PT  - JOURNAL ARTICLE
AU  - Leslie S. Babonis
AU  - Camille Enjolras
AU  - Abigail J. Reft
AU  - Brent M. Foster
AU  - Fredrik Hugosson
AU  - Joseph F. Ryan
AU  - Marymegan Daly
AU  - Mark Q. Martindale
TI  - Knockout of a single <em>Sox</em> gene resurrects an ancestral cell type in the sea anemone <em>Nematostella vectensis</em>
AID  - 10.1101/2021.09.30.462561
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.09.30.462561
4099  - http://biorxiv.org/content/early/2021/10/01/2021.09.30.462561.short
4100  - http://biorxiv.org/content/early/2021/10/01/2021.09.30.462561.full
AB  - Cnidocytes are the explosive stinging cells found only in cnidarians (corals, jellyfish, etc). Specialized for prey capture and defense, cnidocytes are morphologically complex and vary widely in form and function across taxa; how such diversity evolved is unknown. Using CRISPR/Cas9-mediated genome editing in the burrowing sea anemone Nematostella vectensis, we show that a single transcription factor (NvSox2) acts as a binary switch between two alternative cnidocyte fates. Knockout of NvSox2 caused a complete transformation of nematocytes (piercing cells) into spirocytes (ensnaring cells). The type of spirocyte induced by NvSox2 knockout (robust spirocyte) is not normally found in N. vectensis but is common in sea anemones from other habitats. Homeotic control of cell fate provides a mechanistic explanation for the discontinuous distribution of cnidocyte types across cnidarians and demonstrates how simple counts of cell types can underestimate biodiversity.Competing Interest StatementThe authors have declared no competing interest.