475 research outputs found
A novel, mitogen-activated nuclear kinase is related to a Drosophila developmental regulator
Although the ultimate targets of many signal transduction pathways are nuclear transcription factors, the vast majority of known protein kinases are cytosolic. Here, we report on a novel human kinase that is present exclusively in the nucleus. Kinase activity is increased upon cellular proliferation and is markedly elevated in patients with acute and chronic lymphocytic leukemias. We have identified a human gene that encodes this nuclear kinase and find that it is closely related to Drosophila female sterile homeotic (fsh), a developmental regulator with no known biochemical activity. Collectively, these results suggest that this nuclear kinase is a component of a signal transduction pathway that plays a role in Drosophila development and human growth control
Clonal heterogeneity as a driver of disease variability in the evolution of myeloproliferative neoplasms.
Myeloproliferative neoplasms (MPNs) are clonal hematological diseases in which cells of the myelo-erythroid lineage are overproduced and patients are predisposed to leukemic transformation. Hematopoietic stem cells are the suspected disease-initiating cells, and these cells must acquire a clonal advantage relative to nonmutant hematopoietic stem cells to perpetuate disease. In 2005, several groups identified a single gain-of-function point mutation in JAK2 that associated with the majority of MPNs, and subsequent studies have led to a comprehensive understanding of the mutational landscape in MPNs. However, confusion still exists as to how a single genetic aberration can be associated with multiple distinct disease entities. Many explanations have been proposed, including JAK2V617F homozygosity, individual patient heterogeneity, and the differential regulation of downstream JAK2 signaling pathways. Several groups have made knock-in mouse models expressing JAK2V617F and have observed divergent phenotypes, each recapitulating some aspects of disease. Intriguingly, most of these models do not observe a strong hematopoietic stem cell self-renewal advantage compared with wild-type littermate controls, raising the question of how a clonal advantage is established in patients with MPNs. This review summarizes the current molecular understanding of MPNs and the diversity of disease phenotypes and proposes that the increased proliferation induced by JAK2V617F applies a selection pressure on the mutant clone that results in highly diverse clonal evolution in individuals.This is the author's accepted manuscript. The final version of this paper is published in Experimental Hematology here: http://www.exphem.org/article/S0301-472X(14)00622-5/abstract
Planet Hunters. VIII. Characterization of 41 Long-Period Exoplanet Candidates from Kepler Archival Data
The census of exoplanets is incomplete for orbital distances larger than 1
AU. Here, we present 41 long-period planet candidates in 38 systems identified
by Planet Hunters based on Kepler archival data (Q0-Q17). Among them, 17
exhibit only one transit, 14 have two visible transits and 10 have more than
three visible transits. For planet candidates with only one visible transit, we
estimate their orbital periods based on transit duration and host star
properties. The majority of the planet candidates in this work (75%) have
orbital periods that correspond to distances of 1-3 AU from their host stars.
We conduct follow-up imaging and spectroscopic observations to validate and
characterize planet host stars. In total, we obtain adaptive optics images for
33 stars to search for possible blending sources. Six stars have stellar
companions within 4". We obtain high-resolution spectra for 6 stars to
determine their physical properties. Stellar properties for other stars are
obtained from the NASA Exoplanet Archive and the Kepler Stellar Catalog by
Huber et al. (2014). We validate 7 planet candidates that have planet
confidence over 0.997 (3-{\sigma} level). These validated planets include 3
single-transit planets (KIC-3558849b, KIC-5951458b, and KIC-8540376c), 3
planets with double transits (KIC-8540376b, KIC-9663113b, and KIC-10525077b),
and 1 planet with 4 transits (KIC-5437945b). This work provides assessment
regarding the existence of planets at wide separations and the associated false
positive rate for transiting observation (17%-33%). More than half of the
long-period planets with at least three transits in this paper exhibit transit
timing variations up to 41 hours, which suggest additional components that
dynamically interact with the transiting planet candidates. The nature of these
components can be determined by follow-up radial velocity and transit
observations.Comment: Published on ApJ, 815, 127 Notations of validated planets are changed
in accordance with naming convention of NASA Exoplanet Archiv
Conformal Symmetry and Universal Properties of Quantum Hall States
The low-lying excitations of a quantum Hall state on a disk geometry are edge
excitations. Their dynamics is governed by a conformal field theory on the
cylinder defined by the disk boundary and the time variable. We give a simple
and detailed derivation of this conformal field theory for integer filling,
starting from the microscopic dynamics of -dimensional non-relativistic
