MEDICINE

8 UBC MEDICINE
FOCUS ON:
Environmental
Health
A DNA molecule that has been “tagged” through methylation. Illustration: Christoph Bock/Max Planck Institute for Informatics
At the nexus of nature and nurture
By now, the experiment is a familiar reference point – perhaps
the reference point – for the study of epigenetics, the science of
gene expression.
Like many experiments, it involved rats. But this one seemed to
resonate with humans in a way that few others do.
In brief: it compared the pups of nurturing mothers – those who
made their milk readily available, and spent a lot of time licking
their progeny – with the pups of those who were less attentive
to their young. The pups of the less attentive mothers were more
vulnerable to stress, and this difference corresponded to chemical
tags on certain genes.
The findings electrified a whole segment of developmental
scientists by demonstrating how environmental conditions can
affect gene expression, and thus alter the trajectory of cells and
whole organisms. In other words, it showed how life circumstances
can get “under the skin,” affecting behaviour through biological
mechanisms.
But the implications for human development remain almost as
murky as ever, impeded by the hard requirements for scientific
validation: large sample sizes, to establish correlations
with statistical confidence, and long timeframes, to allow
environmental conditions to make their mark.
Michael Kobor, however, is not the least bit intimidated.
“Whenever there is a challenge, I look at it as an opportunity,” says
Dr. Kobor, an Associate Professor of Medical Genetics and a Senior
Scientist of the Centre for Molecular Medicine and Therapeutics
(CMMT). “We’re off to the races.”
Dr. Kobor, a native of the Black Forest region of Germany, concedes
he is predisposed to optimism – whether it’s a genetic inheritance,
or something he developed through experience, is hard to say. But
he has good reason to be confident.
For one, he has teamed up with McGill University Professor
Michael Meaney, the scientist who designed those rat
experiments. Secondly, they have gained access to data about
hundreds of children from around the world, including information
about their upbringing and DNA-rich blood samples. And they have
secured a $1.5 million grant from the Brain Canada Foundation to
make sense of it all.
Their project will be the first genome-wide examination of how
childhood experience affects the human brain.
Their focus is methylation, the bonding of a molecule made up of
carbon and hydrogen to parts of the DNA. These compounds act
as “dimmer switches” on genes, and thus play an enormous role