Essential functions of RNA helicase Vasa in maintaining germline stem cells and piRNA-guided silencing in spermatogenesis.

DEAD-box RNA helicase Vasa is required for gonad development and fertility in multiple animals. Vasa is implicated in many crucial aspects of oogenesis, including translation regulation, primordial germ cell specification, piRNA silencing of transposable elements, and maintenance of germline stem cells (GSCs). However, data about Vasa functions in spermatogenesis remain controversial.

Molecular Insights into Female Hybrid Sterility in Interspecific Crosses between and .

Species of the genus have served as favorite models in speciation studies; however, genetic factors of interspecific reproductive incompatibility are under-investigated. Here, we performed an analysis of hybrid female sterility by crossing females and males. Using transcriptomic data analysis and molecular, cellular, and genetic approaches, we analyzed differential gene expression, transposable element (TE) activity, piRNA biogenesis, and functional defects of oogenesis in hybrids.

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.

[Morphological features of vasoproliferative tumor of the retina].

Vasoproliferative retinal tumor (VPT) is a term proposed by ophthalmologists in relation to the totality of manifestations of an intraocular volumetric process with involvement of the inner lining of the eye, an integral part of which is the active growth of blood vessels. The available literature data on the morphology of this process are very contradictory and ambiguous. The article presents two clinical cases of vasoproliferative retinal tumor with own illustration of morphological studies.

Effects of Chromatin Structure Modifiers on the trans-Acting Heterochromatin Position Effect in Drosophila melanogaster.

The heterochromatin position effect is manifested in the inactivation of euchromatin genes transferred to heterochromatin. In chromosomal rearrangements, genes located near the new eu-heterochromatin boundary in the rearrangement (cis-inactivation) and, in rare cases, genes of a region of the normal chromosome homologous to the region of the eu-heterochromatin boundary of the chromosome with the rearrangement (trans-inactivation) are subject to inactivation. The In(2)A4 inversion is able to trans-inactivate the UAS-eGFP reporter gene located on the normal chromosome.

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.

Comparative transcriptional analysis uncovers molecular processes in early and mature somatic cyst cells of Drosophila testes.

The tight interaction between somatic and germline cells is conserved in animal spermatogenesis. The testes of Drosophila melanogaster are the model of choice to identify processes responsible for mature gamete production. However, processes of differentiation and soma-germline interactions occurring in somatic cyst cells are currently understudied.

as a Model System for Studying of the Evolution and Functional Specialization of the Y Chromosome.

The Y chromosome is one of the sex chromosomes found in males of animals of different taxa, including insects and mammals. Among all chromosomes, the Y chromosome is characterized by a unique chromatin landscape undergoing dynamic evolutionary change. Being entirely heterochromatic, the Y chromosome as a rule preserves few functional genes, but is enriched in tandem repeats and transposons.

Labial mucosal epithelium grafting in an ex vivo human donor cornea model.

The purpose of the study was to establish a simple ex vivo corneal re-epithelization model and study the labial mucosal epithelium grafting as a potential approach for ocular surface reconstruction. Four human donor corneal buttons were overstored in a corneal cold storage solution at 4 °C for 32-52 days. Four labial oral mucosa strips were dissected from four patients during fornix reconstruction after they signed informed consent.

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.

[The prognostic value of uveal melanoma cell type].

Objective: To determine the prognostic value of a uveal melanoma (UM) cell type for the development of metastases (MTS).

Subjects And Methods: The investigation enrolled 96 patients (96 eyes) with UM after enucleation. Forty-one patients without signs of MTS were included in this group, who were followed up for more than 36 months (mean, 70.

Genes and the piRNA Pathway in Speciation and Reproductive Isolation of .

One of the main conditions of the species splitting from a common precursor lineage is the prevention of a gene flow between diverging populations. The study of interspecific hybrids allows to reconstruct the speciation mechanisms and to identify hybrid incompatibility factors that maintain post-zygotic reproductive isolation between closely related species. The regulation, evolution, and maintenance of the testis-specific genetic system in is the subject of investigation worldwide.

[Morphological changes in rabbit cornea after implantation of a new keratoprosthesis supporting plate].

Purpose: To evaluate biocompatibility of the new keratoprosthesis supporting plates (KSP) in rabbits .

Material And Methods: The study included 15 chinchilla rabbits. In the first group (5 rabbit eyes) KSP made of hydrophobic acryl with square penetrating holes of 220×220 micron (model 1) were inserted into rabbits' corneas.

Functional Significance of Satellite DNAs: Insights From .

Since their discovery more than 60 years ago, satellite repeats are still one of the most enigmatic parts of eukaryotic genomes. Being non-coding DNA, satellites were earlier considered to be non-functional "junk," but recently this concept has been extensively revised. Satellite DNA contributes to the essential processes of formation of crucial chromosome structures, heterochromatin establishment, dosage compensation, reproductive isolation, genome stability and development.

piRNA silencing contributes to interspecies hybrid sterility and reproductive isolation in Drosophila melanogaster.

