Structuro-functional organization of the fiber network in the human Achilles tendon

Owing to a complex morphological investigation of the human Achilles tendon, it was possible to distinguish four levels of the structural-functional organization of its fibrous elements and to reveal some regularities of their structure that recur at all the levels. Thus, collagenous molecules, microfibrillae, fibrillae and fibers have a wavy-spiral conformation. This spatial form is stabilized by a complex or a system of transversal connections corresponding to the given level of the organization. In order to maintain integrity (the structural-functional unity) of each level, certain substances of polysaccharide nature take part. Along the course of the long tendinous axis, a re-distribution (branching) of the fibrillar elements is observed at all the levels of the structural-functional organization.     

Structural and functional reorganization of the photosynthetic apparatus in adaptation to cold of wheat plants

In seedlings of a cold-resistant wheat variety, the dynamics was studied of the main structural-functional parameters of the photosynthetic apparatus (PSA) and of cold resistance of leaf cells in low-temperature plant adaptation. It has been established that a complex of structural-functional PSA changes takes place in seedling leaves under the influence of cold. As a result, as early as in the first hours of hardening, the formation of chloroplasts begins to occur in mesophyll cells of larger sizes and with a thylakoid system of the “sun type.” Owing to structural and functional readjustment (a change of content of pigments, stabilization of pigment-protein complexes, and enhancement of nonphotochemical quenching of excess energy) in the process of cold adaptation, the rate of photosynthesis stabilizes. It is suggested that the observed structural-functional PSA rearrangement is a necessary condition for formation of increased cold resistance of leaf cells; this, alongside with other physiological-biochemical changes occurring in parallel in cells and tissues of the plants, provides their survival under conditions of low temperatures.     

System-theoretical (Holistic) approach to the modelling of structural-functional relationships of biomolecules and their evolution: an example of triterpene glycosides from sea cucumbers (Echinodermata, holothurioidea)

Triterpene glycosides from sea cucumbers (Holothurioidea, Echinodermata) are used as a model for studying the biochemical evolution for correlation between the glycoside membranolytic activity and biological functions. Concepts of evolutionary morphology are applied at the molecular level. The concept of Van-der-Klaauve's- Dullemeijer's system-theoretical (holistic) approach is used for the model of structural-functional relationships of the glycosides. Network diagrams of structural-functional relationships have been prepared for many glycosides. The diagrams correlate well with experimental data and show a very complex and flexible action of the natural selection on the structural fragments of the glycosides. The diagrams also show overlapping in the functional components that provide stability to the general structural plan of glycosides during evolution. The method may be applied to other biomolecules.     

Yeast prions, mammalian amyloidoses, and the problem of proteomic networks

Prion proteins are infective amyloids and cause several neurodegenerative diseases in humans and animals. In yeasts, prions are detected as the cytoplasmic heritable determinants of a protein nature. Yeast prion [PSI], which results from a conformational rearrangement and oligomerization of translation termination factor eRF3, is used as an example to consider the structural-functional relationships in a potentially prion molecule, specifics of its evolution, and interactions with other prions, which form so-called prion networks. In addition, the review considers the results of modeling mammalian prion diseases and other amyloidoses in yeast cells. A hypothesis of proteomic networks is proposed by analogy with prion networks, involving interactions of different amyloids in mammals.     

Evolution of cell-to-cell communication and the structural brain organization

The review considers key issues of historical development of the nervous system, including evolution of the brain intercellular contacts and neurotransmitter systems. Special attention is given to the structural-functional organization of the central nervous system in a freshwater pulmonate gastropod, Lymnaea stagnalis.     

Olfactory system of crustaceans: structural, functional organization and perspectives of ecologo-toxicological studies

Based on our own studies and literature data, we considered peculiarities of the structural-functional organization of the crustacean olfactory system and effect of pollutants on it. There are described changes of behavioral reactions based on chemoreception under conditions of pollution of the aquatic medium. Expedience of study of the crustacean olfactory system as a perspective object for ecologo-toxicological studies is substantiated.     

