title: Behavioral responses of the ciliated protozoan Paramecium caudatum to 2,4-dichlorophenoxyacetic acid and its analogues.
abstract: We found that the ciliated protozoan Paramecium caudatum ON-1 was repelled by 2,4-dichlorophenoxyacetic acid (2,4-D). P. caudatum was also repelled by phenoxyacetic acid, while it was attracted to benzoic acid. No significant behavioral response was detected with 2,4-dichlorophenol (2,4-DP) and phenol. These results suggested that the substitution of-OH of phenol with -OCH2COOH, but not the chlorination of phenol, was important for eliciting the avoiding response to 2,4-D in P. caudatum. Electrophysiological analysis revealed that 2,4-D and phenoxyacetic acid were able to trigger the action potential in P. caudatum, whereas 2,4-DP and phenol failed to elicit electrical responses in this organism. Well test assays suggested that the avoiding reactions allowed P. caudatum to escape from the harm caused by this herbicide.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan. tackey@hiroshima-u.ac.jp
authors.forename: Noboru
authors.initials: N
authors.lastname: Takiguchi
authors.forename: Takahisa
authors.initials: T
authors.lastname: Tajima
authors.forename: Kosei
authors.initials: K
authors.lastname: Asayama
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Ikeda
authors.forename: Akio
authors.initials: A
authors.lastname: Kuroda
authors.forename: Junichi
authors.initials: J
authors.lastname: Kato
authors.forename: Hisao
authors.initials: H
authors.lastname: Ohtake