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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 314

Phillip E. Ryals and Harriett E. Smith-Somerville; Studies of Macrostome Formation of Low-Transforming Tetrahymena vorax. Transformation Enhancers, Generation Time, and Membrane Fluidity. J.Protozool. 33(3):382-387, 1986

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Periodically, stocks of Tetrahymena vorax, which normally yield 70-90% macrostomes when subjected to heat shock or other induction methods, become low-transformers and yield < /_ 30% macrostomes. The addition to the post-heat-shock wash buffer (pH 6.8) of 2.7x10E-4 M Fe3+, 1.6x10E-5 M Cu2+, 1x10E-4 M retinol palmitate or the adjustment of the buffer to a pH of 4 to 5 boosts transformation significantly over controls in inorganic medium alone. The addition of Fe2+ or Cu+ has a similar, but less pronounced effect on transformation. Ferric ion (2.7x10E-4 M) will significantly increase transformation in starved non-heat-shocked cells, whereas Fe2+, copper, retional palmitate, and hydrogen ion concentration have no effect. The agents that boost transformation appear to act by delaying cell division in pre-transformants. Membrane fluidity, as inferred by fluorescence polarization measurements of 1,6-diphenyl-1,3,5-hexatriene, is altered in a consistent manner by starvation and heat shock. Enhancing agents, including compounds previously shown to boost heat-shock-induced macrostome formation, produce diverse shifts in membrane fluidity. Their effect on transformation of these low-transforming cells therefore appears to be attributable to some mechanism or mechanisms other than a direct alteration of membrane physical properties.