• Published: Book chapter: Protein-DNA Interactions Studies with Single Tethered Molecule Techniques • Published: paper on 3-dimensional Tethered Particle Motion (TPM) • Published: Book chapter: Nano-optics methods for studying DNA-protein interactions • Greetings to Liat for winning the best poster at the 2011 Israel Physical Society conference.

Introduction

"What is Life?" Ask 10 different people and you will get 10 different answers. Ask scientists from different disciplines, and you will get completely different answers. "What is Life?" was asked by Erwin Schrödinger in 1944 in a book that carries this name. Schrödinger was one of the most famous physicists known for the development of quantum mechanics that revolutionaized physics and the whole science at the time.
Schrödinger touched a fascinating question about the physical nature of life, or in his words:

"The large and important and very much discussed question is: How can the events in space and time which take place within the spatial boundary of a living organism be accounted for by physics and chemistry?"

Schrödinger continues his book by trying to answer the question that he formulated. The full name of his book is actually: "What is Life? The Physical Aspect of the Living Cell".

The attempt to answer that question still continues to date with few major successes as well as mysteries that are yet to be resolved.
The research field is usually called Bio-physics or physical biology. It is an interdisciplinary science that either tries to explain biological phenomena with physical models, develop novel physical tools for biological studies or both.
By studying biological systems with multidisciplinary approach that combines physics with biology, new insights can be achieved. We believe that these studies will lead to better scientific understanding, and in the future would improve mankind health.

We develop methods that are based on nano structures, near-field and far-field optical microscopy, scanning probe microscopy and digital imaging. Our studies inclues:

• Single molecule detection of protein-DNA interaction
• The organization and dynamics of the genome in the nucleus
• Dynamics of genomic mechanisms, such as transcription
• Protein conformational changes

The human genome contains tenth of thousands of genes that are organized in chromosomes and packed in the nucleus of the cell in a non-random manner. We are studying the organization of the genome in normal and cancer cells by observing the telomeres and the telomeres dynamics.
The distribution of the telomeres was found to be cell-cycle dependent and in tumor cells the telomeres form aggregates (PNAS 102, 2005). c-Myc is able to modify chromosomes through telomeric fusions, thereby reorganizing the genetic information. See press releases: News-Medical.Net.

We are currently studying the telomere dynamics by following the telomeres in living cells. These studies require to combine three-dimensional microscopy, image processing algorithms and physical methods. We found that the telomeres dynamics is anomalous and changes to normal at long times. These diffusion properties shades light on the organization of the genome in the nucleus, see late publication (figure reproduced with permission from PRL).

We also develop various methods for studying DNA processing aspects, such as single-molecule methods. Specifically, we develop a three-dimensional tethered particle motion method (TPM) based on a nano bead that are tethered to a DNA strand. The detection of the bead motion provides insight on the biophysical properties of the DNA as well as on protein-DNA interaction. These methods may also be combined with high-resolution microscopy methods that are based on plasmonics effects.