795 research outputs found
Functional interaction of the retinoblastoma and Ini1/Snf5 tumor suppressors in cell growth and pituitary tumorigenesis
The Ini1 subunit of the SWI/SNF chromatin remodeling complex suppresses formation of malignant rhabdoid tumors in humans and mice. Transduction of Ini1 into Ini1-deficient tumor-derived cell lines has indicated that Ini1 arrests cell growth, controls chromosomal ploidy, and suppresses tumorigenesis by regulating components of the retinoblastoma (Rb) signaling pathway. Furthermore, conditional inactivation of Ini1 in mouse fibroblasts alters the expression of various Rb-E2F-regulated genes, indicating that endogenous Ini1 levels may control Rb signaling in cells. We have reported previously that loss of one allele of Ini1 in mouse fibroblasts results only in a 15% to 20% reduction in total Ini1 mRNA levels due to transcriptional compensation by the remaining Ini1 allele. Here, we examine the effects of Ini1 haploinsufficiency on cell growth and immortalization in mouse embryonic fibroblasts. In addition, we examine pituitary tumorigenesis in Rb-Ini1 compound heterozygous mice. Our results reveal that heterozygosity for Ini1 up-regulates cell growth and immortalization and that exogenous Ini1 down-regulates the growth of primary cells in a Rb-dependent manner. Furthermore, loss of Ini1 is redundant with loss of Rb function in the formation of pituitary tumors in Rb heterozygous mice and leads to the formation of large, atypical Rb(+/-) tumor cells lacking adrenocorticotropic hormone expression. These results confirm in vivo the relationship between Rb and Ini1 in tumor suppression and indicate that Ini1 plays a role in maintaining the morphologic and functional differentiation of corticotrophic cells
Factors influencing Hen Harrier Circus cyaneus territory site selection and breeding success
Capsule: Our findings regarding Hen Harrier Circus cyaneus territory site selection and breeding success in Ireland offer an opportunity for the development of initiatives and conservation actions aimed at enhancing the suitability of upland areas for breeding Hen Harriers and ensuring the long-term persistence of the species.Aims: To investigate landscape-scale associations between habitat composition and Hen Harrier territory site selection, and to explore the influence of habitat and climate on breeding success.Methods: We used multi-model inference from generalized linear models and Euclidean distance analyses to explore the influence of habitat, topographic, anthropogenic and climatic factors on Hen Harrier territory selection and breeding success in Ireland, based on data from national breeding surveys in 2010 and 2015.Results: Hen Harrier territories were associated with heath/shrub, bog and pre-thicket coniferous forests. Comparisons between territories and randomly generated pseudo-absences (upland and lowland) showed that breeding pairs preferentially select for these habitats. Breeding success was negatively influenced by rainfall early in the breeding season and by climatic instability, and was positively influenced by the presence of heath/shrub and bog.Conclusions: The results suggest that Hen Harrier breeding success is compromised by the synergistic effects of climate, landscape composition and management. Effective conservation of Hen Harriers in Ireland will therefore rely on landscape-scale initiatives
Detection and phylogenetic analysis of adenoviruses occurring in a single anole species
Adenoviruses (AdVs) infect a wide range of hosts, and they have undergone recent and ancient host transfers multiple times. In reptiles, AdVs have been found in many captive individuals, and have been implicated in morbidity and mortality in several species. Yet the pathogenicity, transmission, phylogenetic distribution, and source of AdVs in the environment are still unknown. We therefore chose to opportunistically sample deceased captive Anolis sagrei individuals that were collected from different populations in the Bahamas and the Cayman Islands, as well as fecal samples from one island population, to explore the disease dynamics and diversity of adenovirus infecting A. sagrei populations. We found that adenovirus infection was present in our captive colony at low prevalence (26%), and was likely not the primary cause of observed morbidity and mortality. Among the 10 individuals (out of 38 sampled) which tested positive for adenovirus, we identified four adenovirus clades, several of which are distantly related, despite the close relationships of the A. sagrei host populations. These results suggest that while adenovirus may not be highly prevalent in the wild, it is present at low levels across much of the range of A. sagrei. It may undergo frequent host switching across both deep and shallow host divergences
Prototype finline-coupled TES bolometers for CLOVER
CLOVER is an experiment which aims to detect the signature of gravitational
waves from inflation by measuring the B-mode polarization of the cosmic
microwave background. CLOVER consists of three telescopes operating at 97, 150,
and 220 GHz. The 97-GHz telescope has 160 feedhorns in its focal plane while
the 150 and 220-GHz telescopes have 256 horns each. The horns are arranged in a
hexagonal array and feed a polarimeter which uses finline-coupled TES
bolometers as detectors. To detect the two polarizations the 97-GHz telescope
has 320 detectors while the 150 and 220-GHz telescopes have 512 detectors each.
