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Fountain
of Youth to be found in the Anthill?
Newswise — Aging – we are all doing it. It
is relentless and terminal. Auguries and
alchemists, mendicants and magicians,
philosophers and science fiction writers,
researchers and plastic surgeons have
employed all their various arts in the
pursuits of “turning back the clock.”
Yet, we stand in modern times with a span of
a century to our name, at most.
Technological wizardry abounds, so why do
the factors that determine life span still
elude us?
If you ask Arizona State University
researcher Juergen Liebig, he would point to
his favorite study animal, the ant, to
provide answers.
Liebig is one of a trio of scientists who
are taking an audacious approach to studying
gene regulation, using the ant to model
human aging, with support from a Howard
Hughes Medical Institute (HHMI) $40 million
pilot program, The Collaborative Innovation
Awards.
As its name suggests, the award will allow
scientists to attack problems that one
person can’t solve, according to Jack Dixon,
HHMI vice president and chief scientific
officer.
“We were looking for projects that could
really represent breakthroughs and change
the way we think.”
One of eight teams selected, Liebig,
assistant professor in School of Life
Sciences and member of the Center for Social
Dynamics and Complexity in ASU’s College of
Liberal Arts and Sciences, will partner with
team leader Danny Reinberg, a Howard Hughes
Medical Institute investigator at the New
York University School of Medicine, and
colleague Shelley Berger of the Wistar
Institute, both top researchers in the field
of epigenetics.
The eight collaborative projects
collectively engage 33 researchers and 16
institutions in the United States and Chile.
What can ants, not typically known for long
life, tell us about human aging? Potentially
much, says Liebig. Ants in a colony are
genetically closely related, yet these
sisters’ body types, behavior and purpose
can become specialized and vastly different.
Queens typically arise as the single
reproductive female in an ant colony, living
for as long as 30 years in some species.
As head of the colony they stay in the nest
dedicated to perform one major task,
egg-laying, for their whole life.
Workers on the other hand perform brood
care, colony maintenance, and complex
foraging tasks. Among the workers additional
behavioral and morphological differences may
exist.
Some individuals are larger and more robust
with a focus on colony defense, which earned
them the name soldiers.
How can such big differences arise in each
of these ant types’ longevity and behavior
without some real differences in their DNA?
According to Liebig and his collaborators,
the answer can be found in the rising field
of epigenetics – the study of inherited
changes in the activity of genes - for
example, when they turned on or off; changes
not caused by alterations in the DNA
sequence.
Epigenetic changes occur during normal
development and tissue differentiation, and
correlate with certain disease states in
humans, such as cancer.
“But,
little is known about the molecular basis
for epigenetic changes that underlie aging
or behavior,” Liebig says.
“One advantage of using ants as models is
that as individuals they follow very
different behavioral and developmental
trajectories, and these changes are
plastic.”
It is this behavioral and developmental
plasticity that drew the collaborators to
work together. Liebig studies three species
of ants, each which allows the HHMI team to
examine a different aspect of how epigenetic
factors can influence outcomes in behavior,
morphology, and longevity.
Harpegnathos saltator (literally meaning
“jumping sickle jaw”) is a primitive species
of ant where workers are able to perform
either reproductive or helper tasks.
A worker can become a reproductive
functional queen, if the original queen dies
or is removed. Such a trait is not found in
“higher” order ants because these species
have become structurally specialized.
Carpenter ants, Camponotus floridanus, allow
Liebig, Reinberg and Berger to examine what
epigenetic factors or genes control
longevity. Queens in this species are
structurally specialized, growing large and
also long-lived.
Finally, using ants from the genus Pheidole,
whose soldier caste development can be
artificially induced, allows the researchers
to closely examine (and potentially
manipulate) what genes are expressed or
repressed, and identify the factors
regulating structural specialization and
behavior.
The first task for the collaborative team
will be to get the complete sequences of the
genomes for these three ant species.
Reinberg is currently identifying partners
specialized to do this task. Then the group
will examine the gene expression profiles of
the different castes (worker, queen,
soldier).
“This collaboration is fortuitous,” says
Liebig. “Danny and Shelley were looking for
a model system to study epigenetic factors
of differences in ant behavior and
development.
"They
contacted my colleague Bert Hölldobler,
who knew I was looking for geneticists
interested in differential gene expression
in behavior, aging, and development in
ants.”
Hölldobler is the Pulitzer Prize winning
coauthor of “The Ants,” and leading expert
in ant communication and social
organization.
Liebig notes that the project is risky. For
example, the complete sequence of the ant
genome has never been achieved before.
“Often potential research partners are
reluctant to cross barriers in scientific
specialties and there is not funding for
such risky ventures when there is interest
to do them,” Liebig says.
“The beauty of this project is that the HHMI
Collaborative Innovation Awards create the
opportunity for us to blend our skills to
develop a new approach and model system for
the study of behavior and aging.”
Arizona State University has become the
world leader in the study of social insects,
and study of their levels of organization
from organism to society, according to
luminary Edward O. Wilson.
Liebig
believes that the study of social insects
and using them as models for human systems
has the potential to transform understanding
about aging, sociobiology, neurobiology,
learning and memory and behavior.
Liebig believes his collaborators on the
HHMI project would agree. “Social insect
societies are remarkable in that their
specialization extends beyond the organism
level, to function at the level of the ‘superorganism,’”
Liebig notes.
“In that way, the division of labor seen
between reproductive and non-reproductive
individuals is analogous to cellular
specialization in different organs in a
multicellular organism.
"The
prediction is that epigenetic regulation may
determine behavioural castes in ant
colonies.”
“Who knows? Separating these effects may
even give us the tools and understanding to
look at what regulates longevity in humans,”
Liebig adds.
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