Ammonium Dinitramide as a Prospective N-NO Synthon: Electrochemical Synthesis of Nitro--Azoxy Compounds from Nitrosoarenes.

In this study, the electrochemical coupling of nitrosoarenes with ammonium dinitramide is discovered, leading to the facile construction of the nitro--azoxy group, which represents an important motif in the design of energetic materials. Compared to known approaches to nitro--azoxy compounds involving two chemical steps (formation of azoxy group containing a leaving group and its nitration) and demanding expensive, corrosive, and hygroscopic nitronium salts, the presented electrochemical method consists of a single step and is based solely on nitrosoarenes and ammonium dinitramide. The dinitramide salt plays the roles of both the electrolyte and reactant for the coupling.

Functions of RNAi Pathways in Ribosomal RNA Regulation.

Argonaute proteins, guided by small RNAs, play crucial roles in gene regulation and genome protection through RNA interference (RNAi)-related mechanisms. Ribosomal RNAs (rRNAs), encoded by repeated rDNA units, constitute the core of the ribosome being the most abundant cellular transcripts. rDNA clusters also serve as sources of small RNAs, which are loaded into Argonaute proteins and are able to regulate rDNA itself or affect other gene targets.

Otu and Rif1 Double Mutant Enables Analysis of Satellite DNA in Polytene Chromosomes of Ovarian Germ Cells in Drosophila melanogaster.

Polytene chromosomes in Drosophila serve as a classical model for cytogenetic studies. However, heterochromatic regions of chromosomes are typically under-replicated, hindering their analysis. Mutations in the Rif1 gene lead to additional replication of heterochromatic sequences, including satellite DNA, in salivary gland cells.

Thermal stability of emerging N6-type energetic materials: kinetic modeling of simultaneous thermal analysis data to explain sensitivity trends.

A number of new high-performing energetic materials possess explosophoric functionalities, high nitrogen content, and fused heterocyclic blocks. Two representatives of these materials have been synthesized recently, namely, 1,2,9,10-tetranitrodipyrazolo[1,5-:5',1'-][1,2,3,4]-tetrazine (1) and 2,9-dinitrobis([1,2,4]triazolo)[1,5-:5',1'-][1,2,3,4]tetrazine (2). The thermal stability of these energetic materials bearing the N-N-N = N-N-N fragment and three closely related compounds has been investigated for the first time.

A Spontaneous Inversion of the X Chromosome Heterochromatin Provides a Tool for Studying the Structure and Activity of the Nucleolus in .

The pericentromeric heterochromatin is largely composed of repetitive sequences, making it difficult to analyze with standard molecular biological methods. At the same time, it carries many functional elements with poorly understood mechanisms of action. The search for new experimental models for the analysis of heterochromatin is an urgent task.

Anions Containing Tripoid Conjugated N System: Salts of 5-(Substituted Amino)-[1,2,3]triazolo[4,5-][1,2,5]oxadiazol-5-ium-4-ides, as well as Their Synthesis, Structure, and Thermal Stability.

A strategy for the synthesis of 5-((2-cyanoethyl)-X-amino)-[1,2,3]triazolo[4,5-][1,2,5]oxadiazol-5-ium-4-ides (X = H; CHCHCN; NO (); CN (); COEt ()) starting from 3-amino-4-azido-1,2,5-oxadiazole was developed. The key step in this strategy is the intramolecular thermolytic cyclization of the azido group and the bis(2-cyanoethyl)triazene group. Removal of the 2-cyanoethyl protecting group from amides - gave potassium salt of the corresponding nitramide and sodium salts of cyano- and ethoxycarbonylamide.

Correction: [(3-Nitro-1-1,2,4-triazol-1-yl)--azoxy]furazans: energetic materials containing an N(O)[double bond, length as m-dash]N-N fragment.

[This corrects the article DOI: 10.1039/D1RA03919A.].

[(3-Nitro-1-1,2,4-triazol-1-yl)--azoxy]furazans: energetic materials containing an N(O)[double bond, length as m-dash]N-N fragment.

