226 research outputs found
Fueling of a marine-terrestrial ecosystem by a major seabird colony
Seabirds redistribute nutrients between different ecosystem compartments and over vast geographical areas. This nutrient transfer may impact both local ecosystems on seabird breeding islands and regional biogeochemical cycling, but these processes are seldom considered in local conservation plans or biogeochemical models. The island of Stora Karlso in the Baltic Sea hosts the largest concentration of piscivorous seabirds in the region, and also hosts a large colony of insectivorous House martins Delichon urbicum adjacent to the breeding seabirds. We show that a previously reported unusually high insectivore abundance was explained by large amounts of chironomids-highly enriched in delta N-15-that feed on seabird residues as larvae along rocky shores to eventually emerge as flying adults. Benthic ammonium and phosphate fluxes were up to 163% and 153% higher close to the colony (1,300 m distance) than further away (2,700 m) and the estimated nutrient release from the seabirds at were in the same order of magnitude as the loads from the largest waste-water treatment plants in the region. The trophic cascade impacting insectivorous passerines and the substantial redistribution of nutrients suggest that seabird nutrient transfer should be increasingly considered in local conservation plans and regional nutrient cycling models.Peer reviewe
Deletion 22q13.3 syndrome
The deletion 22q13.3 syndrome (deletion 22q13 syndrome or Phelan-McDermid syndrome) is a chromosome microdeletion syndrome characterized by neonatal hypotonia, global developmental delay, normal to accelerated growth, absent to severely delayed speech, and minor dysmorphic features. The deletion occurs with equal frequency in males and females and has been reported in mosaic and non-mosaic forms. Due to lack of clinical recognition and often insufficient laboratory testing, the syndrome is under-diagnosed and its true incidence remains unknown. Common physical traits include long eye lashes, large or unusual ears, relatively large hands, dysplastic toenails, full brow, dolicocephaly, full cheeks, bulbous nose, and pointed chin. Behavior is autistic-like with decreased perception of pain and habitual chewing or mouthing. The loss of 22q13.3 can result from simple deletion, translocation, ring chromosome formation and less common structural changes affecting the long arm of chromosome 22, specifically the region containing the SHANK3 gene. The diagnosis of deletion 22q13 syndrome should be considered in all cases of hypotonia of unknown etiology and in individuals with absent speech. Although the deletion can sometimes be detected by high resolution chromosome analysis, fluorescence in situ hybridization (FISH) or array comparative genomic hybridization (CGH) is recommended for confirmation. Differential diagnosis includes syndromes associated with hypotonia, developmental delay, speech delay and/or autistic-like affect (Prader-Willi, Angelman, Williams, Smith-Magenis, Fragile X, Sotos, FG, trichorhinophalangeal and velocardiofacial syndromes, autism spectrum disorders, cerebral palsy). Genetic counseling is recommended and parental laboratory studies should be considered to identify cryptic rearrangements and detect parental mosaicism. Prenatal diagnosis should be offered for future pregnancies in those families with inherited rearrangements. Individuals with deletion 22q13 should have routine examinations by the primary care physician as well as genetic evaluations with referral to specialists if neurological, gastrointestinal, renal, or other systemic problems are suspected. Affected individuals benefit from early intervention programs, intense occupational and communication therapies, adaptive exercise and sport programs, and other therapies to strengthen their muscles and increase their communication skills. No apparent life-threatening organic abnormalities accompany the diagnosis of deletion 22q13
De novo unbalanced translocations have a complex history/aetiology
