Abstract:
:The Paleocene/Eocene thermal maximum (PETM) and associated carbon isotope excursion (CIE) are often touted as the best geologic analog for the current anthropogenic rise in pCO2. However, a causal mechanism for the PETM CIE remains unidentified because of large uncertainties in the duration of the CIE's onset. Here, we report on a sequence of rhythmic sedimentary couplets comprising the Paleocene/Eocene Marlboro Clay (Salisbury Embayment). These couplets have corresponding δ(18)O cycles that imply a climatic origin. Seasonal insolation is the only regular climate cycle that can plausibly account for δ(18)O amplitudes and layer counts. High-resolution stable isotope records show 3.5‰ δ(13)C decrease over 13 couplets defining the CIE onset, which requires a large, instantaneous release of (13)C-depleted carbon. During the CIE, a clear δ(13)C gradient developed on the shelf with the largest excursions in shallowest waters, indicating atmospheric δ(13)C decreased by ~20‰. Our observations and revised release rate are consistent with an atmospheric perturbation of 3,000-gigatons of carbon (GtC).
journal_name
Proc Natl Acad Sci U S Aauthors
Wright JD,Schaller MFdoi
10.1073/pnas.1309188110subject
Has Abstractpub_date
2013-10-01 00:00:00pages
15908-13issue
40eissn
0027-8424issn
1091-6490pii
1309188110journal_volume
110pub_type
历史文章,杂志文章abstract::The formation of myelin by Schwann cells (SCs) occurs via a series of orchestrated molecular events. We previously used global expression profiling to examine peripheral nerve myelination and identified the NAD(+)-dependent deacetylase Sir-two-homolog 2 (Sirt2) as a protein likely to be involved in myelination. Here, ...
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
abstract::Many bacteria use acyl homoserine lactone signals to monitor cell density in a type of gene regulation termed quorum sensing and response. Synthesis of these signals is directed by homologs of the luxi gene of Vibrio fischeri. This communication resolves two critical issues concerning the synthesis of the V. fischeri ...
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.93.18.9505
更新日期:1996-09-03 00:00:00
abstract::Acute and chronic injuries to the heart result in perturbation of intracellular calcium signaling, which leads to pathological cardiac hypertrophy and remodeling. Calcium/calmodulin-dependent protein kinase II (CaMKII) has been implicated in the transduction of calcium signals in the heart, but the specific isoforms o...
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.0813013106
更新日期:2009-02-17 00:00:00
abstract::Poly(A)-containing HeLa cell mRNA prepared from cells labeled with [methyl-(3)H]methionine or [(32)P]phosphate was found to contain a variety of methylated, blocked 5'-terminal structures of two general types: m(7)GpppN(7)-Np and m(7)GpppN(m)-N(m)-Np. In addition, about one-third of the [(3)H]methyl label was present ...
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.72.5.1904
更新日期:1975-05-01 00:00:00
abstract::We have developed a low stringency polymerase chain reaction (LSPCR) to isolate the unknown neighboring region around a known DNA sequence, thus allowing efficient targeted gene walking. The method involves the polymerase chain reaction (PCR) with a single primer under conditions of low stringency for primer annealing...
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.91.8.2975
更新日期:1994-04-12 00:00:00
abstract::It is well known that two regular tetrahedra can be combined with a single regular octahedron to tile (complete fill) three-dimensional Euclidean space . This structure was called the "octet truss" by Buckminster Fuller. It was believed that such a tiling, which is the Delaunay tessellation of the face-centered cubic ...
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.1105594108
更新日期:2011-07-05 00:00:00
abstract::The development of Drosophila requires the function of the CREB-binding protein, dCBP. In flies, dCBP serves as a coactivator for the transcription factors Cubitus interruptus, Dorsal, and Mad, and as a cosuppressor of Drosophila T cell factor. Current models propose that CBP, through its intrinsic and associated hist...
