287 research outputs found
The nature of Composite Seyfert/Star-forming galaxies revealed by X-ray observations
This paper presents new Chandra and BeppoSAX observations aimed at
investigating the optical/X-ray mismatch in the enigmatic class of the
Composite galaxies, discovered by a cross-correlation of IRAS and ROSAT all sky
survey catalogues. These galaxies have been classified as star-forming objects
on the basis of their optical spectra, while the detection of weak broad wings
in the H(alpha) emission in a few of them and their high X-ray luminosity in
the ROSAT band indicated the presence of an active nucleus. The analysis of
Chandra observations for 4 Composites has revealed nuclear point-like sources,
with a typical AGN spectrum (Gamma = 1.7-1.9) and little intrinsic absorption.
A strong flux variability has been observed on different time scales, in
particular most of the sources were brighter at the ROSAT epoch. Although of
relative low luminosity for the AGN class (L(2-10 keV) = 3-60 x 10^{41} erg/s),
the active nucleus is nevertheless dominant in the X-ray domain. At other
wavelengths it appears to be overwhelmed by the starburst and/or host galaxy
light, yielding the Composite classification for these objects.Comment: 20 pages, 10 figures, accepted by Ap
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE).XI. Two dimensional Hα kinematics of the edge-on ram pressure stripped galaxy NGC 4330
Using the VESTIGE survey, a deep narrow-band H imaging survey of the
Virgo cluster carried on at the CFHT with MegaCam, we discovered a long diffuse
tail of ionised gas in the edge-on late-type galaxy NGC 4330. This peculiar
feature witnesses an ongoing ram pressure stripping (RPS) event able to remove
the gas in the outer disc region. Tuned hydrodynamic simulations suggest that
the RPS event is occurring almost face-on, making NGC 4330 the ideal candidate
to study the effects of the perturbation in the direction perpendicular to the
disc plane. We present here two new independent sets of Fabry-Perot
observations (R10000) in order to understand the effects of the RPS
process on the ionised gas kinematics. Despite their limited sensitivity to the
diffuse gas emission, the data allowed us to measure the velocity and the
velocity dispersion fields over the galaxy disc and in several features at the
edges or outside the stellar disc formed after the RPS event. We have
constructed the position-velocity diagrams and the rotation curves of the
galaxy using three different techniques. The data show, consistent with the
hydrodynamic simulations, that the galaxy has an inner solid-body rotation up
to 2.4 kpc, with non-circular streaming motions outwards the disc and in
the several external features formed during the interaction of the galaxy with
the surrounding intracluster medium. The data also indicate a decrease of the
rotational velocity of the gas with increasing distance from the galaxy disc
along the tails, suggesting a gradual but not linear loss of angular momentum
in the stripped gas. Consistent with a RPS scenario, the -band image shows a
boxy shape at the southwest edge of the disc, where the stellar orbits might
have been perturbed by the modification of the gravitational potential well of
the galaxy due to the displacement of the gas in the -direction
Extensive recombination events and horizontal gene transfer shaped the Legionella pneumophila genomes
<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumophila </it>is an intracellular pathogen of environmental protozoa. When humans inhale contaminated aerosols this bacterium may cause a severe pneumonia called Legionnaires' disease. Despite the abundance of dozens of <it>Legionella </it>species in aquatic reservoirs, the vast majority of human disease is caused by a single serogroup (Sg) of a single species, namely <it>L. pneumophila </it>Sg1. To get further insights into genome dynamics and evolution of Sg1 strains, we sequenced strains Lorraine and HL 0604 1035 (Sg1) and compared them to the available sequences of Sg1 strains Paris, Lens, Corby and Philadelphia, resulting in a comprehensive multigenome analysis.</p> <p>Results</p> <p>We show that <it>L. pneumophila </it>Sg1 has a highly conserved and syntenic core genome that comprises the many eukaryotic like proteins and a conserved repertoire of over 200 Dot/Icm type IV secreted substrates. However, recombination events and horizontal gene transfer are frequent. In particular the analyses of the distribution of nucleotide polymorphisms suggests that large chromosomal fragments of over 200 kbs are exchanged between <it>L. pneumophila </it>strains and contribute to the genome dynamics in the natural population. The many secretion systems present might be implicated in exchange of these fragments by conjugal transfer. Plasmids also play a role in genome diversification and are exchanged among strains and circulate between different <it>Legionella </it>species.</p> <p>Conclusion</p> <p>Horizontal gene transfer among bacteria and from eukaryotes to <it>L. pneumophila </it>as well as recombination between strains allows different clones to evolve into predominant disease clones and others to replace them subsequently within relatively short periods of time.</p
Meeting of the Ecosystem Approach Correspondence Group on on Pollution Monitoring (CorMon Pollution)
In accordance with the UNEP/MAP Programme of Work adopted by COP 21 for the biennium 2020-2021, the United Nations Environment Programme/Mediterranean Action Plan-Barcelona Convention Secretariat (UNEP/MAP) and its Programme for the Assessment and Control of Marine Pollution in the Mediterranean (MED POL) organized the Meeting of the Ecosystem Approach Correspondence Group on Pollution Monitoring (CorMon on Pollution Monitoring). The Meeting was held via videoconference on 26-27 April 2021.
