Mutated tam at the endogenous locus: carries a mutation in the exonuclease domain (amino acid replacement D263A). Generated by re-integration of DNA into the attP site present in tamKO. Additional sequences inserted during the re-integration event are also present: 1. a loxP cassette containing the wGMR.PHb marker, upstream of tam, 2. a single attR site, downstream of tam.
A13826904C
A?C
D263A | tam-PA
D263A
D263A mutation in the reintroduced copy of the PolG1 gene at the endogenous site.
tamD263A/+ adults show significantly higher, age-dependent levels of mitochondrial DNA (mtDNA) mutations, as compared to controls: mutation frequency is substantially higher when the tamD263A allele is inherited maternally than paternally, which is likely due to the combined effect in the maternal setting of inherited heteroplasmic copies and clonal expansion of replication errors; both the maternal and paternal setting show a comparable number of mutation sites, but the maternal setting show a drastically higher number of small indels and a substantial proportion of mutations at higher than 1% heteroplasmy; large deletions are rare; maternally inherited tamD263A/+ flies show no significant alterations in mtDNA copy number; although the great majority of mutations are C:G > T:A transitions, a considerable proportion are T:A > C:G or T:A > A:T transversions; however, the NS:S ratio of mutations is not different from controls.
tamD263A heterozygosity does not have a major effect on lifespan or climbing ability, whether the allele is maternally- or paternally-inherited.
tamD263A/tamD263A mutants exhibit lethality, with most dying at the third instar larval stage, and the remainder dying in pupal stage, but do not exhibit a significant reduction in body weight, as compared to controls.
tamD263A/+, tamH1038A/tamD263A and tamD263A/tamD263A flies exhibit a significant increase in mtDNA mutation frequency; and tamD263A/tamD263A, but not tamD263A/+, mutants exhibit a mild reduction in mtDNA levels, as compared to wild type. Offspring of tamD263A/+ mothers exhibit a significant developmental delay, as compared to wild type.
tamKO/tamD263A mutants exhibit an increase in lethality as compared to controls, with only around 20% surviving to adulthood, but do not exhibit a significant difference in body weight, as compared to controls.
tamRescue/tamD263A, tamQ1009A/tamD263A, and tamH1038A/tamD263A mutants do not exhibit a significant difference in mtDNA levels; tamQ1009A/tamD263A and tamH1038A/tamD263A flies do not exhibit any significant difference in body weight; but offspring of tamRescue/tamD263A, tamQ1009A/tamD263A or tamH1038A/tamD263A mothers exhibit a significant developmental delay.
tam4/tamD263A and tam3/tamD263A mutants exhibit complete lethality.
