Flint in its diverse natural occurrences: geo-­‐tools for a better definition of the sourcing of secondary outcrops

International audiencePrecise identification of siliceous geo-resources used during prehistory still poses many problems, and archaeologists make ever-increasing demands for this data. The purpose is to provide a database containing an exact and descriptive identity for each different type of geological flint found within a region. The parameters we have chosen to characterize are the mineralogical composition (by optical microscopy, SEM, microprobe, cathodo-luminescence), microfacies characteristics (identified during microscopy and SEM image analysis), porosity measurements (by image analysis and porosimeter), and the presence and distribution of major and trace elements (using ICP, LA-ICP-MS, XRF, PIXE, Raman and SEM-EDS) at the surface or in the cracks in the matrix

Virulence of Shigatoxigenic and Enteropathogenic Escherichia coli O80:H2 in Galleria mellonella Larvae: Comparison of the Roles of the pS88 Plasmids and STX2d Phage

peer reviewedThe invasiveness properties of Shigatoxigenic and enteropathogenic Escherichia coli (STEC and EPEC) O80:H2 in humans and calves are encoded by genes located on a pS88-like ColV conjugative plasmid. The main objectives of this study in larvae of the Galleria mellonella moth were therefore to compare the virulence of eight bovine STEC and EPEC O80:H2, of two E. coli pS88 plasmid transconjugant and STX2d phage transductant K12 DH10B, of four E. coli O80:non-H2, and of the laboratory E. coli K12 DH10B strains. Thirty larvae per strain were inoculated in the last proleg with 10 μL of tenfold dilutions of each bacterial culture corresponding to 10 to 106 colony-forming units (CFUs). The larvae were kept at 37 °C and their mortality rate was followed daily for four days. The main results were that: (i) not only the STEC and EPEC O80:H2, but also different E. coli O80:non-H2 were lethal for the larvae at high concentrations (from 104 to 106 CFU) with some variation according to the strain; (ii) the Stx2d toxin and partially the pS88 plasmid were responsible for the lethality caused by the E. coli O80:H2; (iii) the virulence factors of E. coli O80:non-H2 were not identified. The general conclusions are that, although the Galleria mellonella larvae represent a useful first-line model to study the virulence of bacterial pathogens, they are more limited in identifying their actual virulence properties

In Vitro and In Vivo Assessments of Two Newly Isolated Bacteriophages against an ST13 Urinary Tract Infection Klebsiella pneumoniae.

peer reviewedAntibiotic resistance represents a major public health concern requiring new alternatives including phage therapy. Klebsiella pneumoniae belongs to the ESKAPE bacteria and can cause urinary tract infections (UTIs). The aims of this study were to isolate and characterize new bacteriophages against a K. pneumoniae strain isolated from UTIs and to assess their efficacy in vitro and in vivo in a Galleria (G.) mellonella larvae model. For this purpose, two bacteriophages were newly isolated against an ST13 K. pneumoniae strain isolated from a UTI and identified as K3 capsular types by wzi gene PCR. Genomic analysis showed that these bacteriophages, named vB_KpnP_K3-ULINTkp1 and vB_KpnP_K3-ULINTkp2, belong to the Drulisvirus genus. Bacteriophage vB_KpnP_K3-ULINTkp1 had the narrowest host spectrum (targeting only K3), while vB_KpnP_K3-ULINTkp2 also infected other Klebsiella types. Short adsorption times and latent periods were observed for both bacteriophages. In vivo experiments showed their ability to replicate in G. mellonella larvae and to decrease host bacterial titers. Moreover, both bacteriophages improved the survival of the infected larvae. In conclusion, these two bacteriophages had different in vitro properties and showed in vivo efficacy in a G. mellonella model with a better efficiency for vB_KpnP_K3-ULINTkp2

Impact Assessment of vB_KpnP_K1-ULIP33 Bacteriophage on the Human Gut Microbiota Using a Dynamic In Vitro Model

peer reviewedNew control methods are needed to counter antimicrobial resistances and the use of bacteriophages as an alternative treatment seems promising. To that end, the effect of the phage vB_KpnP_K1-ULIP33, whose host is the hypervirulent Klebsiella pneumoniae SA12 (ST23 and capsular type K1), was assessed on intestinal microbiota, using an in vitro model: the SHIME® system (Simulator of the Human Intestinal Microbial Ecosystem). After stabilization of the system, the phage was inoculated for 7 days and its persistence in the different colons was studied until its disappearance from the system. The concentration of short chain fatty acids in the colons showed good colonization of the bioreactors by the microbiota and no significant effect related to the phage treatment. Diversity (α and β), the relative abundance of bacteria, and qPCR analysis targeting different genera of interest showed no significant variation following phage administration. Even if further in vitro studies are needed to assess the efficacy of this phage against its bacterial host within the human intestinal ecosystem, the phage ULIP33 exerted no significant change on the global colonic microbiota

