2,060 research outputs found
Identification of Some Errors in the Genome Assembly of Bovidae by FISH
From an economic point of view, Bovidae represent the most important family of the Ruminantia suborder. Thus, the mitochondrial and nuclear genomes of Bos taurus were among the first genomes to be sequenced after the sequencing of the human genomes. Over the millennia, the evolution of the genomes of the 3 main species belonging to the Bovidae family - B. taurus (BTA), Ovis aries (OAR), and Capra hircus (CHI) - has led to few chromosome rearrangements. Certainly, the availability and free access to the animal genomes significantly contributed to the improvement of animal genetics; however, some errors may exist due to the high automation in the genomic assembly construction process. In this work, some differences between the genomes of cattle, goat, and sheep highlighted by bioinformatics analysis have been verified by FISH, confirming that some errors persist even in the most recent genome assemblies. This type of approach has allowed us to detect a misassembly of a region belonging to BTA16 and to the homologues OAR12 and CHI16, a misassembly of a short tract in BTA22, OAR19, and CHI22, an incorrect mapping of a region of BTA21 and of CHI27 and OAR26, a discrepancy in the BTA26, OAR22, and CHI26 assemblies, a missed inversion in CHI1 compared to BTA1 and OAR1, and the exact assembly of a region of about 7 Mb in OAR10 and CHI12. Incorrect positioning of genomic tracts can cause unintended consequences in genetic analyses, especially when the data represent a starting point for the construction of genetic tools. In the new genomic assemblies published after the conclusion of our experiments, however, the accuracy in the construction of animal assemblies has been much improved, even if the new assemblies present more extended unmapped portions than the previous versions. The gap could be filled by comparative analyses between similar species or FISH
Multiple jumps and vacancy diffusion in a face-centered cubic metal
The diffusion of monovacancies in gold has been studied by computer
simulation. Multiple jumps have been found to play a central role in the atomic
dynamics at high temperature, and have been shown to be responsible for an
upward curvature in the Arrhenius plot of the diffusion coefficient.
Appropriate saddle points on the potential energy surface have been found,
supporting the interpretation of vacancy multiple jumps as distinct migration
mechanisms.Comment: 16 page
Expected spectral characteristics of (101955) Bennu and (162173) Ryugu, targets of the OSIRIS-REx and Hayabusa2 missions
NASA's OSIRIS-REx and JAXA's Hayabusa2 sample-return missions are currently
on their way to encounter primitive near-Earth asteroids (101955) Bennu and
(162173) Ryugu, respectively. Spectral and dynamical evidence indicates that
these near-Earth asteroids originated in the inner part of the main belt. There
are several primitive collisional families in this region, and both these
asteroids are most likely to have originated in the Polana-Eulalia family
complex. We present the expected spectral characteristics of both targets based
on our studies of our primitive collisional families in the inner belt:
Polana-Eulalia, Erigone, Sulamitis, and Clarissa. Observations were obtained in
the framework of our PRIMitive Asteroids Spectroscopic Survey (PRIMASS). Our
results are especially relevant to the planning and interpretation of in-situ
images and spectra to be obtained by the two spacecraft during the encounters
with their targets.Comment: 22 pages, 11 figures. Accepted for publication in Icarus on May 11,
201
Dark-Matter Content of Early-Type Galaxies with Planetary Nebulae
We examine the dark matter properties of nearby early-type galaxies using
planetary nebulae (PNe) as mass probes. We have designed a specialised
instrument, the Planetary Nebula Spectrograph (PN.S) operating at the William
Herschel telescope, with the purpose of measuring PN velocities with best
efficiency. The primary scientific objective of this custom-built instrument is
the study of the PN kinematics in 12 ordinary round galaxies. Preliminary
results showing a dearth of dark matter in ordinary galaxies (Romanowsky et al.
2003) are now confirmed by the first complete PN.S datasets. On the other hand
early-type galaxies with a "regular" dark matter content are starting to be
observed among the brighter PN.S target sample, thus confirming a correlation
between the global dark-to-luminous mass virial ratio (f_DM=M_DM/M_star) and
the galaxy luminosity and mass.Comment: 5 pages, 2 figures. To appear in the proceedings of the IAU Symposium
244 "Dark Galaxies and Lost Baryons", Cardiff 25-29 June 2007, eds. J.I.
