A goldfish named John opened the channel to science for HHMI predoctoral fellow Jeffrey Marcus. He acquired the fish as a preschooler and went on to keep and breed numerous tropical fish throughout his school and college years. "One way you learn that big fish eat little fish is if you accidentally put them in the same aquarium!" Marcus says. "In science, if you try something and it doesn't work, you do it a little differently next time."
Marcus built up extensive knowledge about fish and secured research jobs involving shad, salamanders, swordtails, and brine shrimp. Then in a wrenching move, he switched to the world of insects for his Ph.D., although he still keeps some green swordtails as a hobby. "I wanted very much to use genetic techniques to look at how various species are different from one another," he recalls. "In 1995, by far the best organism for that was the fruit fly, which could be compared with other insects. If I were to have to make that decision now, it would be far more difficult because of new genetic knowledge about the zebrafish."
Marcus, who is in the final year of his Ph.D. in zoology at Duke University, is studying genes involved in creating the eyespots on the wings of the luna moth and some of its close relatives. "Virtually all species of butterflies and moths have eyespots in the same position near the wing margin," he explains. "The luna moth has eyespots on top of the cross-veins in the middle of the wing. I am working out the signaling patterns that determine how the cross-veins are made on the wing and where the eyespot is positioned. By studying simple systems such as eyespot development, you can understand more complex systems." Marcus hopes to uncover more about how the signaling process works normally, how it can go wrong, and how similar signals that go haywire can lead to tumor development. Ultimately, this knowledge could help scientists devise treatments for human tumors.
For Marcus, an attractive aspect of scientific research is its array of tasks. "When doing experiments, I get to do a lot of different activities, whether sorting, counting, measuring, looking under the microscope, or taking photos. I like the variety." On the negative side, he cites the "bureaucracy" that goes along with his work, such as filling out forms and arranging committee meetings.
Reflecting on the qualities of a successful scientist, Marcus says, "One of the most difficult parts of science is figuring out which questions you should ask and how you might try answering them. For this, you need a lot of imagination." Determination and organizational skills are also key, he adds, "to ensure you do all the hard work it takes to get the answer."