Plasma Membrane Aquaporins in the Motor Cells of Samanea saman: Diurnal and Circadian Regulation

AUTOR(ES)

Moshelion, Menachem

FONTE

American Society of Plant Biologists

RESUMO

Leaf-moving organs, remarkable for the rhythmic volume changes of their motor cells, served as a model system in which to study the regulation of membrane water fluxes. Two plasma membrane intrinsic protein homolog genes, SsAQP1 and SsAQP2, were cloned from these organs and characterized as aquaporins in Xenopus laevis oocytes. Osmotic water permeability (Pf) was 10 times higher in SsAQP2-expressing oocytes than in SsAQP1-expressing oocytes. SsAQP1 was found to be glycerol permeable, and SsAQP2 was inhibited by 0.5 mM HgCl2 and by 1 mM phloretin. The aquaporin mRNA levels differed in their spatial distribution in the leaf and were regulated diurnally in phase with leaflet movements. Additionally, SsAQP2 transcription was under circadian control. The Pf of motor cell protoplasts was regulated diurnally as well: the morning and/or evening Pf increases were inhibited by 50 μM HgCl2, by 2 mM cycloheximide, and by 250 μM phloretin to the noon Pf level. Our results link SsAQP2 to the physiological function of rhythmic cell volume changes.

Documentos Relacionados

• Potassium Channels in Motor Cells of Samanea saman1: A Patch-Clamp Study
• Membrane-Delimited Phosphorylation Enables the Activation of the Outward-Rectifying K Channels in Motor Cell Protoplasts of Samanea saman.
• Extracellular Protons Inhibit the Activity of Inward- Rectifying Potassium Channels in the Motor Cells of Samanea saman Pulvini1
• Potassium-Efflux Channels in Extensor and Flexor Cells of the Motor Organ of Samanea saman Are Not Identical. Effects of Cytosolic Calcium1
• Potassium-Efflux Channels in Extensor and Flexor Cells of the Motor Organ of Samanea saman Are Not Identical. Effects of Cytosolic Calcium1