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.052509799
更新日期:2002-03-05 00:00:00
abstract::High levels of inbreeding cause populations to become composed of homozygous, inbred lines. High levels of homozygosity limit the effectiveness of recombination, and therefore, retard the rate of decay of linkage (gametic phase) disequilibrium (LD) among mutations. Inbreeding and recombination interact to shape the ex...
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.0409804102
更新日期:2005-02-15 00:00:00
abstract::Rhomboid domain-containing protein 3 (Rhbdd3), which belongs to a family of proteins with rhomboid domain, is widely expressed in immune cells; however, the roles of the Rhbdd members, including Rhbdd3, in immunity remain unknown. Natural killer (NK) cells are critical for host immune defense and also can mediate infl...
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.1220466110
更新日期:2013-05-07 00:00:00
abstract::A near-full-length casbene synthase cDNA clone, pCS7, was isolated by using a partial cDNA clone, pCS4, to probe a lambda gt10 library constructed from poly(A)+ RNA from elicited castor bean seedlings. The cDNA insert had a length of 1983 bases with a polyadenylate tail of 19 bases. Translation of the cDNA sequence re...
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.91.18.8497
更新日期:1994-08-30 00:00:00
abstract::The goldfish (Carassius auratus) visual pathway displays continuous growth and plasticity throughout life. Since homeobox genes are important transcriptional regulators in development, we searched for homeobox genes in the adult goldfish retina and brain. Using the PCR, we discovered a repertoire of homeobox sequences...
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.90.7.2729
更新日期:1993-04-01 00:00:00
abstract::Electron micrographs of replicating lambda DNA molecules, during the period of progeny-particle DNA formation, show single-tailed circular structures. The tails are, predominantly, shorter than one viral genome. ...
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.68.1.112
更新日期:1971-01-01 00:00:00
abstract::Phylogenetic comparison of rRNA sequences has suggested that a pseudoknot structure exists in the central domain of small-subunit rRNA. In Escherichia coli 16S rRNA, this pseudoknot would form when positions 570 and 571 pair with positions 865 and 866. Mutations were introduced into this pseudoknot at the phylogenetic...
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.91.23.11148
更新日期:1994-11-08 00:00:00
abstract::A defect in the yeast GEF1 gene, a CLC chloride channel homolog leads to an iron requirement and cation sensitivity. The iron requirement is due to a failure to load Cu2+ onto a component of the iron uptake system, Fet3. This process, which requires both Gef1 and the Menkes disease Cu2+-ATPase yeast homolog Ccc2, occu...
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.95.7.4046
更新日期:1998-03-31 00:00:00
abstract::Sodium influx is an important early signal during the onset of mitogenesis in many types of cells. From this observation, one would predict that a decrease in extracellular Na+ concentration might retard cell proliferation. We tested this prediction by exposing sets of cultures of monkey kidney epithelial cells (BSC-1...
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.83.13.4764
更新日期:1986-07-01 00:00:00
abstract::Termites are responsible for ∼1 to 3% of global methane (CH4) emissions. However, estimates of global termite CH4 emissions span two orders of magnitude, suggesting that fundamental knowledge of CH4 turnover processes in termite colonies is missing. In particular, there is little reliable information on the extent 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.1809790115
更新日期:2018-12-26 00:00:00
abstract::Precise spatiotemporal control of mRNA translation machinery is essential to the development of highly complex systems like the neocortex. However, spatiotemporal regulation of translation machinery in the developing neocortex remains poorly understood. Here, we show that an RNA-binding protein, Hu antigen R (HuR), re...
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.1408305111
更新日期:2014-09-09 00:00:00
abstract::The TrkC neurotrophin receptor belongs to the functional dependence receptor family, members of which share the ability to induce apoptosis in the absence of their ligands. Such a trait has been hypothesized to confer tumor-suppressor activity. Indeed, cells that express these receptors are thought to be dependent on ...
