peared abruptly in the fourth generation.
“It was really quite beautiful. The find-
ing was very clear and consistent,” com-
ments Cynthia Kenyon, a pioneer in the
genetics of aging who directs the Hillblom
Center for the Biology of Aging at UCSF.
“There’s some imprint that’s left behind
by events that happen in one generation
that can be carried forth for several more
generations; and then there’s a switch
back to normal.”
Multiple variations of the experiment
yielded the same results, so it’s unlikely
that the findings were due to an extrane-
ous mutation in the strain or another arti-
fact. “An extraordinary claim requires
extraordinary proof, so we had to test it
rigorously,” Brunet says. The results were
published in the journal Nature last fall.
“It’s really just remarkable,” says Ken-
yon. “I think this is one of the most impor-
tant papers in decades in the aging field.”
Exactly how the epigenetic signal is
transmitted across generations remains
unclear. At first, Brunet’s team assumed
that the mutant parents passed the aber-
rant pattern of methyl marks directly to
their progeny. However, they found that
global levels of this mark, which were
reduced in the parents, appeared normal
in the progeny.
TOP: COURTESY PORTOLA VALLEY ARCHIVES, BOTTOM: ROY WILLIAMS
Greer, now a postdoctoral fellow at
Harvard Medical School, speculates that
perhaps the mark remains altered at only
a few hotspots in the genome that are
important in aging. Alternatively, the
changes in the parents’ chromosomes may
set off a chain of events; and one of these
downstream effects may be inherited.
“Eggs have a certain amount of their moth-
er’s proteins and RNA, which are necessary
for the initial stages of development,” he
says. “So it’s possible that the progeny of
these long-lived worms are inheriting
some sort of information in the form of
protein or RNA.”
Brunet’s group hopes to replicate the
phenomenon in higher animals, including
African killifish and mice. Chances are
good that “it’s not just a worm thing,” says
Kenyon. “Of all the genes that have been
discovered to affect aging in the worm,
almost all of them have been found to
affect aging in other organisms.” Already,
others have shown that the gene that Greer
mutated in worms also increases lifespan
when mutated in fruit flies. “This suggests
that the gene has a conserved effect on lon-
gevity. And, if that’s true, then it may also
have a conserved effect on transgenera-
tional longevity,” says Greer.
Kristin Sainani, MS ’99, PhD ’02, is a
freelance writer and clinical assistant professor in the department of health research
and policy.
ART & HISTORY
A Stroll Down Memory Lane
‘Performance hike’ is a walk to remember.
STILL LIFE AT SEARSVILLE: Students, faculty and members of the community recreate
an idyllic scene from a 1930s postcard as part of “Picture Jasper Ridge,” a project
conceived and produced by choreographer Ann Carlson. The biological preserve’s first
visiting artist, Carlson staged nine tableaux vivants in which actors brought historical
photographs to life at or near the locations where they were originally shot.
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