Étude de la réponse immunitaire chez la sangsue theromyzon tessulatum (approches différentielles)

Les modèles invertébrés ont apporté un renouveau dans l'étude de l'immunité innée. Les études présentées dans ce travail de thèse se sont intégrées à cette volonté de découvrir de nouveaux acteurs de l'immunité innée chez les invertébrés. Elles se sont appuyées sur des approches différentielles chez notre modèle, la sangsue Theromyzon tessulatum. D'abord, l'analyse biochimique par chromatographie liquide aura permis la mise en évidence de modulations peptidiques dans le liquide cœlomique après une infection par de LPS. Un peptide portant une activité anti-bactérienne a été détecté. Il fait l'objet de travaux plus approfondis concernant son activité et sa régulation après une infection expérimentale. Puis, l'analyse s'est orientée vers les modulations d'expression génique induites après une infection bactérienne au sein de l'organisme complet. Cette étude a été validée par l'élaboration de biopuces à ADN confectionnées à façon avec les candidats différentiels. Les gènes dont l'expression est modulée par l'infection expérimentale débouchent tous sur autant de perspectives afin de déterminer leur rôle dans l'immunité chez la sangsue. Le gène de la cystatine B est surexprimé après une infection bactérienne dans un seul type de cœlomocyte circulant dans le liquide cœlomique. La cathepsine L est retrouvée spécifiquement dans les mêmes cellules. Mais son gène n'est pas modulée par l'infection. Cette concentration dans un seul type de cellule circulante apporte de précieuses informations sur l'identité probable des cellules immunitaires de T. tessulatum. Les résultats suggèrent l'importance de la balance Cystatines-Cathepsines dans l'immunité innée.LILLE1-BU (590092102) / SudocSudocFranceF

Transcriptomic underpinning of toxicant-mediated physiological function alterations in three terrestrial invertebrate taxa: A review.

Diverse anthropogenic activities often lead to the accumulation of inorganic and organic residues in topsoils. Biota living in close contact with contaminated soils may experience stress at different levels of biological organisation throughout the continuum from the molecular-genetic to ecological and community levels. To date, the relationship between changes at the molecular (mRNA expression) and biochemical/physiological levels evoked by exposures to chemical compounds has been partially established in a limited number of terrestrial invertebrate species. Recently, the advent of a family of transcriptomic tools (e.g. Real-time PCR, Subtractive Suppressive Hybridization, Expressed Sequence Tag sequencing, pyro-sequencing technologies, Microarray chips), together with supporting informatic and statistical procedures, have permitted the robust analyses of global gene expression changes within an ecotoxicological context. This review focuses on how transcriptomics is enlightening our understanding of the molecular-genetic responses of three contrasting terrestrial macroinvertebrate taxa (nematodes, earthworms, and springtails) to inorganics, organics, and agrochemicals

Transcriptomic analysis in the leech Theromyzon tessulatum: involvement of cystatin B in innate immunity.

At the present time, there is little information on mechanisms of innate immunity in invertebrate groups other than insects, especially annelids. In the present study, we have performed a transcriptomic study of the immune response in the leech Theromyzon tessulatum after bacterial challenge, by a combination of differential display RT (reverse transcriptase)-PCR and cDNA microarrays. The results show relevant modulations concerning several known and unknown genes. Indeed, threonine deaminase, malate dehydrogenase, cystatin B, polyadenylate-binding protein and alpha-tubulin-like genes are up-regulated after immunostimulation. We focused on cystatin B (stefin B), which is an inhibitor of cysteine proteinases involved in the vertebrate immune response. We have cloned the full-length cDNA and named the T. tessulatum gene as Tt-cysb. Main structural features of cystatins were identified in the derived amino acid sequence of Tt-cysb cDNA; namely, a glycine residue in the N-terminus and a consensus sequence of Gln-Xaa-Val-Xaa-Gly (QXVXG) corresponding to the catalytic site. Moreover, Tt-cysb is the first cystatin B gene characterized in invertebrates. We have determined by in situ hybridization and immunocytochemistry that Tt-cysb is only expressed in large coelomic cells. In addition, this analysis confirmed that Tt-cysb is up-regulated after bacterial challenge, and that increased expression occurs only in coelomic cells. These data demonstrate that the innate immune response in the leech involves a cysteine proteinase inhibitor that is not found in ecdysozoan models, such as Drosophila melanogaster or Caenorhabditis elegans, and so underlines the great need for information about innate immunity mechanisms in different invertebrate groups

Distribution of oxytocin-like and vasopressin-like immunoreactivities within the central nervous system of the cuttlefish, Sepia officinalis

International audienceWe have investigated the distribution of oxytocin/vasopressin (OT/VP) superfamily peptides in the central nervous system (CNS) of the cuttlefish, Sepia officinalis, by using antibodies raised against mammalian OT and VP. Several populations of OT-like and VP-like immunoreactive cell bodies and fibers were widely distributed in cerebral structures involved in learning processes (vertical lobe complex, optic lobes), behavioral communication (peduncle, lateral basal and chromatophore lobes), feeding behavior (inferior frontal, brachial and buccal lobes), sexual activity (dorsal basal, subpedunculate, olfactory lobes), and metabolism (visceral lobes). The two most remarkable findings of this study were the occurrence of OT-like immunoreactivity in many amacrine cells of the vertical lobe and the dense accumulation of VP-like immunoreactive cell bodies in the subpedunculate 1 lobe. No double-immunolabeled cell bodies or fibers were found in any lobes of the CNS, indicating, for the first time in a decapod cephalopod mollusc, the existence of distinct oxytocinergic-like and vasopressinergic-like systems. The widespread distribution of the immunoreactive neurons suggests that these OT-like and VP-like peptides act as neurotransmitters or neuromodulators

Villages

Parallèlement aux définitions historiques et géographiques, l’archéologie pose pour toutes les périodes la question des modalités selon lesquelles les sociétés choisissent ou non de regrouper leurs habitats. Qu’est-ce qu’un village ? Comment se forme-t-il, évolue-t-il, disparaît-il ? Quels sont ses éléments constitutifs et comment se recoupent-ils (vocation, échange, structuration de l’espace, type de bâtiment…) ? De quel tout le village est-il une composante ? Along with historical and geographic definitions, archaeology poses for all periods the question of how do societies choose to group or not their habitats. What is a village? How does it shape itself, evolve or disappear? What are its constitutive elements and how do they overlap (vocation, exchange, structuration of space, type of buildings ...)? Of what whole is the village a component? Además de las definiciones históricas y geográficas, la arqueología plantea la cuestión de las formas en que las sociedades deciden agrupar sus asentamientos. ¿Qué es un pueblo? ¿Cómo se forma, evoluciona y desaparece? ¿Cuáles son sus elementos constitutivos y cómo se entrecruzan (vocación, intercambio, estructuración del espacio, tipo de edificio, etc.)? ¿De qué conjunto es el pueblo un componente