ELECTRONIC AUTORADIOGRAPHY

From Big Medical Encyclopedia

ELECTRONIC AUTORADIOGRAPHY (a synonym an electronic and microscopic autoradiography) — the method allowing to define location and quantitative content of radioactive material at electronic microscopic examination of a biological object. AA. and. apply to studying of cytobiology and a pathogeny of diseases.

The principle of a method is that substance, one of atoms to-rogo is replaced with the corresponding radioisotope (labeled substance), enter into an organism, body, fabric or culture of cells. Then the studied material is fixed and subjected to further processing for the purpose of receiving ultrathin sections for electronic and microscopic studying. Ultrathin sections cover with a layer of a special photoemulsion and leave in the dark for a period of several weeks up to several months. At the same time radioactive atoms, being exposed to disintegration, influence an emulsion and by that find themselves, leaving «autograph» (the name of a method from here), i.e. in the shown drug of grain of metal silver are located in those places where the coming from radiation of a cut worked on bromic silver of a photoemulsion. The number of grains corresponds to the number of the radioactive decays which happened during exhibiting in the dark. AA. and. widely uses many receptions of a histochemistry (see), e.g. processing by enzymes and inhibitors. Perhaps combined use of methods of a histochemistry and electronic autoradiography.

Methods of an autoradiography (see) and an electronic autoradiography are essentially uniform, however the last is technically more difficult. For viewing in a supermicroscope of ultrathin sections through the photolayer covering them and increases in resolving power in comparison with an autoradiography it is necessary to put very thin (thickness in the size of one microcrystal of bromic silver) a film of an emulsion (mono-layer), to delete remained after manifestation to gelatin, to use the emulsions and ways of manifestation creating minimum on the grain size of silver. First attempts of use E. and. were unsuccessful since these features were not considered, and for viewing in a supermicroscope used the drugs made by techniques of an autoradiography. With development of the corresponding techniques and emulsions since 1961 the method E began to be used. and., reflecting topography of the studied processes more precisely, than an autoradiography.

In the beginning by means of E. and. studied, hl. obr., ultrastructures of a normal cell. Many important features of functioning of a genome and intracellular organellas were established. In these experiments communication of structure and function of a cell and intracellular educations was very accurately shown. E.g., the way of concentration in rather small kernel of huge volume of information which is contained in DNA was defined. The electronic autoradiography showed that synthesis of RNA happens only in euchromatin, and the most part of the genetic material of a cell which is not used by it in general or in this phase se development keeps within densely and turns into not active heterochromatin. By means of E. and. it was succeeded to track topography and the sequence of education in a cell proteinaceous sekretag to establish a role of various organellas in processes of metabolism, to define sites of synthesis of fats, carbohydrates, to find sites where carbohydrates connect to proteins in a proteinaceous polisakharidnye complexes, and also sites and structures, on to-rykh mediators (adrenaline, a histamine) and cell-bound immune complexes are fixed. The method of an electronic autoradiography also allowed to define mobility of biosynthetic processes and to describe temporary features of functioning of cells and intracellular structures is normal also at action of pathogenic factors. It became clear that intensity of processes of biosynthesis constantly fluctuates. At the same time in a separate cell maxima of functionally connected processes, napr, synthesis of RNA and protein, can occur not at the same time, and is consecutive, replacing each other. At the damaging influences in the remained structures the rhythm and amplitude of fluctuations of biosynthetic activity are broken, the number of the structures which are in a phase of a maximum of synthesis that provides compensation of damage at the initial stage increases; however development of dystrophic changes of these structures is possible further. It was shown that intracellular regeneration is most quickly and sharply shown in an intensification of function of kernels (see). At long action of a disturbing factor kernels are exposed to dystrophy that ooze and transformation of kernels into intranuclear vacuoles is expressed, in particular, in increase in volume of the heterochrome connected with kernels. The possibility of reparative acceleration of replication of mitochondrial DNA in cardiomyocytes after an intensive exercise stress is revealed.

Method E. and. it was the most effective for studying inf. processes since unlike other methods it not only reflects a condition of a macroorganism, but also allows to define many features of microorganisms — speed razmno marrying, the level of viability, intensity of various biosynthetic processes. There is an experience of successful use E. and. for definition of sites of a cell, in to-rykh there is a replication virus nucleinic to - t.

Bibliography: Sarkisov D. S., Paltsyn A. A. and Vtyurin B. V. Adaptive reorganization of biorhythms, M., 1975; they, Electronic and microscopic radio autography of a cell. M, 1980, bibliogr.; Principles and techniques of electron microscopy, ed. by M. A. Hayat, v. 2, p. 219, N. Y. a. o., 1972; Puvion-Dutilleul F. Puvion E. New aspects of intranuclear structures following partial decondensation of chromatin: cytochernical and highresolution autoradiographical study, J. Cell Sci., v. 42, p. 305, 1980.

A. A. Paltsyn.

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