Ctenophore Module

Ctenophores (‘comb-bearers’) are a monophyletic group of globally distributed gelatinous, primarily pelagic, marine predators. The sea walnut, Mnemiopsis leidyi, is a lobate ctenophore widely distributed along coastal Atlantic environments and can be found during summer months in Eel Pond, the NOAA jetty and other nearby harbors. The gelatinous adults produce a blue-green bioluminescence when disturbed, are self-fertile hermaphrodites, and typically release thousands of eggs in a single spawning event. Experimental embryologists have a long history of using Mnemiopsis for cell lineage analyses due to easy access to large numbers of synchronized, highly transparent, rapidly developing embryos. These studies have been instrumental in describing cell fates associated with a ctenophore specific invariant early cell cleavage program. Moreover, the Mnemiopsis leidyi genome has been sequenced, facilitating the adoption of functional genomics approaches to this model system. A resurgent interest in ctenophore biology stems from recent phylogenomic analyses that have highlighted the early branching relationship of ctenophores relative to other animal phyla, making Mnemiopsis a particularly interesting and informative system for investigating character trait evolution during metazoan diversification.

The ctenophore module will introduce students to Mnemiopsis as a ctenophore model system and provide a number of reagents for cellular/molecular biology that can be used to explore ctenophore embryonic development. Gametes and live embryos at different embryonic stages will be available for DIC and fluorescent imaging with the wide range of microscopy resources available to the course. Also single cell embryos for lineage tracing and CRISPR/Cas9 genome editing via microinjection will be available to students in the course.