The strategy for the synthesis of substituted [(3-nitro-1-1,2,4-triazol-1-yl)--azoxy]furazans 4-7, in which the distal nitrogen of the azoxy group is bonded to the nitrogen atom of the azole ring, includes, firstly, the reaction of 1-amino-3-nitro-1-1,2,4-triazole with 2,2,2-trifluoro--(4-nitrosofurazan-3-yl)acetamide in the presence of dibromisocyanuric acid followed by removing of the trifluoroacetyl protecting group to afford aminofurazan (4). Transformation of the amino group in the latter made it possible to synthesize the corresponding nitro (5), azo (6), and methylene dinitramine (7) substituted furazans. The compounds synthesized are thermally stable (decomposition onset temperatures 147-228 °C), exhibit acceptable densities (1.

Impaired function of rDNA transcription initiation machinery leads to derepression of ribosomal genes with insertions of R2 retrotransposon.

Eukaryotic genomes harbor hundreds of rRNA genes, many of which are transcriptionally silent. However, little is known about selective regulation of individual rDNA units. In Drosophila melanogaster, some rDNA repeats contain insertions of the R2 retrotransposon, which is capable to be transcribed only as part of pre-rRNA molecules.

Complex Genetic Interactions between Piwi and HP1a in the Repression of Transposable Elements and Tissue-Specific Genes in the Ovarian Germline.

Insertions of transposable elements (TEs) in eukaryotic genomes are usually associated with repressive chromatin, which spreads to neighbouring genomic sequences. In ovaries of , the Piwi-piRNA pathway plays a key role in the transcriptional silencing of TEs considered to be exerted mostly through the establishment of H3K9me3 histone marks recruiting Heterochromatin Protein 1a (HP1a). Here, using RNA-seq, we investigated the expression of TEs and the adjacent genomic regions upon Piwi and HP1a germline knockdowns sharing a similar genetic background.

Various modes of HP1a interactions with the euchromatic chromosome arms in Drosophila ovarian somatic cells.

Heterochromatin protein 1a (HP1a) is a well-known component of pericentromeric and telomeric heterochromatin in Drosophila. However, its role and the mechanisms of its binding in the chromosome arms (ChAs) remain largely unclear. Here, we identified HP1a-interacting domains in the somatic cells of Drosophila ovaries using a DamID-seq approach and compared them with insertion sites of transposable elements (TEs) revealed by genome sequencing.

Special vulnerability of somatic niche cells to transposable element activation in Drosophila larval ovaries.

In the Drosophila ovary, somatic escort cells (ECs) form a niche that promotes differentiation of germline stem cell (GSC) progeny. The piRNA (Piwi-interacting RNA) pathway, which represses transposable elements (TEs), is required in ECs to prevent the accumulation of undifferentiated germ cells (germline tumor phenotype). The soma-specific piRNA cluster flamenco (flam) produces a substantial part of somatic piRNAs.

Long Noncoding RNAs and Stress Response in the Nucleolus.

Long noncoding RNAs (lncRNAs) perform diverse functions in the regulation of cellular processes. Here we consider a variety of lncRNAs found in the ribosome production center, the nucleolus, and focus on their role in the response to environmental stressors. Nucleolar lncRNAs ensure stress adaptation by cessation of resource-intensive ribosomal RNA (rRNA) synthesis and by inducing the massive sequestration of proteins within the nucleolus.

Yb body assembly on the piRNA precursor transcripts reduces genic piRNA production.

In ovarian somatic cells, PIWI-interacting small RNAs (piRNAs) against transposable elements are mainly produced from the ∼180-kb () locus. transcripts are gathered into foci, located close to the nuclear envelope, and processed into piRNAs in the cytoplasmic Yb bodies. The mechanism of Yb body formation remains unknown.

[Participation of the piRNA pathway in recruiting a component of RNA polymerase I transcription initiation complex to germline cell nucleoli].

