Oral β-glucans modulate systemic antigen responses in dogs and pigs

The cell wall glucans of yeasts and fungi consist of a linear backbone of -1,3-linked glucosylunits with -1,6-linked side chains (1, 2). Although a lot is already known about the mechanism of action of -1,3/1,6-glucans on the innate immune system (3, 4), there is still a lot to be learned about their effects on the adaptive immune system in mammals. We aimed to determine if oral supplementation could modulate a systemic immune response. The latter was examined in pigs using a model antigen, but also in dogs analyzing the response against a parenteral vaccine. In three experiments using newly weaned pigs, Macrogard, a β-1,3/1,6-glucan from Saccharomyces cerevisiae, was administered in the feed during three different time periods (one, two and three weeks) and the adjuvant effect of this β-glucan was determined on a systemic immunisation with thyroglobulin. A first immunisation occurred during β-glucan supplementation, while the second one occurred after ceasing the administration. Macrogard exerted significantly higher thyroglobulin-specific primary immunoglobulin (Ig) M and secondary IgA antibody responses in serum. However, Macrogard suppressed the thyroglobulin-specific proliferation of peripheral blood mononuclear cells. A higher dose of Macrogard significantly increased thyroglobulin-specific IgM but not IgA responses, and the animals itself showed hyperaemia. Suppression of the T-lymphocyte proliferation might account for the absence of the switch from IgM to IgA. Weight gain and feed conversion were also determined, without significant differences between groups. In another study, also dogs were orally given Macrogard in tablets, daily for four weeks. At the end of this period, the total serum IgA level decreased significantly in the group treated with the glucan compared to that in the control group as well as compared to the concentrations before supplementation. In contrast, the total serum IgM level rose significantly, whereas no effect on the IgG level occurred. Similar changes were seen in Bordetella-specific IgA and IgM titres following vaccination during the supplementation period. The IgA concentration also became significantly lower in the saliva and tears of the glucan group than in the placebo group. The effects disappeared one week after the cessation of the supplementation. There seems to be a temporary decrease in the switch from IgM to IgA due to oral Macrogard supplementation in dogs probably by its suppression of T-lymphocyte proliferation as seen in pigs. In conclusion, oral β-glucans are able to modulate the humoral as well as the cellular immunity against a systemically administered antigen

Oral β-1,3/1,6-glucans as immunmodulators in pigs

The cell wall glucans of yeasts and fungi consist of a linear backbone of -1,3-linked glucosylunits with -1,6-linked side chains (1). Although a lot is already known about the mechanism of action of -1,3/1,6-glucans on the innate immune system (2), there is still a lot to be learned about their effects on the adaptive immune system in mammals. We aimed to determine if oral supplementation could modulate a systemic immune response. The latter was examined in pigs using a model antigen. In three experiments using newly weaned pigs, Macrogard, a β-1,3/1,6-glucan from Saccharomyces cerevisiae, was administered in the feed during three different time periods (one, two and three weeks) and the adjuvant effect of this β-glucan was determined on a systemic immunisation with thyroglobulin. A first immunisation occurred during β-glucan supplementation, while the second one occurred after ceasing the administration. Macrogard exerted significantly higher thyroglobulin-specific primary immunoglobulin (Ig) M and secondary IgA antibody responses in serum. However, Macrogard suppressed the thyroglobulin-specific proliferation of peripheral blood mononuclear cells. A higher dose of Macrogard significantly increased thyroglobulin-specific IgM but not IgA responses, and the animals itself showed hyperaemia. Suppression of the T-lymphocyte proliferation might account for the absence of the switch from IgM to IgA. Weight gain and feed conversion were also determined, without significant differences between groups. In conclusion, oral β-glucans are able to modulate the humoral as well as the cellular immunity against a systemically administered antigen

The ESO-Sculptor Survey: Luminosity functions of galaxies per spectral type at redshifts 0.1-0.5

