Seminar Series on Bio-Soft Matter Out-of-Equilibrium (3)Date:

15:30-17:00, March 20, Thursday, 2014

Place:Room #414, 4th Floor, Science Building #1, The University of Tokyo(東大、本郷キャンパス、理学部 1 号館 414 セミナー室)

15:30-16:15
Dr. Wasim Abuillan, (Institute of Physical Chemistry, University of Heidelberg)“Surface Scattering Techniques to Quantify Soft, Biofunctional Interfaces”
Abstract: Cell membranes are crucial components to the life of cells and organelles.
In some small organisms such as Trypanosoma brucei and gram negative bacteria,
the outer surface of their cell membrane is coated with a dense layer of proteins or
lipopolysaccharides (LPSs), respectively.

These molecules are responsible for cell

viability and defense against the host immune system. In the talk, I will present amodel system of the cell membranes of such organisms at the air/water interface.
The fine structures perpendicular to the membrane plane are characterized byspecular X-ray reflectivity (XRR). A new surface scattering technique called grazing
incidence small angle X-ray scattering (GISAXS) is used to probe the lateralstructure and the inter-molecular correlation of membrane-anchored proteins. In
addition, the element distributions across the interface are constructed by grazing
incidence X-ray fluorescence (GIXF) with a high spatial resolution.
Reference:[1] W. Abuillan, A. Vorobiev, A. Hartel, NG. Jones, M. Engstler, M. Tanaka, JCP
137, 2012 [2] W. Abuillan, E. Schneck, A. Koerner, K. Brandenburg, T. Gutsmann, T.
Gill, A. Vorobiev, O. Konovalov and M. Tanaka, Phys. Rev. E 88, 2013

[3] A.

Koerner, W. Abuillan, C. Deichmann, F. Rossetti, A. Koehler, O. Konovalov, D.
Wedlich and M. Tanaka, J. Phys. Chem. B 117, 2013
16:15-17:00
Dr. Cornelia Monzel (Institute of Physical Chemistry, University of Heidelberg)“Quantitative Studies on Hematopoietic Progenitor Cell Adhesionand Migration by Nanometric Presentation of Niche Ligand Molecules”

Abstract: The bone marrow niche that harbors hematopoietic stem and progenitor
cells (HSPCs) is critical to explore for a better understanding of HSPC homing andmobilization during health and disease. Since little is known about the complex
interplay of these cells and their environment, we design simplified models of theniche environment, which allow for quantitative studies of HSPC adhesion andmigration mediated by niche relevant ligand-receptor pairs. The model consists of a
supported lipid bilayer displaying either human SDF1α or recombinant N-cadherin
at controlled intermolecular distances ranging from 5 nm to 100 nm. Label-free, live
cell imaging of adhesion and motion was facilitated using micro-interferometry(Reflection Interference Contrast Microscopy, RICM) and time-lapse phase contrast
imaging. Our results demonstrate a highly sensitive response of HSPCs towards
small changes in the lateral spacing of SDF1α and N-cadherin. Moreover,time-lapse analysis of cellular motion resulted in characteristic distances ofmigration and distinct maps of HSPC modes of motion depending on the underlying
substrate. Thus, our studies provide valuable information on the relative
significance of niche ligand-receptor pairs, which may contribute to future adhesion
regulation in leukemia therapy
Contact Person: Masaki Sano, e-mail: sano@phys.s.u-tokyo.ac.jp