Banca de QUALIFICAÇÃO: LUÍZA ARAÚJO DA COSTA XAVIER
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.STUDENT : LUÍZA ARAÚJO DA COSTA XAVIER
DATE: 09/11/2021
TIME: 14:00
LOCAL: Videoconferência - Link para acesso: meet.google.com/knb-jwpt-ger
TITLE:
Impact of natural ionizing radiation in genome stability
KEY WORDS:
Epigenetic, background radiation, radiobiology, alpha particles, radon
PAGES: 80
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:
The present work aims to evaluate the mutagenic and epigenetic effects induced by natural ionizing radiation in individuals exposed to high concentrations of radon (Rn). Furthermore, epigenetic effects were also investigated in assays with cell cultures exposed to different doses of alpha particles. For that purpose, an observational case-control study was conducted with 224 individuals from Lajes Pintadas (LP group) and 66 individuals from Natal city (control group). Blood and urine samples were collected from participants of both cities to perform the following tests: (a) biochemical clinical analysis tests; (b) quantification of 8-hydroxy-2’-deoxyguanosine (8-OHdG) in urine; (c) determination of the Ser326Cys polymorphism in hOGG1 gene; (d) quantification of lead in blood; (e) quantification of methylated cytosines (mC) in LINE-1 sequences as bioindicators of global genome methylation of the participant’s blood cells. In addition, all recruited individuals were interviewed with a questionnaire to collect sociodemographic information, environmental and occupational exposures, lifestyle and general health history. About the in vitro experiments, human lung fibroblasts were exposed to 0 (control), 0.25, 0.5 and 1 Gy of alpha particles and their %mC in the promoter region of the LINE-1 sequences were determined. This assay was repeated for the progeny of irradiated cells. It was observed that individuals exposed to high indoor Rn levels had 8-OHdG concentrations approximately 1.5 times higher than those exposed to low levels of this gas (p-value < 0.01). People heterozygous for the hOGG1 polymorphism had significantly lower concentrations of 8-OHdG compared to those homozygous for the wild-type allele, considering exposure to the highest Rn levels (from 145 Bq/m3 upwards; p-value < 0.05). The mean concentrations of blood lead between the control and LP groups showed no significant difference: 1.15 ± 0.91 µg/dL and 1.66 ± 1.55 µg/dL, respectively, and these values were below the limit established by the Center Disease Prevention Control (5 µg/dL). In epigenetics, there was a significant difference between the means of %mC in LINE-1 of the groups – 50.23% ± 3.44 for control and 51.87% ± 2.96 for the LP group (p-value < 0.001). Indoor Rn levels, blood lead concentrations and the individuals’ sex were factors that significantly influenced the mean %mC of LINE-1 sequences of the participants. For the in vitro assays, there was no significant difference between the means of %mC among the different doses of alpha particles applied to the cells. It can be concluded that high levels of natural ionizing radiation can cause genome instability through oxidative and epigenetic pathways even in passenger non-irradiated cells from the human body.
BANKING MEMBERS:
Externo ao Programa - 1880243 - DANIEL CARLOS FERREIRA LANZA
Externa ao Programa - 2085604 - SUSANA MARGARIDA GOMES MOREIRA
Externa à Instituição - MARIALVA SINIGAGLIA - UFRGS