Project description:Our genomic, bulk and single-cell transcriptomic, functional, and developmental characterization of the Terrazzo corn snake color morph and the extensive comparison with wild-type snakes puts forward the dual role of PMEL in snake skin coloration, both in the differentiation of chromatophores during embryogenesis and the melanogenesis in melanophores.
Project description:Our genomic, bulk and single-cell transcriptomic, functional, and developmental characterization of the Terrazzo corn snake color morph and the extensive comparison with wild-type snakes puts forward the dual role of PMEL in snake skin coloration, both in the differentiation of chromatophores during embryogenesis and the melanogenesis in melanophores.
Project description:While the vertebrate body plan is highly conserved amongst all species of this taxon, extreme variations thereof can be documented in snakes, which display both an absence of limbs and an unusually elongated trunk. As Hox genes are strong candidates both for the making and the evolution of this body plan, their comparative study in such a morphologically diverged group is informative regarding their potential causative importance in these processes. In this work we use an interspecies comparative approach where different aspects of regulation at the HoxD locus are investigated. We find that although spatial collinearity and associated epigenetic mark dynamics are conserved in the corn snake, other regulatory modalities have been largely restructured. A BAC transgenic approach indeed revealed that, while the majority of mesodermal enhancers in vertebrates appear to be mostly located outside of the cluster, the corn snake contains most mesodermal trunk enhancers within the HoxD cluster. We also find that, despite the absence of limbs and an altered Hoxd gene regulation in external genitalia, the bimodal chromatin structure at the corn snake HoxD locus is maintained. The analysis of particular enhancer sequences initially defined in the mouse and further isolated at the snake orthologous locus showed differences in their specificities for the limb and genital bud expression. Of particular interest, a snake counterpart of a mouse limb-only enhancer sequence evolved into a genital-only enhancer. Such a regulatory exaptation suggests that enhancer versatility may have been an important factor to accompany the transition towards the snake body plan. These results show that vertebrate morphological evolution is likely to have been associated with extensive reorganization at the HoxD regulatory landscapes while respecting a very conserved general regulatory framework.
Project description:We report the characterization of the major regulator of virulence gene expression (CovR) in Group B Streptococcus. The ChIP-seq experiments define the binding of CovR on the chromosome of the BM110 strain, a representative of the hypervirulent GBS lineage responsible of neonatal meningitis. Regulatory evolution of CovR signaling was investigated by comparing ChIP-seq done in parallel in a second GBS clinical isolate (NEM316) not belonging to the hypervirulent lineage.
Project description:The aim of this study was to investigate the response of human brain endothelial cells to bacterial (group B streptococcus, GBS) infection. Results: GBS WT strain infection results in a specific gene induction pattern that is different from the pilA mutant, but not other mutants such as pilB and srr-1. Conclusion: These findings suggest that the GBS PilA protein contributes to gene induction in brain endothelium.
Project description:While the vertebrate body plan is highly conserved amongst all species of this taxon, extreme variations thereof can be documented in snakes, which display both an absence of limbs and an unusually elongated trunk. As Hox genes are strong candidates both for the making and the evolution of this body plan, their comparative study in such a morphologically diverged group is informative regarding their potential causative importance in these processes. In this work we use an interspecies comparative approach where different aspects of regulation at the HoxD locus are investigated. We find that although spatial collinearity and associated epigenetic mark dynamics are conserved in the corn snake, other regulatory modalities have been largely restructured. A BAC transgenic approach indeed revealed that, while the majority of mesodermal enhancers in vertebrates appear to be mostly located outside of the cluster, the corn snake contains most mesodermal trunk enhancers within the HoxD cluster. We also find that, despite the absence of limbs and an altered Hoxd gene regulation in external genitalia, the bimodal chromatin structure at the corn snake HoxD locus is maintained. The analysis of particular enhancer sequences initially defined in the mouse and further isolated at the snake orthologous locus showed differences in their specificities for the limb and genital bud expression. Of particular interest, a snake counterpart of a mouse limb-only enhancer sequence evolved into a genital-only enhancer. Such a regulatory exaptation suggests that enhancer versatility may have been an important factor to accompany the transition towards the snake body plan. These results show that vertebrate morphological evolution is likely to have been associated with extensive reorganization at the HoxD regulatory landscapes while respecting a very conserved general regulatory framework.