2. The main objectives of the Meeting were to:
a) Review the Monitoring Guidelines/Protocols for IMAP Common Indicator 18, as well as the Monitoring Guidelines/Protocols for Analytical Quality Assurance and Reporting of Monitoring Data for IMAP Common Indicators 13, 14, 17, 18 and 20;
b) Take stock of the state of play of inter-laboratory testing and good laboratory practice related to IMAP Ecological Objectives 5 and 9;
c) Analyze the proposal for the integration and aggregation rules for IMAP Ecological Objectives 5, 9 and 10 and assessment criteria for contaminants and nutrients;
d) Recommend the ways and means to strengthen implementation of IMAP Pollution Cluster towards preparation of the 2023 MED Quality Status Report
IMI - Myopia Genetics Report
The knowledge on the genetic background of refractive error and myopia has expanded
dramatically in the past few years. This white paper aims to provide a concise summary of
current genetic findings and defines the direction where development is needed.
We performed an extensive literature search and conducted informal discussions with key
stakeholders. Specific topics reviewed included common refractive error, any and high
myopia, and myopia related to syndromes.
To date, almost 200 genetic loci have been identified for refractive error and myopia, and risk
variants mostly carry low risk but are highly prevalent in the general population. Several
genes for secondary syndromic myopia overlap with those for common myopia. Polygenic
risk scores show overrepresentation of high myopia in the higher deciles of risk. Annotated
genes have a wide variety of functions, and all retinal layers appear to be sites of expression.
The current genetic findings offer a world of new molecules involved in myopiagenesis. As
the missing heritability is still large, further genetic advances are needed. This Committee
recommends expanding large-scale, in-depth genetic studies using complementary big data
analytics, consideration of gene-environment effects by thorough measurement of environmental exposures, and focus on subgroups with extreme phenotypes and high familial
occurrence. Functional characterization of associated variants is simultaneously needed to
bridge the knowledge gap between sequence variance and consequence for eye growth
Genome-wide meta-analysis associates HLA-DQA1/DRB1 and LPA and lifestyle factors with human longevity
Genomic analysis of longevity offers the potential to illuminate the biology of human aging. Here, using genome-wide association meta-analysis of 606,059 parents' survival, we discover two regions associated with longevity (HLA-DQA1/DRB1 and LPA). We also validate previous suggestions that APOE, CHRNA3/5, CDKN2A/B, SH2B3 and FOXO3A influence longevity. Next we show that giving up smoking, educational attainment, openness to new experience and high-density lipoprotein (HDL) cholesterol levels are most positively genetically correlated with lifespan while susceptibility to coronary artery disease (CAD), cigarettes smoked per day, lung cancer, insulin resistance and body fat are most negatively correlated. We suggest that the effect of education on lifespan is principally mediated through smoking while the effect of obesity appears to act via CAD. Using instrumental variables, we suggest that an increase of one body mass index unit reduces lifespan by 7 months while 1 year of education adds 11 months to expected lifespan
Genome-wide analysis identifies 12 loci influencing human reproductive behavior.
The genetic architecture of human reproductive behavior-age at first birth (AFB) and number of children ever born (NEB)-has a strong relationship with fitness, human development, infertility and risk of neuropsychiatric disorders. However, very few genetic loci have been identified, and the underlying mechanisms of AFB and NEB are poorly understood. We report a large genome-wide association study of both sexes including 251,151 individuals for AFB and 343,072 individuals for NEB. We identified 12 independent loci that are significantly associated with AFB and/or NEB in a SNP-based genome-wide association study and 4 additional loci associated in a gene-based effort. These loci harbor genes that are likely to have a role, either directly or by affecting non-local gene expression, in human reproduction and infertility, thereby increasing understanding of these complex traits
Childhood gene-environment interactions and age-dependent effects of genetic variants associated with refractive error and myopia : The CREAM Consortium
Myopia, currently at epidemic levels in East Asia, is a leading cause of untreatable visual impairment. Genome-wide association studies (GWAS) in adults have identified 39 loci associated with refractive error and myopia. Here, the age-of-onset of association between genetic variants at these 39 loci and refractive error was investigated in 5200 children assessed longitudinally across ages 7-15 years, along with gene-environment interactions involving the major environmental risk-factors, nearwork and time outdoors. Specific variants could be categorized as showing evidence of: (a) early-onset effects remaining stable through childhood, (b) early-onset effects that progressed further with increasing age, or (c) onset later in childhood (N = 10, 5 and 11 variants, respectively). A genetic risk score (GRS) for all 39 variants explained 0.6% (P = 6.6E-08) and 2.3% (P = 6.9E-21) of the variance in refractive error at ages 7 and 15, respectively, supporting increased effects from these genetic variants at older ages. Replication in multi-ancestry samples (combined N = 5599) yielded evidence of childhood onset for 6 of 12 variants present in both Asians and Europeans. There was no indication that variant or GRS effects altered depending on time outdoors, however 5 variants showed nominal evidence of interactions with nearwork (top variant, rs7829127 in ZMAT4; P = 6.3E-04).Peer reviewe
- …