« Transmigrants » mais pas « nomades »

RÉSUMÉPour rendre compte de ce qui semble être une nouvelle manière de vivre les expériences de migration, certains auteurs ont forgé de nouveaux concepts comme celui de « transnationalisme ». Ce terme est employé pour décrire les processus à travers lesquels les migrants créent des champs sociaux qui traversent les frontières géographiques et politiques. Les migrants wolof mourides en Italie constituent une bonne illustration de migration transnationale. Après une introduction au débat sur l'approche transnationale aux migrations, dans la première partie, on analyse les activités qui permettent aux migrants mourides d'organiser leur mobilité et leur séjour temporaire grâce à des réseaux sociaux et à la transnationalisation du religieux. Toutefois, une tendance générale dans la littérature sur le transnationalisme postule la nécessité pour ce genre d'organisations migratoires de produire automatiquement des identifications multiples aux divers contextes et un style de vie « nomade ». Au contraire, comme on le montre dans la partie finale, les migrants mourides ne semblent pas trop changer leurs repères existentiels. Une grande partie d'entre eux préserve et renforce un sens d'appartenance au terroir, ils sont tournés vers l'idée de retour et investissent toutes leurs ressources, affectives et matérielles, au Sénégal.ABSTRACT"Transmigrants" but not "Nomads".   Mouride Transnationalism in Italy.To take into account what seems a new way to live the experiences of migration some scholars shaped new concepts such as that of "transnationalism".   This term is used to describe the processes through which migrants create social fields, which cut across geographical and political boundaries.   Wolof mouride migrants in Italy are a good example of such a transnational migration.   After an introduction to the debate over the transnational approach to migrations, in the first part I discuss the activities that allow mouride migrants to organize their mobility and their temporary settlement thanks to the transnationalisation of their social and religious networks.   Yet, there exists a general tendency within the transnationalism literature to assume that such a migratory organization necessarily implies multiple identifications to various contexts and a "nomadic" way of life.   On the contrary, as I show in the final section, mouride migrants do not seem to change their existential point of reference.   Many of the migrants preserve and contribute towards shaping a strong sense of identity.   They are oriented towards a return and invest materially and emotionally in Sénégal

(+/-)-Gelliusines A and B, two diastereomeric brominated tris-indole alkaloids from a deep water New Caledonian marine sponge (Gellius or Orina sp.)

Two new diastereomeric brominated tris-indole alkaloids occurring as enantiomeric pairs, (±)-gelliusine A (I) and its isomer (±)-gelliusine B, have been isolated from a deep water New Caledonian sponge (Gellius or Orina sp.), whose crude ext. exhibited cytotoxicity against KB cells. Their structures were elucidated by spectroscopic methods including one- and two-dimensional NMR spectroscopy. The major compd., I, which showed very weak cytotoxicity, proved to be active at the serotonin receptor

Synthesis, structural aspects and cytotoxicity of the natural cyclopeptides yunnanins A, C and phakellistatins 1, 10

Yunnanins A and C, two cyclic heptapeptides occurring in the roots of Stellaria yunnanensis, and phakellistatins 1 and 10, a hepta- and an octacyclopeptide first isolated from marine sponges of the genus Phakellia, were efficiently synthesized using a combination of solid and solution-phase techniques. Structural analysis on the synthetic members of the yunnanin series showed that the synthetic sample of yunnanin A exhibited a configurational pattern at the Pro peptide linkages identical to the natural product (trans-Pro3, trans-Pro5), while yunnanin C was obtained as a complex mixture of geometric/conformational isomers; the major isomer (trans-Pro3) was indistinguishable from the natural cyclopeptide and co-occurred along with lower amounts of a mixture (1:1 ratio) of two different rotamers, both displaying cis geometry at the Pro3 linkage. In the phakellistatin series, the synthetic phakellistatin 1 (determined as cis-Pro1, cis-Pro3, cis-Pro5) was identical to the natural one, while two different isomeric products of phakellistatin 10 could be obtained: a major one (trans-Pro1, trans-Pro4, trans-Pro6) showing spectral properties superimposable with the natural metabolite, and a minor geometric isomer of the natural cyclopeptide. Interestingly, the synthetic cyclopeptides, although found to be chemically identical with their natural counterparts, did not display the same biological properties (in vitro cytotoxicity against a panel of cancer cell lines), leaving presently open the question whether or not the potent bioactivity reported in the literature should really be attributed to these natural cyclic peptides. q 2003 Elsevier Ltd. All rights reserved

Discovery of new molecular entities able to strongly interfere with Hsp90 C-terminal domain

Heat shock protein 90 (Hsp90) is an ATP dependent molecular chaperone deeply involved in the complex network of cellular signaling governing some key functions, such as cell proliferation and survival, invasion and angiogenesis. Over the past years the N-terminal protein domain has been fully investigated as attractive strategy against cancer, but despite the many efforts lavished in the field, none of the N-terminal binders (termed “classical inhibitors”), currently in clinical trials, have yet successfully reached the market, because of the detrimental heat shock response (HSR) that showed to induce; thus, recently, the selective inhibition of Hsp90 C-terminal domain has powerfully emerged as a more promising alternative strategy for anti-cancer therapy, not eliciting this cell rescue cascade. However, the structural complexity of the target protein and, mostly, the lack of a co-crystal structure of C-terminal domain-ligand, essential to drive the identification of new hits, represent the largest hurdles in the development of new selective C-terminal inhibitors. Continuing our investigations on the identification of new anticancer drug candidates, by using an orthogonal screening approach, here we describe two new potent C-terminal inhibitors able to induce cancer cell death and a considerable downregulation of Hsp90 client oncoproteins, without triggering the undesired heat shock response