Avian neural crest cell attachment to laminin: involvement of divalent cation dependent and independent integrins

The mechanisms of neural crest cell interaction with laminin were explored using a quantitative cell attachment assay. With increasing substratum concentrations, an increasing percentage of neural crest cells adhere to laminin. Cell adhesion at all substratum concentrations was inhibited by the CSAT antibody, which recognizes the chick β_1 subunit of integrin, suggesting that β_(1-)integrins mediate neural crest cell interactions with laminin. The HNK-1 antibody, which recognizes a carbohydrate epitope, inhibited neural crest cell attachment to laminin at low coating concentrations (>1 µg ml^(-1); Low-LM), but not at high coating concentration of laminin (10 µg ml^(-1); High-LM). Attachment to Low-LM occurred in the absence of divalent cations, whereas attachment to High-LM required >0.1 mM Ca^(2+) or Mn^(2+). Neural crest cell adherence to the E8 fragment of laminin, derived from its long arm, was similar to that on intact laminin at high and low coating concentrations, suggesting that this fragment contains the neural crest cell binding site(s). The HNK-1 antibody recognizes a protein of 165,000 Mr which is also found in immunoprecipitates using antibodies against the β_1 subunit of integrin and is likely to be an integrin alpha subunit or an integrin-associated protein. Our results suggest that the HNK-1 epitope on neural crest cells is present on or associated with a novel or differentially glycosylated form of β_(1-)integrin, which recognizes laminin in the apparent absence of divalent cations. We conclude that neural crest cells have at least two functionally independent means of attachment to laminin which are revealed at different substratum concentrations and/or conformations of laminin

Common heritage of mankind: when science challenges legal concepts

By demonstrating the role of marine organisms in the formation and composition of deep-sea mineral resources, the aim of this poster is to demonstrate that legal definitions can sometimes be relatively simplistic and limited. Considering that on the deep seafloor, the meaning of legal terms can determine the applicable legal regime, this study represents an important aspect of academic legal research. The overall goal is to introduce the interpretation methodology that will be used in the author’s PhD research project on the legal framework of deep-sea mining

Learning to Read Bilingually Modulates the Manifestations of Dyslexia in Adults

Published online: 28 Mar 2018According to the Grain Size Accommodation hypothesis (Lallier & Carreiras, 2017), learning to read in two languages differing in orthographic consistency leads to a cross-linguistic modulation of reading and spelling processes. Here, we test the prediction that bilingualism may influence the manifestations of dyslexia. We compared the deficits of English monolingual and early Welsh–English bilingual dyslexic adults on reading and spelling irregular English words and English-like pseudowords. As predicted, monolinguals were relatively more impaired in reading pseudowords than irregular words, whereas the opposite was true for bilinguals. Moreover, monolinguals showed stronger sublexical processing deficits than bilinguals and were poorer spellers overall. This study shows that early bilingual reading experience has long-lasting effects on the manifestations of dyslexia in adulthood. It demonstrates that learning to read in a consistent language like Welsh in addition to English gives bilingual dyslexic adults an advantage in English literacy tasks strongly relying on phonological processing.This research was funded by the Fyssen Foundation, the European Commission (FP7-PEOPLE-2010-IEF, Proposal N°274352, BIRD, to M.L) the European Research Council (ERC advanced grant, BILITERACY, to M.C., and ERC- 209704 to G.T.), the Spanish government (PSI2015-65338-P to M.L, and PSI2015-67353-R to M.C.), and the Economic and Social Research Council UK (RES-E024556-1 to G.T.). BCBL acknowledges funding from Ayuda Centro de Excelencia Severo Ochoa SEV-2015-0490

Cross-linguistic transfer in bilinguals reading in two alphabetic orthographies: The grain size accommodation hypothesis

Published online: 12 April 2017Reading acquisition is one of the most complex and demanding learning processes faced by children in their first years of schooling. If reading acquisition is challenging in one language, how is it when reading is acquired simultaneously in two languages? What is the impact of bilingualism on the development of literacy? We review behavioral and neuroimaging evidence from alphabetic writing systems suggesting that early bilingualism modulates reading development. Particularly, we show that cross-linguistic variations and cross-linguistic transfer affect bilingual reading strategies as well as their cognitive underpinnings. We stress the fact that the impact of bilingualism on literacy acquisition depends on the specific combination of languages learned and does not manifest itself similarly across bilingual populations. We argue that these differences can be explained by variations due to orthographic depth in the grain sizes used to perform reading and reading-related tasks. Overall, we propose novel hypotheses to shed light on the behavioral and neural variability observed in reading skills among bilinguals.This work was supported by the European commission (BILITERACY- SH4, ERC-2011-ADG) and the Ministry of Economy and Competitiveness, Madrid, Spain (Grant Nos. PSI20153653383P to M.L., PSI20153673533R to M.C., and SEV3201530490 to the Basque Center on Brain and Language Cognition)

