[Changes in lipid composition and respiratory activity of wheat roots treated with inhibitor of phosphoinositide cycle of lithium ions]. / Izmeneniia lipidnogo sostava i dykhatel'noi aktivnosti kornei prorostkov pshenitsy pri deistvii ingibitora fosfoinozitidnogo tsikla ionov litiia.

A study was made of the effect of lithium ions (5 mM LiCl) on the growth and respiration of roots of 2-5 day old wheat seedlings, composition of phospholipids, free fatty acids and sterols, and superoxide radical generation. Significant growth depression was shown in roots treated with lithium, increasing with age of seedlings. The growth of seedlings on a 5 mM LiCl containing medium influenced the lipid composition in roots. In the roots of these seedlings phospholipid contents increased along with a decrease in free fatty acids, and the ratio of sterol/phospholipids, while superoxide radical production was stimulated. Lithium stimulated oxygen consumption of excised roots of 5 day old seedlings. Due to its physical and chemical properties lithium is supposed to be able to disrupt gradients of Ca2+, H+, K+, and to lead to a partial blockade of signal transduction for triggering proliferation via the phosphoinositide cycle. Changes in the lipid composition, increase in the membrane permeability for ions, and respiration of roots of seedlings grown in LiCl-containing medium are presumably associated with growth depression and juvenility of roots.

[Effect of lithium ions on the growth of wheat roots and the role of phosphoinositide cycle in growth regulation]. / Vliianie ionov litiia na rost kornei pshenitsy i rol' fosfoinozitidnogo tsikla v reguliatsii rostovykh protsessov.

The influence of lithium ions (LiCl in concentrations of 0.5, 1.0, and 5.0 mM) on the growth processes of roots of 2-5-day old wheat seedlings was studied. It was shown that the inhibition of the root growth increased with the increase of LiCl concentration and seedling age. The membrane potential of root cells was lower and the loss of K+ by cells was greater when roots were treated with 5 mM LiCl, compared with the control. The growth inhibition by lithium was decreased by univalent ions, partially by potassium at the beginning of growth and completely by sodium throughout the experimental period. The divalent ions calcium and barium decreased the Li(+)-induced inhibition of root growth by reducing the rate of lithium uptake by cells. Myoinositol, controlled by Li-sensitive inositolmonophosphatase, reversed the Li-induced root growth inhibition in 2-day old seedlings, but did not prevent the inhibition during subsequent elongation. It can be concluded that lithium effects on wheat root growth are mediated by a partial blockage of signal transduction for proliferation (via the phosphoinositide cycle), because of calcium deficiency and caused by modification of ion transporting systems of the plasmalemma, and by disturbance of ion gradients, primarily H+ and K+.

[Energy metabolism in wheat roots during modification of cell surface]. / Energeticheskii obmen kornei psenitsy pri modifikatsii kletochnoi poverkhnosti.

A study was made of dynamics of wheat production, intensity of respiration and changes in bioelectric characteristics of exised roots. Response reactions of two wheat varieties were compared in the process of adaptive reactions. The varieties differed in bioelectric characteristics of root cells in intact seedlings grown in CaCl2 and EDTA containing media. Different changes of membrane characteristics of root cells were observed: in soft wheat MP and Rin increased, but in hard wheat these decreased after a 5 h incubation of excised root. The rate of heat production was at the same level in both wheat varieties, but oxygen absorption of the root cells was lower in hard wheat compared with soft wheat. The rate of respiration of excised roots was stable in EDTA-containing medium. The obtained data allow to discuss more in detail the role of Ca(2+)-ions in the regulation of cell functions under formation of adaptive processes as the tissue level.