[ABRIDGED] We present the first statistical analysis of the complete ESO-Sculptor redshift survey (ESS). The flux-calibrated sample of 617 galaxy spectra with R_c<20.5 is separated into 3 spectral classes (early, intermediate, and late). We report in detail on the spectral classification, the polynomial K-corrections, and all sources of corresponding random and systematic errors. The derived luminosity functions (LF) in the Johnson-Cousins B and Rc bands are in agreement with the results from the comparable CNOC2 survey (Lin et al. 1999), whereas the ESS provides the first estimates of LFs per spectral type in the Johnson V band. A renewed interpretation of the galaxy LFs from a redshift survey are obtained by fitting the ESS LFs with composite functions based on the local LFs per morphological type (Sandage, Binggeli & Tammann 1985; Jerjen & Tammann 1997). As good or better fits than with pure Schechter functions are obtained using: for the early-type LF, a two-wing Gaussian; for the intermediate-type LF, the sum of a Gaussian modeling the Spiral galaxies and a steep Schechter function (alpha=-1.5) representing the dwarf elliptical galaxies; for the late-type LF, a similar composite function with a flat or weaker slope (-0.8<alpha<-0.3) for the Schechter component which represents the dwarf Irregular galaxies. This analysis illustrates how LFs per spectral type may be affected by morphological type mixing, and emphasizes the need for a quantitative morphological classification at z>0.1 which separates the giant and dwarf galaxy populations.Comment: 33 Pages, 13 color figures, A&A Latex macro. Published in A&

The interactive impact of dietary PUFA on the deposition of DHA in the egg yolk

C

Clustering at high redshift

The addition of deep near infrared images to the database provided by the HDF-S WFPC2 is essential to monitor the SEDs of the objects on a wide baseline and address a number of key issues including the total stellar content of baryonic mass, the effects of dust extinction, the dependence of morphology on the rest frame wavelength, the photometric redshifts, the detection and nature of extremely red objects (EROs). For these reasons deep near infrared images were obtained with the ISAAC instrument at the ESO VLT in the Js, H and Ks bands reaching, respectively, 23.5, 22.0, 22.0 limiting Vega-magnitude. A multi-color (F300, F450, F606, F814, Js, H, Ks) photometric catalog of the HDF-S has been produced. Photometric redshifts have been generated both fitting templates to the observed SEDs and with neural network techniques. Spectroscopic observations of the 9 candidates with I_AB <24.25 have confirmed all of them to be galaxies with 2<z<3.5. The photometric redshifts for all the galaxies brighter than I_AB< 27.5 have been used to study the evolution of galaxy clustering in the interval 0<z<4.5.Comment: 2 pages Latex, To appear in the proceedings of "The mass of galaxies at low and high redshift", Venice, Oct 24-26, 2001,eds. R. Bender and A. Renzini (ESO Astrophysics Symposia, Springer-Verlag

Building the red sequence through gas-rich major mergers

Understanding the details of how the red sequence is built is a key question in galaxy evolution. What are the relative roles of gas-rich vs. dry mergers, major vs. minor mergers or galaxy mergers vs. gas accretion? In Wild et al. 2009 we compare hydrodynamic simulations with observations to show how gas-rich major mergers result in galaxies with strong post-starburst spectral features, a population of galaxies easily identified in the real Universe using optical spectra. Using spectra from the VVDS deep survey with z~0.7, and a principal component analysis technique to provide indices with high enough SNR, we find that 40% of the mass flux onto the red-sequence could enter through a strong post-starburst phase, and thus through gas-rich major mergers. The deeper samples provided by next generation galaxy redshift surveys will allow us to observe the primary physical processes responsible for the shut-down in starformation and build-up of the red sequence.Comment: 4 pages, 7 figures, proceedings of IAU symposium 262 "Stellar populations, planning for the next decade

Photometric redshifts and selection of high redshift galaxies in the NTT and Hubble Deep Fields

