Moscow State UniversityBelozersky Institute of Physico-Chemical Biology

Department of Electron Microscopy is a sub-division of A.N. Belozersky Institute of Physico-Chemical Biology. The Department was founded in 1965 as a microscopic unit of the Institute, simultaneously with the organization of the Institute. All the time we give an opportunity to work with electron and light microscopes for Institute employees. The active research work was carried out too. We are interested of how eukaryotic cell is organized, formed and functioned.

Since A.N. Belozersky Institute of Physico-Chemical Biology is one of the scientific departments of Moscow State University – the first university in Russia, the research workers of the Department are constantly involved in teaching of cell biology and microscopy for students of The Faculty of Bioengineering and Bioinformatics.

Research • Microscopy Core FacilityTeachingComputational tools

Research

Study of interphase chromatin architecture.

Understanding principles of chromatin architecture is important if we want to know how the cell functions as a whole. In present study we demonstrated that the common feature of hetero- and euchromatin is a globular unit about 100 nm in diameter. In euchromatin these units are usually separated from each other by thinner fibres, while in heterochromatic domains they are tightly packed (stacked) in thick fibres. Further packing of these fibres results in formation of large chromatin blocks, as seen in pericentric heterochromatin in mouse cells. It was shown that above mentioned globular subunits are disrupted during DNA replication and recovers then replication in this part genome is completed.

Архитектура интерфазного хроматина в клетках L929, пермеабилизированных в растворе с низкой силой в присутсвие двухвалентных катионов. CP - цитоплазма, NP - нуклеоплазма, NE - ядерная оболочка, RS - сайт репликации в периферическом гетерохроматине, гранулы золота связаны с антителами против БрдУ, тонкие  стрелки - эухроматин, звездочка - хромоцентр (домен конститутивного гетерохроматина), указатели - контакт переферического гетерохроматина с ядерной оболочкой.

Architecture of interphase chromatin in permeabilized mouse cell (in presence of divalent cations). CP - cytoplasm, NP - nucleoplazm, NE - nuclear envelope, RS - replication site in peripherial hetechromatin, colloidal gold partical conjugated with anti-BrdU-antibodies, thin arrows - euchromatic fibres, asterisc - constitutive heterochromatin domain, arrowheads - chromatin-nuclear envelope contacts.

Synthesis of radial loop and hierarchical folding models.

Understanding the metaphase chromosome architecture remains a basic challenge in cell biology. At present, different models of chromosome compaction are discussed. Two major models of chromosome organization – radial loop and hierarchical folding models – are based on the experimental data obtained by different methods (i.e. analysis of extracted chromosomes or morphological analysis of intermediates of chromosome compaction, respectively). We believe that they describe different aspects of mitotic chromosome organization rather than deviations of general architectural principle. Therefore, the attempt to synthesize the postulates of radial loop model and model of hierarchical folding was made in our laboratory. Figure depicts one possible hypothetical model of chromosome structure, where loop domains condense into regular complexes – chromomeres, and this condensation leads to a formation of 100-130 nm chromatin fibers (Sheval, Polyakov, 2006). Elsewhere, we have suggested that non-matrix (non-scaffolding) proteins may participate in the compaction of loop domains into higher-order chromatin complexes (Sheval et al., 2002; 2004).

Model of chromosome organization. (A) The chromosome decondensation stages. (a) Condensed metaphase chromosomes with axial scaffold. (b) Swelled chromosome after dextran sulphate/heparin extraction. (c) High-salt extracted chromosome. Red – axial scaffold containing topoisomerase IIα, blue – chromatin. (B) The chromonema decondensation stages. (a) Condensed 100-130 nm chromonema. (b) Partial extraction of chromatin proteins by dextran sulphate/heparin reveals intermediates of loop domain compaction with rosette-like organization. (c) Loop domains revealed after high-salt extraction. Red rectangulars – SARs/MARs. (B) Synthesis of radial loop and hierarchical folding models. The compaction of loop domains leads to 100-130 nm chromonema formation. Scaffold components involved into organization of loop domain bases are included into condensed chromonema. The chromonema folds into 200-250 nm fiber, which folds into metaphase chromatid. The axial chromosome scaffold is participated in compaction of prophase chromatid (200-250 nm fiber) and is not participated in chromonema maintenance.

