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Anyone who’s had pet fish knows how hard it is to keep the tank filtered, chemically balanced and temperate—and the fish from becoming floaters due to mysterious ailments. Now imagine caring for half a million fish, some as small as specks, while they’re being studied as scientific research subjects. That’s the challenge fish biologist Christian Lawrence faces as manager of Children’s Hospital Boston’s five fish facilities. Together, the 5,000 square feet of fish laboratories hold about 10,000 tanks filled with hundreds of lines of zebrafish bred to help scientists study diseases.
When Lawrence tells people he’s a fish expert at a hospital, they’re usually taken aback. It’s come as a bit of a surprise for him too; he got a Master’s degree in fish biology and worked with fish in their natural habitats. “I was pulling fish out of a net from a river in an Arizona canyon, and the next thing I know I’m pulling fish out of tanks in Boston,” he says. At Children’s, his skills are invaluable, since the researchers using the fish to study diseases aren’t schooled in how to keep fish healthy. “I bridge the gap between aquaculture and the biomedical science being done here,” he says.
Children’s is a leader in the field of zebrafish research. Because zebrafish are genetically similar to humans, dozens of researchers study zebrafish models of human disease, and researchers have created countless strains by altering their genetic makeup. Keeping track of the many “mutants” is a huge undertaking: Lawrence maintains mutant lines for certain studies, while interbreeding others, and there’s always the possibility of accidentally contaminating a research tank with an errant fish and ruining an experiment. “It’s one of the very large challenges,” he says. “Our labeling system used to be color-coded tape. Now we’re moving into computerized tracking.”
Many of the researchers work with Leonard Zon, MD, director of the Stem Cell Research Program, to study cancer. They monitor how a disease like cancer develops and then treat the fish with experimental drugs that might prevent or slow it down. The drugs are usually added into the tank’s water, since fishes’ permeable skin can absorb it, but the researchers can also inject drugs by skillfully manipulating a needle. Lawrence consults with investigators on treatment issues like these, making sure that when people design experiments they take into account the overall health of the fish. “There are a number of ways to measure the well-being of a fish, you can just look at it and tell by its skin color,” he says. “A healthy fish will have a shine to it.”
There’s another reason to make sure the fish stay in top form. “Unhappy fish won’t make eggs,” Lawrence says. Since the labs depend on a regular roster of embryos, making sure the fish are comfortable enough to breed is critical. (“Environmental enrichment” helps too—couples sometimes are placed in private breeding bowls replete with fake trees.) Keeping such a large number of fish happy requires constant vigilance. Lawrence and his team keep careful track of the fishes’ nutrition and ensure optimal water quality by monitoring computerized systems and flushing 20 percent of the water each day. He also conducts manual tests to make sure contaminants aren’t introduced to the system from things like nets or researchers’ hands.
According to Lawrence, zebrafish research is a rapidly growing field. “They’re used all over the globe to study everything from genomics to toxicology,” he says. Lawrence often exchanges fish and embryos with other organizations, and Children’s see-through Casper fish has been an especially hot commodity. (If properly packed, the fish travel well.) The field has grown so quickly, in fact, that biomedical research has outpaced the knowledge about the fish’s biology. “Only now is there realization that we need to know more about the fish,” says Lawrence. So, in his spare time, he connects with other experts as president of the international Zebrafish Husbandry Association and a member of several other fishery societies.
After 10 years working with fish in labs, Lawrence doesn’t mind the labs’ humidity and pungent smell, and can even tune out the constant sound of water splashing in the tanks. “I’m completely used to it,” he says. “Some researchers find the fish setting to be soothing, like cutting grass can be.” And he counts himself lucky. “The bottom line is I really love fish,” he says. “If I didn’t, I wouldn’t be here.” |
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