Adaptations respiratoires des invertébrés inféodés aux sources hydrothermales profondes

En 1993, j'obtenais un poste de Maître de Conférences à Roscoff et, début 1994, suite à la nomination d'André Toulmond au poste de Directeur de l'Observatoire Océanologique de Roscoff, celui-ci me confiait la responsabilité de l'équipe de recherche d'Ecophysiologie. Issue du rapprochement d’un groupe de phycologie benthique et d’un groupe de physiologie comparée, cette équipe est structurée autour d'une thématique commune, l’étude des mécanismes d’échange de métabolites et de leurs adaptations. Ainsi, nos études portent sur des organismes vivant dans des milieux marins particulièrement contraignants, la zone intertidale en régime mégatidal et les sources hydrothermales profondes, et nous nous intéressons à des fonctions diverses, respiration et excrétion chez les animaux, respiration et photosynthèse chez les végétaux. Mais, au-delà de cette diversité de modèles et de milieux d'étude, nous partageons surtout une approche comparative et intégrée. Comparative, car les problèmes biologiques que nous cherchons à comprendre sont étudiés en utilisant la variété des réponses offertes par les différentes espèces modèles que nous sélectionnons. Et intégrée car dans l'étude d'un problème donné nous nous efforçons d'aborder différentes échelles d’organisation biologique. Le pivot central, à la fois point de départ et objectif ultime, c'est la compréhension du fonctionnement de l'organisme dans son milieu, véritable définition de l'écophysiologie. Mais pour arriver à cette compréhension nous nous efforçons de décortiquer les mécanismes sous-jacents, jusqu'à l'échelle moléculaire si cela s'avère possible et nécessaire, en essayant de dégager des processus généraux à partir des relations structure-fontion particulières que nous sommes amenés à décrire. Enfin, plus récemment, nous nous sommes intéressés à la dimension évolutive de ces problèmes en travaillant à l'échelle de la population ou de l'espèce, analysant notamment nos résultats en termes de phylogénie. La double signification du terme adaptation prend alors tout son sens, à la fois processus physiologique permettant à un organisme de moduler les propriétés de tel ou tel système de façon à s'accommoder des variations du milieu dans lequel il vit, mais également le résultat d'un processus évolutif associant mutations et sélection naturelle et ayant abouti à l'espèce considérée. Dans l'un ou l'autre cas, je suis persuadé que l'approche comparative peut se révéler extrêmement fructueuse, surtout lorsque l’on s’intéresse à des milieux « extrêmes » dans lesquels les adaptations, qu’elles soit physiologiques ou évolutives, sont exacerbées. Cette démarche se rapproche de celle, courante dans le domaine de la recherche médicale, qui consiste à étudier des cas pathologiques (donc « anormaux ») pour en inférer des règles physiologiques « normales ».Naturellement, une telle approche, aussi transversale, réclame un éventail de techniques très large qui dépasse largement les capacités d'un seul individu. La constitution d'une équipe de recherche polyvalente prend alors tout son sens et, à la suite d'André Toulmond, je m'efforce de maintenir et de développer ce potentiel au sein de l'équipe d'Ecophysiologie. Celle-ci réunit ainsi des collaborateurs aux compétences diverses ce qui nous permet de maitriser un certain nombre des techniques nécessaires à la réalisation des projets abordés : anatomie et histologie (techniques de microscopie), biochimie fonctionnelle et structurale (enzymologie, spectroscopie), biologie moléculaire (séquençage, phylogénie), etc. Mais il n'en demeure pas moins essentiel de nous appuyer sur des collaborations scientifiques nationales et internationales. D'une part avec des équipes ayant une vision plus large, plus écologique, des milieux que nous étudions tout en nous offrant un accès privilégié aux campagnes océanographiques . D’autre part, avec des équipes ayant une approche plus pointue, plus biophysique, et maîtrisant parfaitement l'une ou l'autre des techniques qui nous sont nécessaires .Dans le texte qui suit, j'essaierai d'illustrer les deux approches évoquées ci-dessus, en me limitant à deux grands projets dans lesquels je suis plus particulièrement impliqué : •l'approche intégrée pour comprendre les mécanismes de transport du dioxyde de carbone et de l'hydrogène sulfuré chez le vestimentifère Riftia pachyptila;•l'approche comparative de l'équilibre acide-base et du transport de l'oxygène chez les crustacés hydrothermaux. A la suite de chacune des présentations rédigées en français, on trouvera une copie des articles originaux correspondants. Mes autres travaux concernent l'étude du transport de l'oxygène chez deux annélides polychètes inféodées au milieu hydrothermal: Alvinella pompejana, le ver de Pompéï qui colonise les cheminées, et Branchipolynoe, polynoidé commensal des modioles. Ces travaux ont fait l'objet de la thèse de Stéphane Hourdez et des articles qui en sont issus. Enfin, je concluerai en essayant de répondre à une question qui m’est souvent posée : pourquoi diable aller chercher des modèles biologiques aussi loin que sur les sources hydrothermales profondes