We present and compare in this paper new photometric redshift catalogs of the galaxies in three public fields: the NTT Deep Field, the HDF-N and the HDF-S. Photometric redshifts have been obtained for thewhole sample, by adopting a $\chi^2$ minimization technique on a spectral library drawn from the Bruzual and Charlot synthesis models, with the addition of dust and intergalactic absorption. The accuracy, determined from 125 galaxies with known spectroscopic redshifts, is $\sigma_z\sim 0.08 (0.3)$ in the redshift intervals $z=0-1.5 (1.5-3.5)$. The global redshift distribution of I-selected galaxies shows a distinct peak at intermediate redshifts, z~0.6 at I_{AB}<26 and z~0.8 at I_{AB}<27.5 followed by a tail extending to z~6. We also present for the first time the redshift distribution of the total IR-selected sample to faint limits ($Ks \leq 21$ and $J\leq22$). It is found that the number density of galaxies at 1.25<z<1.5 is ~ 0.1 /arcmin^22 at J<=21 and ~1./arcmin^2} at J<22, and drops to 0.3/arcmin^2 (at J<22) at 1.5<z<2. The HDFs data sets are used to compare the different results from color selection criteria and photometric redshifts in detecting galaxies in the redshift range 3.5<z<4.5 Photometric redshifts predict a number of high z candidates in both the HDF-N and HDF-S that is nearly 2 times larger than color selection criteria, and it is shown that this is primarily due to the inclusion of dusty models that were discarded in the original color selection criteria by Madau et al 1998. In several cases, the selection of these objects is made possible by the constraints from the IR bands. Finally, it is shown that galactic M stars may mimic z>5 candidates in the HDF filter set and that the 4 brightest candidates at $z>5$ in the HDF-S are indeed most likely M stars. (ABRIDGED)Comment: Version accepted on July, 20, 2000. To appear on Astronomical Journal, Nov 2000. The data and photometric redshift catalogs presented here are available on line at http://www.mporzio.astro.it/HIGH

The ESO-Sculptor Faint Galaxy Redshift Survey: The Photometric Sample

We present the photometric sample of a faint galaxy survey carried out in the southern hemisphere, using CCDs on the 3.60m and NTT-3.5m telescopes at La Silla (ESO). The survey area is a continuous strip of 0.2 deg x 1.53 deg located at high galactic latitude (-83 deg) in the Sculptor constellation. The photometric survey provides total magnitudes in the bands B, V (Johnson) and R (Cousins) to limiting magnitudes of 24.5, 24.0, 23.5 respectively. To these limits, the catalog contains about 9500, 12150, 13000 galaxies in B, V, R bands respectively and is the first large digital multi-colour photometric catalog at this depth. This photometric survey also provides the entry catalog for a fully-sampled redshift survey of ~ 700 galaxies with R < 20.5 (Bellanger et al. 1995). In this paper, we describe the photometric observations and the steps used in the data reduction. The analysis of objects and the star-galaxy separation with a neural network are performed using SExtractor, a new photometric software developed by E. Bertin (1996). The photometric accuracy of the resulting catalog is ~ 0.05 mag for R < 22. The differential galaxy number counts in B, V, R are in good agreement with previously published CCD studies and confirm the evidence for significant evolution at faint magnitudes as compared to a standard non evolving model (by factors 3.6, 2.6, 2.1). The galaxy colour distributions B-R, B-V of our sample show a blueing trend of ~ 0.5 mag between 21 < R < 23.5 in contrast to the V-R colour distribution where no significant evolution is observed.Comment: LATEX, 18 Postscript figures, 20 pages. To appear July 1997. Modified version of article. Abstract corrected for missing lin

De deur klemt : Nederland op slot door Natura 2000: de discussie ontrafeld

Het is overdreven om te zeggen dat Nederland op slot zit door Natura 2000-regels. Wel zit er een kern van waarheid in de bewering: bij de uitvoering van het Natura 2000-beleid is een aantal problemen opgetreden waardoor verschillende activiteiten (nog) niet mogelijk zijn. In WOt-paper 7 wordt hierop ingegaan. De problemen komen volgens betrokken organisaties vooral voort uit de manier waarop Nederland Natura 2000 heeft geïnterpreteerd en vervolgens heeft uitgewerkt in de nationale wetgeving. Het grootste knelpunt is dat dit niet toegesneden lijkt op de praktijk. Daarnaast veroorzaakt de voortdurende belangenstrijd tussen voor- en tegenstanders van Natura 2000 problemen