Vol 45, No 3 (2018)

The effect of the nerve growth factor (NGF) on the proliferation and differentiation of mouse embryonic stem cells (ESCs) during long-term culturing in vitro was studied using genetically modified cells with stable expression of ngf and gfp (green fluorescent protein) genes (clone R₁^NGF). It was shown that, under standard conditions in vitro with the addition of mouse cytokine LIF, R₁^NGF cells lose their adhesive properties and acquire the ability to form cellular conglomerates or embryoid bodies (EBs) spontaneously. It is noted that, after attachment to the surface of the culture on days 3–5, EBs differentiated towards the neuroectoderm, as evidenced by the appearance of markers of early (nestin) and late (vimentin) neural differentiation. During long-term cultivation up to 22 days, the production of endogenous NGF protein promotes predominant selection and survival of neuroectodermal derivatives.

The initial stages of apoptotic damage to the conjunctiva and corneal epithelium, in the renewing cell populations of the eye has been studied in adult rats exposed to acute hypobaric hypoxia in vivo, and the effect of para-aminobenzoic acid (PABA) administered as the Aktipol pharmaceutical preparation (0.007% PABA) has been assessed in this experimental setup. Apoptotic damage to cell DNA was aggravated after two instances of hypoxia, and this change was accompanied by an increase in the intensity of the regenerative process inferred from the expression levels of phosphorylated histone pH3, a mitotic cell marker, and phosphorylated histone γ-H2AX, a DNA repair marker. Parabulbar injection of Aktipol 24 h before hypoxia has been shown to block development of the apoptotic process and to maintain a physiologically normal level of apoptosis, and thus the preparation exerted a protective effect in hypoxia.

The component composition and content of mycotoxins in the terrestrial parts of perennial legumes of the genera Medicago (M. falcata L., M. lupulina L., M. sativa L.), Melilotus (M. albus Medik., M. officinalis (L.) Pall.), as well as Caucasian goat’s rue (Galega orientalis Lam.), Spanish licorice (Glycyrrhiza glabra L.), and Washington lupine (Lupinus polyphyllus Lindl.) selected from natural biocenoses within different periods of vegetation, were studied. The intensity of accumulation and the variety of fungal metabolites are most clearly expressed in licorice and lupine and more weakly expressed in goat’s rue; the species of alfalfa and melilot, the contamination of which did not differ noticeably, occupied an intermediate position. The general features and peculiarities of the mycotoxin profile during the period of vegetation in the plants of the genera Medicago and Melilotus are discussed.

A partial sequence of the 18S rRNA gene (1979 bp) of the cestode Nippotaenia mogurndae Yamaguti et Miyata, 1940, a parasite of the Chinese sleeper Perccottus glenii Dybowski, 1877, is obtained. The maximum likelihood (ML) and Bayesian Inference (BI) algorithms are used for phylogenetic analysis that included the sequence and data obtained from GenBank. Both algorithms reveal a close phylogenetic relationship of our N. mogurndae and the N. mogurndae s. str. from its type host, Odontobutis obscura (Temminck et Schlegel, 1845), from Japan. The genetic divergence between these helminths (0.005) corresponds to the level of intraspecies differences typical for groups of cestodes phylogenetically close to the nippotaeniids: Mesocestoididae and Hymenolepididae. The results of the phylogenetic analysis also do not support the separation of nippotaeniid cestodes into two genera: Amurotaenia Achmerow, 1941 and Nippotaenia Yamaguti, 1939.

The structure of the root systems and roots of the invasive plant Heracleum sosnowskyi and the local species H. sibiricum have been compared in three habitats of the southern taiga subzone by the standard methods of plant morphology and anatomy. Differences in the structure of the root systems and roots of H. sosnowskyi and H. sibiricum ensuring the ability of the invasive species to absorb resources under optimum soil conditions have been revealed. These are the occurrence frequency of ephemeral roots, the number of orders of root branching, the size of absorbing roots, and the development of xylem elements.

Changes in the distribution of game animals that have living ranges with northern and southern boundaries in the northwestern regions of Russia have been analyzed and compared to horological materials published by a group of researchers almost 50 years ago. An anthropogenic impact has been identified as the major factor for the changes named above.

The response of bees to lead contamination of a carbohydrate feed has been studied. It was established that Pb in sucrose solution had a toxic and repelling effect on the bees. It was found that the amount of contaminated feed consumed by the bees decreased with a corresponding increase in the content of Pb in it. It is noted that this element accumulates unevenly in different body parts and parts of the digestive tract of the bees, thereby affecting their metabolic activity and accelerating processes of physiological aging, and the specific reaction of the bees to contaminated feed is expressed in their rejection of its consumption and in inhibition of their locomotion.