Meeting Abstract
The lateral line system in fishes helps them sense the water flow in their environment, and is a powerful model to better understand the functional architecture of vertebrate hair cell systems. The lateral line is made up of neuromasts composed of bundles of mechanosensory hair cells. These hair cells are innervated by two types of neurons: afferent neurons and efferent neurons. The afferents receive information while the efferents can desensitize the lateral line system during self-generated motions. How efferent neurons are spatially organized? Specifically, we are interested in whether there is a somatotopic arrangement, as has been found for the afferent lateral line neurons. In order to visualize the efferent neurons in the hindbrain of 4-6 dpf larval zebrafish, Danio rerio, we used Islet GFP fish, a transgenic line that labels the efferent neurons. We backfilled the neuromasts along the body by electroporating rhodamine and Alexa 647 (MW 3000 and 10000) with Axoporator 800A (pulse train protocol 50-75v, square pulse, 5.5ms width, 1s duration). We performed live imaging with a Leica SP5 confocal microscope to see if there was a pattern in efferent neuron organization. We discovered that efferent neurons located caudally in the hindbrain innervated caudal neuromasts while efferent neurons located rostrally in the hindbrain innervated rostral neuromasts (n=3 fish). These findings indicate that efferent neurons are indeed dedicated to specific neuromasts along the body. In addition, we discovered fine afferent processes that we hypothesize would contribute to sensory integration between the left and right sides of the animal.
