Biophysical Newsletter - August 2014

12

BIOPHYSICAL SOCIETY NEWSLETTER

2014

AUGUST

Biophysical Journal Corner

Know the Editors

the same laws as the propagation of excitation in neurons or of the front of a flame. However, in contrast to these well-studied excitation waves, the clotting waves can stop. This discovery has led to new thoughts about the pathway of blood clot- ting in general. Apparently, different blocks of the clotting reactions are responsible for different as- pects of clotting: the activation, propagation, and termination. For example, the intrinsic pathway of blood clotting has previously been viewed as a “metabolic atavism,” which plays no significant role in humans. Our work has revealed that the reactions of the intrinsic pathway are critical for the propagation of clotting in space. These results have also stimulated interest in the new type of active medium, represented by blood, which we call “double active.” Such an excitation medium can give rise to very unusual mechanisms of self-organization, which are likely to be involved in other biological phenomena, including cell dif- ferentiation and pattern formation. Mechanisms of chromosome segregation. One of the most crucial steps in cell division, equal segregation of duplicated chromosomes, is carried out by the mitotic spindle. A primary spindle component is tubulin, which polymer- izes to form dynamic microtubules. We have developed novel mathematical models to study the mechanics and dynamics of tubulin polymers, leading to the quantitative prediction and then experimental confirmation of the force generated by tubulin disassembly. Shortening microtubules can generate force that is sufficiently large to explain poleward chromosome motion in cells, but capturing this large force requires specialized coupling mechanisms. We are now investigating the operation of different protein complexes with the goal of attaching a chromosome to the tips of the disassembling microtubules.

Fazly Ataullakhanov National Research Center for Hematology Moscow, Russia Editor in Molecular Machine, Motors and Nanoscale Biophysics Section

What is your area of research?

My research focuses on the dynamics of biologi- cal systems. I have worked on a broad spectrum of projects including enzymatic reactions, such as the peroxidase-oxidase system, and complex metabolic pathways: their hierarchy, overall integration, and impact on cell physiology. I also study spatiotemporal dynamics of blood clotting system and mechanisms of chromosome segrega- tion during cell division. The goal of these differ- ent studies has been to define the basic principles and mechanisms of self-organization of complex biological systems to understand how they func- tion efficiently and intelligently. Work toward this goal has required the tandem use of theoreti- cal and experimental approaches, while seeking a consistency between mathematical models and experimental results. Progress in these directions cannot be achieved working alone, and I was for- tunate to have excellent colleagues and talented students. Two ongoing projects are described below. We have constructed different mathematical models of blood clotting pathways and developed novel experimental approaches to monitor and analyze the clotting reactions with high spatial and temporal resolution. This work has estab- lished that the propagation of clotting abides by Spatio-temporal dynamics of blood clotting.