Реферат: Untitled Essay Research Paper Involvement of K

An experiment with soybeans (Cronland) examined the role of K+ channels

and H+/ATPase in the plasma membrane in paraheliotropic movement. This was done by

treating the pulvini with the K+ channel blocker tetraethylammonium chloride (TEA), the

H+/ATPase activator fusicoccin, and the H+/ATPase inhibitors vanadate and erythrosin-B. In

all cases the leaf movements of the plant were inhibited, leading to the hypothesis that

the directional light results in an influx of K+ into the flexor cells from the apoplast

and an efflux of K+ from the extensor cells into the apoplast, and these movements are

driven by H+/ATPase pumps. This combined reaction results in the elevation of the leaflet

towards the light.

In this study, the diheliotropic movements of C. pallida are examined.

The purpose of this experiment is to determine which ions, if any, are used by pulvini

cells of Crotalaria pallida Aiton to control the uptake of water, thereby affecting

diheliotropic movement. As mentioned before, most studies investigating the mechanisms of

leaf movement have been performed on nyctinastic plants. These plants respond to light and

dark changes, not direction or intensity of a light stimulus. Therefore, it is of interest

to learn whether the same principles can be applied to diheliotropic movement.

Different inhibitors at varying concentrations will be injected

individually into the pulvinus of C. pallida, and the suntracking ability of the plant

will then be measured. Tetraethylammonium (TEA), a K+ channel blocker will be added to

test whether K+ is involved in suntracking. Likewise, , a Cl- channel blocker will be

added to determine if Cl- is used. Vanadate, a H+/ATPase inhibitor, will determine if

hydrogen ions are pumped across the plasma membrane, causing a hyperpolarization of the

membrane. Fusicoccin, a H+/ATPase activator will also be tested .