No abstract

In eukaryotes, damage tolerance of matrix DNA is mainly determined by the repair pathway under the control of the RAD6 epistatic group of genes. This pathway is also a main source of mutations gen erated by mutagenic factors. The results of our recent studies show that gene HSM3 participating in the con trol of adaptive mutagenesis increases the frequency of mutations induced by different mutagens. Mutations rad18, rev3, and mms2 controlling various stages of the RAD6 pathway are epistatic with mutation hsm3 that decreases UV induced mutagenesis to the level typical for single radiation sensitive mutants. The level of mutagenesis in the double mutant srs2 hsm3 was lower than in both single mutants. Note that a decrease in the level of mutagenesis relative to the single mutant srs2 depends on the mismatch repair, since this level in the triple mutant srs2 hsm3 pms1 corresponds to that in the single mutant srs2. These data show that the muta tor phenotype hsm3 is probably determined by processes occurring in a D loop. In a number of current works, the protein Hsm3 was shown to participate in the assembly of the proteasome complex S26. The assembly of proteasomes is governed by the N terminal domain. Our results demonstrated that the Hsm3 protein contains at least two domains; the N terminal part of the domain is responsible for the proteasome assembly, whereas the C terminal portion of the protein is responsible for mutagenesis.

The work is devoted to the study of the climatic effects of black carbon (BC) transferred from forest fires to the Arctic zone. The HYSPLIT (The Hybrid Single-Particle Lagrangian Integrated Trajectory model) trajectory model was used to initially assess the potential for particle transport from fires. The results of the trajectory analysis of the 2019 fires showed that the probability of the transfer of particles to the Arctic ranges from 1% to 10%, and in some cases increases to 20%. Detailed studies of the possible influence of BC ejected as a result of fires became possible by using the climate model of the INMCM5 (Institute of Numerical Mathematics Climate Model). The results of the numerical experiments have shown that the maximum concentration of BC in the Arctic atmosphere is observed in July and August and is associated with emissions from fires. The deposition of BC in the Arctic increases by about 1.5–2 times in the same months, in comparison with simulation without forest fire emissions. This caused an average decrease in solar radiation forcing of 0.3–0.4 Wt/m2 and an increase in atmospheric radiation heating of up to 5–6 Wt/m2. To assess the radiation forcing from BC contaminated snow, we used the dependences of the change in the snow albedo on the snow depth, and the albedo of the underlying surface for a given amount of BC fallen on the snow. These dependences were constructed on the basis of the SNICAR (Snow, Ice, and Aerosol Radiative) model. According to our calculations, the direct radiative forcing from BC in the atmosphere with a clear sky is a maximum of 4–5 W/m2 in July and August.

This paper describes the modification of land snow cover module of INM RAS climate model. The possible liquid water content in the snow layer and refreezing of melt water are taken into account by modified version of the model. This is especially important for transition season modelling, because of this phenomenon is observed mainly during the formation and melting of the snow cover, when surface temperature fluctuates around 0 °C. Simulation of snow density evolution is also added. The snow model is verified on observation and reanalysis data, including with using the ESM-SnowMIP-like protocol. As a result of these updates, mean climate snowmelting periods according to INM RAS climate model are refined, particularly in middle and high latitudes. Snow covered area reproduction is also improved. Modified version of snow model on the land can be used coupled with albedo model of a snow-covered surface, which takes into account snow metamorphism, and it can also be applied for sea ice case.