Ethnicity in the Roman north-west

It is impossible, within the confines of this chapter, to present a comprehensive account of ethnic developments in the Roman northwest, nor can I do justice to the enormous amount of scholarly work that has focused on precisely this question, particularly in the past 20-30 years. What this chapter aims to do is to present, using selected case studies, a range of different scenarios that give some insight into the complex and varied nature of ethnicity and ethnogenesis in this region in the first-third centuries AD. As the most personal, and at the same time most public, form of material culture, dress stands somewhat apart as a particularly valuable source for ethnic identity, providing, of course, we have the sources for it. It is not a coincidence that Tacitus mentions the toga in his canonical inventory of Roman cultural traits. As Andrew Wallace-Hadrill has recently shown (2008:38-70), the toga played a similar membership-defining role in Roman consciousness as language did in the Greek, with one important difference: as the dress of the Roman citizen, the toga expressed more than any other element of culture the civil and legal nature of Roman identity. It is this characteristic that makes so hard to equate "being Roman" with anything amounting to ethnicity. However, it is also this characteristic which meant that practically anyone in the empire, regardless of their background, could become a Roman citizen, and as such, a "Roman" (see Farney, Chapter 29). The scenario Tacitus describes is not entirely imaginary: the toga was indeed worn in wide parts of the Roman northwest; but so was native dress. The very different nature of Roman identity to more localized group identities means that this is no paradox. Dress, in fact, reflects especially well the varying layers of cultural identity a person living in Rome's northwest provinces could and did have. As a result, in some of the case studies that follow, it will play a central role as a constant for identifying similarities and differences

Guidelines for the use of flow cytometry and cell sorting in immunological studies

International audienceThe classical model of hematopoiesis established in the mouse postulates that lymphoid cells originate from a founder population of common lymphoid progenitors. Here, using a modeling approach in humanized mice, we showed that human lymphoid development stemmed from distinct populations of CD127(-) and CD127(+) early lymphoid progenitors (ELPs). Combining molecular analyses with in vitro and in vivo functional assays, we demonstrated that CD127(-) and CD127(+) ELPs emerged independently from lympho-mono-dendritic progenitors, responded differently to Notch1 signals, underwent divergent modes of lineage restriction, and displayed both common and specific differentiation potentials. Whereas CD127(-) ELPs comprised precursors of T cells, marginal zone B cells, and natural killer (NK) and innate lymphoid cells (ILCs), CD127(+) ELPs supported production of all NK cell, ILC, and B cell populations but lacked T potential. On the basis of these results, we propose a "two-family" model of human lymphoid development that differs from the prevailing model of hematopoiesis