Clytia Hemisphaerica Background

Research in the Malamy lab is focused on epithelial wound healing in the emerging model system Clytia hemisphaerica.

Clytia is a small marine organism of the phylum Cnidaria and class Hydrozoa. Its life cycle includes a sessile polyp form and a medusa (jellyfish) form. Medusa start at less than 1mm and grow to about 0.5cm.

Life cycle of Clytia hemisphaerica

A visual representation of the life cycle of Clytia
Ryan et al., 2006

Below you can see a video of a fully grown Clytia medusa swimming happily in a dish in the lab. This medusa is about 0.5cm in diameter.

Clytia as a model for epithelial wound healing

Many features of the Clytia medusa make it an excellent model for studying epithelial wound healing.  Epithelial cells form a simple monolayer on the upper surface of the medusa. These cells can be gently scratched to create a wound. The transparency of the system makes it ideal for imaging.

Clytia hemisphaerica damaged and healed
A Clytia medusa is shown from the top and side (upper panels). In the lower panels, DIC imaging was used to visualize an intact (left) and wounded (right) epithelium.

Clytia are torn in these regions for testing
We create wounds by gently scratching the surface of the animal with a pipette tip and mounting it on a depression slide.

Wounds in Clytia heal very rapidly (~3-6 mm2/min2), 100X+ faster than other reported systems, as seen in this time-lapse movie that spans the 50 minutes after wounding.
This was our first time-lapse movie of wound healing in Clytia – MBL 2015.

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Epithelial wounds heal using mechanisms that have been seen in other invertebrates as well as vertebrates such as ourselves. These mechanisms include:

1. Cell Spreading & Lamellipodia-based Cell Crawling. Total time elapsed: 55 minutes

3. Collective Cell Migration.
Total time elapsed: 16 minutes

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This tells us that these wound healing mechanisms are likely to be very ancient, before the divergence of the cnidarian lineage from the bilaterian lineage ~600 million years ago.
Tree from Ryan et al., 2006, annotated to show the predicted emergence of wound healing mechanisms

Morphological Mechanisms Diagram