Nº 1 (2025)

Histological events occurring in morphogenic calluses of Lavandula angustifolia Mill. are described for the first time during long-term (2–5 passages) in vitro culture. In the calluses of passage 2, buds and leaves of normal structure (the de novo organogenesis pathway), as well as somatic embryos of normal structure originating from the bud epidermis cells (the somatic embryogenesis in vitro pathway) were revealed. As the calluses were cultivated further, its normal morphogenetic potential was gradually lost. If only the buds were characterized by the normal structure in the calluses of passage 3, and the leaves had an abnormal structure, then the buds of mainly abnormal structure were noted in the calluses of passage 4, and only structurally degenerated tissues were noted in the calluses of passage 5. The question about reducing the properties of pluri- and totipotency of callus cells as they were cultured in vitro discussed. The histological data obtained can be used in choosing the duration of callus culture in vitro to obtain full-fledged regenerants of this valuable essential oil and medicinal plant in various cell biotechnologies.

A method for evaluating the methemoglobin reductase activity of nuclear erythrocytes of teleost fish is proposed. The work was performed on a bottom marine species (Scorpaena porcus, Linnaeus, 1758). In an in vitro experiment, the erythrocyte suspension of this type was weighed in solutions with different concentrations of NaNO₂, after washing from this compound, the process of methemoglobin (MetHb) reduction was studied for 150 min. The functional state of hemoglobin was judged by the results of spectral analysis. The study of the kinetics of MetHb reduction showed that the dependence was well described by the equation of an exponential function with a coefficient of determination (R²) greater than 0.9. The nature of the dependence remained at different levels of oxidative stress. This made it possible to calculate the velocity constant of the first order k (25 ^oC). In this species, it was 5.75–6.45 (10^–3) min^–1, which slightly exceeded the known values for mammals, and was close to the data obtained for other species of bony fish. It was found that the MetHb-reductase activity of the nuclear erythrocytes of the sea ruff increased with a rise in the oxidative load. At a concentration of 6.0 mM NaNO₂, it was 1.73 ± 0.21 µM MetHb min^–1 g^–1 Hb. It is assumed that this is due to the process of deoxygenation of hemoglobin.

The present article is devoted to optimizing rooting of Cattleya gaskelliana regenerants in vitro, and to identifying anatomical features of root under various culture conditions in vitro. the results showed that semi-solid ½ MS nutrient medium containing 50.0 g/L banana puree and 1.0 mg/L IAA is more effective in the growth and rooting of C. gaskelliana regenerants. Also, it has been determined the histological differentiation of C. gaskelliana roots formed on nutrient media with different concentrations of agar. Plants cultured on semi-solid nutrient medium had roots with more developed diameter and a central cylinder. To obtain maximum survival rate (100%), it is recommended to use sphagnum moss and a substrate consisting of bark, perlite, and peat in equal ratio.

Two lines of the parasitoid Habrobracon hebetor were analysed: one infected with the Wolbachia endosymbiotic bacterium and the other free of it. Differences in morphological characters were observed between the lines, specifically in the degree of cuticle melanisation and body size of adult parasitoids. The sizes of both male and female parasitoids were significantly larger in the line infected with the bacterium. The research found that Wolbachia affects the levels of dopamine, tyrosine, and phenoloxidase activity, as well as the amount of proline in the whole body homogenate during different stages of parasitoid development.

In April 2023, the main components of pelagic plankton communities were studied in the northern part of the Barents Sea. The seasonal (SP) and the main (MP) pycnoclines were formed in the study area. Seasonal pycnocline separated the surface desalinated layer (SDL) and had a significant effect on the vertical distribution of chlorophyll-a (Cl-a). The main barrier to the free movement of phytoplankton was the line of maximum density gradient of SP (MDG-SP). The maximum concentrations of Cl-a were focused in the SDL (6.84 ± 1.16 mg/m³) and in the top of SP (upper MDG-SP) (7.29 ± 0.26 mg/m³). Below the MDG-SP, the concentration decreased sharply. In the absence of the SP, the main barrier served as the MP. Zooplankton, bacteria and viruses in the conditions of phytoplankton “blooming” were characterized by low abundance and did not have a notable effect on the phytoplankton development.

The article presents the results of a comparative analysis of the main habitats of natural populations of Prunus armeniaca L. in Dagestan based on a set of climate data and digital elevation models. The grouping of the species’ range into ecogeographical units (EGE) is shown and the main bioclimatic predictors that determine the spatial differentiation of natural populations are identified. The main patterns of distribution of the species in the altitudinal direction have been determined. The optimal growing areas for the species have been identified.

Ulmus laciniata is a strategic food resource for Cervus elaphus xanthopygus, especially in autumn and spring. The article presents the results of a study of the seasonal content of water-soluble polysaccharides, their monosaccharide composition, extracted from the bark and bast of U. laciniata. Two maxima in content of water-soluble polysaccharides were revealed: during the shoot growth period (June) and a slightly lower one during the preparation for winter dormancy (October). The minimum content is observed during the beginning of the growing season (April–May). Content of pectin substances, unlike water-soluble polysaccharides, changed slightly during the year. The studied groups of substances are classified as the most bioavailable polysaccharides with extensive physiological activity. In addition, the data obtained may explain the feeding behavior of the C. elaphus xanthopygus, which lives in the Primorsky Territory.