Mare Geneticum : Balancing Governance of Marine Genetic Resources in International Waters

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Spatial and temporal changes in the distribution of proteoglycans during avian neural crest development

In this study, we describe the distribution of various classes of proteoglycans and their potential matrix ligand, hyaluronan, during neural crest development in the trunk region of the chicken embryo. Different types of chondroitin and keratan sulfate proteoglycans were recognized using a panel of monoclonal antibodies produced against specific epitopes on their glycosaminoglycan chains. A heparan sulfate proteoglycan was identified by an antibody against its core protein. The distribution of hyaluronan was mapped using a biotinylated fragment that corresponds to the hyaluronan-binding region of cartilage proteoglycans. Four major patterns of proteoglycan immunoreactivity were observed. (1) Chondroitin-6-sulfate-rich proteoglycans and certain keratin sulfate proteoglycans were absent from regions containing migrating neural crest cells, but were present in interstitial matrices and basement membranes along prospective migratory pathways such as the ventral portion of the sclerotome. Although initially distributed uniformly along the rostrocaudal extent of the sclerotome, these proteoglycans became rearranged to the caudal portion of the sclerotome with progressive migration of neural crest cells through the rostral sclerotome and their aggregation into peripheral ganglia. (2) A subset of chondroitin/keratan sulfate proteoglycans bearing primarily unsulfated chondroitin chains was observed exclusively in regions where neural crest cells were absent or delayed from entering, such as the perinotochordal and subepidermal spaces. (3) A subset of chondroitin/keratan sulfate proteoglycans was restricted to the perinotochordal region and, following gangliogenesis, was arranged in a metameric pattern corresponding to the sites where presumptive vertebral arches form. (4) Certain keratan sulfate proteoglycans and a heparan sulfate proteoglycan were observed in basement membranes and in an interstitial matrix uniformly distributed along the rostrocaudal extent of the sclerotome. After gangliogenesis, the neural crest-derived dorsal root and sympathetic ganglia contained both these proteoglycan types, but were essentially free of other chondroitin/keratan-proteoglycan subsets. Hyaluronan generally colocalized with the first set of proteoglycans, but also was concentrated around migrating neural crest cells and was reduced in neural crest-derived ganglia. These observations demonstrate that proteoglycans have diverse and dynamic distributions during times of neural crest development and chondrogenesis of the presumptive vertebrae. In general, chondroitin/keratan sulfate proteoglycans are abundant in regions where neural crest cells are absent, and their segmental distribution inversely correlates with that of neural crest-derived ganglia

Cranial and trunk neural crest cells use different mechanisms for attachment to extracellular matrices

We have used a quantitative cell attachment assay to compare the interactions of cranial and trunk neural crest cells with the extracellular matrix (ECM) molecules fibronectin, laminin and collagen types I and IV. Antibodies to the β_1 subunit of integrin inhibited attachment under all conditions tested, suggesting that integrins mediate neural crest cell interactions with these ECM molecules. The HNK-1 antibody against a surface carbohydrate epitope under certain conditions inhibited both cranial and trunk neural crest cell attachment to laminin, but not to fibronectin. An antiserum to α_1 intergrin inhibited attachment of trunk, but not cranial, neural crest cells to laminin and collagen type I, though interactions with fibronectin or collagen type IV were unaffected. The surface properties of trunk and cranial neural crest cells differed in several ways. First, trunk neural crest cells attached to collagen types I and IV, but cranial neural crest cells did not. Second, their divalent cation requirements for attachment to ECM molecules differed. For fibronectin substrata, trunk neural crest cells required divalent cations for attachment, whereas cranial neural crest cells bound in the absence of divalent cations. However, cranial neural crest cells lost this cation-independent attachment after a few days of culture. For laminin substrata, trunk cells used two integrins, one divalent cation-dependent and the other divalent cation-independent (Lallier, T. E. and Bronner-Fraser, M. (1991) Development 113, 1069–1081). In contrast, cranial neural crest cells attached to laminin using a single, divalent cation-dependent receptor system. Immunoprecipitations and immunoblots of surface labelled neural crest cells with HNK-1, α_1 integrin and β_1 integrin antibodies suggest that cranial and trunk neural crest cells possess biochemically distinct integrins. Our results demonstrate that cranial and trunk cells differ in their mechanisms of adhesion to selected ECM components, suggesting that they are non-overlapping populations of cells with regard to their adhesive properties

Access to and use of marine genetic resources : understanding the legal framework

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Acknowledgements This work was supported by the PharmaSea project funded by the EU Seventh Framework Programme, and reects only the authors' views. Contract number 312184. www.pharma-sea.eu.Peer reviewedPublisher PD