Above: Weddell seals and their ability to dive deep into the waters of Antarctica will help York researcher Thomas Hawke learn more about helping victims of heart and stroke.
“Weddell seals can dive down to 400 metres and hold their breath for up to 30 minutes to find food,” says Hawke. “That is equivalent to a human taking a deep breath, walking into a darkened Wal-Mart, shopping, and emerging 30 minutes later before taking their next breath.”
Right: Thomas Hawke
The implications for human application of this research are important, Hawke says. “If we can replicate the oxygen-transfer capabilities of the Weddell seals’ skeletal muscle cells, it is likely we can develop therapies for treating people with cardio-vascular or ischemic disease to give their systems a better chance to rebuild damaged areas after a heart attack or stroke.”
Hawke will make his first visit to Antarctica in the fall as the only Canadian member of the four-person team that plans to set foot on the ice on Oct. 1.
As a researcher into the unique attributes of muscle cells and their response to injury and exercise, Hawke’s interest is in determining the molecular and cellular qualities that allow the seals to be active for so long without fresh oxygen and yet escape vascular disease or muscle injury. Hawke and his colleagues from the University of Texas Southwestern Medical Centre at Dallas will extract tiny biopsies of the half-tonne mammals to study how muscle cells create and regulate the “super-proteins” that are the keys to the seals’ prodigious ability to conserve and transfer oxygen.
If people were to exercise while holding their breath they would quickly become fatigued, in part, because of the build-up of anaerobic metabolites (such as lactic acid). However, the Weddell seal is actually able to maintain aerobic metabolism in the absence of breathing thereby preventing this build-up and allowing it to maintain its exercise efficiency. Some of the proteins that work to maintain the muscles’ ability to function – such as myoglobin – are found in far higher quantities in the seals than in humans. “Seals have 14 times the amount of myoglobins in their muscle cells,” Hawke says, “so that’s a good lead into what’s going on and gave us a good start into the research.”
Hawke worked for three years at UT Southwestern as a post-doctoral fellow with Shane Kanatous, principal investigator, before becoming a faculty member at York in 2003. He said the team’s research from three previous visits to Antarctica had reached a point where they needed to study the seals’ muscles at the molecular level, which is his specialty. Hawke received his PhD in biophysics at the University of Guelph in 2000.
Left: Weddell seal with camera mounted on its head
While other species of the seal have similar capacities, the Weddell seals were chosen for the study because of their predictable territorial habits and the lack of fear they exhibit toward humans. Named after a 19th century sealing captain who wrote about his encounters with the seals in the 1820s, Weddell seals can weigh up to 400-600 kg and live up to 22 years. On a previous expedition, the research team was able to outfit the seals with head-mounted “helmet-cams” to record their feeding, swimming and diving habits.
Hawke will spend approximately 10 weeks “on the ice” in Antarctica. In addition to outreach provided through the US National Science Federation, and the Southwestern’s STARS (Science Teacher Access to Resources at Southwestern) program, Hawke also plans to set up a personal Web site to record his observations for a Canadian audience.
“The main site will provide a weekly diary, pose challenging questions for high school students to answer and discuss experiments that science classes can perform, comparing their results with ours. My hope is that we can recruit some Canadian science teachers to get their schools interested and bring our research to the attention of thousands of Canadian students,” he says.
For more information on Hawkes’ research, visit the Hawke Laboratory Web site. For more information on the team’s Antarctic expedition visit the team’s Web site, Physiology at the Extremes.