1,485 research outputs found
miRNAs regulate SIRT1 expression during mouse embryonic stem cell differentiation and in adult mouse tissues
SIRT1
is increasingly recognized as a critical regulator of stress responses,
replicative senescence, inflammation, metabolism, and aging. SIRT1
expression is regulated transcriptionally and post-transcriptionally, and
its enzymatic activity is controlled by NAD+ levels and
interacting proteins. We found that SIRT1 protein levels were much higher
in mouse embryonic stem cells (mESCs) than in differentiated tissues.
miRNAs post-transcriptionally downregulated SIRT1 during mESC
differentiation and maintained low levels of SIRT1 expression in
differentiated tissues. Specifically, miR-181a and b, miR-9, miR-204,
miR-199b, and miR-135a suppressed SIRT1 protein expression. Inhibition of
mir-9, the SIRT1-targeting miRNA induced earliest during mESC
differentiation, prevented SIRT1 downregulation. Conversely, SIRT1 protein
levels were upregulated post-transcriptionally during the reprogramming of
mouse embryonic fibroblasts (MEFs) into induced pluripotent stem (iPS)
cells. The regulation of SIRT1 protein levels by miRNAs might provide new
opportunities for therapeutic tissue-specific modulation of SIRT1
expression and for reprogramming of somatic cells into iPS cells
Tohoku-Hiroshima-Nagoya planetary spectra library: A method for characterizing planets in the visible to near infrared
There has not been a comprehensive framework for comparing spectral data from
different planets.Such a framework is needed for the study of extrasolar
planets and objects within the solar system. We have undertaken observations to
compile a library of planet spectra for all planets, some moons, and some dwarf
planets in the solar system to study their general spectroscopic and
photometric natures. During May and November of 2008, we acquired spectra for
the planets using TRISPEC, which is capable of simultaneous three-band
spectroscopy in a wide wavelength range of 0.45 - 2.5 microns with low
resolving power (lambda-over-Delta-lambda is 140 - 360). Patterns emerge from
comparing the spectra. Analyzing their general spectroscopic and photometric
natures, we show that it is possible to distinguish between gas planets, soil
planets and ice planets. These methods can be applied to extrasolar
observations using low resolution spectrography or broad-band filters. The
present planet spectral library is the first library to contain observational
spectra for all of the solar system planets, based on simultaneous observations
in visible and near infrared wavelengths. This library will be a useful
reference for analyzing extrasolar planet spectra, and for calibrating
planetary data sets.Comment: 11 pages, 6 figures, Accepted on 28/08/2009 to appear in Section 10.
Planets and planetary systems of Astronomy and Astrophysic
MITSuME--Multicolor Imaging Telescopes for Survey and Monstrous Explosions
Development of MITSuME is reported. Two 50-cm optical telescopes have been
built at Akeno in Yamanashi prefecture and at Okayama Astrophysical Observatory
(OAO) in Okayama prefecture. Three CCD cameras for simultaneous g'RcIc
photometry are to be mounted on each focal plane, covering a wide FOV of about
30" x 30". The limiting magnitude at V is fainter than 18. In addition to these
two optical telescopes, a 91-cm IR telescope with a 1 deg x 1 deg field of view
is being built at OAO, which performs photometry in YJHK bands. These robotic
telescopes can start the observation of counterparts of a GRB within a minute
from an alert. We aim to obtain photometric redshifts exceeding 10 with these
telescopes. The performance and the current construction status of the
telescopes are presented.Comment: 4 pages, 3 figures, 4th Workshop on Gamma-Ray Burst in the Afterglow
Era, Roma, October 18-22, 200
Heat Treatment Inhibits Skeletal Muscle Atrophy of Glucocorticoid- Induced Myopathy in Rats
