3,325 research outputs found
Genes Dev
Almost half of our genome is occupied by transposable elements. Although most of them are inactive, one type of non-long terminal repeat (LTR) retrotransposon, long interspersed nuclear element 1 (LINE1), is capable of retrotransposition. Two studies in this issue, Pezic and colleagues (pp. 1410-1428) and Castro-Diaz and colleagues (pp. 1397-1409), provide novel insight into the regulation of LINE1s in human embryonic stem cells and mouse germ cells and shed new light on the conservation of complex mechanisms to ensure silencing of transposable elements in mammals
Genes Dev
Producing competent gametes is essential for transmitting genetic information throughout generations. Spermatogenesis is a unique example of rearrangements of genome packaging to ensure fertilization. After meiosis, spermatids undergo drastic morphological changes, perhaps the most dramatic ones occurring in their nuclei, including the transition into a protamine-packaged genome. In this issue of Genes & Development, Montellier and colleagues (pp. 1680-1692) shed new light on the molecular mechanisms regulating this transition by ascribing for the first time a function to a histone variant, TH2B, in the regulation of this process
Cell Rep
Cell plasticity or potency is necessary for the formation of multiple cell types. The mechanisms underlying this plasticity are largely unknown. Preimplantation mouse embryos undergo drastic changes in cellular potency, starting with the totipotent zygote through to the formation of the pluripotent inner cell mass (ICM) and differentiated trophectoderm in the blastocyst. Here, we set out to identify and functionally characterize chromatin modifiers that define the transitions of potency and cell fate in the mouse embryo. Using a quantitative microfluidics approach in single cells, we show that developmental transitions are marked by distinctive combinatorial profiles of epigenetic modifiers. Pluripotent cells of the ICM are distinct from their differentiated trophectoderm counterparts. We show that PRDM14 is heterogeneously expressed in 4-cell-stage embryos. Forced expression of PRDM14 at the 2-cell stage leads to increased H3R26me2 and can induce a pluripotent ICM fate. Our results shed light on the epigenetic networks that govern cellular potency and identity in vivo
A clean sightline to quiescence: multiwavelength observations of the high Galactic latitude black hole X-ray binary Swift J1357.2-0933
We present coordinated multiwavelength observations of the high Galactic latitude (b = +50°) black hole X-ray binary (BHXB) Swift J1357.2−0933 in quiescence. Our broad-band spectrum includes strictly simultaneous radio and X-ray observations, and near-infrared, optical, and ultraviolet data taken 1–2 d later. We detect Swift J1357.2−0933 at all wavebands except for the radio (f5 GHz < 3.9 μJy beam−1; 3σrms). Given current constraints on the distance (2.3–6.3 kpc), its 0.5–10 keV X-ray flux corresponds to an Eddington ratio LX/LEdd = 4 × 10−9–3 × 10−8 (assuming a black hole mass of 10 M⊙). The broad-band spectrum is dominated by synchrotron radiation from a relativistic population of outflowing thermal electrons, which we argue to be a common signature of short-period quiescent BHXBs. Furthermore, we identify the frequency where the synchrotron radiation transitions from optically thick-to-thin (νb ≈ 2–5 × 1014 Hz), which is the most robust determination of a ‘jet break’ for a quiescent BHXB to date. Our interpretation relies on the presence of steep curvature in the ultraviolet spectrum, a frequency window made observable by the low amount of interstellar absorption along the line of sight. High Galactic latitude systems like Swift J1357.2−0933 with clean ultraviolet sightlines are crucial for understanding black hole accretion at low luminosities
Results of donor after cardiac death circulation activation: recuperation of spontaneous circulation analysis.
The activation procedure of a potential donor after cardiac death begins after recognition of a situation of unrecovered PCR patient meets the criteria donor after cardiac death. Still have to meet a number of medical conditions and logistical both for the potential donor becomes effective donor. The aim of this study is to describe this procedure and know the number of potential donors who finally become effective donors.
Method: Collection of all activations procedure after cardiac death donor HU 12 de Octubre for 5 years (2009-2013). Data collection is performed on a web platform created for this purpose.post-print255 K
A VSA search for the extended Sunyaev-Zel'dovich Effect in the Corona Borealis Supercluster
We present interferometric imaging at 33 GHz of the Corona Borealis
supercluster, using the extended configuration of the Very Small Array. A total
area of 24 deg^2 has been imaged, with an angular resolution of 11 arcmin and a
sensitivity of 12 mJy/beam. The aim of these observations is to search for
Sunyaev-Zel'dovich (SZ) detections from known clusters of galaxies in this
supercluster and for a possible extended SZ decrement due to diffuse warm/hot
gas in the intercluster medium. We measure negative flux values in the
positions of the ten richest clusters in the region. Collectively, this implies
a 3.0-sigma detection of the SZ effect. In the clusters A2061 and A2065 we find
decrements of approximately 2-sigma. Our main result is the detection of two
strong and resolved negative features at -70+-12 mJy/beam (-157+-27 microK) and
-103+-10 mJy/beam (-230+-23 microK), respectively, located in a region with no
known clusters, near the centre of the supercluster. We discuss their possible
origins in terms of primordial CMB anisotropies and/or SZ signals related to
either unknown clusters or to a diffuse extended warm/hot gas distribution. Our
analyses have revealed that a primordial CMB fluctuation is a plausible
explanation for the weaker feature (probability of 37.82%). For the stronger
one, neither primordial CMB (probability of 0.33%) nor SZ can account alone for
its size and total intensity. The most reasonable explanation, then, is a
combination of both primordial CMB and SZ signal. Finally, we explore what
characteristics would be required for a filamentary structure consisting of
warm/hot diffuse gas in order to produce a significant contribution to such a
spot taking into account the constraints set by X-ray data.Comment: 16 pages, 10 figures. Accepted in MNRA
Characterization, conservation and loss of dignity at the end-of- life in the emergency department. A qualitative protocol
Aims: to explore and understand the experiences of terminally-ill patients and their relatives regarding dignity during end-of-life care in the emergency department.
