Une ethnographie de la relation d'aide : de la ruse à la fiction, comment concilier protection et autonomie, rapport de recherche pour la MiRe (DREES):Rapport de recherche pour la MiRe (DREES)

Ce rapport propose une description et une analyse de l’activité d’aide à domicile. L’enquête a porté sur le réseau des proches, aidants et soignants, intervenant auprès de personnes atteintes de troubles psychiques et cognitifs. Les aides visent à assurer le bien‐être des personnes en apportant soins et assistance. Mais ce souci ne suffit pas à caractériser leur activité : à chaque instant, les aides doivent composer entre des aspirations contradictoires, comme la protection et l’autonomie, et assumer des prises de risque. Nous n’opposons pas leur activité réelle à des principes abstraits, nous faisons au contraire l’hypothèse que ce sont les pratiques des aides qui peu à peu, à partir des situations d’épreuve, donnent un sens concret à de telles notions. En trouvant des façons de les composer, elles montrent que leur mise en oeuvre est possible. Selon une méthode ethnographique, nous avons suivi treize cas, entre six et dix-huit mois, choisis dans trois services d’aide à domicile contrastés, en mettant l’accent sur les moments d’épreuve, qui montrent en permanence ces compromis obligés de l’action en situation : problèmes d’hygiène, de médicaments, de clés, risque de chute, décision de placement, relation à la famille, etc. Le principal rendu de notre recherche est la mise en récit de ces treize expériences collectives. Comment faire faire quelque chose à des personnes qui ne l’ont pas demandé ou n’en voient pas l’intérêt ? À condition d’en restituer aussi la valeur positive, deux notions ambiguës, la ruse et la fiction, aident à mieux comprendre l’expérience du domicile, et les compétences des personnels et des proches. L’aide est installation incertaine d’une relation, d’un espace commun. Instaurer cette fiction partagée fait en partie porter par l’aidant à la place de l’aidé son exigence d’autonomie : traiter en être autonome la personne fragilisée, c’est faire persister ce qui n’est plus tout à fait là. Curieuse autonomie, par procuration, qui doit être supposée et supportée par les autres pour exister. C’est tout l’enjeu éthique, politique et social de la relation d’aide : l’invention d’une autonomie élargie au collectif

Overexpression of Partner of Numb Induces Asymmetric Distribution of the PI4P 5-Kinase Skittles in Mitotic Sensory Organ Precursor Cells in Drosophila

Unequal segregation of cell fate determinants at mitosis is a conserved mechanism whereby cell fate diversity can be generated during development. In Drosophila, each sensory organ precursor cell (SOP) divides asymmetrically to produce an anterior pIIb and a posterior pIIa cell. The Par6-aPKC complex localizes at the posterior pole of dividing SOPs and directs the actin-dependent localization of the cell fate determinants Numb, Partner of Numb (Pon) and Neuralized at the opposite pole. The plasma membrane lipid phosphatidylinositol (4,5)-bisphosphate (PIP2) regulates the plasma membrane localization and activity of various proteins, including several actin regulators, thereby modulating actin-based processes. Here, we have examined the distribution of PIP2 and of the PIP2-producing kinase Skittles (Sktl) in mitotic SOPs. Our analysis indicates that both Sktl and PIP2 reporters are uniformly distributed in mitotic SOPs. In the course of this study, we have observed that overexpression of full-length Pon or its localization domain (LD) fused to the Red Fluorescent Protein (RFP::PonLD) results in asymmetric distribution of Sktl and PIP2 reporters in dividing SOPs. Our observation that Pon overexpression alters polar protein distribution is relevant because RFP::PonLD is often used as a polarity marker in dividing progenitors

Nucleoporin98-96 Function Is Required for Transit Amplification Divisions in the Germ Line of Drosophila melanogaster

Production of specialized cells from precursors depends on a tightly regulated sequence of proliferation and differentiation steps. In the gonad of Drosophila melanogaster, the daughters of germ line stem cells (GSC) go through precisely four rounds of transit amplification divisions to produce clusters of 16 interconnected germ line cells before entering a stereotypic differentiation cascade. Here we show that animals harbouring a transposon insertion in the center of the complex nucleoporin98-96 (nup98-96) locus had severe defects in the early steps of this developmental program, ultimately leading to germ cell loss and sterility. A phenotypic analysis indicated that flies carrying the transposon insertion, designated nup98-962288, had dramatically reduced numbers of germ line cells. In contrast to controls, mutant testes contained many solitary germ line cells that had committed to differentiation as well as abnormally small clusters of two, four or eight differentiating germ line cells. This indicates that mutant GSCs rather differentiated than self-renewed, and that these GSCs and their daughters initiated the differentiation cascade after zero, or less than four rounds of amplification divisions. This phenotype remained unaffected by hyper-activation of signalling pathways that normally result in excessive proliferation of GSCs and their daughters. Expression of wildtype nup98-96 specifically in the germ line cells of mutant animals fully restored development of the GSC lineage, demonstrating that the effect of the mutation is cell-autonomous. Nucleoporins are the structural components of the nucleopore and have also been implicated in transcriptional regulation of specific target genes. The nuclear envelopes of germ cells and general nucleocytoplasmic transport in nup98-96 mutant animals appeared normal, leading us to propose that Drosophila nup98-96 mediates the transport or transcription of targets required for the developmental timing between amplification and differentiation

Localisation des ARN messagers dans l' ovocyte de drosophile

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Organisation des microtubules et polarité cellulaire chez la Drosophile

