Biology professor researches parasites

With 4.5 billion humans infected with parasitic worms, its no surprise that half of all living creatures are parasites.

While the mere mention of internal parasites may make some queasy, Dennis Minchella finds their unique lifestyles and cleverness fascinating.

Minchella, a professor of biological sciences and associate dean of the College of Science, became interested in parasites while taking an invertebrate zoology course as an undergraduate student. He enjoyed learning about parasites mechanisms for survival and how they can transmit themselves to different hosts.

Coevolution between hosts and parasites is one of the main areas Minchella studies. As hosts develop defense mechanisms against parasitic infection, the parasites find intelligent ways of adapting against the hosts defenses, entering what is known as a coevolutionary arms race.

Within a coevolutionary arms race, hosts are coming up with ways to thwart their parasites and then their parasites are getting over those obstacles, said Alyssa Gleichsner, a Ph.D. candidate in biology and assistant in Minchellas lab.

Minchella works mainly with schistosomes, parasites which penetrate humans skin after their larvae complete a stage of their life cycle in snails. Within his lab in Lilly Hall, Minchella replicates the schistosomes entire life cycle ... minus the human host.

We have tanks of freshwater snails, and we run (the parasites) through mice, so mice are the vertebrate host, Minchella said. If you want to study the parasite, you have to be able to have it in a life cycle. It has to be alive and the only way to keep it alive is to keep it cycling through snails and vertebrate hosts.

Minchella said some of the parasites come from endemic areas, and most are collected from the wild to maximize genetic variability. He has strains of parasites from Egypt, Brazil and Kenya.

After many years of research and 80 publications, Minchella said he was most surprised by snails having what he called fecundity compensation. After the parasite enters the snail, the snail is no longer able to produce offspring. To compensate for this, the snail has a burst of reproduction before the parasite renders it infertile.

The surprise was that hosts are able to change their life history strategy in order to deal with a parasitic infection, Minchella said. Before that, people just said, Youre resistant or youre not resistant, and there was nothing in between. I think people are much more willing to not think about life history changes and how that can help you deal with parasitic infections.

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Biology professor researches parasites