1,563 research outputs found
Life history and ecological genetics of the colonial ascidian Botryllus schlosseri
The colonial ascidian Botryllus schlosseri is a cosmopolitan, marine filter feeder, introduced as a laboratory research
organism in the 1950s. Currently, it is widely used in many laboratories to investigate a variety of biological questions.
Recently, it has become a species of concern, as it is an invasive species in many coastal environments. Here, we review
studies on the geographical distribution of the species, sexual and asexual reproduction in the field, tolerance to
temperature, salinity and anthropogenic activity, polychromatism, enzymatic polymorphism, and the genetic basis of
pigmentation. Studying the relationship between genetic polymorphism and the adaptation of B. schlosseri to
environmental stress is a challenge of future research and will improve our understanding of its evolutionary success
and invasive potential
UV observations of the globular cluster M10 from HST and GALEX. The BSS population
We present a combination of high-resolution Hubble Space Telescope and
wide-field ground-based and Galaxy Evolution Explorer data of the Galactic
Globular Cluster M10 (NGC6254). By using this large data-set we determined the
center of gravity of the cluster and we built its density profile from star
counts over its entire radial extension. We find that the density profile is
well reproduced by a single-mass King model with structural parameters c=1.41
and r_c=41". We also studied the Blue Straggler Star population and its radial
distribution. We count a total number of 120 BSS within the tidal radius. Their
radial distribution is bimodal: highly peaked in the cluster center, decreasing
at intermediate distances and rising again outwards. We discuss these results
in the context of the dynamical clock scheme presented by Ferraro et al. (2012)
and of recent results about the radial distribution of binary systems in this
cluster.Comment: Accepted for publication by ApJ; 26 pages, 11 figures, 1 tabl
Sow rearing in north Italy: I. analysis of technical and productive characteristics of different herds
There is a lack of information about reference values for the main productive and reproductive indexes for the sow herds in North Italy. This investigation was aimed to collect data from different kind of sow herds placed in the Veneto Region, in order to achieve representative values, in terms of mean and variability, for the main indexes of productivity: herd composition, feed consumption and feed composition
An optimal estimator for the CMB-LSS angular power spectrum and its application to WMAP and NVSS data
We use a Quadratic Maximum Likelihood (QML) method to estimate the angular
power spectrum of the cross-correlation between cosmic microwave background and
large scale structure maps as well as their individual auto-spectra. We
describe our implementation of this method and demonstrate its accuracy on
simulated maps. We apply this optimal estimator to WMAP 7-year and NRAO VLA Sky
Survey (NVSS) data and explore the robustness of the angular power spectrum
estimates obtained by the QML method. With the correction of the declination
systematics in NVSS, we can safely use most of the information contained in
this survey. We then make use of the angular power spectrum estimates obtained
by the QML method to derive constraints on the dark energy critical density in
a flat CDM model by different likelihood prescriptions. When using
just the cross-correlation between WMAP 7 year and NVSS maps with 1.8
resolution, the best-fit model has a cosmological constant of approximatively
70% of the total energy density, disfavouring an Einstein-de Sitter Universe at
more than 2 CL (confidence level).Comment: 12 pages, 12 figure
Selenium biofortification in the 21st century: status and challenges for healthy human nutrition
Background: Selenium (Se) is an essential element for mammals and its deficiency in the diet is a global problem. Plants accumulate Se and thus represent a major source of Se to consumers. Agronomic biofortification intends to enrich crops with Se in order to secure its adequate supply by people. Scope: The goal of this review is to report the present knowledge of the distribution and processes of Se in soil and at the plant-soil interface, and of Se behaviour inside the plant in terms of biofortification. It aims to unravel the Se metabolic pathways that affect the nutritional value of edible plant products, various Se biofortification strategies in challenging environments, as well as the impact of Se-enriched food on human health. Conclusions: Agronomic biofortification and breeding are prevalent strategies for battling Se deficiency. Future research addresses nanosized Se biofortification, crop enrichment with multiple micronutrients, microbial-integrated agronomic biofortification, and optimization of Se biofortification in adverse conditions. Biofortified food of superior nutritional quality may be created, enriched with healthy Se-compounds, as well as several other valuable phytochemicals. Whether such a food source might be used as nutritional intervention for recently emerged coronavirus infections is a relevant question that deserves investigation
A Panchromatic Study of the Globular Cluster NGC 1904. I: The Blue Straggler Population
By combining high-resolution (HST-WFPC2) and wide-field ground based (2.2m
ESO-WFI) and space (GALEX) observations, we have collected a multi-wavelength
photometric data base (ranging from the far UV to the near infrared) of the
galactic globular cluster NGC1904 (M79). The sample covers the entire cluster
extension, from the very central regions up to the tidal radius. In the present
paper such a data set is used to study the BSS population and its radial
distribution. A total number of 39 bright () BSS has been
detected, and they have been found to be highly segregated in the cluster core.
No significant upturn in the BSS frequency has been observed in the outskirts
of NGC 1904, in contrast to other clusters (M 3, 47 Tuc, NGC 6752, M 5) studied
with the same technique. Such evidences, coupled with the large radius of
avoidance estimated for NGC 1904 ( core radii), indicate that
the vast majority of the cluster heavy stars (binaries) has already sunk to the
core. Accordingly, extensive dynamical simulations suggest that BSS formed by
mass transfer activity in primordial binaries evolving in isolation in the
cluster outskirts represent only a negligible (0--10%) fraction of the overall
population.Comment: ApJ accepte
Quanti-qualitative evaluation of pectins in the dietary fibre of 24 foods
The dietary fibre of 24 foods was analysed for its proportions of insoluble and soluble (SDF) fractions and for its contentof high methoxyl pectins (HM), low methoxyl pectins (LM) and protopectin. The fractional extraction and quantitativedetermination of pectins were performed on the total dietary fibre residue, following the procedure suggested byRobertson (1979). Total pectin content (TP), calculated as sum of the three fractions, ranged from 2.4 to 49.8 g/kg ofdry matter. The variation coefficient of TP measurements repeated on the same foods were, on average, 2%. Total pectincontent was 49.8 g/kg DM in dried beet pulp and averaged 33.8+_0.3 g/kg DM in fruits and vegetables, 13.2+_8.4 g/kgDM in legumes and tubers and only 2.8+_0.5 g/kg DM in cereals. HM fraction prevailed in apple and pear samples (>40%of TP), while LM and protopectin largely prevailed in legumes and vegetables. A strong variability among foods was foundfor the TP/SDF ratio. In general, within each food category, increasing levels of SDF were associated with decreasing valuesof TP/SDF ratio. Since many foods contain low amounts of pectins, care in the development of calibration curves forspectrophotometric reading is required. Finally, the whole procedure for pectin extraction and quantification on dietaryfibre of food is very complex and time-consuming
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