Monovalent Ions and Stress-Induced Senescence in Human Mesenchymal Endometrial Stem Cells

Monovalent ions are involved in growth, proliferation, differentiation of cells as well as in their death. This work concerns the ion homeostasis during senescence induction in human mesenchymal endometrium stem cells (hMESC): hMESCs subjected to oxidative stress (pulse H2O2 treatment) enter the premature senescence accompanied by persistent DNA damage, irreversible cell cycle arrest, cell hypertrophy, lipofuscin accumulation, enhanced β-galactosidase activity. Using flame photometry to estimate K+, Na+ content and Rb+ (K+) fluxes we found that during the senescence development in stress-induced hMESCs, Na+/K+pump-mediated K+ fluxes are enhanced due to the increased Na+ content in senescent cells, while ouabain-resistant K+ fluxes remain unchanged. Senescence progression is accompanied by a peculiar decrease in the K+ content in cells from 800-900 µmol/g to 500-600 µmol/g. Since cardiac glycosides are offered as selective agents for eliminating senescent cells, we investigated the effect of ouabain on ion homeostasis and viability of hMESCs and found that in both proliferating and senescent hMESCs, ouabain (1 nM-1 µM, 24-48 h) inhibited pump-mediated K+ transport (ID50 5x10-8 M), decreased cell K+/Na+ ratio to 0,1-0,2, however did not induce apoptosis. Comparison of the effect of ouabain on hMESCs with the literature data on the selective cytotoxic effect of cardiac glycosides on senescent or cancer cells suggests the ion pump blockade and intracellular K+ depletion should be synergized with target apoptotic signal to induce the cell death.

Vitamin K Deficiency and Vascular Calcification. Is There Any Evidence about Its Impact on Coronary Artery Disease?

Nowadays cardiovascular disease remain globally the leading cause of mortality. Coronary artery disease is the predominant clinical entity related to fatal cardiovascular events, while its development is mostly associated with progressive atherosclerosis of the vessels combined with gradual vascular calcification. It is well described and understood that vascular calcification is strongly associated with the occurrence of CVD and increased mortality rates. Therefore, it is essential to understand the metabolic pathways leading to its formation in order to develop effective therapies. A group of vitamin-k dependent proteins seems to play a significant role on the prevention of the arterial wall. Several past studies have shown that in cases of vitamin-k deficiency the process of vessel calcification is accelerated. Vitamin-k depletion and high levels of uncarboxylated and dephosphorylated forms of the aforementioned proteins are considered as important factors that contribute significantly to this rapid progression. Promising studies are giving the stimulus for further research in the field of vitamin-k supplementation and the suspension of vascular calcification.

Subsoil-potassium depletion accounts for the nutrient budget in high-potassium agricultural soils

Continuous potassium (K) removal without replenishment is progressively mining Argentinean soils. Our goals were to evaluate the sensitivity of soil-K to K budgets, quantify soil-K changes over time along the soil profile, and identify soil variables that regulate soil-K depletion. Four on-farm trials under two crop rotations including maize, wheat and soybean were evaluated. Three treatments were compared: (1) control (no fertilizer applied); (2) application of nitrogen, phosphorus, and sulfur fertilizers -NPS-; and (3) pristine condition. After nine years, crops removed from 258 to 556 kg K ha−1. Only two sites showed a decline in the exchangeable-K levels at 0–20 cm but unrelated to K budget. Topsoil exchangeable-K levels under agriculture resulted 48% lower than their pristine conditions, although still above response levels. Both soil exchangeable-K and slowly-exchangeable K vertical distribution patterns (0–100 cm) displayed substantial depletion relative to pristine conditions, mainly concentrated at subsoil (20–100 cm), with 55–83% for exchangeable-K, and 74–95% for slowly-exchangeable-K. Higher pristine levels of exchangeable-K and slowly-exchangeable-K and lower clay and silt contents resulted in higher soil-K depletion. Soil K management guidelines should consider both topsoil and subsoil nutrient status and variables related to soil K buffer capacity.

