[Transport of ions in mitochondria in connection with osmotic concentration of media]. / Peredvizhenie ionov v mitokhondriiakh v sviazi s kontsentratsiei osmotika v srede.

Studies on mitochondria has revealed apparent violation of laws of osmosis, apparently, related to ion transport. In this context, we studied changes in the content of potassium, sodium, magnesium, and calcium in mitochondria from wheat (Triticum aestivum L.) roots incubated in the buffer without the substrate with 0.3 or 0.5 M sucrose as well as potassium, and phosphate. The most pronounced changes were observed for potassium. Potassium arrival to mitochondria was more active at 0.5 than 0.3 M sucrose. The direction of the cation transport depended on its content in the initial buffer. At the certain threshold level, the inflow was replaced with the outflow; this threshold was lower at 0.3 than 0.5 M sucrose. Magnesium was also released from mitochondria; its stable outflow was primarily observed at its lower initial content in the suspension at 0.3 rather than 0.5 M sucrose. The obtained data demonstrated that the apparent violation of laws of osmosis was false and resulted from ion transport. Passive ion transport as a possible mechanism of adaptation to osmotic properties of the external medium is discussed.

[Mitochondria respiration in developing sunflower seeds]. / Dykhanie mitokhondrii razvivaiushchikhsia semian podsolnechnika.

We studied the oxidative and phosphorylative activity of mitochondria in the seeds of three sunflower cultivars (Polevik, Peredovik, and Yubileinyi) during development of the seed embryo within 1 to 54 days after flowering. The rates of succinate oxidation by the mitochondria were 1.5-2 times those of malate or alpha-ketoglutarate oxidation. The ratio of substrate oxidation rates underwent changes during the seed growth. The differences were recorded between cultivars as concerns the times when the maximum oxidation rates were reached. Oxidation was coupled with phosphorylation during the entire period of seed development: the value of respiratory control after Chang changed from 1.4 to 7. By the time of transition to maturation, the rates of oxidation of both substrates and the values of respiratory control and ADP/O decreased. The results we obtained suggest that by days 13-15 of seed embryo growth, the rate of ATP production decreases upon oxidation of Krebs cycle products.