Searching for variable stars in Galactic Open Clusters

A long-term project, aiming at systematic search for variable stars in Galactic Open Clusters, was started at the Geneva Observatory in 2002. We have been observing regularly a sample of twenty-seven Galactic Open Clusters in the U, B, V Geneva filters. The goal is to identify and to study their variable stars, as well as the connection between the variable stars in a cluster and the cluster properties. We present the status of this work in progress, and show preliminary results for one of these clusters, IC 4651.Comment: To appear in the proceedings of Stellar Pulsation: Challenges for theory and observations Conference, Santa Fe, NM, US

Looking for variable stars in galactic open clusters

A long-term project, aiming at systematic search for variable stars in Galactic Open Clusters (OCs), was started at the Geneva Observatory in 2002. We have been observing regularly a sample of twenty-seven Galactic Open Clusters in the U, B, V Geneva filters (hereafter U, B, V). The goal is to identify and to study their variable stars, as well as the connection between the variable stars in a cluster and the cluster properties. We present the status of this work in progress, and show preliminary results for one of these clusters, IC 465

Xenacoelomorpha Survey Reveals That All 11 Animal Homeobox Gene Classes Were Present in the First Bilaterians

Homeodomain transcription factors are involved in many developmental processes across animals and have been linked to body plan evolution. Detailed classifications of these proteins identified 11 distinct classes of homeodomain proteins in animal genomes, each harboring specific sequence composition and protein domains. Although humans contain the full set of classes, Drosophila melanogaster and Caenorhabditis elegans each lack one specific class. Furthermore, representative previous analyses in sponges, ctenophores, and cnidarians could not identify several classes in those nonbilaterian metazoan taxa. Consequently, it is currently unknown when certain homeodomain protein classes first evolved during animal evolution. Here, we investigate representatives of the sister group to all remaining bilaterians, the Xenacoelomorpha. We analyzed three acoel, one nemertodermatid, and one Xenoturbella transcriptomes and identified their expressed homeodomain protein content. We report the identification of representatives of all 11 classes of animal homeodomain transcription factors in Xenacoelomorpha and we describe and classify their homeobox genes relative to the established animal homeodomain protein families. Our findings suggest that the genome of the last common ancestor of bilateria contained the full set of these gene classes, supporting the subsequent diversification of bilaterians

Gaia Data Release 3: The first Gaia catalogue of variable AGN

One of the novelties of the Gaia-DR3 with respect to the previous data releases is the publication of the multiband light curves of about 1 million AGN. The goal of this work was the creation of a catalogue of variable AGN, whose selection was based on Gaia data only. We first present the implementation of the methods to estimate the variability parameters into a specific object study module for AGN. Then we describe the selection procedure that led to the definition of the high-purity variable AGN sample and analyse the properties of the selected sources. We started from a sample of millions of sources, which were identified as AGN candidates by 11 different classifiers based on variability processing. Because the focus was on the variability properties, we first defined some pre-requisites in terms of number of data points and mandatory variability parameters. Then a series of filters was applied using only Gaia data and the Gaia Celestial Reference Frame 3 (Gaia-CRF3) sample as a reference.The resulting Gaia AGN variable sample, named GLEAN, contains about 872000 objects, more than 21000 of which are new identifications. We checked the presence of contaminants by cross-matching the selected sources with a variety of galaxies and stellar catalogues. The completeness of GLEAN with respect to the variable AGN in the last Sloan Digital Sky Survey quasar catalogue is about 47%, while that based on the variable AGN of the Gaia-CRF3 sample is around 51%. From both a comparison with other AGN catalogues and an investigation of possible contaminants, we conclude that purity can be expected to be above 95%. Multiwavelength properties of these sources are investigated. In particular, we estimate that about 4% of them are radio-loud. We finally explore the possibility to evaluate the time lags between the flux variations of the multiple images of strongly lensed quasars, and show one case.Comment: 19 pages, 31 figures, 2 table. This paper is part of Gaia Data Release 3 (DR3). In press for A&

Gaia Early Data Release 3: Structure and properties of the Magellanic Clouds

We compare the Gaia DR2 and Gaia EDR3 performances in the study of the Magellanic Clouds and show the clear improvements in precision and accuracy in the new release. We also show that the systematics still present in the data make the determination of the 3D geometry of the LMC a difficult endeavour; this is at the very limit of the usefulness of the Gaia EDR3 astrometry, but it may become feasible with the use of additional external data. We derive radial and tangential velocity maps and global profiles for the LMC for the several subsamples we defined. To our knowledge, this is the first time that the two planar components of the ordered and random motions are derived for multiple stellar evolutionary phases in a galactic disc outside the Milky Way, showing the differences between younger and older phases. We also analyse the spatial structure and motions in the central region, the bar, and the disc, providing new insights into features and kinematics. Finally, we show that the Gaia EDR3 data allows clearly resolving the Magellanic Bridge, and we trace the density and velocity flow of the stars from the SMC towards the LMC not only globally, but also separately for young and evolved populations. This allows us to confirm an evolved population in the Bridge that is slightly shift from the younger population. Additionally, we were able to study the outskirts of both Magellanic Clouds, in which we detected some well-known features and indications of new ones