To achieve the target NEPs (1.5, 2.5, and 4.5x10^-17 W/rtHz) the detectors are
cooled to 100 mK for the 97 and 150-GHz polarimeters and 230 mK for the 220-GHz
polarimeter. Each detector is fabricated as a single chip to ensure a 100%
operational focal plane. The detectors are contained in linear modules made of
copper which form split-block waveguides. The detector modules contain 16 or 20
detectors each for compatibility with the hexagonal arrays of horns in the
telescopes' focal planes. Each detector module contains a time-division SQUID
multiplexer to read out the detectors. Further amplification of the multiplexed
signals is provided by SQUID series arrays. The first prototype detectors for
CLOVER operate with a bath temperature of 230 mK and are used to validate the
detector design as well as the polarimeter technology. We describe the design
of the CLOVER detectors, detector blocks, and readout, and present preliminary
measurements of the prototype detectors performance.Comment: 4 pages, 6 figures; to appear in the Proceedings of the 17th
International Symposium on Space Terahertz Technology, held 10-12 May 2006 in
Pari
The PAndAS Field of Streams: stellar structures in the Milky Way halo toward Andromeda and Triangulum
We reveal the highly structured nature of the Milky Way stellar halo within
the footprint of the PAndAS photometric survey from blue main sequence and main
sequence turn-off stars. We map no fewer than five stellar structures within a
heliocentric range of ~5 to 30 kpc. Some of these are known (the Monoceros
Ring, the Pisces/Triangulum globular cluster stream), but we also uncover three
well-defined stellar structures that could be, at least partly, responsible for
the so-called Triangulum/Andromeda and Triangulum/Andromeda 2 features. In
particular, we trace a new faint stellar stream located at a heliocentric
distance of ~17 kpc. With a surface brightness of \Sigma_V ~ 32-32.5
mag/arcsec^2, it follows an orbit that is almost parallel to the Galactic plane
north of M31 and has so far eluded surveys of the Milky Way halo as these tend
to steer away from regions dominated by the Galactic disk. Investigating our
follow-up spectroscopic observations of PAndAS, we serendipitously uncover a
radial velocity signature from stars that have colors and magnitudes compatible
with the stream. From the velocity of eight likely member stars, we show that
this stellar structure is dynamically cold, with an unresolved velocity
dispersion that is lower than 7.1 km/s at the 90-percent confidence level.
Along with the width of the stream (300-650 pc), its dynamics points to a
dwarf-galaxy-accretion origin. The numerous stellar structures we can map in
the Milky Way stellar halo between 5 and 30 kpc and their varying morphology is
a testament to the complex nature of the stellar halo at these intermediate
distances.Comment: 11 pages, 8 figures, accepted for publication in the ApJ, Figure 3 is
the money plo
Major substructure in the M31 outer halo: the South-West Cloud
We undertake the first detailed analysis of the stellar population and spatial properties of a diffuse substructure in the outer halo ofM31. The South-West Cloud lies at a projected distance of Ì100 kpc from the centre of M31 and extends for at least Ì
A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument
We describe the cryogenic half-wave plate rotation mechanisms built for and
used in Spider, a polarization-sensitive balloon-borne telescope array that
observed the Cosmic Microwave Background at 95 GHz and 150 GHz during a
stratospheric balloon flight from Antarctica in January 2015. The mechanisms
operate at liquid helium temperature in flight. A three-point contact design
keeps the mechanical bearings relatively small but allows for a large (305 mm)
diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows
for precise positioning and prevents undesired rotation when the motors are
depowered. A custom-built optical encoder system monitors the bearing angle to
an absolute accuracy of +/- 0.1 degrees. The system performed well in Spider
during its successful 16 day flight.Comment: 11 pages, 7 figures, Published in Review of Scientific Instruments.
v2 includes reviewer changes and longer literature revie
A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
Dwarf satellite galaxies are thought to be the remnants of the population of
primordial structures that coalesced to form giant galaxies like the Milky Way.
An early analysis noted that dwarf galaxies may not be isotropically
distributed around our Galaxy, as several are correlated with streams of HI
emission, and possibly form co-planar groups. These suspicions are supported by
recent analyses, and it has been claimed that the apparently planar
distribution of satellites is not predicted within standard cosmology, and
cannot simply represent a memory of past coherent accretion. However, other
studies dispute this conclusion. Here we report the existence (99.998%
significance) of a planar sub-group of satellites in the Andromeda galaxy,
comprising approximately 50% of the population. The structure is vast: at least
400 kpc in diameter, but also extremely thin, with a perpendicular scatter
<14.1 kpc (99% confidence). Radial velocity measurements reveal that the
satellites in this structure have the same sense of rotation about their host.
This finding shows conclusively that substantial numbers of dwarf satellite
galaxies share the same dynamical orbital properties and direction of angular
momentum, a new insight for our understanding of the origin of these most dark
matter dominated of galaxies. Intriguingly, the plane we identify is
approximately aligned with the pole of the Milky Way's disk and is co-planar
with the Milky Way to Andromeda position vector. The existence of such
extensive coherent kinematic structures within the halos of massive galaxies is
a fact that must be explained within the framework of galaxy formation and
cosmology.Comment: Published in the 3rd Jan 2013 issue of Nature. 19 pages, 4 figures, 1
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