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This volume engages the reader's interest in the relationship that binds man to nature, a relationship which makes itself manifest through certain literary or visual artefacts produced by Native or non-Native writers and artists. It ranges from the study of literatures (mainly from Canada - including Quebec and Acadia - but also from Britain, the United States of America, France, Turkey, and Australia) to the exploration of films, photographs, paintings and sculptures produced by Aboriginal artists from North America. Thanks to a relational paradigm founded on spatial and temporal enlargement, it re-imagines the critical outlook on indigenous production by instigating a dialogue between endogenous and exogenous scholars, novelists and artists, and by weaving together interdisciplinary approaches spanning anthropology, geology, ecocriticism and the study of myths. From the writings by Scott Momaday to those by Tomson Highway, from Pauline Johnson to Louise Erdrich, or from the photographs by William McFarlane Notman and Edward Burtynsky or the films by Randy Redroad to the paintings by Emily Carr, it explores art as the sedimentation of nature. It simultaneously interrogates the representation of nature and the nature of representation as a geological and generic process inscribed in the history of mankind. Without eclipsing differences and imposing a reified Eurocentric critical discourse upon indigenous productions, this volume does not colonize indigenous texts or indulge in cultural appropriation of works of art, but looks for historical, mythological or geological traces of the past; a past characterized by the intimacy between man and animal, man and rock, or man and plant, a past which is allowed to resurface through the creative and critical outlooks that are bestowed upon its subjacent or subterranean existence. It resurfaces, not as nostalgic memory but as an interactive fertilization giving the present a new life in which the non-human provides a key to the understanding of the human bond to nature.

Growing evidence suggests that membrane microdomains enriched in cholesterol and sphingomyelin are sites for numerous cellular processes, including signaling, vesicular transport, interaction with pathogens, and viral infection, etc. Recently some members of the annexin family of conserved calcium and membrane-binding proteins have been recognized as cholesterol-interacting molecules and suggested to play a role in the formation, stabilization, and dynamics of membrane microdomains to affect membrane lateral organization and to attract other proteins and signaling molecules onto their territory. Furthermore, annexins were implicated in the interactions between cytosolic and membrane molecules, in the turnover and storage of cholesterol and in various signaling pathways. In this review, we focus on the mechanisms of interaction of annexins with lipid microdomains and the role of annexins in membrane microdomains dynamics including possible participation of the domain-associated forms of annexins in the etiology of human lysosomal storage disease called Niemann-Pick type C disease, related to the abnormal storage of cholesterol in the lysosome-like intracellular compartment. The involvement of annexins and cholesterol/sphingomyelin-enriched membrane microdomains in other pathologies including cardiac dysfunctions, neurodegenerative diseases, obesity, diabetes mellitus, and cancer is likely, but is not supported by substantial experimental observations, and therefore awaits further clarification.

The molecular mode of action of the lipopeptide SF with zwitterionic and negatively charged model membranes has been investigated with solid-state NMR, light scattering, and electron microscopy. It has been found that this acidic lipopeptide (negatively charged) induces a strong destabilization of negatively charged micrometer-scale liposomes, leading to the formation of small unilamellar vesicles of a few 10s of nanometers. This transformation is detected for very low doses of SF (Ri=200) and is complete for Ri=50. The phenomenon has been observed for several membrane mixtures containing phosphatidylglycerol or phosphatidylserine. The vesicularization is not observed when the lipid negative charges are neutralized and a cholesterol-like effect is then evidenced, i.e., increase of gel membrane dynamics and decrease of fluid membrane microfluidity. The mechanism for small vesicle formation thus appears to be linked to severe changes in membrane curvature and could be described by a two-step action: 1), peptide insertion into membranes because of favorable van der Waals forces between the rather rigid cyclic and lipophilic part of SF and lipid chains and 2), electrostatic repulsion between like charges borne by lipid headgroups and the negatively charged SF amino acids. This might provide the basis for a novel mode of action of negatively charged lipopeptides.

Les antibiotiques ituriniques, produits par Bacillus subtilis, représentent une famille qui comprend l’iturine A, la mycosubtilline, les bacillomycines D, F et Lc. Ce sont des lipopeptides cycliques possédant des acides gras β-aminés reliés à un peptide formé par sept acides α-aminés avec une séquence chirale invariable dont la configuration type est LDDLLDL. Ils possèdent tous en commun les trois premiers acides α-aminés incluant le résidu tyrosyl. Ils sont connus essentiellement par leur pouvoir antifongique et ils ont également des propriétés antibactériennes et hémolytiques. Ces propriétés proviennent de leur nature amphiphile qui leur permet d’interagir avec différents constituants membranaires. Les stérols, qui se trouvent dans les membranes plasmiques, constituent le partenaire privilégié d’interaction de ces antibiotiques. Aussi, le groupement phénol du résidu tyrosine des antibiotiques est supposé avoir un rôle important pour la fixation des antibiotiques au niveau de la membrane plasmique. La finalité de cette fixation est souvent la lyse cellulaire. Il existe, au sein de la membrane plasmique, des régions particulières contenant une forte concentration en stérol. Ces microdomaines membranaires diffèrent du reste de la membrane plasmique par leur composition ; ils sont également enrichis en certains lipides et en certaines protéines. Les microdomaines interviennent dans divers processus cellulaires clés, leur perturbation peut donc engendrer de nombreuses conséquences. Du fait de leur composition, ces microdomaines peuvent constituer la cible des activités biologiques des antibiotiques ituriniques. Cette revue a pour but de faire la synthèse des travaux réalisés sur les antibiotiques ituriniques au niveau de leurs activités biologiques en focalisant sur la compréhension de celles-ci à l’échelle moléculaire avec une discussion sur leurs groupements chimiques clés et sur le potentiel des microdomaines membranaires en tant que cible privilégiée pour ces molécules. Interactions of iturinic antibiotics with plasma membrane. Contribution of biomimetic membranes. Iturinic antibiotics are produced by Bacillus subtilis strains and constitute a family including iturin A, mycosubtilin and bacillomycins D, F and Lc. These are cyclic lipopeptides with β-amino fatty acids linked up to a peptide constituted by seven α-aminoacids with an invariable LDDLLDL chiral sequence. The first three α-aminoacids containing the tyrosyl residue are the same for all members. They are well known for their strong antifungal activities but they also have antibacterial and hemolytic properties. These biological properties are due to their amphiphilic nature, allowing interactions with different membrane components. Sterols found in plasma membranes are the privileged interaction partners of these lipopeptides. Moreover, the tyrosyl residue of the iturinic antibiotics seems to play an important role during their fixation to the plasma membrane, the result of which is often cellular lysis. Within plasma membranes, there are particular regions with a high sterol content. These microdomains have a different composition compared to the rest of the membrane; they are rich in certain lipids and proteins and are involved in many key cellular processes. The perturbation of these microdomains could therefore have an important impact on the cell. Due to their composition, these microdomains may constitute the preferential target of iturin antibiotics. This review aims to summarize the studies relating to the biological activities of iturinic antibiotics. It focuses in particular on the existing knowledge regarding iturin antibiotics at the molecular level and discusses both the key chemical groups of these drugs and the potentiality of microdomains to constitute a target for these molecules.

