INDUCTION OF DIGOXIN-LIKE MATERIAL PRODUCTION, AND THE DIGOXIN BINDING IN THE UNICELLULAR ORGANISMTETRAHYMENABY DIGITOXIN

Abstract

Thin layer chromatographic, and laser-confocal microscopic analyses with a monoclonal antibody to digoxin also displaying high affinity to digoxigenin, were used to determine the presence and localization of cardioactive glycosides.Tetrahymena pyriformiswas found to possess digitoxigenin-like material, but digoxin, digitoxin, digoxigenin, gitoxin and lanatoside C were not detected. Digitoxin treatment elicited the appearance of a digoxin-like material in the progeny generations. Digoxin was taken up by untreatedTetrahymena, especially strongly 24h after digitoxin treatment. While the cardenolide was localized in vesicles of the cell body in untreatedTetrahymena, the engulfed digoxin appeared in the epiplasmic layer and also in the cilia after digitoxin pretreatment. Digoxin pretreatment did not increase digoxin uptake. These data indicate thatTetrahymenahas: (1) the capacity to discriminate between closely related molecules; (2) the ability to induce digoxin-like material production; and/or (3) enzymes that can effect a digitoxin–digoxin transformation.