ABSTRACT
The vertebral hormone, atrial natriuretic peptide (ANP) has characteristic effects in Tetrahymena cells. ANP is able to induce the release of sodium ions, probably via the membrane rather than the contractile vacuole. The hormone is a potent inhibitor of Chinese ink-phagocytosis. A 10(-12) M concentration of ANP has the maximum positive effect on the division of cells but long-term treatments indicate the presence of a down-regulation-like mechanism. ANP has a strong chemoattractant characteristic between 10(-13) and 10(-11) M concentrations. Significant concentration dependent FITC-ANP binding at pretreatments of 10(-12) M suggest the presence of special receptor-dependent mechanisms which are responsible for the development of hormonal imprinting. The similarities between the most effective concentrations (10(-13) - 10(-12) M) and the human serum level of ANP shows that the effects of ANP have a more evolutionary background than previously considered.
Subject(s)
Atrial Natriuretic Factor/pharmacology , Tetrahymena pyriformis/drug effects , Animals , Chemotaxis/drug effects , Models, Biological , Sodium-Potassium-Exchanging ATPase/drug effects , Tetrahymena pyriformis/growth & developmentABSTRACT
The peptide type hormones such as insulin and adenocorticotropic hormone (ACTH) have a positive chemoattractant effect on Tetrahymena. Non-hormone protein-sulphate provoked negative chemoattraction. Of the amino acid type hormones, serotonin produced negative, and the histamine and di-iodotyrosine induced positive chemotactic effects. The first encounter with these molecules may modify the chemotactic behaviour of the progeny cells. In a significant number of cases there was a different response after repeated encounters of cells and hormones.
Subject(s)
Chemotaxis/drug effects , Hormones/pharmacology , Tetrahymena pyriformis/physiology , Adrenocorticotropic Hormone/pharmacology , Animals , Chemotaxis/physiology , Histamine/pharmacology , Insulin/pharmacology , Monoiodotyrosine/pharmacology , Protamines/pharmacology , Serotonin/pharmacology , Tetrahymena pyriformis/drug effectsABSTRACT
The peptides secreted by Tetrahymena cells into inorganic medium were chromatographed. Six fractions showing a marked enzyme-like activity were examined for influence on certain physiological parameters of Tetrahymena. The enzymatically active fractions increased the phagocytic activity of Tetrahymena and decreased its binding capacity for lectins and hormone (insulin), but enhanced insulin imprinting at primary interaction. It remains to be clarified whether these effects were due to the enzymatic or other components of the fractions investigated, or to lack of the compensatory influence of the fractions not studied.
