CHEMOATTRACTION INTETRAHYMENA: ON THE ROLE OF CHEMOKINESIS

Abstract

Chemoattraction of Tetrahymena pyriformis, strain GL, was measured during starvation and under different growth conditions. Log phase cells starved in buffer are attracted by certain amino acids, peptides, and proteins. Cysteine, methionine, and phenylalanine are attractants at 1CT 4 M. The peptides in proteose peptone (PP) and yeast extract (YE) are active at 10~ 6 M. Epidermal growth factor (EOF) is active at >3 X 10~ 5 M. Among the proteins, platelet derived growth factor (PDGF) is the most active (3 X 10 8 M}. Cells growing in denned medium are attracted by PP, YE, and some proteins (PDGF).Swimming speed was measured for starved cells with and without added attractants or repellents. With addition of PP the swimming speed increases from 0.42 to 0.51 mm/s., but for PDGF it is unchanged. The swimming speed of starved cells increases when the cells approach a solidified attractant (PP) as measured by the speed at a given distance. The speed of cells moving towards the attractant is higher than that of cells moving away from it.In conclusion, certain amino acids, peptides, and proteins are chemoattractants for Tetrahymena. Chemokinesis likely plays a considerable role in the case of PP (and YE), since they increase swimming speeds, whereas attraction by PDGF may involve chemotaxis.

Chemo-accumulation without changes in membrane potential in the microstome form of the ciliate Tetrahymena vorax

“…In agreement with earlier studies on Tetrahymena (Levandowsky et al, 1984;Hellung-Larsen et al, 1986;Leick and Hellung-Larsen, 1992;Koppelhus et al, 1994), we have shown that the microstome form of T. vorax is highly attracted to L-cysteine and the complex meat hydrolysate proteose peptone. The swimming behaviour of aggregated cells was studied in the 14th minute after exposure to the attractants and may reveal how cells continue to be aggregated in an attractive environment.…”

“…However, it has been reported that Lcysteine elicits an initial increase in swimming speed in Tetrahymena thermophila but the swimming speed returned to the control level during sustained exposure (Levandowsky et al, 1984). In T. pyriformis, the swimming speed was higher in cells stimulated by proteose peptone compared to unstimulated cells even after 12min exposure (Hellung-Larsen et al, 1986).…”

“…Amino acids are known to induce chemo-attraction in Tetrahymena (Hellung-Larsen et al, 1986;Levandowsky et al, 1984). Several amino acids were initially tested, and L-cysteine, which was among the most potent attractants, was selected for more detailed experiments.…”

“…Tetrahymena cells are attracted to various substances, such as amino acids, amines and peptides (Levandowsky et al, 1984;Hellung-Larsen et al, 1986). However, effects of chemo-attractants on the membrane potential in Tetrahymena have not been previously reported.…”

“…200 µm standard attractant in studies concerning behavioural responses in ciliates (Hellung-Larsen et al, 1986;Koppelhus et al, 1994). Therefore, we also examined the accumulation of microstome T. vorax cells in registration solution containing 1% proteose peptone.…”