232 research outputs found
Differential Functions of mPer1, mPer2, and mPer3 in the SCN Circadian Clock
AbstractThe role of mPer1 and mPer2 in regulating circadian rhythms was assessed by disrupting these genes. Mice homozygous for the targeted allele of either mPer1 or mPer2 had severely disrupted locomotor activity rhythms during extended exposure to constant darkness. Clock gene RNA rhythms were blunted in the suprachiasmatic nucleus of mPer2 mutant mice, but not of mPER1-deficient mice. Peak mPER and mCRY1 protein levels were reduced in both lines. Behavioral rhythms of mPer1/mPer3 and mPer2/mPer3 double-mutant mice resembled rhythms of mice with disruption of mPer1 or mPer2 alone, respectively, confirming the placement of mPer3 outside the core circadian clockwork. In contrast, mPer1/mPer2 double-mutant mice were immediately arrhythmic. Thus, mPER1 influences rhythmicity primarily through interaction with other clock proteins, while mPER2 positively regulates rhythmic gene expression, and there is partial compensation between products of these two genes
Full nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks
Dramatic progress has been made over the last decade in the numerical study
of quantum chromodynamics (QCD) through the use of improved formulations of QCD
on the lattice (improved actions), the development of new algorithms and the
rapid increase in computing power available to lattice gauge theorists. In this
article we describe simulations of full QCD using the improved staggered quark
formalism, ``asqtad'' fermions. These simulations were carried out with two
degenerate flavors of light quarks (up and down) and with one heavier flavor,
the strange quark. Several light quark masses, down to about 3 times the
physical light quark mass, and six lattice spacings have been used. These
enable controlled continuum and chiral extrapolations of many low energy QCD
observables. We review the improved staggered formalism, emphasizing both
advantages and drawbacks. In particular, we review the procedure for removing
unwanted staggered species in the continuum limit. We then describe the asqtad
lattice ensembles created by the MILC Collaboration. All MILC lattice ensembles
are publicly available, and they have been used extensively by a number of
lattice gauge theory groups. We review physics results obtained with them, and
discuss the impact of these results on phenomenology. Topics include the heavy
quark potential, spectrum of light hadrons, quark masses, decay constant of
light and heavy-light pseudoscalar mesons, semileptonic form factors, nucleon
structure, scattering lengths and more. We conclude with a brief look at highly
promising future prospects.Comment: 157 pages; prepared for Reviews of Modern Physics. v2: some rewriting
throughout; references update
The B -> D* l nu form factor at zero recoil from three-flavor lattice QCD: A model independent determination of |V_cb|
We present the first lattice QCD calculation of the form factor for B-> D* l
nu with three flavors of sea quarks. We use an improved staggered action for
the light valence and sea quarks (the MILC configurations), and the Fermilab
action for the heavy quarks. The form factor is computed at zero recoil using a
new double ratio method that yields the form factor more directly than the
previous Fermilab method. Other improvements over the previous calculation
include the use of much lighter light quark masses, and the use of lattice
(staggered) chiral perturbation theory in order to control the light quark
discretization errors and chiral extrapolation. We obtain for the form factor,
F_{B-> D*}(1)=0.921(13)(20), where the first error is statistical and the
second is the sum of all systematic errors in quadrature. Applying a 0.7%
electromagnetic correction and taking the latest PDG average for F_{B->
D*}(1)|V_cb| leads to |V_cb|=(38.7 +/- 0.9_exp +/- 1.0_theo) x 10^-3.Comment: 48 pages, 9 figures. Sections VI and VII D clarified, minor typos
corrected and references added. Version published in PR
A CRISPR-Cas9 gene drive system targeting female reproduction in the malaria mosquito vector Anopheles gambiae.