The neurofilament derived-peptide NFL-TBS.40-63 enters in-vitro in human neural stem cells and increases their differentiation

International audienceRegenerative medicine is a promising approach to treat neurodegenerative diseases by replacing degenerating cells like neurons or oligodendrocytes. Targeting human neural stem cells directly in the brain is a big challenge in such a strategy. The neurofilament derived NFL-TBS.40-63 peptide has recently been introduced as a novel tool to target neural stem cells. Previous studies showed that this peptide can be internalized by rat neural stem cells in vitro and in vivo, which coincided with lower proliferation and self-renewal capacity and increase of differentiation. In this study, we analyzed the uptake and potential effects of the NFL-TBS.40-63 peptide on human neural stem cells isolated from human fetuses. We showed that the peptide inhibits proliferation and the ability to produce neurospheres in vitro, which is consistent with an increase in cell adhesion and differentiation. These results confirm that the peptide could be a promising molecule to target and manipulate human neural stem cells and thus could serve as a strategic tool for regenerative medicine.</p

Comparison of Four Commercial IgG-Enzyme-Linked Immunosorbent Assays for the Detection of Tick-Borne Encephalitis Virus Antibodies.

Tick-borne encephalitis (TBE) is the most important arboviral disease in many parts of Europe and Asia. Both the diagnosis of TBE as well as the conduction of surveillance studies are based on the demonstration of specific antibodies. For reasons of simplicity, automatization, and quick availability of test results, enzyme-linked immunosorbent assays (ELISAs) are the method of choice for anti-TBE virus antibody detection. In this study, we evaluated four commercial IgG-ELISAs using 876 epidemiological plasma samples: the Enzygnost Anti-TBE/FSME Virus IgG assay (Siemens; assay 1), the Anti-FSME/TBE Virus ELISA (IgG) assay (Euroimmun; assay 2), the Anti-FSME/TBE Virus ELISA "Vienna" (IgG) assay (Euroimmun; assay 3), and the RIDASCREEN FSME/TBE IgG EIA assay (R-Biopharm; assay 4). In total, discrepant results were observed for 37.2% of all samples. The evaluated assays significantly differed in qualitative data (p < 0.0001, Cochran-Mantel-Haenszel test) and showed Spearman's rank correlation coefficients ranging between 0.88 and 0.97 for quantitative data. The degree of disagreement between the different assays was exceptionally high for samples originating from blood donors with vaccination against TBE virus. For this sample group, the proportion of positive results was considerably higher for assay 3 (52.7%) and assay 4 (57%) than for assay 1 (7.5%) and assay 2 (6.4%), respectively, indicating that assays 1 and 2 are less suitable for the detection of vaccination antibodies than assays 3 and 4. Indirect immunofluorescence testing data available for a subset of samples (n = 238) mostly originating from nonflavivirus-vaccinated blood donors (n = 234) revealed problems in both sensitivity and specificity of the evaluated assays; whereas sensitivity issues were most prominent for the Euroimmun assay, specificity concerns were most pronounced for the Euroimmun Vienna and the RIDASCREEN assays

The NFL-TBS.40-63 peptide affects the proliferation of hNSCs.

<p><b>(A)</b> Percentage of hNSCs at G0/G1, S or G2/M of the cell cycle after treatment with colchicine (1µg/ml) or increasing concentrations of biotinylated-NFL-TBS.40-63 peptide. Data are presented as means ± SEM. <b>(B-C)</b> Thymidine analogue incorporation: The number of BrdU <b>(B)</b> or EdU positive cells <b>(C)</b> was counted after 72 hours incubation with 1 µg/ml of colchicine or with increasing concentrations of peptide, and compared to the control condition. Thymidine analogues were incubated for 5 hours before the end of the test. Data presented as means ± SEM. <b>(D-E)</b> Cell proliferation: Number of cells after 72 hours incubation with the NFL peptide was quantified using Trypan blue exclusion <b>(D)</b> or using the CyQUANT assay <b>(E)</b>. *P<0.05, **P<0.01, ***P<0.001, ****P<0,0001.</p