In situ analysis of neuronal dynamics and positional cues in the patterning of nerve connections

Recently developed imaging techniques permit individual cells to be uniquely labeled and followed over time as development proceeds in intact vertebrate embryos. Small groups of cells in the developing eye rudiment of the frog Xenopus have been labeled with the vital dyes DiI, lysinated fluorescein dextran (LFD) or lysinated rhodamine dextran (LRD). Individual optic axons and their growth cones were clearly visible in the intact living animal using confocal microscopy or epifluorescence microscopy with a low light level video camera and computer-based video image enhancement. To follow the dynamics of single optic nerve fiber terminal arborizations, small groups of cells, or even single retinal ganglion cells, were labeled with DiI, and the resulting labeled optic nerve fibers were imaged using a confocal microscope. The images show a profound alteration in morphology from day to day, demonstrating that optic nerve terminal arborizations are dynamic structures constantly extending and retracting branches. To follow the topography of the developing projection and analyze the cues that guide its formation, small groups of eyebud cells from LFD- and LRD-labeled donor embryos were grafted to an unlabeled host in either a location equivalent to that from which they had been removed (homotopic grafts) or a non-equivalent location (heterotopic grafts). Axons from homotopic grafts projected to the tectum as expected from the adult topography of the retinotectal projection. Dorsoventral topography was present from the time that the optic nerve fibers were observable in the tectum, in agreement with previous work. Nasotemporal topography was subtle or absent for the first few days, and then slowly refined. The importance of positional cues was tested by performing heterotopic eyebud grafts, in which the labeled eyebud cells are grafted to inappropriate places in the host eyebud. The heterotopic grafts appeared to integrate with the ectopic site in the eyebud in a functional manner. They should, therefore, project to the tectum together with their new neighbors if neighbor interactions or activity-based cues were of primary importance in the initial patterning of the map. However, the experiments showed that the axons from heterotopic grafts always behaved in a fashion appropriate to their position of origin in the donor, regardless of their final position in the host. These observations indicate that small groups of eyebud cells (as small as a single cell) possess positional information that plays a dominant role in guiding the optic nerve fibers to their target sites in the tectum

Penser la justice sociale : entre redistribution et revendications identitaires

L’émergence dans le paysage politique des sociétés modernes de revendications identitaires a eu tendance à recibler l’entendement que l’on a généralement de la justice sociale. Pour plusieurs, désormais, la volonté authentique de reconnaissance des différences identitaires constitue la marque fondamentale d’une société juste. Cette vision des choses s’oppose à la vision plus traditionnelle de la justice qui pose d’abord la problématique en termes de redistribution des ressources matérielles. Cette dichotomisation conceptuelle de la justice est politiquement improductive et ne correspond pas à la réalité, car les manifestations d’injustice opèrent dans les faits sur l’un et l’autre pôle à la fois. Cet article développe un modèle théorique et normatif qui intègre plutôt en un cadre unifié les revendications identitaires et celles formulées à des fins de redressement économique.The recent emergence of identity claims in modern politics has transformed the conventional understanding of social justice. While the pursuit of social justice was long perceived as a function of economic redistribution, identity politics now predicates social justice on the political recognition of identity claims. Both visions are often opposed in current theoretical discourse. This conceptual polarization is politically useless and does not correspond to reality : injustice manifests itself simultaneously on both the economic and cultural fronts. This essay proposes a theoretical and normative model which integrates both dimensions of justice in a unified framework

REDEFINIENDO EL CONCEPTO DE JUSTICIA EN UN MUNDO GLOBALIZADO

Globalization is changing the way we argue about justice. Not so long ago, in the heyday of social democracy, disputes about justice presumed what I shall call a “Keynesian-Westphalian frame”. Typically played out within modern territorial states, arguments about justice were assumed to concern relations among fellow citizens, to be subject to debate within national publics, and to contemplate redress by national states. This was true for each of two major families of justice claims, claims for socioeconomic redistribution and claims for legal or cultural recognition.La globalización está cambiando nuestra forma de discutir sobre la justicia. No hace mucho, en la edad de oro de la socialdemocracia, las disputas sobre la justicia presuponían lo que denominaré “el marco keynesiano-westfaliano”. Se asumía que los enfrentamientos en materia de justicia, desarrollados normalmente en el interior de estados territoriales, concernían a las relaciones entre conciudadanos, eran tema de debate en el ámbito nacional público y planteaban una reparación por parte de los estados nacionales. Éste fue el caso respecto de dos tipos fundamentales de reivindicación de justicia: reivindicaciones de redistribución socioeconómica y reivindicaciones de reconocimiento legal o cultural

Social justice in the age of identity politics: redistribution, recognition, participation

