Number of
protein-coding
banana genes
Number of
protein-coding
human genes
Space trek cuts
signs of aging
Worm study shows gene
changes after 11-day orbit
By Tina Hesman Saey
In space they can barely see you age — if
you’re a worm.
Tiny, transparent nematodes that
spent a gravity-free 11 days — equivalent to about 16 years for a person — en
route to and aboard the International
Space Station appeared to age much
more slowly than earthbound worms,
Yoko Honda of the Tokyo Metropolitan
Institute of Gerontology and colleagues
report online July 5 in Scientific Reports.
The result is the opposite of what
some scientists expected, based on
experience with human spaceflight and
studies of other animals. Mammals,
including people, are under physiological stress in the microgravity of space,
says D. Marshall Porterfield, director of
NASA’s Space Life and Physical Sciences
Research and Applications Division in
Washington, D. C. In low gravity, muscles
atrophy and aging accelerates.
While the space station worms, from
the species Caenorhabditis elegans, may
have been under stress, they didn’t have
those side effects. Their muscles did not
degrade, and clumps of aging-related
proteins known as Q35 aggregates did
not build up in them as much as in worms
on the ground, indicating that worms
don’t age as fast in space as on Earth.
Worms that visited the space station
were frozen immediately after returning
to Earth, so the researchers weren’t able
to test whether time in space enabled the
critters to live longer.
The researchers also discovered that
relative to ground-based nematodes, the
spacefaring worms had lower activity of
199 genes, including 11 genes involved in
transmitting information through the
nervous or endocrine systems. For seven
of the 11 genes, mutations that lowered
the genes’ activity also caused ground-based worms in a separate experiment
to live longer.
Reduced activity of three of the life-extending genes — called gar- 3, cha- 1
and shk- 1 — also lowered the number of
Q35 clumps that built up in aging worms.
Those genes encode proteins that are
produced in the nervous system, and
two of them encode proteins that are
Tiny worms that spent time in space
(like the one shown here) have fewer
clumps of aging-related proteins
(green) than worms that stayed on the
ground. That could mean that worms
live longer in microgravity.
also made in muscles.
Lowering the levels of those proteins
during spaceflight might affect how
worms perceive their environment,
leading the nematodes to reduce their
metabolism and extend their life spans,
says Catharine Conley, NASA’s planetary protection officer. Conley helped
develop the system the worms lived in
while in space.
Studying worms in space may help
scientists learn more about how low
gravity affects organisms, regardless of
the impact on life span, Porterfield says.
“It doesn’t really matter what the outcome is if we learn about the biophysical
environment,” he says. That knowledge
may help engineers design ways of better protecting the health of astronauts. s
Genome of a fruit besieged
The banana genome has been unpeeled. The genetic makeup
of Musa acuminata (top), a fertile banana species that gave rise
to the seedless Cavendish (bottom) and other clonal varieties
people eat today, sheds light on the plant’s evolutionary history
and ripening process. This information may also help research-
ers boost the crop’s resistance to fungal and viral pathogens
threatening its survival. M. acuminata has 36,542 protein-
encoding genes and 235 genes that make small snippets of
protein-regulating RNA, called microRNAs, an international
team of researchers reports online July 11 in Nature. The
team also found the genetic remains of a pathogen called
the banana streak virus scattered on 10 of the banana’s
11 chromosomes. “It’s probably a footprint of an attack that
was successful, but the banana somehow overcame it,” says
Thomas Givnish, a plant ecologist and evolutionary biologist at
the University of Wisconsin–Madison. — Tina Hesman Saey
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