סמינר מחלקתי

אורית אישטיין

תלמידת המחלקה להנדסה ביו רפואית לתואר שני תרצה בנושא:

Walking through the Axoplasmic Jungle, a Cargo’s Perspective

Neurofilaments (NFs) lie parallel to the longitudinal axis of the axon. Their unique structure includes side-arms that protrude from the NF backbone and have a net charge. Due to their charge, side-arms of neighboring filaments form cross-links thereby forming a dense net-like structure that occupies most of the axon cytoplasm. Therefore, the net creates unavoidable obstacles for motor proteins, transporting essential cargos from one end of the axon to another. Since these cargos reach diameters much larger than the spaces within the net, the motor-cargo complex is expected to encounter these obstacles every few steps. Although there is an abundance of data today regarding the motor's mechanism of movement, the local reciprocal effect between the motor-cargo movement and its surrounding environment has not yet been modeled. For this purpose we developed a physical model in which two coping scenarios are proposed: (1) cross-links are modeled as barriers which require the motor to pay an energy penalty in order to break it. (2) The motor can stretch the cross-links which therefore constitute as an additional friction factor. Each option gives a different prediction regarding the different attributes of the motor-cargo movement such as the step size, step time etc.

Another aspect of the reciprocal effect between motor and environment is the question whether motor-cargo movement can cause sufficient drag force as to cause micro-streams in the intracellular fluid as detected in plant cells.

העבודה נעשתה בהנחיית דר' אורי נבו , המחלקה להנדסה ביו-רפואית, אוניברסיטת תל-אביב