Background: the respect given to the concept of dignity is significantly modifying the clinical relationship and the care framework involving the end-of-life patient in palliative care units, critical care units, hospices and their own homes. This situation is applicable to in-hospital emergency departments, where there is a lack of research which takes the experiences of end-of-life patients and their relatives into account.
Design: a phenomenological qualitative study.
Methods: the protocol was approved in December 2016 and will be carried out from December 2016 to December 2020. The Gadamer's philosophical underpinnings will be used in the design and development of the study. The data collection will include participant observation techniques in the Emergency Department, in-depth interviews with terminally-ill patients and focus groups with their relatives. For the data analysis, the field notes and verbatim transcriptions will be read and codified using ATLAS.ti software to search for emerging themes.
Discussion: emerging themes that contribute to comprehending the phenomenon of dignity in end-of-life care in the Emergency Department are expected to be found. This study's results could have important implications in the implementation of new interventions in Emergency Departments. These interventions would be focused on improving: the social acceptance of death, environmental conditions, promotion of autonomy and accompaniment, and assumption (takeover) of dignified actions and attitudes (respect for human rights)
Optical and near-infrared spectroscopy of the black hole transient 4U 1543-47 during its 2021 ultra-luminous state
We present simultaneous optical and near-infrared spectra obtained during the
2021 outburst of the black hole transient 4U 1543-47. The X-ray
hardness-intensity diagram and the comparison with similar systems reveal a
luminous outburst, probably reaching the Eddington luminosity, as well as a
long-lasting excursion to the so-called ultra-luminous state. VLT/X-shooter
spectra were taken in two epochs 14 days apart during the early and brightest
part of the outburst, while the source was in this ultra-luminous accretion
state. The data show strong H and HeI emission lines, as well as
high-excitation HeII and OIII transitions. Most lines are single-peaked in both
spectra, except for the OIII lines that exhibit evident double-peaked profiles
during the second epoch. The Balmer lines are embedded in broad absorption
wings that we believe are mainly produced by the contribution of the A2V donor
to the optical flux, which we estimate to be in the range of 11 to 14 per cent
in the band during our observations. Although no conspicuous outflow
features are found, we observe some wind-related line profiles, particularly in
the near-infrared. Such lines include broad emission line wings and skewed red
profiles, suggesting the presence of a cold (i.e. low ionisation) outflow with
similar observational properties to those found in other low-inclination black
hole transients.Comment: Accepted for publication in A&
Fast infrared winds during the radio-loud and X-ray obscured stages of the black hole transient GRS 1915+105
The black hole transient GRS 1915+105 entered a new phase of activity in
2018, generally characterised by low X-ray and radio fluxes. This phase has
been only interrupted by episodes of strong and variable radio emission, during
which high levels of X-ray absorption local to the source were measured. We
present 18 epochs of near-infrared spectroscopy (2018-2023) obtained with
GTC/EMIR and VLT/X-shooter, spanning both radio-loud and radio-quiet periods.
We demonstrate that radio-loud phases are characterised by strong P-Cygni line
profiles, indicative of accretion disc winds with velocities of up to
. This velocity is consistent with those measured
in other black hole transients. It is also comparable to the velocity of the
X-ray winds detected during the peak outburst phases in GRS 1915+105,
reinforcing the idea that massive, multi-phase outflows are characteristic
features of the largest and most powerful black hole accretion discs.
Conversely, the evolution of the Br line profile during the radio-quiet
phases follows the expected trend for accretion disc lines in a system that is
gradually decreasing its intrinsic luminosity, exhibiting weaker intensities
and more pronounced double-peaks.Comment: Accepted for publication in A&A Letter
The role of ZFP57 and additional KRAB-zinc finger proteins in the maintenance of human imprinted methylation and multi-locus imprinting disturbances.
Genomic imprinting is an epigenetic process regulated by germline-derived DNA methylation that is resistant to embryonic reprogramming, resulting in parental origin-specific monoallelic gene expression. A subset of individuals affected by imprinting disorders (IDs) displays multi-locus imprinting disturbances (MLID), which may result from aberrant establishment of imprinted differentially methylated regions (DMRs) in gametes or their maintenance in early embryogenesis. Here we investigated the extent of MLID in a family harbouring a ZFP57 truncating variant and characterize the interactions between human ZFP57 and the KAP1 co-repressor complex. By ectopically targeting ZFP57 to reprogrammed loci in mouse embryos using a dCas9 approach, we confirm that ZFP57 recruitment is sufficient to protect oocyte-derived methylation from reprogramming. Expression profiling in human pre-implantation embryos and oocytes reveals that unlike in mice, ZFP57 is only expressed following embryonic-genome activation, implying that other KRAB-zinc finger proteins (KZNFs) recruit KAP1 prior to blastocyst formation. Furthermore, we uncover ZNF202 and ZNF445 as additional KZNFs likely to recruit KAP1 to imprinted loci during reprogramming in the absence of ZFP57. Together, these data confirm the perplexing link between KZFPs and imprint maintenance and highlight the differences between mouse and humans in this respect
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