The piRNA pathway is an adaptive mechanism that maintains genome stability by repression of selfish genomic elements. In the male germline of Drosophila melanogaster repression of Stellate genes by piRNAs generated from Supressor of Stellate (Su(Ste)) locus is required for male fertility, but both Su(Ste) piRNAs and their targets are absent in other Drosophila species. We found that D.

Regulated Gene Expression as a Tool for Analysis of Heterochromatin Position Effect in Drosophila.

Position effect variegation (PEV) is a perturbation of genes expression resulting from the changes in their chromatin organization due to the abnormal juxtaposition with heterochromatin. The exact molecular mechanisms of PEV remain enigmatic in spite of the long history of PEV studies. Here, we developed a genetic model consisting of PEV-inducing chromosome rearrangement and a reporter gene under control of the UAS regulatory element.

Trans-inactivation: Repression in a wrong place.

Trans-inactivation is the repression of genes on a normal chromosome under the influence of a rearranged homologous chromosome demonstrating the position effect variegation (PEV). This phenomenon was studied in detail on the example of brown allele causing the repression of wild-type brown gene on the opposite chromosome. We have investigated another trans-inactivation-inducing chromosome rearrangement, In(2)A4 inversion.

The Differences Between Cis- and Trans-Gene Inactivation Caused by Heterochromatin in Drosophila.

Position-effect variegation (PEV) is the epigenetic disruption of gene expression near the de novo-formed euchromatin-heterochromatin border. Heterochromatic cis-inactivation may be accompanied by the trans-inactivation of genes on a normal homologous chromosome in trans-heterozygous combination with a PEV-inducing rearrangement. We characterize a new genetic system, inversion In(2)A4, demonstrating cis-acting PEV as well as trans-inactivation of the reporter transgenes on the homologous nonrearranged chromosome.

Heterochromatin formation and transcription in relation to trans-inactivation of genes and their spatial organization in the nucleus.

The role of transcription in heterochromatin formation in the nuclei of eukaryotes, originally shown for the pericentromeric heterochromatin assembly in fission yeasts, has now become an accepted paradigm extended to multicellular eukaryotes. It has been shown that small RNAs involved in the RNA interference system in its broadest sense can play an important role in this multi-step process - they are recognized by complementary interactions with the newly formed nuclear transcripts and recruit protein complexes to the local genomic sites for heterochromatinization. The role of transcription as a trigger of this process at the sites of genomic repeats will be considered in this review using various examples of heterochromatin formation, with an emphasis on discussion of its role in trans-chromosomal interactions causing gene inactivation.

[Intraocular electrochemical lysis at the stage of endoresection of uveal melanoma (clinical experimental study)].

Introduction of novel techniques of tumor destruction allows endoresection to be a perspective eye-preserving method of uveal melanoma treatment. Further investigations are essential to assess endoresection efficacy.

[Correlation on a cellular level of gene transcriptional silencing and heterochromatin compartment dragging in case of PEV-producing eu-heterochromatin rearrangement in Drosophila melanogaster].

Eu-heterochromatic rearrangements transfer genes into the heterochromatin and cause their variegated inactivation (PEV). Genes affected by PEV often demonstrate association with heterochromatic nuclear compartment (a distinct area composed of heterochromatin sequences like satellite DNA and enriched in specific chromatin proteins e.g.

CORE needle biopsy of orbital tumors.

Background: In some orbital mass lesions, histology may be the only way to establish an accurate diagnosis. Core needle biopsy (CNB) is widely performed in oncology, and unlike fine needle aspiration biopsy (FNAB), it can provide sufficient tissue sample for histology and immunohistochemistry. The purpose of this study was to evaluate the usefulness and possible complications of CNB of orbital tumors.

[Functional significance of sulfated glycosaminoglycan complex for the control of fibroblast proliferation in vitro].

The effect of an original sulfated glycosaminoglycan (sGAG) mixture (keratan sulfate with chondroitin sulfate) was examined in the in vitro experiment with the cell culture of murine fibroblasts (cell line L929). Two forms (solution and gel) of the active substance were tested in different concentrations (0.1-5.

[Potential of ultrasound biomicroscopy of retinal periphery in cataract of different etiology].

Presence and pattern of peripheral retinal changes were studied using ultrasound biomicroscopy (UBM) in patients with cataract of different etiology. UBM was performed in 85 eyes of 65 patients. Mean age was 65, 75+8, 19 years old.

[Involvement of hydrogen peroxide in the regulation of coexpression of alternative oxidase and rotenone-insensitive NADH dehydrogenase in tomato leaves and calluses].

The involvement of active oxygen forms in the regulation of the expression of mitochondrial respiratory chain components, which are not related to energy storing, has been in vitro and in vivo studied in Lycopersicum esculentum L. The highest level of transcription of genes encoding alternative oxidase and NADH dehydrogenase has been observed in green tomato leaves. It has been shown that even low H2O2 concentrations activate both aoxlalpha and ndb1 genes, encoding alternative oxidase and external mitochondrial rotenone-insensitive NADH dehydrogenase, respectively.