The micromechanics of the lateral line system of zebrafish

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Project Description for"The micromechanics of the lateral line system of zebrafish."Fish have a sixth sense that detects the flow of water around their bodies. This ability, known as"distant touch" or the lateral line sense, allows fish to find the direction of flow in a stream, detect obstaclesin the dark, coordinate schooling, locate prey, and avoid predators. Despite the broad importance of thelateral line sense to the behavior and ecology of fish, it is not understood what mechanical information thelateral line organ extracts from its environment. The work proposed by Dr. McHenry will examine themechanics of individual lateral line structures in order to understand how they filter the mechanical signalsthat facilitate flow sensing.The lateral line detects water movement with an array of microscopic, finger-like structures thatproject from the surface of the body. Each structure, known as a superficial neuromast, is composed of agelatinous cylinder that is anchored at its base to a group of hair cells, which is the type of mechanosensorycell found in the human ear. Water movement over the body's surface causes a deflection in the neuromastthat is transduced into a nervous signal by the hair cells. The properties of this signal depend of how muchthe neuromast deflects in response to flow, which depends on its shape and material stiffness.In order to examine the mechanics of superficial neuromasts, McHenry and collaborators will uselarval zebrafish because their transparent bodies allow superficial neuromasts to easily be observed andmanipulated. By measuring the deflection of neuromasts in response to a push by a force probe, they willcalculate their material stiffness. The shape of neuromasts will be measured from a series of high-resolutionimages at varying distance away from the body's surface. These measurements will provide the basis of amathematical model that treats the neuromast as a flexible beam anchored to a stiff spring.This model will allow investigators to consider how flow speed affects the signals filtered by theneuromasts and how different neuromast shapes and their position on the body affects the signals that theydetect. With this understanding for the mechanics of superficial neuromasts, neurobiologists andbehavioral biologists may consider what mechanical signals the lateral line system uses for schooling,obstacle avoidance, and predator/prey interactions.