Proteins of the Piwi family and short Piwi-interacting RNAs (piRNAs) ensure the protection of the genome from transposable elements. We have previously shown that nuclear Piwi protein tends to concentrate in the nucleoli of the cells of Drosophila melanogaster ovaries. It could be hypothesized that the function of Piwi in the nucleolus is associated with the repression of R1 and R2 retrotransposons inserted into the rDNA cluster.

Induction of Transposon Silencing in the Drosophila Germline.

In this review we consider the role of the piRNA system in transposable element silencing in the Drosophila melanogaster germline. We focus on new data that demonstrate the mechanisms of initiation of piRNA biogenesis in ovarian germinal cells and the role of Piwi protein in this process, including our own results.

Piwi interacts with chromatin at nuclear pores and promiscuously binds nuclear transcripts in Drosophila ovarian somatic cells.

Piwi in a complex with Piwi-interacting RNAs (piRNAs) triggers transcriptional silencing of transposable elements (TEs) in Drosophila ovaries, thus ensuring genome stability. To do this, Piwi must scan the nascent transcripts of genes and TEs for complementarity to piRNAs. The mechanism of this scanning is currently unknown.

Behavior Risk Factors Among Russian Students.

Purpose To analyze the prevalence of risk factors among Russian students. Methods In this study, 834 students were included from five Federal universities which were localized in four Federal regions of Russian Federation. Future doctors, school teachers, and wellness trainers were included in this study.

[The role of Piwi nuclear localization in the differentiation and proliferation of germline stem cells].

The Piwi protein and its orthologs are considered as the key components of the piRNA machinery implicated in transcriptional silencing of transposons. Неre, we show that nuclear localization of the Piwi protein is required not only for transposon repression, but also for proper differentiation of germline stem cells (GSCs). piwi^(Nt) mutation that causes loss of nuclear Piwi and its retention in the cytoplasm leads to the accumulation of undifferentiated GSC-like cells.

Behavior Risk Factors Among Russian University Students Majoring in Medicine, Education, and Exercise Science.

Purpose To analyze the prevalence of select behavioral risk factors among Russian university students majoring in medicine, education, and exercise science. Methods A total of 834 students from five Federal universities located in four federal regions of Russia were included in the study. The purposive sample included future doctors, school teachers, and fitness trainers.

Synthesis of Tetrazino-tetrazine 1,3,6,8-Tetraoxide (TTTO).

This study presents the first synthesis and characterization of a new high energy compound [1,2,3,4]tetrazino[5,6-e][1,2,3,4]tetrazine 1,3,6,8-tetraoxide (TTTO). It was synthesized in ten steps from 2,2-bis(tert-butyl-NNO-azoxy)acetonitrile. The synthetic strategy was based on the sequential closure of two 1,2,3,4-tetrazine 1,3-dioxide rings by the generation of oxodiazonium ions and their intramolecular coupling with tert-butyl-NNO-azoxy groups.

[Functions of piRNAs and the Piwi Protein in Drosophila].

Short (25-35 nucleotides) regulatory piPHK, along with RNA-binding proteins of the Piwi family, constitute an evolutionarily conserved system that functions mainly in eukaryotic gonads. The system can be regarded as a variant of the mechanism of RNA interference, which is based on the recognition of target RNA as a result of complementary interactions with piRNA. The variants of this regulatory system function in the germline cells, including stem cells and somatic cells of the niche, ensuring maintenance of the germline stem cells and their differentiation.

[PIWI protein as a nucleolus visitor in Drosophila melanogaster].

The evolutionarily conserved nuclear Piwi protein of Drosophila melanogaster is a representative of the Argonaute small RNA binding protein family. Guided by small piRNAs, Piwi functions in transposon silencing in somatic and germ cells of the gonad. We found that in ovarian somatic and germ cells, as well as in the established ovarian somatic cell line, Piwi is concentrated predominantly in the nucleolus--the main nuclear compartment, participating not only in rRNA synthesis, but also in various cell stress responses.