In Situ Potentiation of the Glutathione-binding Protein for the Tentacle Ball Formation by a Protease and Efficient Ingestion of Prey in Hydra

Abstract

Within minutes, brief treatment with trypsin potentiated tentacle ball formation in Hydra japonica, a new behavioral response to reduced glutathione. With the potentiation of this behavioral response, new glutathione-binding proteins were immediately detected after the trypsin treatment of live Hydra, indicating that trypsin activated the glutathione-binding protein in situ. Fixed brine shrimp ( Artemia francisca) were more efficiently ingested in the presence of trypsin and S-methylglutathione (GSM) than in the presence of GSM alone, suggesting a biological role of this behavioral potentiation by trypsin in the feeding chain of Hydra. Ingestion of live A. francisca was significantly reduced in the presence of soybean trypsin inhibitor, suggesting that a protease, possibly released from the wounded prey, plays a role in the feeding in vivo. As for Hydra swallowing its captured prey, a small hydra head piece was isolated and measured as it crept along a thin nylon line; advancement of the head was the same in the presence of both GSM alone, and in that of GSM and trypsin together. Together, these results indicate that the chemoreceptor potentiated in situ by a trypsin-like protease specifically evokes tentacle ball formation resulting in an efficient transfer of prey on the tentacle to the mouth.