William Duncan

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  Student Presentation: A Model for Transport in Stereocilia
  William Duncan, China Mauck

  Stereocilia are highly regulated structures vital for hearing and balance in mammals. However, it is not known how their lengths are maintained. Models have been made to study possible mechanisms for actin filament maintenance in cellular protrusions, but they rely on actin treadmilling, which recent work suggests does not occur in stereocilia. We modify an existing model of motor and cargo distributions in cellular protrusions to account for the absence of treadmilling. We consider cargo which is incorporated at the tip of stereocilia as would be typical of actin cross-linking proteins. The qualitative properties of the distributions do not change by removing retrograde flow from the model, but there is less cargo along the majority of the stereocilium with retrograde flow. With degradation of the motors and cargo, the proteins are concentrated at the tip of the stereocilium as is seen in experimental data.