STEM GLAM GALLERY: Elizabeth Blackburn
Elizabeth Blackburn, the Australian-American, Nobel Prize-winning molecular biologist (1948-present)
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Elizabeth Blackburn has always been fascinated by how life works. Born in 1948, she grew up by the sea in a remote town in Tasmania, Australia, collecting ants from her garden and jellyfish from the beach. When she began her scientific career, she moved on to dissecting living systems molecule by molecule. She was drawn to biochemistry, she says, because it offered a thorough and precise understanding "in the form of deep knowledge of the smallest possible subunit of a process."
Working with biologist Joe Gall at Yale in the 1970s, Blackburn sequenced the chromosome tips of a single-celled freshwater creature called Tetrahymena (“pond scum”, as she describes it) and discovered a repeating DNA motif that acts as a protective cap. The caps, dubbed telomeres, were subsequently found on human chromosomes too. They shield the ends of our chromosomes each time our cells divide and the DNA is copied, but they wear down with each division. In the 1980s, working with graduate student Carol Greider at the University of California, Berkeley, Blackburn discovered an enzyme called telomerase that can protect and rebuild telomeres. Even so, our telomeres dwindle over time. And when they get too short, our cells start to malfunction and lose their ability to divide – a phenomenon that is now recognised as a key process in ageing. This work ultimately won Blackburn the 2009 Nobel Prize in Physiology or Medicine.
In 2000, she received a visit that changed the course of her research. The caller was Elissa Epel, a postdoc from UCSF’s psychiatry department. Psychiatrists and biochemists don’t usually have much to talk about, but Epel was interested in the damage done to the body by chronic stress, and she had a radical proposal.
With some trepidation at approaching such a senior scientist, Epel asked Blackburn for help with a study of mothers going through one of the most stressful situations that she could think of -- caring for a chronically ill child. Epel's plan was to ask the women how stressed they felt, then look for a relationship between their state of mind and the state of their telomeres. Collaborators at the University of Utah would measure telomere length, while Blackburn's team would measure levels of telomerase.
It took four years before they were finally ready to collect blood samples from 58 women. This was to be a small pilot study. To give the highest chance of a meaningful result, the women in the two groups – stressed mothers and controls – had to match as closely as possible, with similar ages, lifestyles and backgrounds. Epel recruited her subjects with meticulous care. Still, Blackburn says, she saw the trial as nothing more than a feasibility exercise. Right up until Epel called her and said, “You won’t believe it.”
The results were crystal clear. The more stressed the mothers said they were, the shorter their telomeres and the lower their levels of telomerase.
The most frazzled women in the study had telomeres that translated into an extra decade or so of ageing compared to those who were least stressed, while their telomerase levels were halved. “I was thrilled,” says Blackburn. She and Epel had connected real lives and experiences to the molecular mechanics inside cells. It was the first indication that feeling stressed doesn’t just damage our health – it literally ages us.
When their paper finally was published, in the Proceedings of the National Academy of Sciences in December 2004, it sparked widespread press coverage as well as praise, and triggered an explosion of research. Researchers have since linked perceived stress to shorter telomeres in healthy women as well as in Alzheimer’s caregivers, victims of domestic abuse and early life trauma, and people with major depression and post-traumatic stress disorder. “Ten years on, there’s no question in my mind that the environment has some consequence on telomere length,” says Mary Armanios, a clinician and geneticist at Johns Hopkins School of Medicine who studies telomere disorders.
In the decade since Blackburn and Epel’s original study, the idea that stress ages us by eroding our telomeres has also permeated popular culture. In addition to Blackburn’s many scientific accolades, she was named one of Time magazine’s “100 most influential people in the world” in 2007, and received a Good Housekeeping achievement award in 2011. A workaholic character played by Cameron Diaz even described the concept in the 2006 Hollywood film The Holiday. “It resonates,” says Blackburn.
But as evidence of the damage caused by dwindling telomeres piles up, she is embarking on a new question: how to protect them.
**A full-length version of this article can be found on Mosaic’s website.