Dr. Elizabeth Heath Heckman
Assistant Professor, Michigan State University
Personal Website

Beneficial bacteria influence epithelial and neuronal development
in the Hawaiian Bobtail Squid

Tuesday, November 19
11:30 AM
AHF 153 (Torrey Webb Room)

Abstract: Upon birth or hatching animals encounter myriad microbial species which can have wide-reaching effects as they develop.  The association between the Hawaiian Bobtail Squid (Euprymna scolopes) and its luminous symbiont (Vibrio fischeri) is one of the most powerful models for bacterial induction of host development.  The squid acquires its bacterial symbionts from the surrounding seawater, which then induce apoptosis in and regression of external epithelial appendages. As the signaling mechanisms which govern this process have yet to be fully elucidated, we performed an RNASeq analysis on appendages from animals undergoing this process. Our analysis of the pathways regulated by symbiosis revealed that many of the most highly regulated genes were those involved in neuronal development, guidance, and communication, such as the neuropeptide FMRFamide. We localized the FMRFamide peptide to neuronal processes throughout the light organ, but also to the blood sinus inside the appendage, where we confirmed an increase in staining in response to symbiosis. When localizing FMRFamide transcript, we found that instead of neurons the primary site of production appears to be the circulating immune cells that traffic to the blood sinus in response to symbiosis, providing evidence for a new function for this neuropeptide. Finally, preliminary data suggests that treatment with FMRFamide induces apoptosis in aposymbiotic animals, likely through the downregulation of nitric oxide production. These data suggest that FMRFamide is a novel, crucial aspect of bacterial-mediated development and the squid-vibrio symbiosis offers a unique opportunity to study the cross-talk between immunity, development, and neurobiology