This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (27) Citing Articles via Google Scholar Google Scholar Articles by Satter, R. L. Articles by Galston, A. W. Search for Related Content PubMed PubMed Citation Articles by Satter, R. L. Articles by Galston, A. W. Agricola Articles by Satter, R. L. Articles by Galston, A. W.

Articles

Rhythmic Leaflet Movement in Albizzia julibrissin

Effect of Electrolytes and Temperature Alteration ¹

^a Department of Biology, Yale University, New Haven, Connecticut 06520

The rhythmic movement of darkened Albizzia leaflets is accompanied by K⁺ flux in pulvinule motor cells whose turgor changes control opening and closing. The azide-sensitive open phase is promoted by an increase in temperature from 16 to 33C (Q₁₀ = 3), implying active transport of K⁺ ions during this period. The azide-insensitive closed phase is less temperature-sensitive and has a Q₁₀ less than 1, implying diffusion or some other physical process as the predominant pathway of K⁺ flux at this time. Thus rhythmic leaflet movement is probably due to oscillation in active K⁺ transport or membrane permeability or both. External electrolytes (0. 1 N) alter leaflet angle during the open, but not the closed, phase of the rhythm. All chlorides except NH₄⁺ promote opening, with divalent more effective than monovalent ions. Some anions promote and others inhibit opening; activity is not correlated with charge. It is likely that electrolytes alter leaflet movement by altering K⁺ flux, accomplishing this by interacting with key macromolecules in motor cell membranes.

Pfr phytochrome dampens the amplitude of rhythmic leaflet movement; this process is temperature sensitive (Q₁₀ = 2) and unaltered by 0.1 N salt solutions. Although K⁺ flux is a common basis for phytochrome and rhythmic control of leaflet movement, different mechanisms are clearly involved.

¹ This investigation was supported by a National Science Foundation grant to A.W.G.