"Reaching the wind": Fluid dynamical effects of boundary layer thickness on Neurospora conidiophore length

Short abstract: We will perform physical experiments and develop image analysis tools to determine how filamentous fungi measure and respond to the physics of their local environment.

Long Abstract: Filamentous fungi are ubiquitous, successful in almost every terrestial environment, and extraordinarily diverse. But we understand very little about their dispersal strategies. In this project we will try to dissect the physics and biology underlying the growth of conidiophores - structures used by the hyphae to disperse their asexual spores. It is thought that winds in the environment surrounding the conidiophores, which grow to heights of centimeters, liberate the spores. To do this, the conidiophores must reach through a boundary layer of nearly still air, mm, or even centimeters in thickness, to reach the dispersive winds beyond. But how does the fungus measure the thickness of the boundary layer? We hypothesize that it measures wind speed at the conidiophore tips by measuring the rate of evaporation from the conidiophores, rather like we sense wind speed and direction by licking a finger and holding it aloft. We will design and build simple apparatus to manipulate this rate of evaporation, by altering wind speeds and ambient humidity levels.