The behavioral effects of the destruction of the nucleus basalis magnocellularis in the cat forebrain]

Behavioural experiments were carried out on cats by the method modelling complicatedly organized non-automatized behaviour with elements of generalization and abstraction. By the results of fulfillment of test tasks by animals with partial destruction of the macrocellular basal nucleus the conclusion is made on the participation of this formation in the structural-functional ensuring of complex integrative forms of activity-thinking and learning. The suggested mechanism of drawing of the basal nucleus in gnostic and cognitive processes in the non-specific ensuring of the system of structures directly participated in thinking and learning.     

The olfactory system of crustaceans as a model for ecologo-toxicological studies

Based on our own studies and on literature data, there are considered peculiarities of structural-functional organization of the crustacean olfactory system and effects of pollutants on it. The behavioral reaction changes based on chemoreception in the polluted aquatic environment are described. Usefulness of study of the crustacean olfactory system is substantiated as a perspective object of ecologo-toxicological investigations.     

Conservatism of the Insulin Signaling System in Evolution of Invertebrate and Vertebrate Animals

The insulin system including hormone insulin and signaling mechanisms realizing a wide spectrum of its regulatory effect is one of the major systems in the animals and human organism. At present the history of origin of this regulatory system in the course of evolution starts to be formed. There are grounds to believe that it appeared in unicellular eukaryotes, developed in multicellular ones, and achieved significant perfection in higher vertebrates. This paper analyzes the structural-functional organization of insulin-like peptides, their receptors, and the corresponding signaling mechanisms in four types of invertebrates (sponges, nematodes, molluscs, arthropods) in comparison with those in higher vertebrates. There is revealed evolutionary conservatism in the common structural-functional organization of insulin-like peptides of invertebrates and insulin of vertebrate animals; receptors of insulin-like peptides of invertebrates and receptors of insulin and insulin-like growth factor 1 of vertebrates that have tyrosine kinase activity; the insulin-like signaling systems including signaling blocks, similar by their primary structure in invertebrate and vertebrate animals (IRS-proteins, G-proteins, adenylyl cyclase, protein kinases A and C, etc.). The point of view is put forward that the conservatism of the functional blocks of the insulin system does not mean the absence of evolutionary changes of this system as a whole. Examples of such evolutionary changes leading to complication of the insulin system organization at supramolecular and cellular levels and to an increase of efficiency of its functioning are presented.     

Assessing determinants of exonic evolutionary rates in mammals

From studies investigating the differences in evolutionary rates between genes, gene compactness and gene expression level have been identified as important determinants of gene-level protein evolutionary rate, as represented by nonsynonymous to synonymous substitution rate (d(N)/d(S)) ratio. However, the causes of exon-level variances in d(N)/d(S) are less understood. Here, we use principal component regression to examine to what extent 13 exon features explain the variance in d(N), d(S), and the d(N)/d(S) ratio of human-rhesus macaque or human-mouse orthologous exons. The exon features were grouped into six functional categories: expression features, mRNA splicing features, structural-functional features, compactness features, exon duplicability, and other features, including G + C content and exon length. Although expression features are important for determining d(N) and d(N)/d(S) between exons of different genes, structural-functional features and splicing features explained more of the variance for exons of the same genes. Furthermore, we show that compactness features can explain only a relatively small percentage of variance in exon-level d(N) or d(N)/d(S) in either between-gene or within-gene comparison. By contrast, d(S) yielded inconsistent results in the human-mouse comparison and the human-rhesus macaque comparison. This inconsistency may suggest rapid evolutionary changes of the mutation landscape in mammals. Our results suggest that between-gene and within-gene variation in d(N)/d(S) (and d(N)) are driven by different evolutionary forces and that the role of mRNA splicing in causing the variation in evolutionary rates of coding sequences may be underappreciated.     

