Vol 72, No 4 (2017)

In this review, we tried to elucidate the origin and development of different animal and human cell culture methodologies used to evaluate the effects of various factors and substances in vitro. Organ cultures and conventional two-dimensional cultures of dissociated cells of various types, such as primary, tumor, induced pluripotent, stem, etc., have their advantages and drawbacks but usually do not represent accurate models for studying biological processes that take place in living organisms. Nowadays, high-throughput cell assays on the basis of various methods of signal detection (optical utilizing colorimetric, luminescent and fluorescent methods of detection, and electrochemical) are widely used at early stages of drug development for selection of the most active compounds and evaluation of their cytotoxic effects. The use of animals as models for drug testing is being criticized because of the lack of correlation between the results obtained in studies on them and on humans, and also because of the high cost and ethical issues. Therefore, much effort is put to create models based on human cells. This is how cultures emerged that utilize a three-dimensional network to simulate the architecture of tissues in vivo, and then so-called organs-on-chips—microfluidic microfabricated devices combining several types of cells—that replicate physical and chemical parameters of the microenvironment of cells in living organisms. In summary, experimental cell models have come a long way from the whole organs cultivated in a growth medium to almost complete reconstruction of organs in vitro based on the cutting-edge engineering approach with the use of different cell types. This currently enables one to replicate complex biological processes and study the influence of different substances and factors on them more successfully.

Rotaviruses cause an infectious disease that is the main cause of severe diarrhea in children all over the world and one of the factors that determine the level of child mortality. Only live attenuated vaccines are currently used against rotavirus infection. These vaccines are efficient, but a range of side effects, including intussusception risk, is characteristic of them. Complications associated with the use of existing vaccines usually occur in the case of oral administration and develop as the attenuated live vaccines start to replicate in the human intestine. Thus, there is a need for development of modern, efficient, and safe preparations for the prevention of rotavirus infection. These preparations should be incapable of reproduction (replication) in the organism after vaccination. Recombinant vaccines represent a new generation of vaccines against rotavirus infection, and the development and testing of such vaccines, including those intended for parenteral administration, has progressed considerably during recent years. The complex antigenic structure of the rotavirus is one of the problems associated with the production of these vaccines. The present review summarizes published data on genetic and antigenic diversity of rotavirus strains and geographic localization of epidemiologically significant virus variants. The role of capsid proteins in the emergence of immune response against the virus and the current state of research on new candidate recombinant vaccines against rotavirus infection are discussed.

Phytoplankton communities can serve as bioindicators of the water system state. It is necessary to select the appropriate species of microalgae to develop a model of a natural ecosystem that will allow performing multifactor experiments on the influence of physicochemical factors on the biophysical and hydrobiological characteristics of phytoplankton. This study has allowed selecting six species from those available in a museum to establish a model algal community. We have found that similar conditions are required for their optimal growth (light, temperature, and medium nutrients' supply). A medium with low nitrogen content is proposed to be used as a basal medium. Under these conditions, the cells function in a proper way and the cultures show satisfactory growth, while the duration of reaching the stationary stage of growth (10–15 days) allows having more experiments for a limited time. The cells of the selected species have morphological differences that are sufficient for the automated identification within the polyculture. We have obtained the geometric characteristics of cells for the computer counting of each species in the community on the microphotographs.

Using the tissue-engineered constructs based on scaffolds that imitate the extracellular matrix of living tissues unveils new opportunities in the treatment of various pathologies and injuries associated with tissue and organ damage. Silk fibroin of silkworm Bombyx mori is a biocompatible and bioresorbable polymer with high mechanical strength and elasticity that allows creating scaffolds on its basis for regeneration of various tissues, including bone. In the present work, fibroin scaffolds were obtained. They were designed in the form of porous sponges, films, and hybrid scaffolds of a bilayer structure in which the porous sponge threedimensional structure is limited on one side by a film. The structure of the scaffolds and their biocompatibility were studied: immortalized and primary fibroblasts, as well as the osteoblast-like cells, have been shown to successfully adhere and proliferate on the surface of the studied scaffolds. Numerous osteogenesis foci have been observed in the implant region 4 weeks after the fibroin porous scaffold implantation in the in vivo experiments in a rat femoral bone defect model indicating the osteoconduction of the scaffolds.

