These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer‐reviewed by leading experts in the field, making this an essential research companion.

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

Democracy does not evolve sui generis. The spatial clustering in democracy and transitions suggests that international factors play a prominent role in forging democracies as well as influencing their durability. We argue that democracy often comes about as a result of changes in the relative power of important actors and groups as well as their evaluations of particular institutions, both of which are often influenced by forces outside the country in question. The scope and extent of connections with other democratic countries in a region can strengthen support for democratic reform and help sustain institutions in transitional democracies. Results from a transition model demonstrate that international factors can exert a strong influence on the prospects for transitions to democracy, and the spatial clustering in democracy and transitions cannot adequately be explained by the hypothesized domestic social requisites of individual countries.The many transitions to democratic rule in the so-called "third wave" of democratization have renewed scholarly interest in what affects the prospects for democratization. So far, however, an understanding of the causes for the emergence of democratic political institutions has remained elusive. In retrospect, it is easy to look back on particular transitions to democracy as ineluctable. However, providing generalizations on circumstances that have been favorable for democratic transitions requires one to see beyond the idiosyncrasies of individual changes.Is democracy "caused" by economic or social factors, or by political culture, or do transitions come about by just plain luck? The idea that democracy has certain requisites can be traced to Lipset's thesis that economic development is a key precondition for democratic rule.' Other perspectives give prominence to norms or We are grateful for comments from Brian A'

The SARS-CoV-2 nucleocapsid (N) protein is an abundant RNA-binding protein critical for viral genome packaging, yet the molecular details that underlie this process are poorly understood. Here we combine single-molecule spectroscopy with all-atom simulations to uncover the molecular details that contribute to N protein function. N protein contains three dynamic disordered regions that house putative transiently-helical binding motifs. The two folded domains interact minimally such that full-length N protein is a flexible and multivalent RNA-binding protein. N protein also undergoes liquid-liquid phase separation when mixed with RNA, and polymer theory predicts that the same multivalent interactions that drive phase separation also engender RNA compaction. We offer a simple symmetry-breaking model that provides a plausible route through which single-genome condensation preferentially occurs over phase separation, suggesting that phase separation offers a convenient macroscopic readout of a key nanoscopic interaction.