Meeting Abstract
Squid, octopus and cuttlefish have a large and highly complex nervous system that supports a diversity of sophisticated behaviors. The complexity of the cephalopod nervous system evolved independently in molluscs and little is known about its ontogeny. The visual system is an excellent entry into the study of complex nervous systems, and to address fundamental questions in nervous system evolution and development we have established the squid Doryteuthis pealeii as a model for cephalopod visual system development. The cephalopod eye is a camera-type eye with a cup shaped retina and a single lens. The cephalopod retina has two morphologically identified cell-types organized into two distinct layers, the photoreceptor cells and the support cells. The cephalopod photoreceptors synapse directly on the optic lobe where signal processing takes place. Previous work showed that the cephalopod retina develops as a pseudostratified neuroepithelium and the photoreceptor cells exit the cell cycle when they differentiate. Cells found in the support cell layer are the only cells that continue to incorporate BrdU after hatching. Our previous work showed that Notch signaling is essential for proper neurogenesis in the retina and that losing Notch signaling leads to premature cell cycle exit. In an effort to better understand neurodifferentiation and organ physiology, we have generated a library of probes for in situ hybridization of genes expressed in the eye at hatching. Our goal is to use this “eye atlas” to better assess neurogenic phenotypes. In addition, we have performed an RNA-seq experiment on Notch inhibited and control retinas. We are using this sequencing data and our new cell type markers to better understand the role of Notch signaling during neurogenesis and how these processes contribute to the complexity of the cephalopod visual system.
