Plenarvorträge - DPG-Tagungen

Arbeitskreis Biologische Physik Mittwoch
architecture.
Hauptvortrag AKB 30.4 Mi 16:00 H40
Feeling for Cells with Light — •Jochen Guck, Falk Wottawah,
Kort Travis, Stefan Schinkinger, Frank Sauer, Bryan
Lincoln, and Susanne Ebert — Fakultät für Physik und Geowissenschaften,
Univeristät Leipzig
The relationship between the mechanical properties of cells and their
molecular architecture has been the focus of extensive research for
decades. Especially the cytoskeleton, an internal polymer network, determines
a cell’s mechanical strength and morphology. This cytoskeleton
evolves during the normal differentiation of cells, is involved in many
cellular functions, and is characteristically altered in many diseases, including
cancer. We can exploit this link between function and elasticity
to distinguish between different cells using an optical stretcher, a new
laser tool optimized to deform hundreds of single cells per hour by optically
induced surface forces. Optical deformability is sensitive enough
to monitor the subtle changes during the progression of individual human
breast epithelial cells from normal to cancerous and even metastatic
state. The surprisingly low numbers of cells required for this distinction
reflects the tight regulation of the cytoskeleton by the cell. This suggests
using optical deformability as an inherent cell marker for basic cell
biological investigation and diagnosis of disease.
AKB 31 Investigations of Biological Structures
Zeit: Mittwoch 16:30–17:00 Raum: H40
Hauptvortrag AKB 31.1 Mi 16:30 H40
NMR Tomography — •Peter Jakob — Julius-Maximilians-
Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am
Hubland, D-97074 Würzburg
AKB 32 Post-deadline Talks
Zeit: Mittwoch 17:00–19:00 Raum: H40
AKB 32.1 Mi 17:00 H40
Platzhakter für post-deadline Vorträge — • —
AKB 40 Evolution and Complex Systems
Zeit: Donnerstag 14:30–16:30 Raum: H40
Hauptvortrag AKB 40.1 Do 14:30 H40
Structure and Evolution of bio-molecular Networks — •Michael
Lässig — Institut für theoretische Physik, Universität zu Köln, 50937
Köln
The genomes of higher organisms are highly collective systems with
multiple interactions between genes. These genetic networks are linked
to other levels of molecular information processing such as protein interaction
maps or metabolic networks. Their combinatorial complexity is
an essential characteristic of higher organisms, allowing a large number
of functional tasks to be performed by a limited number of genes. This
talk describes our current understanding of the structure and evolution
of molecular networks. How do we recognize modules related to specific
functions in large networks? How does nature evolve complex interaction
patterns and adapts them to fluctuating environments? These questions
lead to the statistical physics of bio-molecular networks and their nonequilibrium
dynamics.
Hauptvortrag AKB 40.2 Do 15:00 H40
Dynamics and Evolution of Networks: From the Genome to
Ecosystems — •Barbara Drossel — Institut für Festkörperphysik,
TU Darmstadt, Hochschulstr. 6, 64289 Darmstadt
This talk presents an overview of my research projects in the field of
genetic networks and foodwebs. The study of genetic network models
begins with Kauffman networks and aims at understanding the relation
between the structural network properties and the properties of its attractors.
The long-term goal is to model network evolution by including
biologically realistic features such as mutator genes, transpositions and
duplications. The main question addressed in the study of foodweb models
is the relation between the population dynamics and the structural
properties of foodwebs under long-term evolution. Our recent research
shows that only certain types of population dynamics allow the formation
and long-term persistence of complex webs.
Hauptvortrag AKB 40.3 Do 15:30 H40
Evolution of a Genetic Switch in a Fluctuating Environment
— •Ulrich Gerland 1 and Terence Hwa 2 — 1 Sektion Physik, Uni
München — 2 Department of Physics, UC San Diego
Gene regulation encompasses a variety of molecular processes which determine
the protein concentrations in cells and their signal dependence.
Perhaps the simplest regulatory unit (or ‘node’ in a genetic network) is
a genetic switch, which sets the transcription rate of a gene either to
‘high’ or ‘low’. Many genetic switches in bacteria respond to a chemical
‘inducer’ signaling the present state of a fluctuating environment.
Mechanically, there are two basic designs, which are both realized in
bacteria: either the transcription level is low by default and the inducer
activates a DNA-binding protein stimulating transcription, or the inducer
deactivates a DNA-binding protein repressing a high default level.
We formulate a theory to quantitate an old evolutionary argument that
attempts to rationalize the observed choice between these two designs
in bacteria. To this end, we are forced to consider explicitly the effects
of environmental fluctuations, which are usually neglected in standard
evolutionary models.
Hauptvortrag AKB 40.4 Do 16:00 H40
Proteins: Structure, Function, and Evolution — •Markus
Porto 1 , Ugo Bastolla 2 , H. Eduardo Roman 3 , and Michele
Vendruscolo 4 — 1 Institut für Theoretische Physik, Technische Universität
Dresden, 01062 Dresden, Germany — 2 Centro de Astrobiología
(INTA-CSIC), 28850 Torrejon de Ardoz, Spain — 3 Dipartimento di
Fisica and INFN, Università di Milano, Via Celoria 16, 20133 Milano,
Italy — 4 Department of Chemistry, University of Cambridge, Lensfield
Road, Cambridge CB2 1EW, UK
In my talk I will discuss very recent theoretical work related to the
evolution of proteins. The starting point is to understand the statistical
properties of neutral evolution of protein sequences under the requirement
that the native state remains thermodynamically stable. As a first
result, such study yields the rigidity profile (the amount of local conservation)
of a given protein fold, which indicates structural and functional
important places. The second central result is the observation of strongly
correlated fluctuations in the substitution rate and the resulting lack of
self-averaging for certain observables, which is important for instance for
bioinformatics applications. Thirdly, a relation between sequence based
quantities and protein structure is established, which might provide a
different route to protein structure prediction.