"In der aktuellen Debatte erscheinen Forderungen nach sozialer Gerechtigkeit in zwei Typen aufgespalten: Forderungen nach Umverteilung von Ressourcen und Forderungen nach Anerkennung kultureller Verschiedenheit. Diese beiden Typen von Forderungen werden zunehmend gegeneinander polarisiert. Entsprechend sollen wir wählen zwischen Klassenpolitik und Identitätspolitik, sozialer Demokratie und Multikulturalismus, Umverteilung und Anerkennung. Es handelt sich dabei jedoch um falsche Gegensätze. Gerechtigkeit erfordert heute beides: Umverteilung und Anerkennung. Eines allein ist unzureichend. Wenn man diese These akzeptiert, rückt die Frage in den Mittelpunkt, wie beide Forderungen zu vereinbaren sind. In dem Papier wird der Standpunkt vertreten, daß die emanzipatorischen Aspekte der beiden Paradigmata in einen umfassenden Rahmen integriert werden müssen. In dem Beitrag werden zwei Dimensionen dieses Vorhabens behandelt. Als erstes wird auf der Ebene der Moralphilosophie eine übergreifende Konzeption von Gerechtigkeit vorgeschlagen, die sowohl vertretbare Forderungen nach sozialer Gleichheit umfaßt als auch vertretbare Forderungen nach Anerkennung von Differenz. Auf der Ebene von Gesellschaftstheorie wird ein Ansatz vorgeschlagen, der den komplexen Beziehungen zwischen Interesse und Identität, Ökonomie und Kultur sowie Klasse und Status in der heutigen globalisierten, kapitalistischen Gesellschaft Rechnung trägt." (Autorenreferat)"Today, claims for social justice seem to divide into two types: claims for the redistribution of resources and claims for the recognition of cultural difference. Increasingly, these two kind of claims are polarized against one another. As a result, we are asked to choose between class politics and identity politics, social democracy and multiculturalism, redistribution and recognition. These, however, are false antitheses. Justice today requires both redistribution and recognition. Neither alone is sufficient. As soon as one embraces this thesis, however, the question of how to combine them becomes paramount. I contend that the emancipatory aspects of the two paradigms need to be integrated in a single, comprehensive framework. In this lecture, I consider two dimensions of this project. First, on the plane of moral philosophy, I propose an overarching conception of justice that can accomodate both defensible claims for social equality and defensible claims for the recognition of difference. Second, on the plane of social theory, I propose an approach that can accomodate the complex relations between interest and identity, economy and culture, class and status in contemporary globalizing capitalist society." (author's abstract

Fragile Empowerment: The Dynamic Cultural Economy of British Drum and Bass Music

This paper discusses the dynamic cultural economy of British drum and bass (D&B) music, which emerged out of Britain’s rave culture in the early 1990s. We suggest that D&B offers insight into more general issues regarding the relation between alternative cultural economies and capitalism. We examine relations between D&B and the mainstream capitalist economy and argue that D&B calls attention to the possibility for alternatives to conventional capitalist relations to survive and possibly thrive without pursuing separation from capitalism. We also theorize D&B as a vehicle towards empowerment regarding the industry segment vis-à-vis the mainstream music industry and also regarding D&B’s practitioners, many of whom can be understood as marginalized discursively and/or materially. However, D&B empowerment is fragile, due in part to technological changes that threaten practices which have helped cultivate innovativeness as well as communal relations. The empowerment of alternative practices is fragile not only for D&B as an industry segment, but also from the vantage point of internal power relations – notably with respect to differences along axes of gender and generation/age. Our conclusions indicate the broader significance of the paper for critical social theory and propose how new research might build on our dynamic view of D&B’s cultural economy

Progressive Neoliberalism isn\u27t the solution. We need a radical, counter-hegemonic and anti-capitalist alliance. A conversation with Nancy Fraser

During the annual meeting of the research network “Alternatives to Capitalism” held at the New School for Social Research in New York City in 2019, Professor Nancy Fraser engaged in a vibrant discussion about one of her latest books, “Capitalism. A Conversation in Critical Theory”, co-authored with Rahel Jaeggi (Polity Press, 2018). Here is a shortened and edited extract of the conversation

Beyond Contract-versus-Charity, Toward Participation and Provision: On the Concept of Social Citizenship

Also CSST Working Paper #76.http://deepblue.lib.umich.edu/bitstream/2027.42/51238/1/472.pd

Phosphorylation stoichiometries of human eukaryotic initiation factors.

Eukaryotic translation initiation factors are the principal molecular effectors regulating the process converting nucleic acid to functional protein. Commonly referred to as eIFs (eukaryotic initiation factors), this suite of proteins is comprised of at least 25 individual subunits that function in a coordinated, regulated, manner during mRNA translation. Multiple facets of eIF regulation have yet to be elucidated; however, many of the necessary protein factors are phosphorylated. Herein, we have isolated, identified and quantified phosphosites from eIF2, eIF3, and eIF4G generated from log phase grown HeLa cell lysates. Our investigation is the first study to globally quantify eIF phosphosites and illustrates differences in abundance of phosphorylation between the residues of each factor. Thus, identification of those phosphosites that exhibit either high or low levels of phosphorylation under log phase growing conditions may aid researchers to concentrate their investigative efforts to specific phosphosites that potentially harbor important regulatory mechanisms germane to mRNA translation