Suppression of S-methylglutathione-induced tentacle ball formation by peptides and nullification of the suppression by TGF-beta in Hydra

Tentacle ball formation (TBF) in Hydra elicited by S-methylglutathione (GSM ) was modulated by a number of biologically active peptides. Hydra fed on A rtemia, which had been hatched in a common salt solution supplemented with LiCl and ZnCl2, easily induced TBF in response to GSM after pretreatment wi th trypsin. After Hydra were treated with 100 pg/ml trypsin for 10 min. the response to GSM (TBF) was sensitively suppressed by acidic fibroblast grow th factor and other biologically active peptides for >10 h. Various peptide s, but not transforming growth factor beta (TGF-beta), suppressed GSM-induc ed TBF ind specific pattern for each peptide. However, TGF-beta was unique in that it did not suppress the response to GSM, but nullified the suppress ive effect of other peptides. Only active TGF-beta nullified the suppressiv e effect of the peptides, and the latent form of TGF-beta neither suppresse d GSM-induced TBF nor nullified the suppressive effect of other peptides. M embers of the TGF-beta family suppressed GSM-induced TBF. These results ind icate that all peptides examined, except for TGF-beta, suppressed the respo nse to GSM in a manner specific to each peptide. This assay system would be useful in identification of biologically active peptides.