Vol 69, No 3 (2024)

Improving the efficiency and precision of gene editing systems is of utmost importance for modern molecular biology and genetic engineering. Of particular interest is the design of controlled CRISPR/Cas9 systems, the activity of which could be regulated using different physico-chemical stimuli such as light irradiation, pH change, temperature, change of molecule concentration and so forth. A promising direction in this area is the development of approaches to control activity at the level of guide RNA through photosensitive modifications to the structure and sequence of guide RNA, and additional oligonucleotides. This review is devoted to the analysis of publications on design of photosensitive guide RNAs and their applications in genome editing systems using CRISPR.

Research into the effects of low-dose radiation exposure is relevant due to an increase in the number of areas to which anthropogenic loading has occurred. Thorium is one of the radioactive elements naturally occurring in ecosystems; the amounts of thorium in the environment may be increased due to the activities related to the extraction of natural resources and operation of thermal power plants. Special interest focuses on the biological effects of thorium in the presence of humic substances as natural detoxicants. The aim of this study is to explore whether humic substances exert "mitigating" effects during exposure to thorium-232 at low-doses (< 0.04 Gy). A bioluminescent system of the enzymatic reactions including the bacterial luciferase and NADH: FMN-oxidoreductase has been chosen as a biological object. It was found that the activation of bioluminescence occurred in the initial stage of the exposure (up to 50 min) and production of reactive oxygen species increased after the 50 min exposure of this system to thorium-232. The relationship between the intensity of bioluminescence and the level of reactive oxygen species (correlation coefficient is −0.86) is shown. The addition of humic substances helps to neutralize thorium activity and reduce the level of reactive oxygen species to the control value. The effects of humic substances on the rate of NADH-dependent enzymatic process including redox reactions are shown. The results obtained contribute to the understanding of the mechanisms of the effects of thorium-232 at molecular level and its neutralization effects on the enzymatic processes.

The present research shows that changes in vegetation conditions have implications both for the expression levels of genes encoding chloroplast carbonic anhydrases and the carbonic anhydrase activity of chloroplast compartments. The results of experiments with mutants of the genes of the chloroplast carbonic anhydrases indicate that the activity of the chloroplast carbonic anhydrases determines the nature of changes in photosynthesis reactions in response to changes in environmental conditions. Possible mechanisms are proposed for participation of carbonic anhydrase in light-dependent processes in the chloroplast. Based on these findings, a hypothesis that carbonic anhydrases in chloroplasts function interdependently is developed.

Photosystem II is one of the main pigment-protein complexes of photosynthesis, which is highly sensitive to unfavorable environmental factors. Heterogeneity of properties in photosystem II is a key factor for the resistance of autotrophic organisms to stress factors. Assessment of the photosystem II heterogeneity can be used in environmental monitoring for rapid detection of environmental pollution. The paper presents an integrated approach for assessing the heterogeneity of photosystem II, based on a mathematical analysis of the shape of the chlorophyll a fluorescence induction curve of samples treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea using a mathematical model and the parameters from the JIP-test. Fluorescence induction curves obtained for treated samples from Chlorella, Scenedesmus, Ankistrodesmus, Pleurochloris, and Stichococcus cell cultures grown under 8 and 16 W·m–2 of light intensities were analyzed. For all cases, the relationship between reaction centers and different antenna sizes (alpha and beta centers) was assessed, and the part of active and inactive oxygen-releasing complexes was determined.

The effects of cationic antiseptics (used in micromolar concentrations) on active PS II core complexes isolated from spinach plants with an intact water oxidation complex and on PS I core complexes from the cyanobacterium Synechocystis sp. PCC6803 were studied. Out of the antiseptics studied (miramistin, chlorhexidine, octenidine and picloxidine) octenidine had the greatest effect. It was concluded that it exerts its action on PS II primarily through the influence on the structure of the light-harvesting antenna (CP43 and CP47) that deliver excitation energy to the reaction center. As a result, the chlorophyll molecules in this structure are destabilized and their optical and functional characteristics change. Similar effects were also observed in cyanobacterial PS I complexes. In addition, the antiseptic influenced the rate of the establishment of the equilibrium distribution of excited states across spectral forms in the antenna complex of PS I. A significant effect of octenidine on the electron transfer rate in the PS I complex was also found: in its presence, the recombination of photo-separated charges between the photoactive pigment P700 and the terminal acceptor FA/FB occurs twice as fast.

The T4-related bacteropihage RB49 is capable of generalized transduction of plasmids at a relatively high frequency. Due to this mechanism, bacteria can obtain the ability to adapt to varying environmental conditions and survive in new ecological niches. The effect of pH, temperature and long-wave ultraviolet irradiation (λ = 366 nm) on the characteristics of the RB49 phage preparation containing transducing particles with pTurboGFP-B plasmid DNA and virulent particles which have their own DNA. The data were obtained for the changes in the titer of virulent particles and the frequency of transduction of the pTurboGFP-B plasmid by the RB49 phage. Two hours after exposure of the pTurboGFP-B plasmid to UV radiation, the frequency of plasmid transduction by the RB49 phage increased by a factor of ~3. Also, after 40 min storage of the phage in ice, the number of transducing particles produced was many folds greater. Based on the data gathered in the experiment, it is suggested that transducing particles of the RB49 phage can be more resistant to longwave UV radiation and temperatures close to 0°C than virulent particles and are able to provide the transduction process more effectively than under normal conditions. Similar processes may occur in well-lit water bodies including cold-water reservoirs where the phages related to RB49 can be found. This might be an indication of the potential of more intense horizontal gene transfer in aquatic ecotopes than previously thought.

