Ontogenez

The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor and its target genes play a fundamental role in detoxification, regulation of developmental processes, maintenance of homeostasis, as well as in the occurrence of oncological and autoimmune diseases and drug metabolism. The high conservatism of vertebrate AHR allowed us to study its functions in vivo using transformed Drosophila melanogaster fruit flies with human or mouse AHR gene and compare the ectopic effect of their expression with the expression of spineless gene, Drosophila AHR homologue. This work demonstrates for the first time that vertebrate AHR exhibits its functional activity in Drosophila embryogenesis, in leg imaginal discs and in somatic cells of female reproductive system in the absence of exogenous ligands.

The germes gene is a marker of germ plasm and primordial germ cells (PGC) described in the African clawed frog Xenopus laevis. It is known that overexpression of its mutant form negatively affects the formation and migration of PGC. However, until now it was not known how widely this gene is represented in animals of different phylogenetic groups. In this work, we performed bioinformatic analysis of genomic and transcriptome sequences of animals with germ plasm. It turned out that germes homologs are present only in representatives of the genera Xenopus and Hymenochirus of the family Pipidae (order Anura). The obtained results were confirmed by RT-PCR analysis of the expression of germes orthologs in the ovaries of six representatives of different Anura families. Phylogenetic analysis of cloned sequences of germes homologs suggests the appearance of this gene in the ancestors of Pipidae and its secondary loss in the genus Pseudohymenochirus. It is also identified that the amino acid sequences of the functional domains of the Germes protein are rather conservative.

Differentiation of induced pluripotent stem (iPS) cells from patients and healthy donors allows in vitro study of genetic disorders. We have previously reported a clinical case of recurrent pregnancy loss in a patient with skewed X-chromosome inactivation in peripheral blood lymphocytes, endometrium, and buccal epithelium. We have found a 239 kb microdeletion at Xq24 that affected eight genes including UBE2A. In this work, we produced iPS cell line iTAF15Xsk4 from the patient’s skin fibroblasts using non-integrating episomal vectors. iPS cell line had a normal karyotype, expressed pluripotency markers, and upon differentiation in embryoid bodies expressed markers of all three germ layers. This cell line could be used for the UBE2A deficiency syndrome study.

Genome editing in human pluripotent stem cells using programmable nucleases makes it possible to create models of hereditary pathologies using directed transgenesis, gene knockout, and replacement of individual nucleotides in DNA sequences. Using CRISPR/SpCas9-mediated homologous recombination at the AAVS1 locus, clones of human induced pluripotent stem cells (iPSCs) ICGi022-A (Malakhova et al., 2020) were obtained, which carry transgenes of two variants of the nuclease AsCas12a (also known as AsCpf1), recognizing different PAM consensuses, and the reverse doxycycline transgene-dependent transactivator – M2rtTA. For each AsCas12a variant, the lines ICGi022-A-6 (AsCas12a, PAM 5'-TTTV-3') and ICGi022-A-7 (AsCas12a, PAM 5'-TYCV-3') were obtained. Using Western blot analysis, it was shown that the addition of doxycycline to the culture medium causes activation of the expression of AsCas12a(TTTV) and AsCas12a(TYCV) proteins. The resulting transgenic iPSC clones were subjected to molecular and cytogenetic analysis. Using quantitative PCR and immunocytochemical analysis, it was shown that they have a high level of mRNA expression of gene markers of pluripotent cells, namely OCT4, NANOG and SOX2, as well as specific expression of protein marker OCT4, SOX2, SSEA-4 and TRA-1-60. In addition, using iPSCs spontaneous differentiation into embryoid bodies, it was found that transgenic clones can give derivatives of all three primitive germ layers: ectoderm, mesoderm and endoderm. Cytogenetic analysis showed that transgenic iPSC clones have a normal karyotype, 46,XX.