1A). diseases and inflammatory disorders make Gal-8 an attractive candidate for therapeutic purposes. Our results offer a solid basis A 77-01 for addressing the use of the newPl-GAL-8 in functional and applicative studies, respectively in the developmental A 77-01 and biomedical fields. Lectins are proteins that preferentially bind to carbohydrate complexes protruding from glycolipids and glycoproteins1. A 77-01 They were shown to bind both to oligosaccharides on cells and to free-floating glycans, at the micromolar to the millimolar range2. Due to their binding properties, lectins are involved in cell homeostasis, which is regulated by the controlled transcription of numerous genes. Thus, multiple signalling pathways and enzymatic cascades are influenced by lectins. Therefore , it is not surprising that certain lectins are expressed in a developmentally regulated fashion, both during early embryonic3and postnatal development4. A subgroup of lectins is represented by the galectins [previously referred to as S-type lectins, emphasizing the activity dependence of some of them on thiols (reducing conditions)]5. A 77-01 Galectins represent a large ancient family of structurally-related proteins identified in phylogenetically diverse species6. Although they have been initially acknowledged as developmentally regulated lectins mainly in vertebrates (amphibians, eel, fish, chick, bovine, rat, mouse and human), galectins have been also identified in sponges and in many protostome and deuterostome invertebrates7, (seeSupplementary Table S1online). Generally physiological functions of invertebrate lectins are not completely understood. Increasing information confirm their involvement in processes like differentiation and development, as well as the elimination of foreign substances through binding to their carbohydrate structures. The Table (S1) lists examples of invertebrates protostome and deuterostome galectins described in the literature, indicating also their location in different cell types and tissues, as well as their putative and proved functions. Galectins exhibit a carbohydrate binding specificity towards disaccharides containing -galactosides found in cellular glycoconjugates or glycoproteins8. The functional domain(s) of galectins involve one or two carbohydrate recognition domains (CRDs) within a single polypeptide chain. Based on their domain organization, galectin subfamilies are designated as proto-, chimera- and tandem repeat-types9. In the tandem repeat type, each one of the two CRDs may have a diverse specificity. Tandem repeat type galectins do not involve diverse functional domains or interaction specificity with non CRDs. This is in contrast to the chimera galectins and the C-type lectins, which often occur together with other A 77-01 domain types in the same peptidic chain10, 11, 12. Structurally, the galectins CRD is a beta-sheet sandwich of about 135 aa, formed by 11 strands; carbohydrates are bound within the groove formed in the concave side by 6 strands13. Galectins were initially discovered in tissue extracts and were analysed for their ability to agglutinate erythrocytes; based on the hypothesis that cell surface carbohydrates take part in cell adhesion14. They were shown to exhibit inhibitory functions in cell adhesion and to induce apoptosis by binding to integrins15. In fact , various functional roles of galectins have been evidenced in cancer16, in innate and adaptive immunity17and in development18, 19. Furthermore, galectins appear to be implicated in diverse activities inside and outside the cell, both in invertebrates and vertebrates, where galectins participate in cell adhesion/proliferation, development/morphogenesis, tumor cell metastasis and immune regulation/innate immunity20. Although several tandem repeat type members of the galectin superfamily have been described in adult and embryonic tissues of invertebrates11(seeSupplementary Table S1online), no characterization of FOXO3 galectin-8 has been reported for Echinoderms so far. The sea urchin has an extraordinary importance as a model for classical developmental and innovative systems biology studies, being in the lineage leading to the vertebrates and humans21. Its genome includes many previously thought to be vertebrate innovations (or known only outside the deuterostomes), providing an evolutionary outgroup for the chordates and yielding insights into the evolution of deuterostomes21. The access to the sea urchin genome of the speciesStrongylocentrotus purpuratus21and to ESTs sequences of the speciesParacentrotus lividus, gave us the opportunity to look for galectin superfamily members. In this study, we report the identification and characterization ofPl-GAL-8, a new member of the galectin-8 family isolated fromP. lividussea urchin embryo. We describe its: i) cDNA sequence, ii) phylogenetic position, iii) protein domain 3D structure, iv) temporal and spatial mRNA expression profile, v) expression as recombinant fusion protein, vi) carbohydrate-binding specificity and vii) anti-adhesive activity. == Results == == Identification, cloning and phylogenetic analysis == We isolated and cloned the completegalectin-8 cDNA fromP. lividussea urchin embryos (gastrula.