Poly(Ethylene Oxide), a New Slowing Agent for Protozoa

Abstract

Water-soluble, viscoelastic resin Polyox (WSR 301), a poly(ethylene oxide) of high MW (.apprx. 4 million) is introduced as a new slowing agent for Protozoa. Generally, as the kinetic viscosity of the resin increased from 0.25% to 1% (w/v), the swimming velocity of Euglena gracilis, Didinium nasutum, Paramecium aurelia, Blepharisma undulans and Prorodon platyodon decreased. The 1.0% solution had the highest viscosity and decreased velocity more effectively than 1.0% methyl cellulose and Protoslo solutions. Polyox solutions differed from those of methyl cellulose and Protoslo by having, in addition to viscous drag, an elastic recoil that pulled the Protozoa backwards when their swimming efforts stopped. Toxicity of these slowing agents was determined using 10 P. aurelia/test slide preparation. Paramecium numbers decreased in 1.0% methyl cellulose and Protoslo to .apprx. 0 by 24 h; in Polyox, not only were most of these ciliates alive after 24 h, but many survived for 96 h and divisions occurred in 0.25% and 0.50% solutions.