Visualization of the earliest steps of gammadelta T cell development in the adult thymus.

The checkpoint in cell development that controls successful T cell receptor (TCR) gene rearrangements remains poorly characterized. Using mice expressing a reporter gene 'knocked into' the Tcrd constant region gene, we have characterized many of the events that mark the life of early cells in the adult thymus. We identify the developmental stage during which the Tcrd locus 'opens' in early T cell progenitors and show that a single checkpoint controls cell development during the penultimate CD4-CD8- stage. Passage through this checkpoint required the assembly of TCR heterodimers on the cell surface and signaling via the Lat adaptor protein. In addition, we show that selection triggered a phase of sustained proliferation similar to that induced by the pre-TCR.

Raymond Geuss’ radicalization of realism in political theory

Raymond Geuss has been viewed as one of the figureheads of the recent debates about realism in political theory. This interpretation, however, depends on a truncated understanding of his work of the past 30 years. I will offer the first sustained engagement with this work (in English and German) which allows understanding his realism as a project for reorienting political theory, particularly the relationship between political theory and politics. I interpret this reorientation as a radicalization of realismin political theory through the combination of the emphasis on the critical purpose of political theory and the provision of practical, contextual orientation. Their compatibility depends on Geuss’ understanding of criticism as negative, of power as ‘detoxified’ and of the critical purchase of political theory as based on the diagnostic engagement with its context. This radicalization particularly challenges the understanding of how political theory relates to its political context.