No 4 (2024)

Elliptic Fourier transform is a common method of describing the shape of objects by an unique sequence of coefficients that allow comparing the shapes by mathematical methods. However, raw coefficients contain unnecessary data unrelated to the shape, which does not provide a correct comparison. For this reason the coefficients are normalised. This removes some of the superfluous data, but leaves information about mirror symmetry and the order in which the contour vertices are declared, that are encoded in the signs of the coefficients. This also interfere with shape comparison. The paper describes an algorithm for harmonizing the coefficients, leveling the influence of the mentioned information. On the example of attachment organs of monogeneas, the advantages of using harmonized coefficients for comparing the shapes of biological structures are shown.

It was studied effect of the lipid extract isolated from the tunic of the marine hydrobiont Halocynthia aurantium. It was evaluated its administration during hypothermia, hyperthermia, muscle load and the introduction of hexenal as well as its embryotoxic and teratogenic effects The impact of stress (vertical fixation of rats by the dorsal neck fold) was accompanied by an increase in plasma levels of total lipids, total cholesterol, cholesterol/phospholipid ratios and a decrease in total phospholipids, as well as by a change in the quantitative characteristics of classes of neutral and phospholipid. It was carried out a correction of the developed changes by a lipid extract of ascidia and a commercial reference preparation “Omega-3”. The lipid extract of H. aurantium showed a higher efficiency in restoring the lipid composition of the blood plasma under stress impact compared to the preparation “Omega-3” due to a wider range of neutral and phospholipid classes, polyunsaturated fatty acids of the n-3 and n-6 families. The tunica of ascidian can be used as a raw material for obtaining preparations with stress-protector and lipid-correcting properties.

The microstructure of the tuberculate dorsal and lamellar ventral skin of the body in rock lizards of different ages (Darevskia raddei, D. nairensis, D. valentini, D. dahli, D. armeniaca) has been described for the first time. The thickness of the skin in the most xerophilic species (D. raddei) is less than that in the more hygrophilic species. Rock lizards have single or paired longitudinal skin folds that are not closed from the side, which stretch along the inner side of the scales to its distal edge. Small folds are also present in the lining of the squamous pocket; they consist of all layers of the skin and subcutaneous tissue. A large fold is able to completely block the cavity of the squamous pocket, the volume of which changes with the contraction of the subcutaneous muscle bundles reaching the bases of the scales. Small folds are also present on the scales of tuberous skin. In hygrophilic lizards (Zootoca vivipara), similar formations appear at later stages of postnatal ontogenesis than in rock lizards. The probable functional significance of the described skin structures is discussed.

The North-West Pre-Caspian saiga (Saiga tatarica tatarica) population numbers was about 800 thousand individuals in the middle of the last century. There was a dramatic decline at the end of the 20th century, and by 2015 this saiga population numbers and was about five thousand animals. Our paper presents the results of microsatellite loci and of the mtDNA control region analysis obtained for the museum saiga samples from the North-West Pre-Caspian population, collected at the peak of their numbers in the 1950s. We compared these data with our previous results for the samples collected during the population depression in1999–2016. There were no noticeable differences of mtDNA control region diversity between the museum and modern saiga samples. The most vivid genetic consequence of the severe decline in population numbers was a significant increase of the inbreeding coefficient (Fis) calculated from the microsatellite loci.

Drained peat soils (Histosols) were studied. In the mode of weak and moderate drainage, the trend of seasonal fluctuations (quadratic parabola) shows a weekly average increase in dehydrogenase activity with a weekly average deceleration, in the intensive mode – a weekly average deceleration with a weekly acceleration for June–October. A reliable nonlinear relationship of enzyme activity was revealed: positive – with redox potential and pH, multidirectional – with soil bulk moisture and soil temperature. According to canonical analysis, the discussed set cumulatively determines the seasonal dehydrogenase activity by 50–81%. The hydrological regime is statistically proved as a dominant factor. A negative conjugate interaction of dehydrogenase and peroxidase activity has been established, confirming their participation in the biochemical transformation of organic matter as a whole.

