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.1619640114
更新日期:2017-07-03 00:00:00
abstract::Early forms of the genetic code likely generated "statistical" proteins, with similar side chains occupying the same sequence positions at different ratios. In this scenario, groups of related side chains were treated by aminoacyl-tRNA synthetases as a single molecular species until a discrimination mechanism develope...
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.2136794100
更新日期:2003-12-23 00:00:00
abstract::Before they even speak, infants become attuned to the sounds of the language(s) they hear, processing native phonetic contrasts more easily than nonnative ones. For example, between 6 to 8 mo and 10 to 12 mo, infants learning American English get better at distinguishing English and [l], as in "rock" vs. "lock," relat...
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.2001844118
更新日期:2021-02-09 00:00:00
abstract::The zinc finger motif, exemplified by a segment of the Drosophila gap gene Krüppel, is a nucleic acid-binding domain present in many transcription factors. To investigate the gene family encoding this motif in the human genome, a placental genomic library was screened at moderate stringency with a degenerate oligodeox...
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.88.21.9563
更新日期:1991-11-01 00:00:00
abstract::It is suggested that active transport, muscle contraction, and ribosomal translocation may all make use of a common allosteric mechanism in which ATP or GTP serves as both the effector and substrate and in which a conformational change in a protein (enzyme) moves or exerts a force on a second ligand. The enzymatic spl...
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.64.1.267
更新日期:1969-09-01 00:00:00
abstract::Organic agriculture promotes sustainability compared to conventional agriculture. However, the multifunctional sustainability benefits of organic farms might be mediated by landscape context. Assessing how landscape context affects sustainability may aid in targeting organic production to landscapes that promote high ...
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.1906909117
更新日期:2020-02-11 00:00:00
abstract::Ascidians are hermaphrodites releasing sperm and eggs simultaneously, but many species are self-sterile because of a self/nonself-recognition system in spermegg interaction. Here, we show that a 70-kDa vitelline coat protein, HrVC70, consisting of 12 epidermal growth factor-like repeats, plays a key role in self/nonse...
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.0401928101
更新日期:2004-11-02 00:00:00