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.1212333110
更新日期:2013-02-19 00:00:00
abstract::All immunoglobulins and T-cell receptors throughout phylogeny share regions of highly conserved amino acid sequence. To identify possible primitive immunoglobulins and immunoglobulin-like molecules, we utilized 3' RACE (rapid amplification of cDNA ends) and a highly conserved constant region consensus amino acid seque...
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.93.8.3289
更新日期:1996-04-16 00:00:00
abstract::Whereas the neurodegeneration associated with various polyglutamine (polyQ) diseases has prompted extensive studies of polyQ-induced cell death, the neuronal loss that typically appears during late stages of the diseases may not account for the preceding movement and mental disorders. The cellular basis for polyQ-indu...
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.1113573108
更新日期:2011-10-04 00:00:00
abstract::W. D. Hamilton's celebrated formula for the age-specific force of natural selection furnishes predictions for senescent mortality due to mutation accumulation, at the price of reliance on a linear approximation. Applying to Hamilton's setting the full nonlinear demographic model for mutation accumulation recently deve...
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.1306656110
更新日期:2013-06-18 00:00:00
abstract::Understanding the causes and consequences of wildfires in forests of the western United States requires integrated information about fire, climate changes, and human activity on multiple temporal scales. We use sedimentary charcoal accumulation rates to construct long-term variations in fire during the past 3,000 y in...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 历史文章,杂志文章
doi:10.1073/pnas.1112839109
更新日期:2012-02-28 00:00:00
abstract::Type I (IFN-alpha/beta) and type III (IFN-lambdas) IFNs are important components of the host antiviral response. Although type III IFNs possess intrinsic antiviral activity similar to that of type I IFNs, they signal through a specific unique receptor complex, and their functional importance for antiviral resistance 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.0610352104
更新日期:2007-06-05 00:00:00
abstract::To achieve accurate aminoacylation of tRNAs with their cognate amino acids, errors in aminoacylation are corrected by the "editing" mechanism in several aminoacyl-tRNA synthetases. Phenylalanyl-tRNA synthetase (PheRS) hydrolyzes, or edits, misformed tyrosyl-tRNA with its editing domain in the beta subunit. We report 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.0603182103
更新日期:2006-10-03 00:00:00
abstract::Type 2 diabetes mellitus (T2DM) is strongly associated with obesity in most, but not all, ethnic groups, suggesting important ethnic differences in disease susceptibility. Although it is clear that insulin resistance plays a major role in the pathogenesis of T2DM and that insulin resistance is strongly associated 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.0608537103
更新日期:2006-11-28 00:00:00
abstract::The generation of toxic oligomers during the aggregation of the amyloid-β (Aβ) peptide Aβ42 into amyloid fibrils and plaques has emerged as a central feature of the onset and progression of Alzheimer's disease, but the molecular pathways that control pathological aggregation have proved challenging to identify. Here, ...
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.1218402110
更新日期:2013-06-11 00:00:00
abstract::Establishment of functional synaptic connections in a selective manner is essential for nervous system operation. In mammalian retinas, rod and cone photoreceptors form selective synaptic connections with different classes of bipolar cells (BCs) to propagate light signals. While there has been progress in elucidating ...
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.2009940117
更新日期:2020-09-22 00:00:00
abstract::Online education is rapidly expanding in response to rising demand for higher and continuing education, but many online students struggle to achieve their educational goals. Several behavioral science interventions have shown promise in raising student persistence and completion rates in a handful of courses, but evid...
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.1921417117
更新日期:2020-06-30 00:00:00
abstract::Hepatitis C virus (HCV) infection is associated with dysregulation of both lipid and glucose metabolism. As well as contributing to viral replication, these perturbations influence the pathogenesis associated with the virus, including steatosis, insulin resistance, and type 2 diabetes. AMP-activated protein kinase (AM...
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.0912426107
更新日期:2010-06-22 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