Mitochondrial DNA heteroplasmy in laboratory XXXX experimentally enclosed in the radioactive Chernobyl environment.

@entity19 @entity1 @entity377 @entity16886
Mitochondrial DNA heteroplasmy using the protein-coding @entity16886 (Mtcyb) gene was assessed in laboratory @entity19 (C57BL/6 and BALB/c) exposed to the Chernobyl environment. Subacute to subchronic (30-40 days) exposure resulted in a cumulative radiation dose of 1.2-1.6 Gy ( approximately 0.04 Gy/day). @entity19 were sampled prior to introduction into the enclosures and again after removal from the enclosures. @entity377 variation (site heteroplasmy) in 306 pre-exposure Mtcyb gene copies (122400 base pairs) was compared to variation in 354 postexposure gene copies (141600 base pairs). Five mutant copies, each characterized by a single @entity377 substitution, were observed (four in the pre-exposure samples, one in a postexposure sample). The frequencies of mutant gene copies and @entity377 substitutions in pre-exposure and postexposure samples were not significantly different. This suggests that this type of exposure (i.e. low dose rate) does not pose a significant mutation risk to the Mtcyb gene in digit tissue. Furthermore, no significant radiation risk to analogous @entity1 tissues may exist when occupational exposures involve low dose rates such as these. Finally, linear, cumulative models of genetic risk currently used to estimate radiation-induced effects are likely to be inappropriate for low-dose-rate exposures and need to be re-evaluated critically.