Summary The purpose of this study was to investigate the influence of heat treatment on glucocorticoid (GC)-induced myopathy. Eight-weekold Wistar rats were randomly assigned to the control, Dex, and Dex + Heat groups. Dexamethasone (2 mg/kg) was injected subcutaneously 6 days per week for 2 weeks in the Dex and Dex + Heat group. In the Dex + Heat group, heat treatment was performed by immersing hindlimbs in water at 42 °C for 60 min, once every 3 days for 2 weeks. The extensor digitorum longus muscle was extracted following 2 weeks of experimentation. In the Dex + Heat group, muscle fiber diameter, capillary/muscle fiber ratio, and level of heat shock protein 72 were significantly higher and atrogene expression levels were significantly lower than in the Dex group. Our results suggest that heat treatment inhibits the development of GC-induced myopathy by decreasing atrogene expression and increasing angiogenesis
Optical Spectropolarimetry of SN 2002ap: High Velocity Asymmetric Explosion
We present spectropolarimetry of the Type Ic supernova SN 2002ap and give a
preliminary analysis: the data were taken at two epochs, close to and one month
later than the visual maximum (2002 February 8). In addition we present June 9
spectropolarimetry without analysis. The data show the development of linear
polarization. Distinct polarization profiles were seen only in the O I \lambda
7773 multiplet/Ca II IR triplet absorption trough at maximum light and in the
Ca II IR triplet absorption trough a month later, with the latter showing a
peak polarization as high as ~2 %. The intrinsic polarization shows three clear
position angles: 80 degs for the February continuum, 120 degs for the February
line feature, and 150 degs for the March data. We conclude that there are
multiple asymmetric components in the ejecta. We suggest that the supernova has
a bulk asymmetry with an axial ratio projected on the sky that is different
from 1 by of order 10 %. Furthermore, we suggest very speculatively that a high
velocity ejecta component moving faster than ~0.115c (e.g., a jet) contributes
to polarization in the February epoch.Comment: 7 pages, 3 figures, accepted for publication in the Astrophysical
Journal (Letters
Homogeneous bubble nucleation limit of mercury under the normal working conditions of the planned European Spallation Source
In spallation neutron sources, liquid mercury is the subject of big thermal
and pressure shocks, upon adsorbing the proton beam. These changes can cause
unstable bubbles in the liquid, which can damage the structural material. While
there are methods to deal with the pressure shock, the local temperature shock
cannot be avoided. In our paper we calculated the work of the critical cluster
formation (i.e. for mercury micro-bubbles) together with the rate of their
formation (nucleation rate). It is shown that the homogeneous nucleation rates
are very low even after adsorbing several proton pulses, therefore the
probability of temperature induced homogeneous bubble nucleation is negligible.Comment: 22 Pages, 11 figures, one of them is colour, we plan to publish it in
Eur. Phys. J.
B1 SINE-binding ZFP266 impedes mouse iPSC generation through suppression of chromatin opening mediated by reprogramming factors
Induced pluripotent stem cell (iPSC) reprogramming is inefficient and understanding the molecular mechanisms underlying this inefficiency holds the key to successfully control cellular identity. Here, we report 24 reprogramming roadblock genes identified by CRISPR/Cas9-mediated genome-wide knockout (KO) screening. Of these, depletion of the predicted KRAB zinc finger protein (KRAB-ZFP) Zfp266 strongly and consistently enhances murine iPSC generation in several reprogramming settings, emerging as the most robust roadblock. We show that ZFP266 binds Short Interspersed Nuclear Elements (SINEs) adjacent to binding sites of pioneering factors, OCT4 (POU5F1), SOX2, and KLF4, and impedes chromatin opening. Replacing the KRAB co-suppressor with co-activator domains converts ZFP266 from an inhibitor to a potent facilitator of iPSC reprogramming. We propose that the SINE-KRAB-ZFP interaction is a critical regulator of chromatin accessibility at regulatory elements required for efficient cellular identity changes. In addition, this work serves as a resource to further illuminate molecular mechanisms hindering reprogramming.Induced pluripotent stem cell (iPSC) reprogramming is inherently inefficient. Here the authors identify 24 reprogramming roadblock genes through a CRISPR/Cas9-mediated genome-wide knockout screen including a KRAB-ZFP Zfp266, knockout of which consistently enhances murine iPSC generation.Peer reviewe
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