Gene drive systems that enable super-Mendelian inheritance of a transgene have the potential to modify insect populations over a timeframe of a few years. We describe CRISPR-Cas9 endonuclease constructs that function as gene drive systems in Anopheles gambiae, the main vector for malaria. We identified three genes (AGAP005958, AGAP011377 and AGAP007280) that confer a recessive female-sterility phenotype upon disruption, and inserted into each locus CRISPR-Cas9 gene drive constructs designed to target and edit each gene. For each targeted locus we observed a strong gene drive at the molecular level, with transmission rates to progeny of 91.4 to 99.6%. Population modeling and cage experiments indicate that a CRISPR-Cas9 construct targeting one of these loci, AGAP007280, meets the minimum requirement for a gene drive targeting female reproduction in an insect population. These findings could expedite the development of gene drives to suppress mosquito populations to levels that do not support malaria transmission
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
Vacuolar ATPase Regulates Surfactant Secretion in Rat Alveolar Type II Cells by Modulating Lamellar Body Calcium
Lung surfactant reduces surface tension and maintains the stability of alveoli. How surfactant is released from alveolar epithelial type II cells is not fully understood. Vacuolar ATPase (V-ATPase) is the enzyme responsible for pumping H+ into lamellar bodies and is required for the processing of surfactant proteins and the packaging of surfactant lipids. However, its role in lung surfactant secretion is unknown. Proteomic analysis revealed that vacuolar ATPase (V-ATPase) dominated the alveolar type II cell lipid raft proteome. Western blotting confirmed the association of V-ATPase a1 and B1/2 subunits with lipid rafts and their enrichment in lamellar bodies. The dissipation of lamellar body pH gradient by Bafilomycin A1 (Baf A1), an inhibitor of V-ATPase, increased surfactant secretion. Baf A1-stimulated secretion was blocked by the intracellular Ca2+ chelator, BAPTA-AM, the protein kinase C (PKC) inhibitor, staurosporine, and the Ca2+/calmodulin-dependent protein kinase II (CaMKII), KN-62. Baf A1 induced Ca2+ release from isolated lamellar bodies. Thapsigargin reduced the Baf A1-induced secretion, indicating cross-talk between lamellar body and endoplasmic reticulum Ca2+ pools. Stimulation of type II cells with surfactant secretagogues dissipated the pH gradient across lamellar bodies and disassembled the V-ATPase complex, indicating the physiological relevance of the V-ATPase-mediated surfactant secretion. Finally, silencing of V-ATPase a1 and B2 subunits decreased stimulated surfactant secretion, indicating that these subunits were crucial for surfactant secretion. We conclude that V-ATPase regulates surfactant secretion via an increased Ca2+ mobilization from lamellar bodies and endoplasmic reticulum, and the activation of PKC and CaMKII. Our finding revealed a previously unrealized role of V-ATPase in surfactant secretion
Genomewide Expression Analysis in Zebrafish mind bomb Alleles with Pancreas Defects of Different Severity Identifies Putative Notch Responsive Genes
10.1371/journal.pone.0001479PLoS ONE3
Microstructural Abnormalities in Subcortical Reward Circuitry of Subjects with Major Depressive Disorder
Previous studies of major depressive disorder (MDD) have focused on abnormalities in the prefrontal cortex and medial temporal regions. There has been little investigation in MDD of midbrain and subcortical regions central to reward/aversion function, such as the ventral tegmental area/substantia nigra (VTA/SN), and medial forebrain bundle (MFB).We investigated the microstructural integrity of this circuitry using diffusion tensor imaging (DTI) in 22 MDD subjects and compared them with 22 matched healthy control subjects. Fractional anisotropy (FA) values were increased in the right VT and reduced in dorsolateral prefrontal white matter in MDD subjects. Follow-up analysis suggested two distinct subgroups of MDD patients, which exhibited non-overlapping abnormalities in reward/aversion circuitry. The MDD subgroup with abnormal FA values in VT exhibited significantly greater trait anxiety than the subgroup with normal FA values in VT, but the subgroups did not differ in levels of anhedonia, sadness, or overall depression severity.These findings suggest that MDD may be associated with abnormal microstructure in brain reward/aversion regions, and that there may be at least two subtypes of microstructural abnormalities which each impact core symptoms of depression
- …