5.2 Key benefits of fish-analysis:

• high resolution (in preparations can identify those chromosomal abnormalities that are not rendered in the ordinary light microscope);

• diagnostic accuracy (sample size can vary from 90-100 thousand to a few million base pairs, so that as the target can be not only individual genes or chromosomal regions, but an entire chromosome).

• FISH-analysis reveals, for example, a few abnormal cells to thousands of cells with normal genotype. All of these benefits are important in a survey of couples with reproductive problems, as chromosomal changes in this group of patients, as a rule, do not have the clinical phenotype.

6.Other methods of cytogenetics researchers:

• Centrifugation (cell subjected to destruction and then divide mixture of organelles in a centrifuge at high speed; organelles accumulate on the bottom of the tube, divided layers according to their density, each layer can isolate and examine separately). This method is used to study specific cellular structures. 1955 Belgian scientist Christian de Dyuv through the use of this method discovered lysosomes, for which he was awarded the Nobel Prize;

• Method "tracer" or autoradiography (substance injected into the cell in which one of the atoms of a chemical element is replaced by its radioactive isotope, using special instruments that can capture these isotopes can trace the migration of these substances in the cell and their conversion) ;

• Method of cell culture (isolated living cells transferred into sterile nutrient medium, which is similar to the natural environment for them, under such conditions, cells are able to proliferate and show other signs of life, changing environment, it is possible to study its effect on the cell). Through this method to study the toxic effects of certain substances not lose laboratory animals. Just use cells grown in culture. Such model systems can check the action of therapeutic drugs, stimulants, and various physical and other factors. Using cultures of human cells is extremely important for medical and biological research. It can replace unacceptable from an ethical point of view experiments on humans. Based on this method is developed cellular technology by which organisms are constructed with desired properties beforehand. Yes, with a few plant cells manage to grow a plant;

Conclusion

Cytogenetic analysis allows you to record the diagnosis of hereditary diseases in a karyotypical formula.

Cytogenetic methods (chromosomal analysis) is based on microscopic examination of the structure and number of chromosomes. It is widely used in the 20-ies of XX century., You have received the first information about the number of chromosomes in humans. In the 30 years were identified first 10 pairs of chromosomes.

In 1956, Swedish scientists Tyyo J. and A. Levan first proved that a person has 46 chromosomes.

Cytogenetic method is used for:

• studying the karyotypes of organisms;

• clarify the number of chromosome sets, the number and morphology of chromosomes to diagnose chromosomal diseases;

• mapping of chromosomes;

• to study the genomic and chromosomal mutation process;

• study of chromosomal polymorphism in human populations.

Chromosome set contains a large number of human chromosomes, a summary of which can be obtained by studying them in metaphase of mitosis and prophase - metaphase of meiosis. Human cells for direct chromosomal analysis obtained by puncture biopsy of bone marrow and gonads or indirect method - by culturing peripheral blood cells (lymphocytes) when receiving a significant number of metaphases. An indirect method of investigating as amniotic fluid cells or fibroblasts obtained by amniocentesis or chorionic villus sampling, cells abortusiv, stillborn and others.

Often examine chromosomes in lymphocytes of peripheral blood heparynizonic. To stimulate mitosis add fitohemaglutynin and to stop mitosis - colchicine. Preparation stained nuclear dyes: 2% solution acetorsein.

Using new methods of staining chromosomes increase crucial ability dytohepetatic method. When using the differential staining of chromosomes are homologous pairs easily, and each chromosome without mistakenly identified by the characteristic transverse band striations. Losses and move small segments of chromosomes fixed investigator. Cytogenetic method is essential for the final diagnosis of chromosomal diseases in humans and is used in genetic counseling.

References

1.Astaurov BL, Cytogenetics of the silkworm and its experimental control, Moscow, 1968;

2.Swanson, K., Merz, T., Yang, W., cytogenetics, trans. from English., Moscow, 1969;

3.Konstantinov, AV, cytogenetics, Minsk, 1971, Cytogenetics of wheat and its hybrids, Moscow, 1971;

4. Karpechenko GD, Fav. Works, Moscow, 1971;

5. Burnham С. R., Discussions in cytogenetics, Minneapolis, 1962.

6.Drets, M. E., & Shaw, M. W. Specific banding patterns of human chromosomes. Proceedings of the National Academy of Sciences 68, 2073–2077 (1971)

7.Francke, U., & Kung, F. Sporadic bilateral retinoblastoma and 13q chromosomal deletion. Medical and Pediatric Oncology 2, 379–385 (1976)