Vol 60, No 6 (2024)

All living systems are characterized by such fundamental properties as the ability to adaptation, self-regulation and formation of resistance. Mammalian non-nuclear erythrocytes also have the ability to adapt to external effects, but their regulatory capabilities are limited by cytoplasmic mechanisms, including phase transitions of proteins and membranes. This is one of the most ancient mechanisms of adaptation of living systems to external and internal conditions. Erythrocytes under changes in plasma composition, aging and energy depletion, undergo a reversible morpho-functional transformation, the transition from a discocyte to an echinocyte. The metabolic shifts occurring in this case correspond to a complex of universal changes that take place during erythrocyte transition to metabolic depression. As a rule, echinocytosis is considered as a pathological process preceding eryptosis and hemolysis. But it can be also considered as the first stage of the implementation of an universal program of passive cell adaptation, the ultimate goal of which is to transfer the system to suspended animation state. The energy status of an erythrocyte is determined by the equilibrium of soluble and membrane-bound hemoglobin (Hb) forms. Compounds with pronounced electrophilic properties – nitric oxide and methylglyoxal, affecting this equilibrium can induce cell’s transition from one metabolic state to another. The mechanism of their regulatory action is largely related to the modification of thiol groups of membrane and cytoskeleton proteins, including reactive SH-groups of Hb. It seems relevant to consider their effect on the state of Hb and erythrocytes.

In the current work we tested single strand binding protein from E. coli (EcSSB) and DNA-binding protein from S. solfataricus (Sso7d) to evaluate its effects on TdT activity for homopolymer substrates (T_n), that unable to form double helix structures. We showed a significant increase in TdT activity after adding of EcSSB even on the example of homopolymer substrates. Effects demonstrated open application of DNA binding proteins in TdT engineering and DNA-printing. The addition of EcSSB to the reaction mixture led to a significant increase in TdT activity and a shift of the reaction products towards longer oligonucleotides. The maximum effect was observed in a close to equimolar stoichiometric ratio (EcSSB)₄:TdT in the presence of Mn²⁺ cations. In addition, the presence of Sso7d in the reaction mixture led to a slight (up to 15%) decrease in TdT activity for substrates T₅ and T₁₅ and a more pronounced decrease for T₃₅ (up to 30%). At the same time, Co²⁺ cations reduced the inhibitory effect of Sso7d.The patterns and relationships established through our research have potential applications in various fields. Specifically, they can be utilized in protein engineering for the development of fusion proteins that are based on TdT. Furthermore, these findings can contribute to the advancement of novel enzymatic principles for de novo DNA synthesis.

The role of reactive oxygen species (ROS) and nitric oxide NO in the protection of common wheat Triticum aestivum L. from the rust fungus Puccinia graminis f. sp. tritici Erikss. and Henn. (Pgt), was studied on the example of interaction with resistant line of cv. Thatcher with the Sr25 gene from the wheatgrass Thinopyrum ponticum (TcSr25) and the susceptible cv. Saratovskaya 29 (C29). The seedlings were treated with salicylic acid (SA) as an inducer of ROS, and verapamil as Ca²⁺ channel inhibitor, and sodium nitroprusside (NP) as NO donor, and 2-phenyl-4, 4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) as NO scavenger. Isolates with reaction 0 (immunity) and 1 (resistance with hypersensitivity reaction, HR) were used to infect the seedlings. NO stimulated the growing tubes orientation and the formation of Pgt appressoria on the surface of resistant plants, and in susceptible plants it increased colony growth if plant were treated one day before or simultaneously with infection. The generation of superoxide anion was the main cause of Pgt appressoria death on the stomata of resistant plants, and NO did not affect tissue penetration. ROS induced HR and accelerated the destruction of the cytoplasm of cells. NO was contributed in the expansion of necrosis zone in resistant plants.

The effect of chitosan-caffeic acid (Ch-CA) conjugate separately and in combination with a mixture of Bacillus subtilis 47 on the plant defense against PVY under optimal hydration and water deficit in soil was evaluated. The treatments of Ch-CA and Ch-CA+B. subtilis 47 on healthy potato plants under optimal soil moisture conditions demonstrated the accumulation of proline and phenolic compounds, as well as the activation of PPO, which collectively led to an increase in the nonspecific plant defenses. The application of Ch-CA resulted in a reduction of PVY infection in potato plants grown under both optimal and soil moisture-deficient conditions and led to an increase the potato mini-tuber’s mass. The combination of B. subtilis 47 and Ch-CA proved effective in reducing the infection level exclusively under conditions of soil water deficit. It has been demonstrated that the primary factor influencing the development of resistance in potato plants to PVY under moisture-limiting conditions is associated with an elevated peroxidase activity and alterations in antioxidant activity within plant tissues.