Selective imprinting of gut-homing T cells by Peyer's patch dendritic cells

Whereas naive T cells migrate only to secondary lymphoid organs, activation by antigen confers to T cells the ability to home to non-lymphoid sites. Activated effector/memory T cells migrate preferentially to tissues that are connected to the secondary lymphoid organs where antigen was first encountered. Thus, oral antigens induce effector/memory cells that express essential receptors for intestinal homing, namely the integrin alpha4beta7 and CCR9, the receptor for the gut-associated chemokine TECK/CCL25 (refs 6, 8, 9). Here we show that this imprinting of gut tropism is mediated by dendritic cells from Peyer's patches. Stimulation of CD8-expressing T cells by dendritic cells from Peyer's patches, peripheral lymph nodes and spleen induced equivalent activation markers and effector activity in T cells, but only Peyer's patch dendritic cells induced high levels of alpha4beta7, responsiveness to TECK and the ability to home to the small intestine. These findings establish that Peyer's patch dendritic cells imprint gut-homing specificity on T cells, and thus license effector/memory cells to access anatomical sites most likely to contain their cognate antigen.     

Historical and other considerations regarding the crystal form of sodium-ammonium d- and l-tartrate,potassium d- and l-tartrate,potassium-ammonium d- and l-tartrate,and potassium racemate.—II

In 1914, the physics discipline had reached a very similar stage of development in Australia and Japan. A generation later the paths of development had considerably diverged. A systematic comparison of the evolution of physics in the two countries during these years identifies factors—political, economic and cultural—that led to this divergence, but it also uncovers a number of underlying parallels.     

Millisecond-timescale motions contribute to the function of the bacterial response regulator protein Spo0F.

Protein backbones and side chains display varying degrees of flexibility, which allows many slightly different but related conformational substates to occur. Such fluctuations are known to differ in both timescale and magnitude, from rotation of methyl groups (nanoseconds) to the flipping of buried tyrosine rings (seconds). Because many mechanisms for protein function require conformational change, it has been proposed that some of these ground-state fluctuations are related to protein function. But exactly which aspects of motion are functionally relevant remains to be determined. Only a few examples so far exist where function can be correlated to structural fluctuations with known magnitude and timescale. As part of an investigation of the mechanism of action of the Bacillus subtilis response regulator SpoOF, we have explored the relationship between the motional characteristics and protein-protein interactions. Here we use a set of nuclear magnetic resonance 15N relaxation measurements to determine the relative timescales of SpoOF backbone fluctuations on the picosecond-to-millisecond timescale. We show that regions having motion on the millisecond timescale correlate with residues and surfaces that are known to be critical for protein-protein interactions.     

好氧颗粒污泥的研究

好氧颗粒污泥是一种全新概念的污水生物处理技术。介绍了好氧颗粒污泥技术的理论基础,包括好氧污泥形成机理及理化特性研究,探讨了影响好氧颗粒污泥形成的因素以及工业应用的方向和前景。