Antibody Evasion by a Gammaherpesvirus O-Glycan Shield

All gammaherpesviruses encode a major glycoprotein homologous to the Epstein-Barr virus gp350. These glycoproteins are often involved in cell binding, and some provide neutralization targets. However, the capacity of gammaherpesviruses for long-term transmission from immune hosts implies that in vivo neutralization is incomplete. In this study, we used Bovine Herpesvirus 4 (BoHV-4) to determine how its gp350 homolog - gp180 - contributes to virus replication and neutralization. A lack of gp180 had no impact on the establishment and maintenance of BoHV-4 latency, but markedly sensitized virions to neutralization by immune sera. Antibody had greater access to gB, gH and gL on gp180-deficient virions, including neutralization epitopes. Gp180 appears to be highly O-glycosylated, and removing O-linked glycans from virions also sensitized them to neutralization. It therefore appeared that gp180 provides part of a glycan shield for otherwise vulnerable viral epitopes. Interestingly, this O-glycan shield could be exploited for neutralization by lectins and carbohydrate-specific antibody. The conservation of O-glycosylation sites in all gp350 homologs suggests that this is a general evasion mechanism that may also provide a therapeutic target

Influence of selenium speciation on its bioavailability from food and food supplements

Like the moon after which it has been named – Selene in Greek –, selenium is an element that has a brigh and a dark side. This oligo-element is essential at a low to moderate level of intake, but becomes toxic at high doses. In Belgium, the recommended values for Se intake have been estimated to be 60 and 70 µg per day for adult women and men respectively. This level of intake is supposed to ensure the maximal activity of the antioxidant selenoenzymes glutathione peroxidases. The Se status of people differs considerably according to the regions of the world because of the heterogeneous repartition of Se in soils, resulting in variable Se contents in food. In Europe, Se content of soils is naturally low and Belgian people could therefore be at risk of Se deficiency. In addition to the dose, another important determinant of the Se impact on the organism is its speciation, i.e. the chemical form of Se. Different species have been shown to have distinct degrees of bioaccessibility, bioavailability, bioactivity and toxicity. This work aimed to improve the current knowledge about how the nature of Se species influences the degree of Se bioavailability, in the context of the Se status and food habits of the Belgian population. This research required the development of an analytical method of Se speciation analysis. This method consisted in an enzymatic ultrasonic-assisted extraction of Se, followed by a chromatographic separation of Se species by HPLC in an ion-pairing reversed-phase partitioning mode, and the final detection of 78Se by ICP-MS in the presence of H2 as a reaction gas. This work first permitted us to calculate that the average Se intake by the general adult Belgian population is 60 µg Se day-1, which is at the lower end of the range of recommended intake. Secondly, we measured decreasing degrees of bioavailability for SeMet > MeSeCys > selenate > selenite, and we showed that these degrees of bioavailability were the consequence of distinct modes of intestinal transport among Se species. Finally, we observed that the bioavailability of Se from different Se-enriched food supplements was generally low, especially for selenite-based ones. This work allowed us to formulate an opinion about the suitability of distinct forms of Se in the context of a Se enrichment of the diet, and opened the door to further research in relation to the species-dependence of Se health effects.(BIOL 3) -- UCL, 201

Melanoma AntiGEn D2 : a new nucleolar protein undergoing delocalization during cell cycle and after cellular stress

MAGED2 belongs to the Melanoma AntiGEn (MAGE) family of proteins. Actually, little is known on MAGED2 function. It contributes to the initiation of melanoma when its overexpression is associated with the mutation of BRAF and it increases apoptosis induced by TRAIL in a p53-dependent manner. MAGED2 was also shown to be a negative regulator of p53, bur we did not confirm this properties. Moreover, proteomic analyses detected numerous phosphorylated or acetylated residues in response to stess and within cell cycle suggesting its involvement in cellular signal transduction. We investigated the intra-cellular re-localization of MAGED2 during cell cycle and after genotixc stress. Both nucleolar and nuclear signals were identifed

Melanoma AntiGEn D2 (MAGED2): a new nucleolar protein undergoing re-localization after cellular stress

MAGED2 belongs to the Melanoma AntiGEn (MAGE) family of proteins. Actually, the only known function of this protein is its involvement in the p53 pathway. Indeed, MAGED2 could be a negative regulator of p53. It contributes to the initiation of melanoma when its overexpression is associated with the mutation of BRAF and it increases apoptosis induced by TRAIL in a p53 dependent manner. Moreover, phosphoproteomic experiments have shown that this protein is likely phosphorylated by kinases implicated in the DNA damage response (DDR). We decided to investigate the intra-cellular localization of MAGED2 in order to find new functions of this protein. In resting cell, MAGE D2 is detected is the nucleus, the nucleolus and the cytoplasm. We observed that MAGED2 localization change during cell cycle and genotoxic stress. Nuclear and nucleolar localization signals were identified. Though present in the nucleolus, the depletion of MAGED2 does not affect the structure of this organel