The role of the roots and root systems of Pinus sylvestris L. in the formation of secondary pine forests in the cuttings of the Kola North was studied. It has been established that in pine seedlings in disturbed areas, root and shoot systems are formed quite quickly. Already in the I-th grade of age, characteristic morphological signs of root systems appear, the feeding areas of trees begin to overlap each other. The bulk of the roots (80–85%) is concentrated in the upper 20-centimeter soil layer. A linear relationship between the taxation indicators of trees and the mass of root systems has been revealed. The conducted studies have shown that the formation of forest communities of Scots pine in the cuttings of the Kola North, their stability and productivity are directly dependent on the degree of development of individual roots and root systems as a whole.

The effect of hypoxia on the expression level of pyruvate kinase (PKM), octopine dehydrogenase (OcDH) and malate dehydrogenase (MDH) genes in the gill tissue of the Mediterranean mussel Mytilus galloprovincialis (L., 1819) was studied experimentally. The control group of mollusks was kept at 9–10°C and the oxygen level in the water was 8.5 mgO₂ l^–1. Experimental – at 9–10°C and 2.2 mgO₂ l^–1. The exposure was 24 and 72 hours. Some of the individuals were subsequently subjected to the reoxygenation procedure. Under conditions of hypoxia, the expression level of OcDH and MDH genes increased by 3 and 2 times, respectively (p < 0.05). At the same time, OcDH expression showed sensitivity to the oxygen content in the medium. Under the conditions of reoxygenation, the process was completely suppressed. The expression of the PKM gene, on the contrary, did not depend on hypoxic effects and remained at the level of control values.

It is shown that the differences in the isotopic composition of carbon in the water-soluble and water-insoluble fractions of plant leaf biomass, as well as phloem, are evolutionarily determined. They associated with metabolic reactions during assimilation and photorespiration and do not depend on the illumination mode and on the spectral ranges of headlights used in illumination. The above isotopic shifts are the cause of isotopic differences in assimilatory and photorespiratory carbon stocks that feed various metabolic processes. Due to the strict temporal and spatial organization of metabolism, carbon fluxes from the funds retain isotopic differences without complete mixing. The differences in the isotopic composition of carbon of the water-soluble fraction of biomass and carbon of phloem juice from carbon of the water-insoluble fraction are small (1–3%), but they are quite stable and easily fixed. The carbon of the water-soluble fraction is very close in isotopic composition to the carbon of the phloem and is noticeably enriched with the isotope ¹³C relative to the water-insoluble fraction, which makes it possible to use it as a marker in the study of assimilate transport in plants, especially during budding and fruiting. It is shown that the reason for the enrichment of autotrophic organs and tissues with isotope ¹²C relative to carbon of heterotrophic parts of the plant is the predominant participation in their formation of an isotopically light assimilation fund, whereas an isotopically heavy photorespiratory fund takes part in the formation of heterotrophic organs. It is shown that the manifestation of the formation of two isotopically different funds is the discovered relationship of the carbon isotope composition of leaves with their age.

The pass of feed through the digestive tract in a herbivorous rodent with a single-chamber gemiglandular stomach, the fat sand rat Psammomys obesus, was studied by multiple marking of the food with inert plastic markers. The total mean retention time of markers in the digestive tract (DT), as well as in the stomach and caecum separately, was determined. The peculiarities of the digesta kinetics depending on the morphology of the digestive tract, diet and the time of markers intake were clarified. The total time for removing markers from DT in the fat sand rat reaches 36 hours. The mean retention time of markers in DT was determined as a whole (17–18 hours), as well as separately in the forestomach (7–9 hours) and caecum (7–12 hours). The uneven passage of feed has been revealed, which is considered as an important mechanism for maximizing the extraction of nutrients from plants, including microbial fermentation of structural carbohydrates of the food.