J. O. D. Coleman

Use of an electrochemical technique to study plasmamembrane redox reactions in cultured cells of Daucus carota L.

By exploiting the electron transfer reactions of ferricyanide-ferrocyanide at a gold electrode, an electrochemical technique was devised and successfully employed for the measurement of extracellular ferricyanide reduction or ferrocyanide oxidation by carrot (Daucus carota L.) cells grown in suspension culture. This technique eliminated problems of cell damage and insensitivity encountered when these activities are measured spectrophotometrically in magnetically stirred cell suspensions. Cells harvested from the mid-exponential phase of culture growth catalysed a rapid reduction of ferricyanide which was accompanied by H+ extrusion and was stimulated by ethanol. These cells also oxidised ferrocyanide, which was not associated with H+ extrusion. These observations can be explained on the basis of a plasmamembrane located, H+-translocating redox system. The electrochemical technique is a useful method of studying this system.

Antibodies to brain clathrin recognise plant coated vesicles

Coated vesicles isolated from carrot suspension culture cells were immune-blotted against four antibodies to porcine brain clathrin. Positive cross-reaction was obtained with three antibodies. Two of these cross-reacted with both the heavy clathrin chain and the putative light chains. Three out of five antibodies immunofluorescently stained permeabilised carrot suspension culture cells.

Recent advances in the study of plant coated vesicles

Abstract Coated vesicles are organelles common in plant cells. They are associated with the plasma membrane, Golgi apparatus, partially coated reticulum and multivesiclular bodies. In this paper we discuss recent developments in the use of immunochemistry and cytochemistry to investigate the structure and function of plant coated vesicles.