electrons in Landau levels. This construction can be generalized to describe
Laughlin's fractional Hall states via chiral bosonization, thereby making
contact with the effective Chern-Simons theory approach. The conformal field
theory dictates the finite-size effects in the energy spectrum. An experimental
or numerical verification of these universal effects would provide a further
confirmation of Laughlin's theory of incompressible quantum fluids.Comment: 39 pages, 7 figures (not included, they are mailed on request),
harvmac CERN-TH 6702/9
Studies of the transmissibility of the agent of bovine spongiform encephalopathy to the domestic chicken
<p>Abstract</p> <p>Background</p> <p>Transmission of the prion disease bovine spongiform encephalopathy (BSE) occurred accidentally to cattle and several other mammalian species via feed supplemented with meat and bone meal contaminated with infected bovine tissue. Prior to United Kingdom controls in 1996 on the feeding of mammalian meat and bone meal to farmed animals, the domestic chicken was potentially exposed to feed contaminated with the causal agent of BSE. Although confirmed prion diseases are unrecorded in avian species a study was undertaken to transmit BSE to the domestic chicken by parenteral and oral inoculations. Transmissibility was assessed by clinical monitoring, histopathological examinations, detection of a putative disease form of an avian prion protein (PrP) in recipient tissues and by mouse bioassay of tissues. Occurrence of a progressive neurological syndrome in the primary transmission study was investigated by sub-passage experiments.</p> <p>Results</p> <p>No clinical, pathological or bioassay evidence of transmission of BSE to the chicken was obtained in the primary or sub-passage experiments. Survival data showed no significant differences between control and treatment groups. Neurological signs observed, not previously described in the domestic chicken, were not associated with significant pathology. The diagnostic techniques applied failed to detect a disease associated form of PrP.</p> <p>Conclusion</p> <p>Important from a risk assessment perspective, the present study has established that the domestic chicken does not develop a prion disease after large parenteral exposures to the BSE agent or after oral exposures equivalent to previous exposures via commercial diets. Future investigations into the potential susceptibility of avian species to mammalian prion diseases require species-specific immunochemical techniques and more refined experimental models.</p
Hubble Space Telescope Ultraviolet Spectroscopy of Fourteen Low-Redshift Quasars
We present low-resolution ultraviolet spectra of 14 low redshift (z<0.8)
quasars observed with HST/STIS as part of a Snap project to understand the
relationship between quasar outflows and luminosity. By design, all
observations cover the CIV emission line. Nine of the quasars are from the
Hamburg-ESO catalog, three are from the Palomar-Green catalog, and one is from
the Parkes catalog. The sample contains a few interesting quasars including two
broad absorption line (BAL) quasars (HE0143-3535, HE0436-2614), one quasar with
a mini-BAL (HE1105-0746), and one quasar with associated narrow absorption
(HE0409-5004). These BAL quasars are among the brightest known (though not the
most luminous) since they lie at z<0.8. We compare the properties of these BAL
quasars to the z1.4 Large Bright Quasar samples. By
design, our objects sample luminosities in between these two surveys, and our
four absorbed objects are consistent with the v ~ L^0.62 relation derived by
Laor & Brandt (2002). Another quasar, HE0441-2826, contains extremely weak
emission lines and our spectrum is consistent with a simple power-law
continuum. The quasar is radio-loud, but has a steep spectral index and a
lobe-dominated morphology, which argues against it being a blazar. The unusual
spectrum of this quasar resembles the spectra of the quasars PG1407+265,
SDSSJ1136+0242, and PKS1004+13 for which several possible explanations have
been entertained.Comment: Uses aastex.cls, 21 pages in preprint mode, including 6 figures and 2
tables; accepted for publication in The Astronomical Journal (projected vol
133
Oxadiazole-Based Cell Permeable Macrocyclic Transition State Inhibitors of Norovirus 2CL Protease
Human noroviruses are the primary causative agents of acute gastroenteritis and a pressing public health burden worldwide. There are currently no vaccines or small molecule therapeutics available for the treatment or prophylaxis of norovirus infections. Norovirus 3CL protease plays a vital role in viral replication by generating structural and nonstructural proteins via the cleavage of the viral polyprotein. Thus, molecules that inhibit the viral protease may have potential therapeutic value. We describe herein the structure-based design, synthesis, and in vitro and cell-based evaluation of the first class of oxadiazole-based, permeable macrocyclic inhibitors of norovirus 3CL protease
Recommended from our members
A high-resolution map of human evolutionary constraint using 29 mammals.
The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering âŒ4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for âŒ60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate- and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease
- âŠ