Siti Nurhayati

Micronucleus assay-based evaluation of radiosensitivity of lymphocytes among inhabitants living in high background radiation area of Mamuju, West Sulawesi, Indonesia

Naturally occurring radiation can be found all around us and account for most of the radiation received by human beings each year. Indonesia has a region with high-dose natural radiation located in the suburb of West Sulawesi province with a dose rate up to 2800 nSv/h; however, its impact was not fully understood. The aim of this study was to evaluate the radiosensitivity of 12 peripheral blood lymphocytes of inhabitant from high background radiation area (HBRA) and 10 from normal background radiation area (NBRA) based on cytokinesis-block micronucleus (CBMN) assay after challenged with 1.5 Gy of gamma ray. The analysis of CBMN was done according to standard procedure as per IAEA guidelines, and frequency of binucleate (mitotic) cells with micronuclei (MN) was scored in around 2000 binucleate lymphocytes cells per culture in microscopic analysis. Mean MN frequency for HBRA was lower than that of NBRA (0.121 vs. 0.189) after irradiation, indicating an adaptive response in HBRA group that resulted in less radiosensitivity; however, there was no statistically significant different (P > 0.05) between these two groups. The MN number was higher in women compared to men for both HBRA (0.15 vs. 0.09) and NBRA (0.216 vs. 0.147) groups. Besides, there was no statistically significant difference (P > 0.05) in Nuclear Division Index (NDI), as measured in 500 metaphase cells with published formula, between HBRA and NBRA samples (1.24 vs. 1.21). The lower MN frequency prompts us to conclude that there is an adaptive response in the lymphocytes of inhabitants as an indicator of lower radiosensitivity to the high natural radiation exposure. Further studies using large number of samples are required to obtain more comprehensive conclusion along with the assessment of other types of radiosensitivity-related biomarkers.

Assessment of DNA damage in lymphocytes of Mamuju (a high background radiation area) inhabitants using alkaline single cell gel electrophoresis

Mamuju in Indonesia has a highest average dose rate and considered as a high background radiation area (HBRA) in Indonesia. Here in this research a preliminary study to evaluate DNA damage using the alkaline comet assay in inhabitants of Takandeang village, Mamuju, was conducted. Blood samples from 55 healthy donors living in Takandeang village and 22 control samples were obtained and processed into the assay. Results showed that there were insignificant differences of comet tail length (TL) and tail moment (TM) between Takandeang village inhabitants and control samples (p = 0.578, 0.174). Regression analysis revealed that the DNA damage was increased with age in control samples, even though the correlation was not significant (p > 0.05). In contrast a significant negative correlation (p = 0.02) was observed in Takandeang inhabitants. Results found in this research should be validating in a larger study using more samples from Mamuju.