Model of chromosome organization. (A) The chromosome decondensation stages. (a) Condensed metaphase chromosomes with axial scaffold. (b) Swelled chromosome after dextran sulphate/heparin extraction. (c) High-salt extracted chromosome. Red – axial scaffold containing topoisomerase IIα, blue – chromatin. (B) The chromonema decondensation stages. (a) Condensed 100-130 nm chromonema. (b) Partial extraction of chromatin proteins by dextran sulphate/heparin reveals intermediates of loop domain compaction with rosette-like organization. (c) Loop domains revealed after high-salt extraction. Red rectangulars – SARs/MARs. (B) Synthesis of radial loop and hierarchical folding models. The compaction of loop domains leads to 100-130 nm chromonema formation. Scaffold components involved into organization of loop domain bases are included into condensed chromonema. The chromonema folds into 200-250 nm fiber, which folds into metaphase chromatid. The axial chromosome scaffold is participated in compaction of prophase chromatid (200-250 nm fiber) and is not participated in chromonema maintenance.

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The peripheral chromosome scaffold, a novel structural component of mitotic chromosomes.

Using an original high-salt extraction protocol, we observed a novel chromosome substructure, referred to as the peripheral chromosome scaffold. This chromosome domain contained the perichromosomal layer proteins pKi-67, B23/nucleophosmin and fibrillarin, but no DNA fragments (i.e. the loop domain bases, SARs, were not associated with the peripheral scaffold). Modern models of chromosome organization do not predict the existence of a peripheral chromosome scaffold domain, and, thus, our observations have conceptual implications for understanding chromosome architecture.

The peripheral chromosome scaffold is labeled with anti-pKi-67 antibodies (arrowheads), and, thus, this structural entity is a residual component of the perichromosomal layer. The axial scaffold does not contain pKi-67 (arrows).

The peripheral chromosome scaffold is labeled with anti-pKi-67 antibodies (arrowheads), and, thus, this structural entity is a residual component of the perichromosomal layer. The axial scaffold does not contain pKi-67 (arrows).

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Microscopy Core Facility

The Microscopy Core Facility has imaging systems including light and electron microscopes. The microscopy core facility provides strong technical support for multi-disciplinary research in the A.N. Belozersky Institute of Physico-Chemical Biology. We also provide services, teaching and training for university researchers.

First time users should contact Prof. Vladimir Y. Polyakov to discuss the proposed work and for advice on which approaches to take. Contact Alexey Lazarev (electron microscopy) or Dr. Sergey Golyshev (light microscopy) to sign up for instrument or computer time.

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Teaching

Methods of Cell Biology (practical work course)

The original course “Methods of Cell Biology” was developed specially for students of The Faculty of Bioengineering and Bioinformatics – a subdivision of Moscow State University, which was organized in 2003 on the basis of A.N. Belozersky Institute of Physico-Chemical Biology. The students study the general methods of cell biology (cell culture, immunocytochemistry, live cell imaging, etc.) and work without assistance in teaching laboratory.

Instructors: KireeV I. I., Alieva I. B., Golyshev S. A., Arifulin E. A., Kurchashova S. Y.

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ResearchMicroscopy Core FacilityTeaching • Computational tools • To top

Computational tools

Modern cell biology research cannot be conducted without extrating quontative data from micrographs and over kinds of images. One of our new objectives is to provide tools for facilitating this data extraction. As a platform for these tools we choose ImageJ - open-source Java-base expandable image analysis software package. Its popularity is mostly based on its expandability by user-programmed modules (plug-ins) and automation instructions (macros).

Now we encourage vizitors to download the following tool

AutoFRAP - wrapper-macro for FRAP-Profiler plugin (MacMaster Biophotonics). It facilitate mass analysis of FRAP movies. Being downloaded from our site zip-folder (111 КБ) contains manual in pdf format, macro file (autofrap_.txt), compiled FRAP_Profiler plugin (FRAP_Profiler.class) and the source code of plugin (FRAP_Profiler.java).

Вверх!

Web-design by Sergei Golyshev