报告题目1：

Pre-TCR ligand binding impacts thymocyte development before αβTCR expression

报告人:                         Dr. Ke Bai

National Institute of Allergy and infectious Diseases, National Institute of Health, USA

时间：2016年9月29日(周四)  9: 00-10: 30          

地点：中科院力学所1号楼礼堂内会议室

报告摘要：

Adaptive cellular immunity requires accurate self- vs. nonself-discrimination to protect against infections and tumorous transformations while at the same time excluding autoimmunity. This vital capability is programmed in the thymus through selection of αβT-cell receptors (αβTCRs) recognizing peptides bound to MHC molecules (pMHC). Here, we show that the pre-TCR (preTCR), a pTα-β heterodimer appearing before αβTCR expression, directs a previously unappreciated initial phase of repertoire selection. Contrasting with the ligand-independent model of preTCR function, we reveal through NMR and bioforce-probe analyses that the β-subunit binds pMHC using Vβ complementarity-determining regions as well as an exposed hydrophobic Vβ patch characteristic of the preTCR. Force-regulated single bonds akin to those of αβTCRs but with more promiscuous ligand specificity trigger calcium flux. Thus, thymic development involves sequential β- and then, αβ-repertoire tuning, whereby preTCR interactions with self pMHC modulate early thymocyte expansion, with implications for β-selection, immunodominant peptide recognition, and germ line-encoded MHC interaction.

报告人简介：

09/2015- present     Postdoctoral scholar, National Institute of Allergy and infectious Diseases, 

                                    National Institute of Health

Dr. Ke Bai laid the groundwork for the proposed research by investigating T cell immunology including T cell development, roll of CD4 and CD8 T cell in viral infection. Her research focused on using biophysical and biological tools to answer immunology questions. The current projects that she is working on are the role of pre-T cell receptor on antigen-receptor interaction, and the mechanism of T cell protection of Ebloa.

白柯简历

报告题目2：

Anomalous Diffusion of Nanoparticles in Complex Fluids

报告人:                           郑旭 博士

非线性力学国家重点实验室

时间：2016年9月29日(周四)  10: 30-11: 30        

地点：中科院力学所1号楼礼堂内会议室

报告摘要：

The diffusive motion of nanoparticles in complex fluids is intriguing as it presents anomalous behaviors distinct from the classic simple Brownian motion. Examples can be found in polymer solutions, porous media, and especially biomacromolecular environments. In this talk, typical behaviors of anomalous diffusion of nanoparticles will be presented. Hopping diffusion is identified as the source of non-Gaussianity of the “anomalous yet Brownian” motion, which results in the striking occurrence of the long-distance motion indicated by the fat-tailed distribution. We further establish a scaling law to illustrate the dependence of the dimensionless hopping timescale on the dimensionless particle size. A competition between the “active” hopping dynamics and the “passive” reptative constraint release is revealed. Our findings offer valuable physical insights of the anomalous diffusion in biomacromolecular systems such as the nanoscale transportation in cytoplasmic fluids.