Nuclear Distribution of the Chromatin-Remodeling Protein ATRX in Mouse Early Embryos during Normal Development and Developmental Arrest In Vitro.

The chromatin-remodeling protein ATRX, which is currently recognized as one of the key genome caretakers, plays an important role in oogenesis and early embryogenesis in mammals. ATRX distribution in the nuclei of mouse embryos developing in vivo and in vitro, including when the embryos are arrested at the two-cell stage-the so-called two-cell block in vitro-was studied using immunofluorescent labeling and FISH. In normally developing two- and four-cell embryos, ATRX was found to be closely colocalized with pericentromeric DNA sequences detected with a probe to the mouse major satellite DNA.

Special Nuclear Structures in the Germinal Vesicle of the Common Frog with Emphasis on the So-Called Karyosphere Capsule.

The karyosphere (karyosome) is a structure that forms in the oocyte nucleus-germinal vesicle (GV)-at the diplotene stage of meiotic prophase due to the assembly of all chromosomes in a limited portion of the GV. In some organisms, the karyosphere has an extrachromosomal external capsule, the marker protein of which is nuclear F-actin. Despite many years of theories about the formation of the karyosphere capsule (KC) in the GV of the common frog , we present data that cast doubt on its existence, at least in this species.

Chromatin Morphology in Human Germinal Vesicle Oocytes and Their Competence to Mature in Stimulated Cycles.

The search for simple morphological predictors of oocyte quality is an important task for assisted reproduction technologies (ARTs). One such predictor may be the morphology of the oocyte nucleus, called the germinal vesicle (GV), including the level of chromatin aggregation around the atypical nucleolus (ANu)-a peculiar nuclear organelle, formerly referred to as the nucleolus-like body. A prospective cohort study allowed distinguishing three classes of GV oocytes among 135 oocytes retrieved from 64 patients: with a non-surrounded ANu and rare chromatin blocks in the nucleoplasm (Class A), with a complete peri-ANu heterochromatic rim assembling all chromatin (Class C), and intermediate variants (Class B).

Chromatin Configuration in Diplotene Mouse and Human Oocytes during the Period of Transcriptional Activity Extinction.

In the oocyte nucleus, called the germinal vesicle (GV) at the prolonged diplotene stage of the meiotic prophase, chromatin undergoes a global rearrangement, which is often accompanied by the cessation of its transcriptional activity. In many mammals, including mice and humans, chromatin condenses around a special nuclear organelle called the atypical nucleolus or formerly nucleolus-like body. Chromatin configuration is an important indicator of the quality of GV oocytes and largely predicts their ability to resume meiosis and successful embryonic development.

DAXX Is a Crucial Factor for Proper Development of Mammalian Oocytes and Early Embryos.

The Death-domain associated protein 6 (DAXX) is an evolutionarily conserved and ubiquitously expressed multifunctional protein that is implicated in many cellular processes, including transcription, cellular proliferation, cell cycle regulation, Fas-induced apoptosis, and many other events. In the nucleus, DAXX interacts with transcription factors, epigenetic modifiers, and chromatin-remodeling proteins such as the transcription regulator ATRX-the α-thalassemia/mental retardation syndrome X-linked ATP-dependent helicase II. Accordingly, DAXX is considered one of the main players involved in chromatin silencing and one of the most important factors that maintain integrity of the genome.

Heterochromatin Morphodynamics in Late Oogenesis and Early Embryogenesis of Mammals.

During the period of oocyte growth, chromatin undergoes global rearrangements at both morphological and molecular levels. An intriguing feature of oogenesis in some mammalian species is the formation of a heterochromatin ring-shaped structure, called the karyosphere or surrounded "nucleolus", which is associated with the periphery of the nucleolus-like bodies (NLBs). Morphologically similar heterochromatin structures also form around the nucleolus-precursor bodies (NPBs) in zygotes and persist for several first cleavage divisions in blastomeres.

The dynamics of DAXX protein distribution in the nucleus of mouse early embryos.

