When Mark Krasnow, MD, PhD, isn’t in his biochemistry lab at Stanford, he might be found in the rainforests of Madagascar chasing down mouse lemurs. These big-eyed, cuddly-looking creatures are the smallest, fastest-maturing primates on earth. Some 20 million of them roam the landscape in Madagascar, the only region of the world where they live.
Krasnow said he turned to lemurs out of frustration with studies in mice, which make up the vast majority of animal model systems but often don't mimic human biology and behavior. From a genetic perspective, lemurs are about half the distance between mice and humans, Krasnow said.
He wondered whether it would be possible to find interesting mutations in the animals and then identify the affected genes, making it possible to use lemurs as genetic models for all aspects of primate biology including human disease. Indeed, after six years of tracking lemurs in the wild and studying their blood samples and DNA, “we are starting to build a new model organism for studying primate genetics,” he said at a symposium on the Stanford campus last week.
Thus far, Krasnow and his colleagues have identified some 20 genetic variants of interest, including individuals with obesity, high cholesterol, cardiac arrhythmias, high blood sugar and unusual eye color. The animals are tagged and released back into the rainforest so researchers can follow their progress over time and see how their conditions affect their behavior and survival in the wild. Each lemur is named for a particular characteristic, including one called Feisty, who is not your usual laid-back lemur, and MurderFace, who has an unusually high-pitched, screechy voice, Krasnow said.
He was among some 20 speakers at the day-long symposium devoted to Madagascar, whose biodiversity makes it a unique living laboratory for research in biology, ecology and the impact of environmental change on human disease.
The island nation is home to a rich ecosystem of animal and plant life that is rapidly being destroyed by human intervention, including slash-and-burn projects to make way for agriculture and other business ventures, said Michele Barry, MD, director of the Stanford Center for Innovation in Global Health, which sponsored the conference together with the Woods Institute for the Environment.
“It’s one of the hotspots of ecology in the world, and we are quickly losing these hotspots,” Barry said.
Land use changes, degradation of water supplies, climate change and habitat loss worldwide all have led to unintended consequences for human health, said Steve Luby, MD, a professor of medicine and director of research for the global health center. “As biological creatures, our health is inextricably linked to the environment in which we live. By destroying the planet, we are destroying the habitat in which we live... Madagascar is a microcosm of the broader problem.”
Madagascar is one of the world’s poorest countries, spending some $14 per capita a year on health care in a population plagued by malaria, tuberculosis and parasitic diseases. Speakers at the symposium described a variety of projects they're working on to address the nation’s heavy burden of disease, including:
- Matt Bonds, PhD, a visiting assistant professor at the Center for Innovation in Global Health and assistant professor at Harvard, who founded the nonprofit organization, PIVOT, designed to be a model health care system for Madagascar and for science and innovation generally. The group has provided treatment to some 65,000 people through a network of clinics and is collecting data on child malnutrition and other health conditions, with an eye to developing interventions.
- Purvesh Khatri, PhD, an assistant professor of medicine at Stanford, has developed a blood test for tuberculosis that will be field-tested in Madagascar starting this summer.
- Manu Prakash, PhD, an assistant professor of engineering at Stanford, has brought his brand of “frugal science” to Madagascar, teaching school children to build their own paper microscopes through which they examined their own head lice, among other projects.
- Robert Siegel, MD, PhD, a professor of microbiology and immunology, has been taking Stanford students to the island nation to teach them about species adaption, ecology and evolution.
Previously: Just one needle saves a life following Stanford physician's trip to Madagascar and Move over, mouse: The search for a better animal model for human disease
Photo by Robert Siegel