Prof. Itay Rousso

Prof. Itay Rousso Profile

Associate Professor

Department : Physiology and Cell Biology
Room : 436
בנין מעבדות מחקר רפואה ע"ש דייכמן - פלאם
Phone : 972-8-6477338
972-8-6477326
Email : roussoi@bgu.ac.il
Office Hours :  

Education

  • B.Sc. School of Chemistry in the Faculty of Exact Sciences, Tel-Aviv University.
  • Direct Ph.D. with Prof. Mudi Sheves, Dept. of Organic Chemistry, Weizmann Institute of Science
  • Thesis: The Role of Water and Light Induced Alterations in the Function Bacteriorhodopsin.
  • Postdoctoral fellow in the laboratory of Prof. Peter Kim, Howard Hughes Medical Institute, Whitehead Institute for Biomedical Research, M.I.T.
  • Subject of Research: HIV assembly and budding

Research Interests

  • Our research focuses on the interrelations between the structure, nanomechanics and function of large biological complexes. Currently our laboratory is engaged with the investigation of the physical properties underlying retrovirus replication, and the role of the mammalian tectorial membrane in hearing micromechanics. In addition, we have developed a time-resolved atomic force microscope with unparalleled combination of lateral and temporal resolutions. This novel microscope allows us to study, for the first time, the dynamic properties of the mammalian tectorial membrane during physiological relevant motion.
  • In our research we use atomic force microscopy (AFM), fluorescence and electron microscopy, as well as techniques such as nano-indentation and fluorescence recovery after photobleaching spectroscopy (FRAPS). We also apply a novel methodology, which we developed, to obtain time-resolved atomic force microscopy images with microsecond temporal resolution.

Research Projects

  • Characterization of the stiffness switch in HIV

Research Abstract

      • Research Topics

      • Nanomechanics and Dynamics of Retrovirus Replication
      • Enveloped retroviruses are complex and efficient self-assembled complexes. To subsist, the virion must satisfy several, potentially conflicting, demands during its life cycle: spontaneous assembly during budding, durability in the outside environment, and efficient membrane fusion during entry into the target cell. As a result, the virus is likely to adopt a different set of physical properties at different stages of its lifecycle. However, these issues have not been addressed.
      • Analyzing the mechanical properties of mature and immature MLV and HIV, we found a clear correlation between the maturation state of the viruses and their stiffness. This was particularly evident in HIV, where maturation is concomitant with a 14-fold decrease in rigidity. Unexpectedly, this large decease was not due to the difference in shell thickness between the mature and immature forms, but rather mediated by the cytoplasmic domain of the envelope protein, as indicated by truncation analysis. Notably, softening of the viruses correlated to their ability to enter cells: immature viruses carrying a truncated env protein are fusogenic. Our results indicate a prominent role of virus mechanical properties in the infection process.
      • Future studies will concentrate on the mechanism by which the envelope protein affects stiffness. In parallel, we will focus on the relation between the viruses' mechanical properties and the efficiency and kinetics of cell entry
      • The Structure and Mechanical Properties of the Mammalian Tectorial Membrane
      • The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the cochlea. Its strategic location, together with the results obtained from recent mutational analyses, suggests that it has an important role in the conversion of mechanical energy arriving at the cochlea to neural excitation. Our studies aim to understand the role of the TM in hearing mechanics.
      • Indentation analyses revealed wide variation in the elastic modulus of the TM zone that is located above the outer hair cells (OHC). Specifically, we found that the elastic modulus increases by an order of magnitude going from the low-frequency to the high-frequency response regions of the cochlea. This finding may explain how the TM can interact with the OHC stereocillia throughout the functional audio frequency range, without causing dumping or over-stimulation. Interestingly, the macromolecular composition of the TM is similar throughout the entire body. We therefore performed structural analysis of fixed and native hydrated TM samples, using scanning electron- and two-photon second-harmonic microscopy, respectively. The images revealed substantial differences in the arrangement of collagen fibers along the structure, which correlated to the observed variations in mechanical properties.
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