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One of the means for body insulation in mammals during their transition from terrestrial to semi-aquatic and then aquatic life is based on the use of fur in water as an effective “dry” insulator. Fur functional conditions are changed drastically and instantaneously when fur makes contact with water. The physical mechanisms underlying fur waterproofing were analyzed, and their relations to both fur structure and animal body size were established. The results of the analysis allow us to define to what extent the structural features of fur of a mammal in relation to its body size are capable of trapping an insulating air layer when the animal swims in water. On the basis of our analysis, both the body size of the ancestors of fur seals and the type of thermal insulation changing in the postnatal ontogeny of fur seals are hypothesized.

The weight parameters that characterize the size and the degree of fullness of fermentation chambers (forestomach and cecum), namely, the weight of the walls and the content of these organs, and the concentration and size distribution of fibers in the chyme have been investigated in five muroid rodent species (Arvicola terrestris, Microtus oeconomus, Microtus arvalis sp., Clethrionomys glareolus, and Sylvaemus flavicollis). No distinct regularities were observed in the above-mentioned parameters of the forestomach. These parameters of the cecum were generally found to be in good agreement with the conventional concept of dietary specialization of the rodent species under investigation, but the results have provided a more precise assessment of the role of dietary fiber in the diet of free-living rodents under specific environmental conditions.

Deformations of particular setae of adhesive toe pad of the tokay gecko were investigated by atomic-force microscopy. The effective elastic modulus of the investigated setae varying within 0.34-19 GPa, a pronounced hysteresis was observed during reversible bending of setae. The hysteresis-related energy losses may be as high as 98% of the total bending work. The pronounced viscous features of the setae contradict the hypothesis of dynamic self-cleaning of the gecko adhesive cover, according to which the setae are considered as absolutely elastic cantilever beams.

The results of the body-surface infrared thermography of rodents of the genus Lophuromys suggest that heat insulation of the black-clawed brush-furred rat L. melanonyx, a large specialized species of the AfroAlpine zone, is worse than that of the related smaller species, the golden-footed (L. chrysopus) and shorttailed (L. brevicaudus) brush-furred rats, that inhabit tropical forest and Erica shrub, respectively. A decrease in heat insulation of the alpine species may facilitate the use of solar radiation for supporting heat balance of these diurnal animals.

According to our computer modeling data obtained earlier, nucleoli in interphase ciliates Didinium nasutum are complex netlike structures, in which the trabeculumor lamella-shaped fibrillar component is located on the periphery, and the granular component in the central part of the nucleolus. Chromatin bodies connected with nucleoli act as the nucleolar organizers in D. nasutum. In the present work, the arrangement of all chromatin bodies, which could correspond to nucleolar organizers by morphological criteria, is studied by means of a 3D-reconstruction. It is shown that all of these chromatin bodies are localized outside the nucleoli, on the fibrillar component’s periphery. Even those chromatin bodies which appeared to be completely surrounded by the fibrillar nucleolar component on single ultrathin sections are actually settled down in nucleolus cavities open to the nucleoplasm. This proves that the RNA processing in D. nasutum nucleoli is directed toward the center of nucleoli, where the granular component is located. The analysis of the nucleolar chromatin distribution made it possible to conclude that different parts of the complex interfase netlike nucleoli of D. nasutum have approximately the same activity.

The nucleolar organization in ciliate Didinium nasutum somatic interphase nuclei was studied using serial ultrathin sections and compared for various physiological states of the cell, namely, fed ciliates, starved ciliates, and dormant cysts. It has been shown that the interphase nucleoli are large structures with a complex architecture: the fibrillar component forms an intricate network in the macronucleus space, while the granular component is located inside this network. The structures looking as individual nucleoli in single sections are actually parts of branched nucleolar networks. The intricate nucleolar networks do not disintegrate after a 30-h starvation; however, the granular component becomes denser and develops numerous cavities filled with fine fibrils of a nonribonucleoprotein nature. In fed D. nasutum, the fibrillar structures on the periphery of nucleoli contain numerous pores (virtually absent in starved cell nucleoli), which can potentially serve for transporting newly synthesized rRNP. Branched nucleolar networks are undetectable in cysts. Their nucleoli are individual structures consisting mainly of the fibrogranular component.