Davis D P, Fiekers J F, Van Houten J L
Department of Biology, University of Vermont, Burlington 05405-0068, USA.
Cell Motil Cytoskeleton. 1998;40(2):107-18. doi: 10.1002/(SICI)1097-0169(1998)40:2<107::AID-CM1>3.0.CO;2-C.
Paramecium are attracted to ammonium chloride solutions relative to sodium chloride control solutions, but little is known about the mechanisms by which attraction is evoked. A known effect of ammonium solutions in other cell types is an alteration of intracellular pH. We show here that intracellular pH is elevated upon initial exposure to 5 mM NH4Cl, but appears to decline within 10 minutes, both in wild type cells and in two mutants which do not show sustained attraction to NH4Cl using the standard behavioral assay, the T-maze. We also present quantitative values of swimming parameters that underlie the response to NH4Cl.
