Exploring Hydra Biology Using Chemical Genetics

Abstract

Studies using chemical genetics allow the researcher to perform the equivalent of classical genetics in real time using molecules that can produce a phenotype when applied to either cultured cells or a whole organism. We have initiated a chemical genetic screen using the AEP strain of Hydra vulgaris to identify bioactive molecules that modulate signaling pathways involved in development and regeneration. One compound, DAC‐2–25, induced the growth of ectopic tentacles in regenerating heads and buds. Chronic exposure to DAC‐2–25 induces ectopic tentacles in H. vulgaris AEP, H. vulgaris 950f, and H. viridissima , but not H. vulgaris Zurich. In chronically treated animals, the first ectopic tentacles appear just below the tentacle ring. Subsequent tentacles emerge in a wave down the body column. We are using AEP/Zurich chimeras to identify which cell lineage is targeted by DAC‐2–25. Structure‐activity relationship (SAR) studies have been initiated to determine what features of the molecule are required for activity. Ultimately we will use affinity chromatography coupled with mass spectrometry to identify the protein target of DAC‐2–25. Crosses of AEP and Zurich have been produced with the intention of doing bulk segregant analysis as an alternative approach to identifying the gene encoding the DAC‐2–25 target protein.