Projects and People
What's happening in Joe Shaw's lab?
This past fall, SPEA welcomed assistant professor Joseph Shaw and research technician Chip Glaholt, who continue research they started at Dartmouth College.
What do you plan to do here in Bloomington?
Shaw: I’m a molecular toxicologist. By that I mean I’m interested in the impact of environmental contaminants across all levels of bio-complexity from molecules such as DNA all the way up to individuals, populations, communities, and ecosystems.
What kinds of contaminants do you study?
Shaw: Metals such as cadmium, arsenic, zinc, and nickel are my primary focus and our field sites include areas impacted by mining and smelting operations. One of the key animals I study is a microcrustacean, a relative of lobsters and crabs, called Daphnia.
Why do you focus on Daphnia?
Shaw: It’s probably the most central player in every freshwater lake or pond. By that I mean it’s the primary consumer of algae and bacteria and serves as the primary food source for fish and higher organisms. So it’s central to the ecology of every freshwater lake and pond.
Glaholt: You can call them a keystone species in freshwater systems.
Shaw: They’re also distributed worldwide, which means they’ve adapted to withstand almost any environment. So for someone like me who is interested in how organisms survive different environments, they are amazing critters to study. One of the things we’re interested in is how individuals change to tolerate higher metal concentrations. Then, how do populations of these individuals restructure themselves genetically through selection and actually adapt to these conditions.
And how do you go about studying the changes in populations?
Shaw: Well, here’s another beautiful thing about Daphnia. Typically, Daphnia are females that reproduce by cloning themselves. But environmental cues can elicit male production and when males are around, Daphnia go through sexual reproduction resulting in eggs, which then settle out in lakes. We can collect these eggs from the lakes, and the further down we go, the older the eggs are. In this way, we have access over evolutionary time to past populations.
What are some of the ways Daphnia populations are affected?
Shaw: Here is one of our most recent findings – we found that when Daphnia are pre-conditioned to low levels of metals (i.e., acclimated), they make more of a protein called metallothionein. But it turns out that initially making this protein comes with a cost. So when metals aren’t around, these acclimated animals don’t reproduce as well.
Glaholt: But now we have this new finding that if populations have been exposed long enough, they’ll actually adapt.
Shaw: Every measurement we’ve looked at shows that adapted populations of Daphnia have lost the cost that initially came with acclimation.
Do Daphnia help identify susceptible populations?
Shaw: Daphnia have been an indicator species for a long time. If you lose Daphnia from a system, you’ll know that the lake or pond is in trouble.
What makes Indiana University the right place for this research?
Shaw: Well, one of the reasons that we’re excited about being at Indiana University is because if you want to work with Daphnia, IU is by far the center of the Daphnia world. For example, the Center for Genomics and Bioinformatics has been coordinating the work of scientists worldwide through the Daphnia Genomics Consortium, which we were involved with even before we came to IU. In July 2007 the Consortium released the complete Daphnia gene sequence, the first whole genome of any crustacean. We now have one of the best collections of molecular tools available for any organism.
What other types of projects are going on in your lab?
Shaw: In one of my other projects I study the killifish. It turns out that you can take this fish from the purest, freshest water to very concentrated seawater and it will survive. The mechanism it uses involves the same protein that is mutated in cystic fibrosis patients. I study how environmental exposure to arsenic in this fish affects this protein, which has implications for the disease.
This is another example of how we look at the way organisms adjust to survive in changing or altered environments, whether they’re Daphnia adapting to metals or fish responding to different salinity concentrations.
What are the benefits of your research to the general population?
Shaw: Well…clean water is necessary for all life, not just Daphnia, but fish and people, too. So ultimately, my research, which is centered on water quality, attempts to improve human health and the environment. To borrow a line from SPEA: “Smart policy. Sound science. Stronger communities.”
Does life as a toxicologist affect your everyday decisions – about food, chemicals, or products you use, places you go, swim, fish, etc.?
Shaw: My family and I definitely try to limit our exposure to metals, pesticides, and other harmful compounds. For example, we try to eat more local and organic foods. However, my overall approach is most things in moderation.
Glaholt: Our work does impact my own and my family’s daily life. For example, we stay away from or minimize our intake of top predatory fish such as tuna, sharks, and bass. But as for my recreational practices, they have not been affected. I feel things haven’t gotten that bad yet!
– Liz Rosdeitcher
Joe Shaw is an environmental toxicologist whose research focuses on understanding how environmental chemicals, particularly toxic metals, affect molecular processes in ways that might contribute to impacts on individual fitness, population dynamics, and higher-levels of response. His doctorate is from University of Kentucky.