Incorporation of tritiated amino acids into the ultrastructure of the cerebral cortex following phenamine stimulation]

The method of electronoscopic autoradiography has revealed an increased biosynthesis of protein by neuronal and glial cells of the motor cortex of rats under phenamine stimulation. The increased level of incorporation of labelled precursors in the molecular layer of the cortex is likely to be associated with increased accumulation of newly synthetized protein in axo-dendritic synapses due to stimulation of the rapid component of the axonal transport of macromolecules. At the same time, participation of the autonomic protein-synthetizing system in the biosynthesis of synaptic proteins is not excluded. The labelled products were found to localize in the field of the thorn apparatus in processes of the "structural-functional" adaptation of synaptic entrances (A. A. Manina, 1972).     

Vacuolar symplast and methodological approach to monitoring water self-diffusion between vacuoles of contacting root cells

New concepts of structural-functional organization of the transport system in higher plants were evolved at the current stage of investigations. In addition to the classical (cytoplasmic) symplast, another supra-cellular continuum was supposed to exist in the plant tissue, which interconnects vacuoles of neighboring cells through desmotubules and represents the second transport pathway within the plasmodesmata. This study describes and experimentally validates the method for monitoring the self-diffusion of water molecules between vacuoles of contacting cells in the maize (Zea mays L.) root by means of NMR method with a pulsed magnetic field gradient. The method is based on the fact that, at long period of self-diffusion observation, when water molecules in the apoplast and cytoplasm had already completed their relaxation and did not contribute significantly to the proton echo signal, the slope of the initial portion of the diffusional decay is independent of water permeability of the vacuolar membrane and is determined exclusively by water permeability of intervacuolar pathway through the desmotubules.     

Homeostatic mechanisms of biological systems: Development homeostasis

Homeostasis as an ability to maintain structural-functional parameters of the system at the required level is a basic characteristic for providing the stability of any biological system (from biosphere and separate ecosystems to communities, populations, and individuals). The study of homeostatic mechanisms that provide the stability of biological systems is the main task for solving many theoretical and practical questions. The search for criteria of homeostasis estimation and study of homeostatic mechanism ratio at different levels are principally important in this direction. Estimation of the role of homeostatic mechanisms of the organism and population for providing the stability of biological systems of different levels when using the approach based on estimation of the population state from ontogenetic positions (population developmental biology) seems promising.     

Structural and functional aspects of the nucleolar organizing region of interphase cell nuclei during hemoblastosis

Data on concept of the nucleolar-organizing regions of the human somatic cell interphase nuclei, methods of their revealing, classifications, as well as their structural-functional peculiarities in norm and under different diseases of blood system, in particular under hemoblastosis, are reviewed in historical aspect.     

Protective and adaptive reactions of the air-conducting and respiratory portions of the lungs to exposure to atmospheric pollutants

A complex structural-functional investigation of protective-adaptive reactions of various parts in the lungs has been performed under inhalation of some toxic substances. To a continuous inhalation effect of 1,2-dichlorpropane, 132 non-inbred white rats have been subjected. At the first stage of the investigation, using specific loading tests, periods for formation of increased and decreased resistivity of the experimental animals have been defined. Under the given scheme of the experiment the state of a maximal resistivity develops by the 30th day of the influence, then it gradually decreases and in 60 days becomes significantly lower than in the control animals. Synchronous changes in resistivity and in loading of the respiratory organs are revealed. The structural-functional investigation of the pneumatic and respiratory parts of the lungs during the period of formation (in 5 days of the influence), at maximum (in 30 days of the influence) and at decreased resistivity (in 60 days of the influence) makes it possible to establish that functional activity of the aero-hematic, aero-epithelial barriers and the surfactant system of the lungs increases during the period of elevated resistivity and decreases at the stage of reduced endurance to the loading. A suggestion is made that, together with other factors, increasing functional activity in the systems studied is an essential component for formation of the elevated stability of the organism against toxic inhalation.     