We investigated 52 cases of de novo unbalanced translocations, consisting in a terminally deleted or inverted-duplicated deleted (inv-dup del) 46th chromosome to which the distal portion of another chromosome or its opposite end was transposed. Array CGH, whole-genome sequencing, qPCR, FISH, and trio genotyping were applied. A biparental origin of the deletion and duplication was detected in 6 cases, whereas in 46, both imbalances have the same parental origin. Moreover, the duplicated region was of maternal origin in more than half of the cases, with 25% of them showing two maternal and one paternal haplotype. In all these cases, maternal age was increased. These findings indicate that the primary driver for the occurrence of the de novo unbalanced translocations is a maternal meiotic non-disjunction, followed by partial trisomy rescue of the supernumerary chromosome present in the trisomic zygote. In contrast, asymmetric breakage of a dicentric chromosome, originated either at the meiosis or postzygotically, in which the two resulting chromosomes, one being deleted and the other one inv-dup del, are repaired by telomere capture, appears at the basis of all inv-dup del translocations. Notably, this mechanism also fits with the origin of some simple translocations in which the duplicated region was of paternal origin. In all cases, the signature at the translocation junctions was that of non-homologous end joining (NHEJ) rather than non-allelic homologous recombination (NAHR). Our data imply that there is no risk of recurrence in the following pregnancies for any of the de novo unbalanced translocations we discuss here
LBT/ARGOS adaptive optics observations of z lensed galaxies
Gravitationally lensed systems allow a detailed view of galaxies at high
redshift. High spatial- and spectral-resolution measurements of arc-like
structures can offer unique constraints on the physical and dynamical
properties of high-z systems. We present near-infrared spectra centred on the
gravitational arcs of six known z ~ 2 lensed star-forming galaxies of stellar
masses of 10^9-10^11 Msun and star formation rate (SFR) in the range between 10
and 400 Msun/yr. Ground layer adaptive optics (AO)-assisted observations are
obtained at the Large Binocular Telescope (LBT) with the LUCI spectrographs
during the commissioning of the ARGOS facility. We used MOS masks with curved
slits to follow the extended arched structures and study the diagnostic
emission lines. Combining spatially resolved kinematic properties across the
arc-like morphologies, emission line diagnostics and archival information, we
distinguish between merging and rotationally supported systems, and reveal the
possible presence of ejected gas. For galaxies that have evidence for outflows,
we derive outflow energetics and mass-loading factors compatible with those
observed for stellar winds in local and high-z galaxies. We also use flux ratio
diagnostics to derive gas-phase metallicities. The low signal-to-noise ratio in
the faint H and nitrogen lines allows us to derive an upper limit of ~
0.15 dex for the spatial variations in metallicity along the slit for the
lensed galaxy J1038. Analysed near-infrared spectra presented here represent
the first scientific demonstration of performing AO-assisted multi-object
spectroscopy with narrow curved-shape slits. The increased angular and spectral
resolution, combined with the binocular operation mode with the 8.4-m-wide eyes
of LBT, will allow the characterisation of kinematic and chemical properties of
a large sample of galaxies at high-z in the near future.Comment: 18 pages, 13 figures, accepted for publication in A&
Near-Infrared Observations of Outflows and YSOs in the Massive Star-Forming Region AFGL 5180
Methods: Broad- and narrow-band imaging of AFGL 5180 was made in the NIR with
the LBT, in both seeing-limited (\sim0.5\arcsec) and high angular resolution
(\sim0.09\arcsec) Adaptive Optics (AO) modes, as well as with HST. Archival
ALMA continuum data was also utilized.
Results: At least 40 jet knots were identified via NIR emission from H
and [FeII] tracing shocked gas. Bright jet knots outflowing from the central
most massive protostar, S4, are detected towards the east of the source and are
resolved in fine detail with the AO imaging. Additional knots are distributed
throughout the field, likely indicating the presence of multiple driving
sources. Sub-millimeter sources detected by ALMA are shown to be grouped in two
main complexes, AFGL 5180 M and a small cluster \sim15\arcsec to the south,
AFGL 5180 S. From our NIR continuum images we identify YSO candidates down to
masses of . Combined with the sub-mm sources, this yields a
surface number density of such YSOs of within a
projected radius of about 0.1 pc. Such a value is similar to those predicted by
models of both Core Accretion from a turbulent clump environment and
Competitive Accretion. The radial profile of is relatively flat on scales
out to 0.2~pc, with only modest enhancement around the massive protostar inside
0.05~pc.
