The tadpole's tail

This whole area of science was virtually unknown during Slack's early education. After earning his bachelor's degree, he decided he wanted to pursue a Ph.D. in something involving nucleic acids because "it was clear even then that they were the molecules of the future." His first lab experiences were under what he calls Britain's old "sink-or-swim" philosophy, which allowed students to succeed or fail on their own—a way to quickly identify the few capable of making a contribution to science. Slack swam with the best in his class but emerged uninspired from his Ph.D. in precloning molecular biology.

Then he discovered Principles of Embryology, a 1956 textbook written by the British scientist and philosopher Conrad Waddington. Slack heard Waddington speak at a seminar in 1973 and was fascinated by his descriptions of unexplained—and sometimes bizarre—laboratory results. For example, if a very early duck embryo is cut into two parts, it becomes two separate embryos, but with an unusual twist: the rear half has the same head-to-tail orientation, but the front half has a random orientation.

Later Slack attended a lecture by the developmental biologist Lewis Wolpert and became hooked. Wolpert is famous for creating the theory of positional information, which essentially suggests that cells need instructions about their positions within the embryo before they can become differentiated cells. Slack got a fellowship to work in Wolpert's lab and soon started doing experiments to learn more about how limbs grow and orient themselves in axolotls, a type of salamander.

His enthusiasm for this area of research sustains him to this day. One of his primary lines of investigation studies the regeneration of missing limbs and tails, primarily using Xenopus frogs and tadpoles as model organisms. In fact, it's often the research he describes when non-scientists ask him about his work.

"It's an obvious question that's instantly interesting," he explains. "Why can tadpoles regrow their limbs and humans can't?"

Slack also studies the mechanisms of transdifferentiation, or the ways cells convert from one type into another. Recently, his lab developed methods for reprogramming certain liver cells into pancreatic cells—and vice versa—by introducing specific proteins. This line of research holds tremendous promise, as finding ways to generate insulin-producing pancreatic beta cells could lead to a new therapy for diabetics who must now rely on daily insulin injections or a limited supply of pancreas donors. It's also an area ripe for collaboration with University of Minnesota researchers who are leading the way in improving islet-cell transplantation to treat diabetes.

« prev | 1 2 3 | next »

The University of Minnesota Stem Cell Institute