Cadmium- and flood-induced anoxia stress in pea roots measured by electrical impedance.

Electrical impedance measurement--complex resistance in the presence of alternating current--is a useful tool for the investigation of structural characteristics of solid materials but also for plant tissues. This measurement is easily done: only two electrodes are inserted into the plant tissue, so it can be considered as a non-invasive technique and it may be a successful method for detecting structural changes in plants caused by environmental stresses. The effects of flood and cadmium stress were investigated by electrical impedance measurement, because both of them cause structural changes in plant tissues.

Electric field promotion of the bacteriorhodopsin BR570 to BR412 photoconversion in films of Halobacterium halobium purple membranes.

The combined action of electric field (105-107 V x m-1) and light (380-580 nm, 80 W x m-2) activating the photoenergetic reaction of bacteriorhodopsin (BR) in dry films of purple membranes from Halobacterium halobium was studied. A new stimulating effect of the field on the BR412 intermediate accumulation in the normal photochromic cycle of BR570 has been observed. The formation of the product BR412 is supposed to be accompanied by specific rearrangements of certain charged, polar and polarizable groups in the BR pigment-protein matrix.

Electric field-induced polarization of photosynthetic membranes and reaction centers of Rhodopseudomonas sphaeroides, strain 1760-1.

Electric fields of 10(5) V/cm cause the polarization of chromatophore and reaction center films prepared from photosynthesizing purple bacteria. Photosynthetic pigments, and in particular carotenoids, the absorption spectra of which are changed in response to electric fields (electrochromism), may serve as intrinsic indicators of the development of a polarized state. Polarization occurs due to changes in the orientation and the spatial position of different charged groups and particles.