Its specific application can be divided into the following parts:
Application of 1 in genetic toxicology: SCAG is a very sensitive method to evaluate genetic toxicological damage, which can induce cell DNA damage in vivo and in vitro to explore the specific activities of known genetic poisons and mutagens, including cell-specific metabolism and DNA repair in vitro, the relationship between metabolic kinetics and dose response of compounds administered by related routes in vivo, and the genotoxicity of some compounds. Some poisons in some environments often have tissue specificity or cell specificity. Mutagenic effect and carcinogenic effect are long-term effects of genotoxicity, and the degree and type of mutation are related to the damage and repair of DNA strand. SCGE can detect DNA strand breaks, DNA excision and repair, oxidative damage and DNA cross-linking caused by various physical and chemical factors. Sardas et al. analyzed the inhaled anesthetic isoflurane, and found that the average tail moment of comet increased obviously after anesthesia 1h, reached the peak after 2 hours, decreased after 1d, and returned to normal after 5 days. Experiments show that the drug is genotoxic and the genetic damage can be repaired, but the damage repair of xeroderma pigmentosum patients is incomplete. In vivo SCGE analysis can reduce false negative results, provide information on DNA damage and repair in tissues, organs and cells, and infer tissue and cell specificity. For controversial compounds, DNA detection with SCGE can evaluate whether the compound has genotoxicity at a certain dose.
Detection of DNA damage and repair: SCGE not only reflects DNA strand breaks, but also includes enzyme-mediated damage and repair. When T lymphocytes are irradiated with ultraviolet rays, it is found that the damage and repair of T lymphocytes are related to the repolymerization of DNA strands. The excision and repair after injury are completed by endonuclease. SCGE can be used for one-step observation from damage to repair, synthesis and connection. Ma et al. have reported that different kinds of cells have different DNA oxidative damage and self-repair ability. Cells with high proliferation rate (such as Hela cells) are more sensitive to H2O2 than cells without proliferation (such as lymphocytes), and their repair speed is obviously higher than that of lymphocytes. At the same time, it is also used to study the damage and repair of cell DNA caused by some external factors such as protein, inhibitors and deoxynucleotides, and to study the damage and repair of defective cell DNA.
Biological detection and epidemiological study: SCGE can detect DNA strand breaks as a biomarker of genotoxicity of fish and other aquatic organisms. In vivo and in vitro experiments show that chemical poisons do affect a series of cell types of vertebrate and invertebrate aquatic organisms. Pan et al. studied the DNA damage of crucian carp lymphocytes caused by cadmium chloride. With the increase of cadmium dose, DNA damage is aggravated. At the same time, it induces chromosome aberration of fish cells, which leads to abnormal red cell nuclei, and protein changes qualitatively and quantitatively in different tissues. SCGE can also be used to detect DNA damage of various people in places where harmful substances exist. After detecting the peripheral blood lymphocytes of workers who have been exposed to high concentration of benzene for a long time, service workers in gas stations with benzene exposure level of 3 mg/m and workers exposed to high temperature and CO, it was found that the DNA damage of lymphocytes was obviously improved. After smokers quit smoking, the tail length of comets decreased significantly. Many factors such as age, sex, smoking and drinking should be considered in crowd detection, so the control and exposed individuals should be at the same physiological stage when sampling.
Application of SCGE in Oncology: SCGE can detect the DNA damage of single cells, evaluate the damage and repair ability of cells, and explore the etiology, occurrence and pathogenesis of tumors. The ability of tumor cells and normal cells to damage and repair DNA caused by physical and chemical therapy will determine whether the treatment plan is correct or not. If tumor cells have higher repair ability than normal cells, it means that treatment is more dangerous and treatment will fail. There is an anoxic cell in cancer cells, and its DNA fragmentation is lower than that of aerobic cells. SCGE analysis can estimate the number of hypoxic cells and further identify and check the response of cancer cells to anticancer agents. It is mainly used for tumor cells receiving chemotherapy, which is helpful to evaluate the difference of tumor response to radiotherapy and chemotherapy and predict the effect of treatment scheme. Olive PL et al. used SCGE to verify that nicotinamide can reduce tumor hypoxia cells, thus increasing the sensitivity of tumor cells to radiation, and at the same time, it shows that the drug can prevent tumor cells from repairing more and achieve the purpose of anti-cancer. Rao used SCGE to detect peripheral blood lymphocytes in patients with oral squamous cell carcinoma. The results showed that the results of cell DNA electrophoresis in different clinical stages were obviously different, which was statistically different from that in clinical stages.
Application of 5 in environmental monitoring: SCGE is widely used in environmental monitoring, and can be used as an early evaluation index of environmental pollutants on health to some extent. Yuan et al. used tadpoles as indicator organisms to judge whether the water body was polluted by detecting DNA breakage. In foreign countries, using this method to detect water pollution is earlier and more standardized, and a more scientific, practical and standardized detection system has been established. 1998, Steven et al. used this system to detect the pollution degree of the water body in the south of the United States 10; The establishment of SCGE detection method for red blood cells of Misgurnus anguillicaudatus is also helpful to reveal the harm and essence of different pollutants to aquatic organisms, especially the comprehensive analysis combined with the results of micronucleus test of red blood cells will be of great significance to the evaluation of water environment quality. 1998, Gichner et al. applied SCGE technology to plant cells and established a new environmental detection system. In addition, SCGE is also an ideal detection technology to study air pollutants, heavy metals, aldehydes, radiation and other environmental pollution.
Others: SCGE can also be used in the fields of apoptosis, immunology, oxidative damage, clinical etiology and diagnostics. Liu Qiang and others first applied this technology to radiation dosimeter. By studying the consistency of DNA double strand breaks caused by whole body irradiation and external irradiation, the feasibility of SCGE as a radiation dosimeter is expounded. The effects of age, cell type and cell growth cycle on the experimental results should be considered in practical application. It should be noted that under alkaline conditions, the swimming band in single cell electrophoresis may be the result of DNA breakage or alkaline region. Pay special attention to this situation when using sperm specimens.
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SCGE can sensitively detect DNA breakage at the single cell level, which has the advantages of rapidity, simplicity and cheapness, and is widely used in genetic toxicology, biological detection, oncology and other fields. However, there are still some problems to be improved and solved in the experiment, such as the formation principle of "comet", the exploration of electrophoresis conditions, the improvement of slide preparation method and the development of image analysis software. With the continuous improvement of experimental methods, these problems will be solved, and the application of SCGE in this field will be further broadened.