Effects of solar activity and geographic latitude on genetic homeostasis of human somatic cells

Abstract

BACKGROUND: Associations between genetic stability of human somatic cells and solar activity across latitudes have been studied. A human buccal epithelium micronucleus test was selected as a method for evaluating genetic homeostasis.
 AIM: To assess effects of solar activity on the genetic stability of human somatic cells using the micronucleus test in buccal epithelium in relation to the geographical location of subjects.
 METHODS: Men aged 18 to 21 years with no harmful habits and taking no medication comprised the sample. Studies were conducted simultaneously in four cities of the Russian Federation: Sevastopol, Voronezh, Tomsk, and Khanty-Mansiysk. The effect of three types of solar flares, whose classification is based on changes in the amplitude of the thermal X-ray burst, was studied. Material for the cytogenetic study was collected on days 3, 7, and 10 after the solar flare. The human buccal epithelium micronucleus test was selected as a method to evaluate genetic homeostasis. At least 1,000 cells were examined on each preparation, among which the number of cells with micronuclei, perinuclear vacuoles, notches, “broken egg” and “tongue” type protrusions, karyorexis, karyolisis, and karyopyknosis was determined. In total, 495 thousand buccal epithelial cells were analyzed. Statistical processing of the data was performed using “Stadia” and “Statistica” software packages. Effecs of solar andlatitude on genetic homeostasis of somatic cells was performed using multivariate analysis of variance and two-factor analysis of variance with fixed effects.
 RESULTS: Solar activity affected the stability of the human genetic apparatus by increasing the influence of the city pollution and its geographical location on the number of cells with nucleus abnormalities. We also observed a combined effect of solar flare and season on the number of cells with nucleus aberrations. More nuclear anomalies were registered in the winter. We did not detect any difference in the number of cells with nucleus anomalies on the 3rd, the 7th, the 10th, and the 17th days after the flare suggesting no associations between solar activity and the number of cells with nuclear abnormalities.
 CONCLUSION: The highest number of cells with nucleus abnormalities is observed in Sevastopol reflecting with the greatest level of anthropogenic pollution of this city compared to the other locations. Solar activity increases the influence of the city pollution and its geographical location on the number of cells with nucleus abnormalities. The results obtained can be used in conducting a micronucleus test of human buccal epithelium and in planning measures to assess the genotoxicity of the environment.