Zebrafish Transgenic Constructs Label Specific Neurons inXenopus laevisSpinal Cord and Identify Frog V0v Spinal Neurons
A correctly functioning spinal cord is crucial for locomotion and communication between body and brain but there are fundamental gaps in our knowledge of how spinal neuronal circuitry is established and functions. To understand the genetic program that regulates specification and functions of this circuitry, we need to connect neuronal molecular phenotypes with physiological analyses. Studies usingXenopus laevistadpoles have increased our understanding of spinal cord neuronal physiology and function, particularly in locomotor circuitry. However, theX. laevistetraploid genome and long generation time make it difficult to investigate how neurons are specified. The opacity ofX. laevisembryos also makes it hard to connect functional classes of neurons and the genes that they express. We demonstrate here that Tol2 transgenic constructs using zebrafish enhancers that drive expression in specific zebrafish spinal neurons label equivalent neurons inX. laevisand that the incorporation of aGal4:UASamplification cassette enables cells to be observed in liveX. laevistadpoles. This technique should enable the molecular phenotypes, morphologies and physiologies of distinctX. laevisspinal neurons to be examined togetherin vivo. We have used anislet1enhancer to label Rohon-Beard sensory neurons andevxenhancers to identify V0v neurons, for the first time, inX. laevisspinal cord. Our work demonstrates the homology of spinal cord circuitry in zebrafish andX. laevis, suggesting that future work could combine their relative strengths to elucidate a more complete picture of how vertebrate spinal cord neurons are specified, and function to generate behavior.