This paper highlights the possibilities of applicability of a test system based on E. coli BL-21 Codon Plus (DE3) living cells expressing pH-tolerant thermostable Luciola mingrelica firefly luciferase to study the kinetic mechanism by which aminoglycosides, such as gentamicin used in this study, act taking into account changes in the ATP and firefly luciferase levels inside and outside the cells. It has been shown that it is possible to evaluate the changes in cell viability, assess the effectiveness of the antibiotic action, and predict the formation of persisters after incubation of bacteria with antibiotic for 3 hours. The method is promising for rapid primary high-throughput screening of antibacterial agents and dosage forms to assess their effectiveness and mechanism of action.

The paper presents the results of study on the luminescent system of the culture of the fungus Mycena gombakensis derived out of wood samples. The changes on samples stored for duration of 10 years in non-sterile conditions and the dynamics of luminescent signals are described. A phylogenetic approach was used to recognize fungal species. A number of unique features of M. gombakensis are presented expanding the understanding of the properties of luminescent fungi. Research data indicate that M. gombakensis can potentially be used both in biotechnology and in the study of biophysics of the complex system of basidiomycetes.

The development of remote and proximal sensing techniques for early detection of photosynthetic responses under action of stressors is an important agricultural and environmental task. The photochemical reflectance index (PRI), typically calculated on the basis of the reflected light at 531 and 570 nm, is potentially sensitive to rapid changes in photosynthesis under unfavorable conditions. Mechanisms of PRI changes are thought to include chloroplast shrinkage and aggregation of light-harvesting complexes, transitions in the xanthophyll cycle, and changes in chlorophyll and carotenoid concentrations, making PRI difficult to be applied for monitoring plant health. Light measurement, the study of light-induced changes in PRI, and the analysis of modified PRIs are the ways for improving the efficiency of the application of PRI. Other ways may also favor improvement of the efficiency (for example, the development of methods of PRI estimation based on RGB imaging). The development of PRI measurement and analysis techniques holds significant promise for monitoring photosynthetic responses of plants to stressed environments.

Measurements of the spectral composition of light at the boundary of the photic zone in seven coastal bodies of water, to varying degrees separated from the sea, exposed to the sea and freshwater lake showed that in marine and brackish water bodies green light is predominantly transmitted, and in lakes the top layer of which is freshwater, orange, red and far red light is absorbed. In meromictic reservoirs, the photic zone was limited by a colored layer of water with the massive development of phototrophic microorganisms. Their pigment composition and the spectral composition of transmitted light are well matched. The sea bays and lagoons were dominated by taxa with red pigments: phycoerythrin-545 from cryptophyte algae, or purple sulfur bacteria with the carotenoid okenone, or brown-colored green sulfur bacteria with isorenieratin and bacteriochlorophyll e. In the lakes the top layer of which is freshwater, unicellular algae or green sulfur bacteria with chlorobactene and bacteriochlorophyll d developed. The spectral range can serve as a selective factor that determines the composition of the community of phototrophs with structurally different antennas, but similar light absorption spectra.

The kinetics of delayed fluorescence and phosphorescence of the photosensitizer erythrosine in fragments of normal tissues and malignant breast tumors of patients at an oncology clinic was studied in vitro. It has been shown that the kinetics of delayed fluorescence of the dye is formed as a superposition of signals of thermally activated luminescence and luminescence resulting from singlet-triplet annihilation of photosensitizer molecules and singlet oxygen. The quenching of the annihilation component of delayed fluorescence was discovered when molecules were excited by a series of n pulses with a frequency of 5–10 Hz. The shape of the delayed fluorescence curve, the intensity and duration of the afterglow of dye molecules are determined by the ratio of the rates of consumption/regeneration of oxygen content in tissues. A correlation between delayed fluorescence indicators and the clinical and morphological characteristics of tumors has been established, and the application of the results in rapid optical diagnostics of tissues is discussed.

The saliva of athletes participating in anaerobic (track and field athletes) or aerobic (swimmers) physical activity was studied. Saliva sample was collected before (control) and after the workout. It was found that physical activity significantly increased the salivary total protein concentration and pH values in the athletes. The activity of catalase in saliva was significantly increased only after aerobic, but not anaerobic exercise performance. The bioluminescent indicator of athletes’ saliva is significantly higher during aerobic workout than anaerobic exercise. Salivary biomarkers such as lactate concentration, catalase activity, total protein concentration, calcium, potassium, magnesium ions, and the amide IV group may have a significant effect on the enhancement of light emission in a bioluminescent assay based on a system of coupled enzymatic reaction. The amide IV group and the presence of the salivary oligosaccharides, polysaccharides, phosphatase, and phospholipids in athletes during anaerobic physical activity can eliminate bioluminescence more efficiently than the concentration of triene conjugates and the amide II group in the saliva of athletes involved in aerobic exercises. Thus, significant biomarkers for the measurement of the physiological status of athletes who engaged in aerobic or anaerobic physical activity have been identified in saliva, these biomarkers can influence the integrated response of the bioluminescent enzymatic biotest. The change in the integrated bioluminescent indicator of athletes' saliva depending on the type of physical exertion can be used in sports medicine to prevent physical overload.

Photobiology is a dynamically developing field of knowledge and practical activity. The Russian Photobiological Society promotes the development of creative activity and communication of scientists and practitioners in the field of photobiology and related disciplines. In September 2023, the X Congress of the Russian Photobiological Society took place. The article provides definitions of photobiology, biophotonics, photobiotechnology, and bioluminescence. A brief history of the Russian Photobiological Society is described, as well as an overview of the program and results of the X Congress, including a summary of articles prepared based on the materials of reports at the Congress, the topics closest to biophysics.