Small interfering RNA (siRNA) is the most important tool for the manipulation of mRNA expression and needs protection from intracellular nucleases when delivered into the cell. In this work, we examined the effects of siRNA modification with the phosphoryl guanidine (PG) group, which, as shown earlier, makes oligodeoxynucleotides resistant to snake venom phosphodiesterase. We obtained a set of siRNAs containing combined modifications PG/2′-O-methyl (2′-OMe) or PG/2′-fluoro (2′-F); biophysical and biochemical properties were characterized for each duplex. We used the UV-melting approach to estimate the thermostability of the duplexes and RNAse A degradation assays to determine their stability. The ability to induce silencing was tested in cultured cells stably expressing green fluorescent protein. The introduction of the PG group as a rule decreased the thermodynamic stability of siRNA. At the same time, the siRNAs carrying PG groups showed increased resistance to RNase A. A gene silencing experiment indicated that the PG-modified siRNA retained its activity if the modifications were introduced into the passenger strand.

The article presents the results of the study on the patterns of behavior of massive open online courses (MOOCs) learners in the context of motives to the learning, set criteria of quality, and also the engagement rate. Within the research the data collected on learners enrolled in online courses of Tomsk State University on the online platforms Courcera, Lectorium and National Open Education Platform was classified and analyzed. It allowed us to define the students' patterns of behavior, to reveal the goals of learning on MOOC, social and demographic characteristics of the students, and also the quality criteria of the courses set by the students. As a result of data processing, a correlation between the above-mentioned parameters was found.

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