Meeting Abstract
A long-standing hypothesis in the field of neuroethology has been that organisms performing similar behaviors have similar underlying neuronal circuitry. Recently, though, studies focused on locomotion have shown that this many not necessarily be true. Work in sea slugs has demonstrated that homologous behaviors can be generated by a variety of neuronal connections. Our work looks at reproductive behaviors and asks whether those behaviors are mediated by the same neuronal connections in two species of leech. Research in Hirudo verbana has shown that copulatory reproduction is mediated by a neurohormone, hirudotocin, which is stored in and is released from a circuit of characterized neurons called Leydig Cells. When this circuit is stimulated, a progression of fictive behaviors consistent with reproduction is induced. A second leech, Macrobdella decora, has the same reproductive strategy as H. verbana, including a similar progression of behaviors. Using immunohistochemistry and electrophysiology, we have identified Leydig Cell homologs in M. decora. Additionally, when we inject either M. decora or H. verbana with a hormone similar to hirudotocin, we observe reproductive-behavior output that is nearly identical. This may indicate that the underlying circuitry is similar. We intend to compare these species further through electrophysiological characterization of the Leydig cell network in M. decora. By fulling characterizing the Leydig Cell network in both species we will be able to clarify the relationship between reproductive behavior and neuronal circuitry in leeches and give insight as to how neural circuits evolve across species.