Potassium isotope anomalies in meteorites inherited from the protosolar molecular cloud

Potassium (K) and other moderately volatile elements are depleted in many solar system bodies relative to CI chondrites, which closely match the composition of the Sun. These depletions and associated isotopic fractionations were initially believed to result from thermal processing in the protoplanetary disk, but so far, no correlation between the K depletion and its isotopic composition has been found. Our new high-precision K isotope data correlate with other neutron-rich nuclides (e.g., 64Ni and 54Cr) and suggest that the observed 41K variations have a nucleosynthetic origin. We propose that K isotope anomalies are inherited from an isotopically heterogeneous protosolar molecular cloud, and were preserved in bulk primitive meteorites. Thus, the heterogeneous distribution of both refractory and moderately volatile elements in chondritic meteorites points to a limited radial mixing in the protoplanetary disk.

In situ gamma ray survey for geological mapping of Kmetasomatized metavolcanics at Bükkszentkereszt, Bükk Mts, Hungary

The Middle-Upper Triassic Bagolyhegy Metarhyolite Formation of the Bükk Mts. (Hungary) hosts silicified bodies with high potassic feldspar content formed by Kmetasomatism. The rocks underwent a multistage deformation history including syn- and postmetamorphic folding and faulting. As the outcrop area is covered by soil and debris with some exposed silicified cliffs only, and potassium content is a characteristic feature of the metasomatized rocks, geological mapping was supported by a spectral gamma ray survey with a scintillation detector of NaI(Tl) crystal. A thunderstorm felling the beech forest made the soil horizon B also accessible in several pits, providing the opportunity to make measurements on the weathered debris instead of the topsoil (horizon A). Measurements in different arrangements were designed to test the effects of measuring time, measuring geometry and soil horizon. Our results show that concentration values obtained on the debris with a 2 min measuring time can be compared with those measured on exposed rock surfaces, producing a more reliable geological map than measurements on the topsoil with randomly variable K depletion. Pit geometry effects can be eliminated by the K/(eU+eTh) ratio. This results in a more realistic K distribution map if neither U nor Th enrichments are present. The survey successfully delineated the unexposed outcrop of K-enriched rocks on the survey area.

Long-term effect of low potassium fertilization on its soil fractions

In the Czech Republic, negative potassium (K) budget in agricultural soils is caused by non-fertilization by K and by a decline of manure application. We investigated soil available, fixed (acid-extractable, K_fix) and structural K pools in the field trial with graduated K application rate, established in 1972 at 8 sites of different climate and soils. The content of K-bearing minerals was evaluated on semi-quantitative scale by XRD diffraction. K-feldspars were a dominant source of structural K. Total soil K consisted of 1.7–7.1% of fixed K, which was in a positive relation to mixed-layer phyllosilicates. Differences in available K in treatments with K budget lower than –30 kg K/ha/year were small compared to those of fixed K. In control treatments, calculated average depletion of available K was –18 kg K/ha/year and the average depletion of fixed K was –12 kg K/ha/year; however at sites of higher altitude fixed K depletion prevailed. Fixed K accounted for 6–31% of the K budget. In negative K budget, monitoring of K_fix is advisable to avoid fertility loss of soil with low K supplying capacity.

Effect of GA3 on photosynthate allocation and invertase activity in radish plants grown on different potassium levels

The effect of GA₃ application to the swollen hypocotyl was studied in radish cultivars Saxa and Tetra Iłowiecka, supplied with various amount of K and grown in greenhouse in hydroponic culture. In low-K plants of both compared cultivars, strong depression of ¹⁴C0₂ assimilation preceded diminished export of current photosynthates. In plants with K⁺-deficit, transfer for 3 days from low- to high-K solution stimulated photosynthesis without effect on ¹⁴C-export. Three days after GA₃ treatment of the swollen hypocotyl ¹⁴C0₂ assimilation was stimulated while ¹⁴C-retention in the blades was diminished, but only in low-K plants. In Tetra low-K plants with poorly developed storage organs, treatment with GA₃ caused their better supply with current photosynthates at the expense of the roots. In the Saxa cultivar, the pattern of photosynthate allocation was only slightly affected by GA₃ even in K-deficient plants; the swollen hypocotyl was already developed before K depletion from the nutrient solution. Nevertheless, in Saxa plants, GA₃ prolonged not only growth of the storage organ, but also enhanced acid invertase which at that time was greatly diminished in low- and high-K plants. In contrast, the relatively high activity of invertase in Tetra cv. was not affected by GA₃ treatment in low-K plants and was even depressed in high-K plants. This suggests that growth and accumulation of substances in the storage organ of radish plants and acid invertase activity greatly differ in their response to applied GAY