Davies & M.J. Disne
Visible and near-infrared observations of asteroid 2012 DA14 during its closest approach of February 15, 2013
Near-Earth asteroid 2012 DA14 made its closest approach on February 15, 2013,
when it passed at a distance of 27,700 km from the Earth's surface. It was the
first time an asteroid of moderate size was predicted to approach that close to
the Earth, becoming bright enough to permit a detailed study from ground-based
telescopes. Asteroid 2012 DA14 was poorly characterized before its closest
approach. We acquired data using several telescopes on four Spanish
observatories: the 10.4m Gran Telescopio Canarias (GTC) and the 3.6m Telescopio
Nazionale Galileo (TNG), both in the El Roque de los Muchachos Observatory
(ORM, La Palma); the 2.2m CAHA telescope, in the Calar Alto Observatory
(Almeria); the f/3 0.77m telescope in the La Hita Observatory (Toledo); and the
f/8 1.5m telescope in the Sierra Nevada Observatory (OSN, Granada). We obtained
visible and near-infrared color photometry, visible spectra and time-series
photometry. Visible spectra together with color photometry of 2012 DA14 show
that it can be classified as an L-type asteroid, a rare spectral type with a
composition similar to that of carbonaceous chondrites. The time-series
photometry provides a rotational period of 8.95 +- 0.08 hours after the closest
approach, and there are indications that the object suffered a spin-up during
this event. The large amplitude of the light curve suggests that the object is
very elongated and irregular, with an equivalent diameter of around 18m. We
obtain an absolute magnitude of H_R = 24.5 +- 0.2, corresponding to H_V = 25.0
+- 0.2. The GTC photometry also gives H_V = 25.29 +- 0.14. Both values agree
with the value listed at the Minor Planet Center shortly after discovery. From
the absolute photometry, together with some constraints on size and shape, we
compute a geometric albedo of p_V = 0.44 +- 0.20, which is slightly above the
range of albedos known for L-type asteroids (0.082 - 0.405).Comment: 7 pages, 4 figures, 1 table. Accepted in A&A (June 17 2013
The outer halos of elliptical galaxies
Recent progress is summarized on the determination of the density
distributions of stars and dark matter, stellar kinematics, and stellar
population properties, in the extended, low surface brightness halo regions of
elliptical galaxies. With integral field absorption spectroscopy and with
planetary nebulae as tracers, velocity dispersion and rotation profiles have
been followed to ~4 and ~5-8 effective radii, respectively, and in M87 to the
outer edge at ~150 kpc. The results are generally consistent with the known
dichotomy of elliptical galaxy types, but some galaxies show more complex
rotation profiles in their halos and there is a higher incidence of
misalignments, indicating triaxiality. Dynamical models have shown a range of
slopes for the total mass profiles, and that the inner dark matter densities in
ellipticals are higher than in spiral galaxies, indicating earlier assembly
redshifts. Analysis of the hot X-ray emitting gas in X-ray bright ellipticals
and comparison with dynamical mass determinations indicates that non-thermal
components to the pressure may be important in the inner ~10 kpc, and that the
properties of these systems are closely related to their group environments.
First results on the outer halo stellar population properties do not yet give a
clear picture. In the halo of one bright galaxy, lower [alpha/Fe] abundances
indicate longer star formation histories pointing towards late accretion of the
halo. This is consistent with independent evidence for on-going accretion, and
suggests a connection to the observed size evolution of elliptical galaxies
with redshift.Comment: 8 pages. Invited review to appear in the proceedings of "Galaxies and
their Masks" eds. Block, D.L., Freeman, K.C. & Puerari, I., 2010, Springer
(New York
Emergence of Drug Tolerance in Cancer Cell Populations: An Evolutionary Outcome of Selection, Nongenetic Instability, and Stress-Induced Adaptation
In recent experiments on isogenetic cancer cell lines, it was observed that exposure to high doses of anticancer drugs can induce the emergence of a subpopulation of weakly proliferative and drug-tolerant cells, which display markers associated with stem cell-like cancer cells. After a period of time, some of the surviving cells were observed to change their phenotype to resume normal proliferation and eventually repopulate the sample. Furthermore, the drug-tolerant cells could be drug resensitized following drug washout. Here, we propose a theoretical mechanism for the transient emergence of such drug tolerance. In this framework, we formulate an individual-based model and an integro-differential equation model of reversible phenotypic evolution in a cell population exposed to cytotoxic drugs. The outcomes of both models suggest that nongenetic instability, stress-induced adaptation, selection, and the interplay between these mechanisms can push an actively proliferating cell population to transition into a weakly proliferative and drug-tolerant state. Hence, the cell population experiences much less stress in the presence of the drugs and, in the long run, reacquires a proliferative phenotype, due to phenotypic fluctuations and selection pressure. These mechanisms can also reverse epigenetic drug tolerance following drug washout. Our study highlights how the transient appearance of the weakly proliferative and drug-tolerant cells is related to the use of high-dose therapy. Furthermore, we show how stem-like characteristics can act to stabilize the transient, weakly proliferative, and drug-tolerant subpopulation for a longer time window. Finally, using our models as in silico laboratories, we propose new testable hypotheses that could help uncover general principles underlying the emergence of cancer drug tolerance
Persistent Müllerian Duct Syndrome in a German Shepherd Dog
In mammals, the regression of the m\ufcllerian ducts is regulated by the action of the AMH hormone which is produced by testes during embryonic development. The action of this hormone is mediated by the only known receptor AMHR2. Mutations occurring in the AHM hormone and/or in the AMHR2 receptor gene cause the lack of regression of m\ufcllerian ducts, which may therefore persist even in male embryos carrying a XY chromosomal arrangement. This is known as the persistent m\ufcllerian duct syndrome (PMDS). A female German Shepherd dog was referred to the veterinary clinic because of urinary incontinence. She also showed an anatomical structure that protruded from and enlarged the vulvar labia. From the morphological appearance, one gonad resembled an ovary and the other a testicle. The histological examination instead showed that the gonads were both testes with an underdeveloped parenchyma and without signs of spermatogenetic activity. No alterations were found with regard to the uterus which showed a correctly developed body, cervix, and horns. Genetic analysis, performed on DNA extracted from blood, showed (i) the presence of both X and Y chromosomes, (ii) the absence of chromosome XX/XY chimerism, (iii) a normal SRY gene coding sequence, (iv) a normal AMHR2 gene coding sequence, and (v) a normal AMH gene coding sequence. In this study, we report and characterize a new case of PMDS in a dog excluding that the only mutation hitherto found in the AMHR2 gene is responsible for the observed phenotype
NARRATIVAS SOBRE A IDENTIDADE NACIONAL NA ABERTURA DOS JOGOS OLĂŤMPICOS RIO/2016: REPERCUSSĂ•ES EM PORTAIS JORNALĂŤSTICOS E NO TWITTER
O estudo descritivo visa compreender que temáticas proporcionaram narrativas transmidiáticas entre
portais digitais de notĂcias (UOL, G1 e Globo.com) e a rede social Twitter no decorrer da cerimĂ´nia de
abertura dos Jogos OlĂmpicos Rio 2016
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