Biology

Astrocytes as Mediators of Integration Processes in the Brain Abstract— The role of astroglial cells is much more complicated than the notion of an “elastic framework,” which provides structural and metabolic support for brain structures. Astrocytes can affect synaptic processes by participating in the transmission of information by releasing or modulating the activity of neurotransmitters. In vitro and in situ studies revealed a large spectrum of molecules secreted by neuroglial cells. Analysis of the patterns that accompany the secretory mission of astrocytes led to the term “gliotransmission,” which gave rise to a new understanding of plastic regulation of the synaptic function and organization of the neural network, memory, and cognitive processes. The concept of the integrating mission of astroglia also opens up new opportunities for understanding the mechanisms of neurodegenerative diseases and identifying new targets for therapy.

Molecular Genetic Diversity and DNA Diagnostics of Hereditary Spastic Paraplegia Abstract—Hereditary spastic paraplegia (HSP) is a heterogeneous group of neurodegenerative disorders predominantly characterized by damage to the pyramidal tract. The major, single symptom of HSP is progressive weakness and spasticity of lower extremities, which ultimately leads to difficulties in walking. HSP has various types of inheritance and clinical characteristics. The development of molecular genetics and the emergence of high-throughput sequencing techniques, such as New Generation Sequencing (NGS) in particular, revealed a pronounced genetic heterogeneity of HSP. Currently, about 80 genetic loci for HSP are designated as spastic paraplegia genes (SPGs) (with numbering according to the mapping history), and the vast majority of causative genes within loci have been identified. The most frequent autosomal dominant forms of HSP are SPG4 and SPG3; SPG11, SPG15, SPG7 are common autosomal recessive HSPs. The mechanisms of HSP molecular pathogenesis are variable and encompassing defects of neuronal membrane transport and the disturbance of myelination processes, lipid metabolism, mitochondrial dysfunctions, etc. The differential diagnosis for HSPs is difficult due to the existence of many geno- and phenocopies within the other neuropathologies that can be partially distinguished by neuroimaging methods. The only method for the precise diagnostics of HSP and the number of genomic copies is DNA diagnostics—the search for mutations in individual genes and/or the analysis of many genes simultaneously by NGS methods (gene panel, whole-exome sequencing, and whole-genome sequencing). Such DNA diagnostics opens up the opportunity to perform prenatal or preimplantation analysis of the fetus for families carrying HSP mutations to predict the risk of HSP inheritance. Currently, HSP treatment is directed against individual symptoms (antispastic drugs, etc.), and the discovery of the pathogenic action of different genes requires the development of new therapeutic approaches.

Current State of the Problems in the Phylogeny of Squamate Reptiles (Squamata, Reptilia) Abstract—The results of recent phylogenetic studies of the main groups of squamate reptiles are summarized. The contributions of various methodological approaches to modern patterns in the analysis of these vertebrates, including the positions of different groups on the phylogenetic tree of reptiles, are considered. Modern patterns in the integrated analysis of the structure of phylogenetic and taxonomic diversity and ecogeographical patterns in its formation are discussed.

Heterochrony as the Basis for Inter- and Intraspecific Diversity of Skin in Vertebrates Abstract—The importance of heterochrony as an evolutionary pathway of the emergence of specific and intraspecific diversity is demonstrated on the example of integuments and their derivatives (scales, hair, glands) as ectosomatic organs of various vertebrates. We used our data and the results of studies on zoology, morphology, biomedicine, and livestock.

Some Aspects of Carcinogenesis Associated with Genetic and Epigenetic Factors Abstract—Various authors have shown that the numerous instances of spontaneous DNA damage (DNA breaks, change in bases) that occur daily in a cell as a result of the metabolism of the human body are the basis of mutational selection. Mutant cells have certain advantages in the microenvironment, which changes due to age characteristics. This contributes to the formation of cancer clones and their dissemination. A significant role in this process belongs to hereditary factors; at the same time, there are a number of hereditary diseases (Xeroderma pigmentosum, etc.) that in most cases lead to the occurrence of cancer. Herein, we describe a number of associated genes that control cellular homeostasis and, at the same time, are suppressor genes; changes in their activity or mutations in their structure contribute to carcinogenesis. The role of epigenetic factors, including noncoding regulatory RNAs, the organization of the chromatin structure, and methylation in the carcinogenesis processes is considered. Modulation of the functional activity of genes is carried out by noncoding RNAs; each RNA can have several target genes and can, in turn, be affected by different genes. Regulatory RNAs include microRNAs and long noncoding RNA proteins, changes in the activity of which can serve as biomarkers of disease onset, have a predictive value, and can be used as a target for therapy. New data on the role of noncoding RNAs, methylation, and chromatin organization in carcinogenesis are presented. Our data on the use of the expression level of some genes and noncoding RNAs as prognostic indicators suitable for the evaluation of treatment efficacy for a number of tumors are presented. Special attention is paid to the structural organization of chromatin and methylation in carcinogenesis, as well as to the interaction of cellular structures that affect the activity of genes and their regulation in carcinogenesis. A brief assessment of the carcinogenic effect of exogenous factors such as natural (cosmic factors and some natural compounds) and anthropogenic ones (radiation, chemicals, and cancer viruses) is given.

