Meeting Abstract
P1.179 Saturday, Jan. 4 15:30 Regional specialization of posterior lateral line efferent neurons in the hindbrain of larval zebrafish SMITH, C.A.*; HAEHNEL-TAGUCHI, M.; LIAO, J.C.; The Whitney Lab for Marine Bioscience/Department of Biology, University of Florida, St. Augustine, FL 32080; The Whitney Lab for Marine Bioscience/Department of Biology, University of Florida, St. Augustine, FL 32080; The Whitney Lab for Marine Bioscience/Department of Biology, University of Florida, St. Augustine, FL 32080 cat.smith@whitney.ufl.edu
The hair cells contained in the neuromasts of the flow-receptive lateral line system in fishes are directly innervated by two populations of efferent neurons. It has been proposed that the efferent system protects neuromasts from desensitization during motion-induced self stimulation and improves signal to noise levels. Efferent cell bodies are located in the octavolateralis efferent nucleus (OEN) and are subdivided into rostral and caudal efferent neurons (REN and CEN, respectively) without knowledge of their post-synaptic targets. To investigate to which posterior lateral line neuromasts the RENs and CENs are connected, we electroporated fluorescent dyes into efferent terminals at specific neuromasts. First, we labeled each neuromast in the trunk posterior lateral line (n = 5 fish), and found that only one REN and two CEN innervate about a dozen neuromasts. We next labeled pairs of neuromasts with two fluorescent dyes of different wavelengths to look at their position relative to each other in the hindbrain. We found that 57.7% of the most rostrally located neuromasts (L1, n = 26 neuromasts) are connected to the REN, while 80.8% were connected to a single CEN. In contrast, L2 (n = 10) and L5 (n = 13) neuromasts were not innervated by the REN but always connected to one or both CENs. By showing that the REN exclusively innervates one rostral trunk neuromast, while one of the CENs specifically innervates more caudal neuromasts, we demonstrate a regional hindbrain specialization of the efferent lateral line system based on peripheral neuromast location in larval zebrafish.