Conclusions: This study demonstrates the utility of high-resolution NIR
imaging, in particular with AO, for detecting outflow activity and YSOs in
distant regions. The presented images reveal the complex morphology of
outflow-shocked gas within the large-scale bipolar flow of a massive protostar,
as well as clear evidence for several other outflow driving sources in the
region. Finally, this work presents a novel approach to compare the observed
YSO surface number density from our study against different models of massive
star formation.Comment: Accepted to Astronomy & Astrophysics (A&A
Orbital and dynamical analysis of the system around HR 8799. New astrometric epochs from VLT/SPHERE and LBT/LUCI
HR\,8799 is a young planetary system composed of 4 planets and a double
debris belt. Being the first multi-planetary system discovered with the direct
imaging technique, it has been observed extensively since 1998. This wide
baseline of astrometric measurements, counting over 50 observations in 20
years, permits a detailed orbital and dynamical analysis of the system. To
explore the orbital parameters of the planets, their dynamical history, and the
planet-to-disk interaction, we made follow-up observations of the system during
the VLT/SPHERE GTO program. We obtained 21 observations, most of them in
favorable conditions. In addition, we observed HR\,8799 with the instrument
LBT/LUCI. All the observations were reduced with state-of-the-art algorithms
implemented to apply the spectral and angular differential imaging method. We
re-reduced the SPHERE data obtained during the commissioning of the instrument
and in 3 open-time programs to have homogeneous astrometry. The precise
position of the 4 planets with respect to the host star was calculated by
exploiting the fake negative companions method. To improve the orbital fitting,
we also took into account all of the astrometric data available in the
literature. From the photometric measurements obtained in different
wavelengths, we estimated the planets' masses following the evolutionary
models. We obtained updated parameters for the orbits with the assumption of
coplanarity, relatively small eccentricities, and periods very close to the 2:1
resonance. We also refined the dynamical mass of each planet and the parallax
of the system (24.49 0.07 mas). We also conducted detailed -body
simulations indicating possible positions of a~putative fifth innermost planet
with a mass below the present detection limits of ~\MJup.Comment: 27 pages, 15 figures, A&A in pres
Molecular mechanisms generating and stabilizing terminal 22q13Deletions in 44 subjects with Phelan/McDermid Syndrome
ARGOS: the laser guide star system for the LBT
ARGOS is the Laser Guide Star adaptive optics system for the Large Binocular Telescope. Aiming for a wide field adaptive optics correction, ARGOS will equip both sides of LBT with a multi laser beacon system and corresponding wavefront sensors, driving LBT's adaptive secondary mirrors. Utilizing high power pulsed green lasers the artificial beacons are generated via Rayleigh scattering in earth's atmosphere. ARGOS will project a set of three guide stars above each of LBT's mirrors in a wide constellation. The returning scattered light, sensitive particular to the turbulence close to ground, is detected in a gated wavefront sensor system. Measuring and correcting the ground layers of the optical distortions enables ARGOS to achieve a correction over a very wide field of view. Taking advantage of this wide field correction, the science that can be done with the multi object spectrographs LUCIFER will be boosted by higher spatial resolution and strongly enhanced flux for spectroscopy. Apart from the wide field correction ARGOS delivers in its ground layer mode, we foresee a diffraction limited operation with a hybrid Sodium laser Rayleigh beacon combination.12 page(s
Evaluation of A2BP1 as an Obesity Gene
OBJECTIVE-A genome-wide association study (GWAS) in Pima Indians (n = 413) identified variation in the ataxin-2 binding protein 1 gene (A2BP1) that was associated with percent body fat. On the basis of this association and the obese phenotype of ataxin-2 knockout mice, A2BP1 was genetically and functionally analyzed to assess its potential role in human obesity. RESEARCH DESIGN AND METHODS-Variants spanning A2BP1 were genotyped in a population-based sample of 3,234 full-heritage Pima Indians, 2,843 of whom were not part of the initial GWAS study and therefore could serve as a sample to assess replication. Published GWAS data across A2BP1 were additionally analyzed in French adult (n = 1,426) and children case/control subjects (n = 1,392) (Meyre et al. Nat Genet 2009;41:157-159). Selected variants were genotyped in two additional samples of Caucasians (Amish, n = 1,149, and German children case/control subjects, n = 998) and one additional Native American (n = 2,531) sample. Small interfering RNA was used to knockdown A2bp1 message levels in mouse embryonic hypothalamus cells. RESULTS-No single variant in A2BP1 was reproducibly associated with obesity across the different populations. However, different variants within intron 1 of A2BP1 were associated with BMI in full-heritage Pima Indians (rs10500331, P = 1.9 x 10(-7)) and obesity in French Caucasian adult (rs4786847, P = 1.9 x 10(-10)) and children (rs8054147, P = 9.2 x 10(-6)) case/control subjects. Reduction of A2bp1 in mouse embryonic hypothalamus cells decreased expression of Atxn2, Insr, and Mc4r. CONCLUSIONS-Association analysis suggests that variation in A2BP1 influences obesity, and functional studies suggest that A2BP1 could potentially affect adiposity via the hypothalamic MC4R pathway. Diabetes 59:2837-2845, 201
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