B Chromosomes Abstract Modern data on the origin and biological significance of B chromosomes in plants and animals, their structure and evolution, and dynamics and polymorphism are considered. Some examples of various animal and plant species show a possible role of population variability in the number and morphological types of B chromosomes.

Effects of Space Radiation and Combined Impact of Radiation and Other Spaceflight Factors on CNS Functions in Model Experiments on Animals Abstract—The effects of space radiation on the central nervous system, which are the most relevant to the assessment of radiation risk in interplanetary flights, can only be addressed in model ground-based experiments on animals. The article substantiates the methodology and presents the results of such experiments: long-term exposure to radiation was simulated using fractionated gamma irradiation of animals combined with exposure to hypogravity (antiorthostatic suspension of rats), and the specific effects of irradiation with 12C carbon ions and protons were simulated in accelerator experiments. Exposure to 12C ions has been shown to evoke significant changes in the brain monoamine metabolism, with the prefrontal cortex, the nucleus accumbens, and the hippocampus characterized as the most sensitive structures. However, the effects of exposure to high-energy protons in similar doses were almost similar to the effects of gamma radiation and could be characterized as minor.

Mechanisms of the Formation, Regulation, and Address Correction of Immune Disorders Abstract—We analyze the literature data and our own results from a survey of more than 3000 patients suffering from a wide range of diseases of differentiated genesis who were subjected to multivariant immunotherapy. Using formalized analytical approaches, we discuss the formation of natural and targeted regulation of immunopathological conditions. A new concept of the mechanisms of the regulation and targeted correction of immunopathology is formulated.

Longitudinal Stolon Pulsations in the Colonial Hydroid Dynamena pumila (Linnaeus, 1758) Abstract It is established via time-lapse video microscopy that the zone of longitudinal extension of the stolon coenosarc in the colonial hydroid Dynamena pumila can extend over two interstitial sites (modules). The stretching occurs in the form of oscillations with a period corresponding to the growth pulsations of the stolon tip. Consequently, the growth zone is not restricted to one stolon module, and the main condition for longitudinal growth of the coenosarc appears to be the stretching created by the advancing growth tip, not only by the increasing number of cells in the growth zone, as the main cause of coenosarc elongation.

Impact of Spatial Heterogeneity on Drosophila melanogaster Adaptation to Unfavourable Food Media: The Results of an Experimental Evolution Study Abstract The spatiotemporal variability of environmental conditions is assumed to have a strong impact on the course of microevolution processes, including the efficiency of adaptation to unfavourable conditions and the probability of ecological specialization or, conversely, generalization (the acquisition of multipurpose adaptations). The experimentаl research on these effects is still at the initial stage, and the temporal, rather than spatial, heterogeneity of the environment is analyzed in most studies. We performed an evolution experiment that involved the adaptation of Drosophila melanogaster lines to two unfavourable media: a high-salt (S) medium and a starch-based (St) medium of low nutritional value. Some of the experimental lines had access to one of the two unfavourable media only (homogeneous environment), whereas the others had access to both media and could choose between them (heterogeneous environment). The control lines were reared on a normal laboratory medium (N) that provided favourable conditions for the species. The degree of adaptation of lines obtained on the S, St, and N media was assessed after one and a half years of adaptation. The reproduction efficiency (the amount of adult progeny derived from a pair of parents within a specified time interval), adult lifespan, oviposition rate, and ageing-related changes in the former were assessed. Flies reared in a heterogeneous environment were superior to those reared in a homogeneous one with regard to most adaptation parameters on all three media. The results agree with the hypothesis concerning the promotion of generalization and more efficient adaptation to unfavourable conditions upon spatial heterogeneity of the environment. The obtained data do not support the hypothesis of antagonistic pleiotropy, which leads to “evolutionary trade-offs” and a lower competitiveness of generalists than that of specialists under stable conditions.