We have some preliminary data suggesting a connection between ageing and
mtDNA (but not necessarily between mtDNA and ageing). When Drosophila
females heteroplasmic for two different-sized length variants of mtDNA
(due to an insertion in the A+T-rich control region [non-coding]) are
allowed to lay eggs in cohorts, the age of the mother is related to the
transmission of the two mtDNAs. When the mother is young, her offspring
show an increase in the frequency of the smaller mtDNA; when the same
mother lays eggs after 15-20 days, the larger mtDNA has an advantage
in transmission. To now clarify my first sentence, all I am prepared to
say now is that as the female ages, she transmits mtDNAs differently; it
may be going to far to say that the reason she ages is that the proportions
of mtDNAs in her cells (germline) changes. More later: there are many blots
to hybridize and a freezer full of young and old flies to grind up.
--David Rand, Brown University, Bio Med Box G-W, Providence, RI 02912 USA
