Oats are one of the most useful and widespread cereal crops in the world. In permafrost conditions (Central Yakutia), based on metabolic changes in late summer-sown oat plants (Avena sativa L.), the key processes involved in the cold acclimation of a valuable cereal species were identified. During the onset of low ambient temperatures, metabolites from leaf samples were profiled using gas chromatography with mass spectrometry (GC-MS) and were analyzed using principal component analysis (PCA). A total of 41 metabolites were identified in oat leaves. It was found that acclimation to suboptimal temperatures during the fall period leads to biochemical (accumulation of mono- and disaccharides and decrease in fatty acids and polyols) as well as physiological and biophysical changes (decrease in leaf PRI reflectance indices and chlorophyll a fluorescence). Therefore, the study contributes to a more holistic understanding of oat metabolism under low-temperature cryolithozone stress. It is believed that the analysis of changes in leaf reflection properties and JIP-test parameters of chlorophyll a fluorescence using leaf metabolomic profiling can be used in the selection of valuable varieties of cereal crops to obtain plant fodders with high nutrient contents under conditions of a sharply continental climate.

In the work, the properties of graphene oxide processed in methane plasma and plasma of a mixture of methane and nitrogen and subjected to subsequent annealing at T = 650 ° C in an argon atmosphere are investigated. It is shown that during plasma treatment, the hydrogenated amorphous carbon film is deposited on the surface of the exhaust gas. During heat treatment, a significant part of this film is removed, another part of the carbon atoms participates in the formation of bonds with the structure of the exhaust gas. This process leads to a decrease in the density of defects introduced by the plasma. The inclusion of nitrogen in methane plasma leads to n or p doping depending on the plasma power level. This effect is explained by the predominant formation of graphite and pyridine nitrogen configurations, which are donor centers in structures with fewer defects. At a high density of defects, pyrrole nitrogen structures, which are acceptor centers, are mainly introduced.

This paper presents the results of an observational study carried out for monitoring three sites along the Moskva River with different pollution levels by using chlorophyll fluorescence parameters. The photosynthetic activity of phytoplankton along the river bed was diverse. The photochemical activity of the phytoplankton was higher in the relatively clean water of the river (the entrance of the river to the city) and lower in the polluted water (middle reaches of the river and at the exit of the city). The efficiency of the light reactions of photosynthesis in photosystem II (F_V/F_M, PI_ABS) for the phytoplankton was higher in the spring than in the summer months. These processes were accompanied by a decrease in the dissipation of absorbed energy into heat (φ_Do). Incubation of the phytoplankton from the Moskva River in the presence of mercury chloride salts was performed. It was found that addition of mercury chloride salts resulted in different sensitivity to the toxic effects of phytoplankton samples collected from different sites along the river, as well as lower resistance of phytoplankton to mercury in summer season compared to that in the spring. The most sensitive parameter to the toxic effects of mercury was the photosystem II performance index (PI_ABS), which can be recommended for bioassay and biomonitoring of the activity of photosynthetic reactions of phytoplankton in natural conditions.

Исследование структуры бивня мамонта методом ИК спектроскопии

The effect of a dangerous toxic substance, methylmercury, on light dependence curves of chlorophyll fluorescence in Chlamydomonas moewusii was studied. We found low concentration of methylmercury (10(-7) M) to cause a decrease in the relative rate of the non-cyclic electron transport activity of PS 2, a decline in the maximum utilization of light energy (α), and a decline in the saturation light intensity (E(s)). Non-photochemical fluorescence quenching increased after short-term exposure and decreased in the course of prolonged incubation. These parameters were more sensitive to the action of the toxic substance than the widely used parameter F(V)/F(M), which reflects the maximum quantum yield of PS 2. We propose the use of the method of fast measurement of light dependence curves of fluorescence to detect the changes in algal cells at the early stages of exposure to mercury salts.