La grande majorité des cellules sont polarisées, c est-à-dire qu une partie de leurs constituants sont localisés de manière asymétrique. Ce phénomène, indispensable pour la physiologie des cellules, est en lien étroit avec l organisation du réseau de microtubules. Au cours de ma thèse, j ai étudié la réorganisation du réseau de microtubules au cours de la formation du système respiratoire de Drosophile. Ce phénomène s accompagne d une relocalisation de l activité de nucléation, depuis le centrosome vers la membrane apicale. Dans un premier temps, le -TuRC est relargué du centrosome grâce à l activité de coupure des microtubules de la spastine puis il est ancré à la membrane apicale de ces cellules via la protéine transmembranaire piopio. La perturbation de ce processus entraîne des défauts de morphogenèse du système respiratoire. J ai également caractérisé la protéine dTBCB (Drosophila tubulin binding cofactor B) et son rôle au cours de l ovogenèse. Cette protéine fait partie d un complexe requis pour la dimérisation de la tubuline. J ai identifié une nouvelle fonction pour cette protéine qui lie les microtubules et stimule leur dynamique. In vivo, la mutation de dTBCB induit une très forte déstabilisation du réseau de microtubules et une perte de la polarité de l ovocyte et des cellules folliculaires.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Nucleus positioning within Drosophila egg chamber

International audienceBoth types of Drosophila egg chamber germ cells, i.e. oocyte and nurse cells, have to control their nucleus positions in order to produce a viable gamete. Interestingly, while actin microfilaments are crucial to position the nuclei in nurse cells, these are the microtubules that are important for oocyte nucleus to migrate and adopt the correct position. In this review, we discuss the mechanisms underlying these positioning processes in the two cell types with respect to the organization and dynamics of the actin and microtubule skeleton. In the nurse cells it is essential to keep firmly the nuclei in a central position to prevent them from obstructing the ring canals when the cytoplasmic content of the cells is dumped into the oocyte cells toward the end of oogenesis. This is achieved by the assembly of thick filopodia-like actin cables anchored to the plasma membrane, which grow inwardly and eventually encase tightly the nuclei in a cage-like structure. In the oocyte, the migration at an early stage of oogenesis of the nucleus from a posterior location to an anchorage site at an asymmetric anterior position, is an essential step in the setting up of the dorsoventral polarity axis of the future embryo. This process is controlled by an interplay between MT networks that just start to be untangled. Although both mechanisms have evolved to fulfill cell-type specific cell processes in the context of fly oogenesis, interesting parallels can be drawn with other nuclear positioning mechanisms in the mouse oocyte and the developing muscle respectively

Le handicap au quotidien. La personne, les proches, les soignants : sept récits d'expérience à domicile

Rapport dans le cadre d'un contrat de recherche avec la Haute Autorité de la Santé et le CNS

Dynein-mediated transport and membrane trafficking control PAR3 polarised distribution

International audienceThe scaffold protein PAR3 and the kinase PAR1 are essential proteins that control cell polarity. Their precise opposite localisations define plasma membrane domains with specific functions. PAR3 and PAR1 are mutually inhibited by direct or indirect phosphorylations, but their fates once phosphorylated are poorly known. Through precise spatiotemporal quantification of PAR3 localisation in the Drosophila oocyte, we identify several mechanisms responsible for its anterior cortex accumulation and its posterior exclusion. We show that PAR3 posterior plasma membrane exclusion depends on PAR1 and an endocytic mechanism relying on RAB5 and PI(4,5)P2. In a second phase, microtubules and the dynein motor, in connection with vesicular trafficking involving RAB11 and IKK-related kinase, IKKε, are required for PAR3 transport towards the anterior cortex. Altogether, our results point to a connection between membrane trafficking and dynein-mediated transport to sustain PAR3 asymmetry

Visualizing Microtubule Networks During Drosophila Oogenesis Using Fixed and Live Imaging.

International audienceThe microtubule cytoskeleton is a plastic network of polarized cables. These polymers of tubulin provide orientated routes for the dynamic transport of cytoplasmic molecules and organelles, through which cell polarity is established and maintained. The role of microtubule-mediated transport in the asymmetric localization of axis polarity determinants, in the Drosophila oocyte, has been the subject of extensive studies in the past years. However, imaging the distribution of microtubule fibers in a large cell, where vitellogenesis ensures the uptake of a thick and hazy yolk, presents a series of technical challenges. This chapter briefly reviews some of these aspects and describes two methods designed to circumvent these difficulties. We provide a detailed protocol for the visualization by immunohistochemistry of the three-dimensional organization of tubulin cables in the oocyte. Additionally, we detail the stepwise procedure for the live imaging of microtubule dynamics and network remodeling, using fluorescently labeled microtubule-associated proteins

Stable Anterior Anchoring of the Oocyte Nucleus Is Required to Establish Dorsoventral Polarity of the Drosophila Egg

In Drosophila, dorsoventral polarity is established by the asymmetric positioning of the oocyte nucleus. In egg chambers mutant for cap ‘n’ collar, the oocyte nucleus migrates correctly from a posterior to an anterior–dorsal position where it remains during stage 9 of oogenesis. However, at the end of stage 9, the nucleus leaves its anterior position and migrates towards the posterior pole. The mislocalisation of the nucleus is accompanied by changes in the microtubule network and a failure to maintain bicoid and oskar mRNAs at the anterior and posterior poles, respectively. gurken mRNA associates with the oocyte nucleus in cap ‘n’ collar mutants and initially the local secretion of Gurken protein activates the Drosophila EGF receptor in the overlying dorsal follicle cells. However, despite the presence of spatially correct Grk signalling during stage 9, eggs laid by cap ‘n’ collar females lack dorsoventral polarity. cap ‘n’ collar mutants, therefore, allow for the study of the influence of Grk signal duration on DV patterning in the follicular epithelium