The Genetic Risk in Mice from Radiation: An Estimate of the Mutation Induction Rate per Genome

Abstract

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Mutagenic Effects of Ionizing Radiation on Immature Rat Oocytes

“…Cloning and sequencing of DNA fragments that had undergone mutations was done as previously described (8). Multiple bacterial clones were isolated and sequenced for each mutation, and a consensus sequence was mapped on the rat reference sequence, Baylor 3.4/rn4, to obtain chromosomal locations and upstream and downstream sequence information.…”

“…In recent years, various new molecular technologies have been developed, one of which is the Restriction Landmark Genome Scanning method (i.e., two-dimensional gel electrophoresis of radio-labeled DNA fragments or 2DE of DNA), making it possible to examine over 1,000 genomic sites for each individual. We previously reported on radiation effects on spermatogonia in mice using the 2DE method to analyze DNA (7,8), and in this current study, we present data on immature oocytes in rats.…”

Why Genetic Effects of Radiation are Observed in Mice but not in Humans

“…Contrary to expectations, only 5 mutations were detected in the irradiated group and one in the control group. Because the 2DE method was able to detect a deletion as small as 6 bp (CTCTCT) at a microsatellite locus (37), it is difficult to imagine that the study overlooked as many as 45 deletions (the difference between the expected and observed) or 90% of the small deletions. The results of this study suggested that radiation responses for the induction of mutations are probably highly variable among genes and that the mean induction rate is low.…”

Preservation of chromosomal integrity in murine spermatozoa derived from gonocytes and spermatogonial stem cells surviving prenatal and postnatal exposure to γ‐rays in mice

“…The incidence of cells containing multivalent chromosomes was originally less than 5% (Table 1). Despite the low occurrence of multivalent chromosomes, a risk of genetic inheritance still exists for the offspring of males exposed to ionizing radiation during the prenatal and postnatal periodsparticularly given that genomic instability can be transmitted to offspring through spermatozoa of irradiated male mice (Asakawa, Kodaira, Cullings, Katayama, & Nakamura, 2013;Barber, Plumb, Boulton, Roux, & Dubrova, 2002;Barber et al, 2006Barber et al, , 2009Dubrova, 2003;Streffer, 2006).…”