Structural and functional mapping of α-fetoprotein

Alpha-fetoprotein (AFP) is a major mammalian oncofetal protein, which is also present in small quantities in adults. It is a member of the albuminoid gene superfamily, which consists of AFP, serum albumin, vitamin D binding protein, and alpha-albumin (afamin). Although physicochemical and immunological properties of AFP have been well-studied, its biological role in embryo- and carcinogenesis and in adult organisms as well as mechanisms underlying its functioning remain unclear. During the recent decades, the biological role of AFP has been evaluated by identification of its functionally important sites. Comparison of primary structure of AFP and some physiologically active proteins revealed similarity of some polypeptide regions. This has been used for prediction of AFP functions (i.e., its multifunctionality). Localization of functionally important sites followed by determination of their amino acid composition and type of biological activity has provided valuable information for structural-functional mapping of AFP. Some peptide fragments of AFP have been synthesized and tested for biological activity. This review summarizes data on structural-functional interrelationships. We also describe functionally important AFP sites found by various groups during the last decade of structural-functional mapping of AFP with experimentally confirmed and putative biologically active sites.     

Common antigenic determinants of the tubulin binding domains of the microtubule-associated proteins MAP-2 and tau.

The structural-functional aspects of the tubulin binding domain on the microtubule-associated protein MAP-2, and its relationship with the tubulin binding domain on tau, were studied using anti-idiotypic antibodies that react specifically with the epitope(s) on MAPs involved in their interaction with tubulin in addition to other tau and MAP-2 specific antibodies. Previous studies showed that MAP-2 and tau share common binding sites on tubulin defined by the peptide sequences alpha (430-441) and beta (422-434) of tubulin subunits. Furthermore, binding experiments revealed the existence of multiple sites for the interaction of the alpha- and beta-tubulin peptides with MAP-2 and tau. Most recent studies showed that the synthetic tau peptide Val187-Gly204 (VRSKIGSTENLKHQPGGG) from the repetitive sequence on tau defines a tubulin binding site on tau. Our present immunological studies using anti-idiotypic antibodies which interact with the synthetic tau peptide and antibodies against the Val187-Gly204 tau peptide indicate that MAP-2 and tau share common antigenic determinants at the level of their respective tubulin binding domains. These antigenic determinants appear to be present in the 35 kDa tubulin binding fragment of MAP-2 and in 18-20 kDa chymotryptic fragments containing the tubulin binding site(s) on MAP-2. These findings, along with structural information on these proteins, provide strong evidence in favor of the hypothesis that tubulin binding domains on MAP-2 and tau share similar structural features.     

Structural-functional features of plant isoperoxidases

Current data on structural-functional features of plant peroxidases and their involvement in functioning of the pro-/antioxidant system responding to stress factors, especially those of biotic origin, are analyzed. The collection of specific features of individual isoforms allows a plant to withstand an aggressive influence of the environment. Expression of some genes encoding different isoperoxidases is regulated by pathogens (and their metabolites), elicitors, and hormone-like compounds; specific features of this regulation are considered in detail. It is suggested that isoperoxidases interacting with polysaccharides are responsible for a directed deposition of lignin on the cell walls, and this lignin in turn is concurrently an efficient strengthening material and protects the plants against pathogens.     

The Mirror-Type Internal Symmetry in the Primary Structure of Proteins: Detection and Functional Role (Review)

This review summarized the data obtained by the author in studies on internal symmetry of the mirror type in primary structures of proteins. The methods for detection of symmetric segments in amino acid sequences are analyzed: (1) the method based on analysis of sequences of roots of amino acid codons; (2) the dot matrix method; (3) the method of internal symmetry scanning. The results of studies of internal symmetry in enzymes and signaling proteins are presented. The probable role of the internal symmetry in the structural-functional organization of proteins is discussed.