مطالعه آثار تابش پرتوهاي فرابنفش C بر ميزان تعويض كروماتيد خواهري در لنفوسيت هاي T انساني

Background and Objectives: Whenever the Ozone layer is destroyed or becomes thinner, damaging ultraviolet will threaten human health and environment. Through studying the impacts of ultraviolet on genomic instability of cells, one can estimate the rate of DNA destruction. Sister Chromatid Exchange (SCE) is an optimal characteristic to study genomic instability of the cells irradiated by UV. Materials and Methods: After isolating of lymphocytes by Ficol, 105 cells were irradiated under UV (20 cm distant from UV-C light with intensity of 420 LUX) for 3 or 5 minutes in the T25 flasks. The irradiated and control cells were cultured in 5 ml F12 medium which had been supplemented with 15% fetal calf serum, T lymphocyte mitogen of phytohemagglutinin and BrdU. Then they were placed in an incubator with 370 temperature. The cultured cells were harvested after 72h and stained by SCE method. The frequency of Sister Chromatid Exchange (SCE) was studied in the 100 metaphasic plaques. Results: The frequency of Sister Chromatid Exchange in the 100 metaphasic plaques showed a mean SCE per cell value of 3.35% for control cells compared with a SCE per cell value of 4.33% and 6.8% for radiation during 3 and 5 minutes. Statistical analysis of the results showed a significant difference(p<0/001). Conclusion: The results indicate that UV-C induces genomic instability and destroys the human T lymphocyte DNAs, sothat the level of genomic instability depends on UV radiation time. Therefore, thinning or destruction of Ozone layer must be taken into consideration seriously.