A polyclonal antibody was raised against a Toxoplasma gondii 14-3-3–gluthatione S-transferase fusion protein obtained by cloning a 14-3-3 cDNA sequence determined from the T. gondii database. This antibody specifically recognized T. gondii 14-3-3 without any cross-reaction with mammalian proteins. Immunofluorescence microscopy studies of the tachyzoites or the T. gondii-infected cells suggested cytosolic and membranous localizations of 14-3-3 protein. Different subcellular fractions were prepared for electrophoresis analysis and immunodetection. 14-3-3 proteins were found in the cytosol, the membrane fraction and Triton X-100-resistant membranes. Two 14-3-3 isoforms were detected. The major one was mainly cytoplasmic and to a lesser extent membrane-associated, whereas the minor isoform was associated with the detergent-resistant lipid rafts.

Iturinic antibiotics are produced by Bacillus subtilis strains and constitute a family including iturin A, mycosubtilin and bacillomycins D, F and Lc. These are cyclic lipopeptides with alpha -amino fatty acids linked up to a peptide constituted by seven alpha -aminoacids with an invariable LDDLLDL chiral sequence. The first three alpha -aminoacids containing the tyrosyl residue are the same for all members. They are well known for their strong antifungal activities but they also have antibacterial and hemolytic properties. These biological properties are due to their amphiphilic nature, allowing interactions with different membrane components. Sterols found in plasma membranes are the privileged interaction partners of these lipopeptides. Moreover, the tyrosyl residue of the iturinic antibiotics seems to play an important role during their fixation to the plasma membrane, the result of which is often cellular lysis. Within plasma membranes, there are particular regions with a high sterol content. These microdomains have a different composition compared to the rest of the membrane; they are rich in certain lipids and proteins and are involved in many key cellular processes. The perturbation of these microdomains could therefore have an important impact on the cell. Due to their composition, these microdomains may constitute the preferential target of iturin antibiotics. This review aims to summarize the studies relating to the biological activities of iturinic antibiotics. It focuses in particular on the existing knowledge regarding iturin antibiotics at the molecular level and discusses both the key chemical groups of these drugs and the potentiality of microdomains to constitute a target for these molecules.

Abstract The 14-3-3 protein was shown to be present into the parasitophorous vacuole of Toxoplasma gondii-infected human monocyte cells and in the excreted/secreted antigens (ESA). The ESA 14-3-3 protein migrates electrophoretically as the cytosol and the main membranous 14-3-3 isoforms. The excretion/secretion of 14-3-3 was not sensitive to cycloheximide, a protein synthesis inhibitor, even at a concentration which inhibited the production of 14-3-3 inside the tachyzoites. Recombinant 14-3-3/GST protein was used to test the presence of 14-3-3 antibodies in different human sera. A positive immunoreactivity was observed with sera corresponding to acute toxoplasmosis and a possible involvement of 14-3-3 in host immunity is discussed.

Iturinic antibiotics are produced by Bacillus subtilis strains and constitute a family including iturin A, mycosubtilin and bacillomycins D, F and Lc. These are cyclic lipopeptides with α-amino fatty acids linked up to a peptide constituted by seven α-aminoacids with an invariable LDDLLDL chiral sequence. The first three α-aminoacids containing the tyrosyl residue are the same for all members. They are well known for their strong antifungal activities but they also have antibacterial and hemolytic properties. These biological properties are due to their amphiphilic nature, allowing interactions with different membrane components. Sterols found in plasma membranes are the privileged interaction partners of these lipopeptides. Moreover, the tyrosyl residue of the iturinic antibiotics seems to play an important role during their fixation to the plasma membrane, the result of which is often cellular lysis. Within plasma membranes, there are particular regions with a high sterol content. These microdomains have a different composition compared to the rest of the membrane; they are rich in certain lipids and proteins and are involved in many key cellular processes. The perturbation of these microdomains could therefore have an important impact on the cell. Due to their composition, these microdomains may constitute the preferential target of iturin antibiotics. This review aims to summarize the studies relating to the biological activities of iturinic antibiotics. It focuses in particular on the existing knowledge regarding iturin antibiotics at the molecular level and discusses both the key chemical groups of these drugs and the potentiality of microdomains to constitute a target for these molecules. [PUBLICATION ABSTRACT]