Nuclear distribution of Death-associated protein 6 (Daxx) was studied using fluorescent and electron microscopy in mouse embryos at different stages of development in vivo, from zygote to morula. Daxx was found in association with transcriptionally silent chromatin predominantly with a heterochromatin rim surrounding the nucleolus precursor bodies (NPBs) at all stages studied. At the zygote stage, Daxx was detected only at the periphery of NPBs both in male and female pronuclei.

Application of the allogenic mesenchymal stem cells in the therapy of the bladder tuberculosis.

Urogenital tuberculosis (TB) often leads to contraction of the bladder, a reduction of the urinary reservoir capacity, and, in the latest stage, to real microcystitis up to full obliteration. Bladder TB Stage 4 is unsuitable for conservative therapy, and cystectomy with subsequent enteroplasty is indicated. In this study, using a model of bladder TB in New Zealand rabbits, the therapeutic efficacy of the interstitial injection of autologous bone-derived mesenchymal stem cells (MSCs) combined with standard anti-TB treatment in the restoration of the bladder function was demonstrated.

Detection of RNA Polymerase II in Mouse Embryos During Zygotic Genome Activation Using Immunocytochemistry.

Mammalian pre-implantation embryos represent a highly dynamic experimental model for comparative studies of nuclear structure and functions in the context of gradual reactivation of transcription. Here, we present details of the methods that allow localizing RNA polymerase II in mouse pre-implantation embryos with specific antibodies, using fluorescent/confocal and electron microscopy. We stress the special aspects of immunolabeling protocols in respect to the embryonic material.

Nuclear distribution of the chromatin-remodeling protein ATRX in mouse early embryogenesis.

The nucleus of mammalian embryos differs by transcriptional activity at different stages of early development. Here, we studied nuclear distribution of the chromatin-remodeling protein ATRX in pre-implantation mouse embryos. Immunofluorescent staining revealed the changes of ATRX nuclear distribution at the initial stages of early mouse development.

Nuclear distribution of RNA polymerase II and mRNA processing machinery in early mammalian embryos.

Spatial distribution of components of nuclear metabolism provides a significant impact on regulation of the processes of gene expression. While distribution of the key nuclear antigens and their association with the defined nuclear domains were thoroughly traced in mammalian somatic cells, similar data for the preimplantation embryos are scanty and fragmental. However, the period of cleavage is characterized by the most drastic and dynamic nuclear reorganizations accompanying zygotic gene activation.

An immunocytochemical study of interchromatin granule clusters in early mouse embryos.

Interchromatin granule clusters (IGCs) are universal nuclear domains. Their molecular composition and functions were studied in detail in somatic cells. Here, we studied IGCs in the nuclei of early mouse embryos during zygotic gene activation (ZGA).

FRET analysis of interactions between actin and exon-exon-junction complex proteins in early mouse embryos.

Spatial interactions between nuclear actin and some proteins of the exon-exon junction complex (EJC) have been demonstrated in the nuclei of early mouse embryos by using Förster resonance energy transfer (FRET). FRET has been registered for the pairs actin-Y14, actin-Aly/REF and actin-NXF1/TAP in nucleoplasmic, irregularly shaped zones and in nucleolus precursor bodies (NPBs). We suggest that FRET signals in the nucleoplasm correspond to the bordering zone of transcriptionally active chromatin.

F-actin distribution pattern in the nuclei of early mouse embryos.

Nuclear actin is the essential component of gene expression. Here we show that the pattern of F- actin distribution in the nuclei of early mouse embryos depends on the experimental conditions and does not represent nonspecific cell reaction for the experimental influence.

Localization of poly(A)(+) RNA and mRNA export factors in interchromatin granule clusters of two-cell mouse embryos.

Interchromatin granule clusters (IGCs), also known as nuclear speckles, splicing factor compartments, or SC35-domains, are one of the most universal nuclear organelles of the cell. We have used two-cell mouse embryos as an experimental system to study the possible association of poly(A)(+) RNA and factors involved in RNA export (Tip-associated protein [TAP] and heterogenous nuclear ribonucleoprotein A/B [hnRNP A/B]) with IGCs. Poly(A)(+) RNA was localized by microinjections of 2'-O-Me(U)(22) probes conjugated with tetramethylrhodamine.