Margarita A. Sobol

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We report that tumor cells without mitochondrial DNA (mtDNA) show delayed tumor growth, and that tumor formation is associated with acquisition of mtDNA from host cells. This leads to partial recovery of mitochondrial function in cells derived from primary tumors grown from cells without mtDNA and a shorter lag in tumor growth. Cell lines from circulating(More)
  • M A Sobol
  • Journal of gravitational physiology : a journal…
  • 2001
A nucleolus is the dynamic part of a cell nucleus where rDNA transcription, rRNA precursor processing and transport are proceeding. Investigations of the influence of microgravity and clinorotation on the structure and function of nucleolus began more than thirty years ago but, unfortunately, now there are only some articles concerning the nucleolar(More)
RNA polymerase I (Pol I) transcription is essential for the cell cycle, growth and protein synthesis in eukaryotes. In the present study, we found that phosphatidylinositol 4,5-bisphosphate (PIP2) is a part of the protein complex on the active ribosomal promoter during transcription. PIP2 makes a complex with Pol I and the Pol I transcription factor UBF in(More)
In this study we present an optimized method of high-pressure freezing and automated freeze-substitution of cultured human cells, followed by LR White embedding, for subsequent immunolabeling. Also, the influence of various conditions of the freeze-substitution procedures such as temperature, duration, and additives in the substitution medium on the(More)
To maintain growth and division, cells require a large-scale production of rRNAs which occurs in the nucleolus. Recently, we have shown the interaction of nucleolar phosphatidylinositol 4,5-bisphosphate (PIP2) with proteins involved in rRNA transcription and processing, namely RNA polymerase I (Pol I), UBF, and fibrillarin. Here we extend the study by(More)
The best available approach of biological sample preparation for transmission electron microscopy currently includes cryoimmobilization by high-pressure freezing (HPF) followed by freeze-substitution (FS). This method has been well established for interphase cells; however, a reliable and easy procedure is still missing for mitotic cells especially because(More)
Using quantitative evaluation of immuno-gold labeling and antigen content, we evaluated various automated freeze-substitution protocols used in preparation of biological samples for immunoelectron microscopy. Protein extraction from cryoimmobilized cells was identified as a critical point during the freeze-substitution. The loss of antigens (potentially(More)
Fibrillarin is an essential protein that is well known as a molecular marker of transcriptionally active RNA polymerase I. Fibrillarin methyltransferase activity is the primary known source of methylation for more than 100 methylated sites involved in the first steps of preribosomal processing and required for structural ribosome stability. High expression(More)
Recently, we showed that generation of tumours in syngeneic mice by cells devoid of mitochondrial (mt) DNA (ρ0 cells) is linked to the acquisition of the host mtDNA. However, the mechanism of mtDNA movement between cells remains unresolved. To determine whether the transfer of mtDNA involves whole mitochondria, we injected B16ρ0 mouse melanoma cells into(More)
The nucleolar protein 2 gene encodes a protein specific for the nucleolus. It is assumed that it plays a role in the synthesis of ribosomes and regulation of the cell cycle. Due to its link to cell proliferation, higher expression of Nop2 indicates a worse tumor prognosis. In this work we used Nop2(gt1gaj) gene trap mouse strain. While lethality of(More)