A new phenol- and 2,4-dichlorophenol (2,4-DCP)-degrading strain Rhodococcus erythropolis 17S isolated from the soil contaminated with phenol and its derivatives for a long time was characterized. The strain was identified based on phenotypic, physiological, and biochemical features as well as on the results of 16S rRNA gene sequencing. The growth of R. erythropolis 17S in batch culture using phenol and 2,4-DCP as sources of carbon and energy has been studied. The concentration of phenol and 2,4-DCP in culture medium decreased by 55% (on the fourth day) and 47% (on the 22nd day) in comparison to the control, respectively. It is concluded that R. erythropolis 17S can be used for phenol removal from industrial wastewaters of petrochemical and tanning extract production plants.

Many bacterial secondary metabolites, including pharmacologically promising compounds, are synthesized by polyketide synthases (PKS) enzyme complexes. In the present work, nucleotide sequences of the genes encoding 16S rRNA and PKS of heterotrophic bacterial strains isolated from epilithic biofilms of the littoral zone of Lake Baikal were determined. On the basis of molecular phylogenetic analysis of the 16S rRNA genes, six heterotrophic strains were identified: Serratia fonticola 1А and 10А, Pseudomonas umsongensis K10-2 and K10-3, Rheinheimera tilapiae K18, and Flavobacterium sp. 43-09. Sequencing of cloned amplification products for PKS gene cluster revealed 33 sequences. Genes involved in biosynthesis of antibiotics (difficidine, erythromycin, curacin, mixalamide, corallopyronin, and myxothiazol) and cytostatics (romidepsin, spiruchostatin, and disorazol) were found among homologous sequences. The low homology (50–83%) of the PKS amino acid sequences of Baikal bacteria with sequences from GenBank attests to the potential capability of strains to produce new, not yet studied bioactive compounds. The obtained results show that the studied strains may be of practical interest for biotechnological application.

Ideas of proponents and opponents of programmed aging concerning the expediency of this phenomenon for the evolution of living organisms are briefly considered. We think that evolution has no “gerontological” purpose, because the obligate restriction of cell proliferation during the development of multicellular organisms is a factor that “automatically” triggers aging due to the accumulation of various macromolecular lesions in cells as a result of the suppression, or even complete cessation of emergence of new, intact cells. This leads to the “dilution” of stochastic damage (the most important of which is DNA damage) at the level of the entire cellular population. Some additional arguments in favor of the inexpediency of aging for both species and individuals are also listed.

Some species of cyanobacteria synthesize toxins whose concentration during water bloom can reach values dangerous for human and animal health. Planktonic cyanobacteria are the most common and well-studied microcystins producers, hepatotoxic cyclic heptapeptides, whereas microcystin-producing benthic cyanobacteria are less known. In recent years, the mass development of benthic cyanobacteria forming extensive fouling on different substrates has been detected in the littoral zone of Lake Baikal. We found microcystins produced by benthic cyanobacteria in the biofouling on different natural and artificial substrates, including diseased and dead endemic sponges Lubomirskia baicalensis and Baikalospongia spp. collected from the littoral area of Lake Baikal. Microscopic analysis of the biofouling revealed prevalence of representatives of Nostocales and Oscillatoriales with predominance of Tolypothrix distorta that is likely the main microcystin producer in Lake Baikal. According to enzyme-linked immunosorbent assay (ELISA), microcystin concentrations in biofouling were 29.8–3050 μg/kg dry weight. We identified eight microcystin variants using MALDI-TOF/TOF; [Dha7]MC-YR was detected in most samples. The presence of microcystins in biofilms formed on the surface of the artificial substrate by Phormidium autumnale was also recorded. The data obtained demonstrated the necessity to monitor potentially toxic species and concentrations of cyanotoxins in plankton and benthos in the littoral zone of Lake Baikal, especially in the regions with intense tourist and recreational activities.