Injecting molecules from a sea slug that received tail shocks into one that didn’t made the recipient animal behave more cautiously.
In a cramped lab overflowing with fruit flies, Thomas Hunt Morgan and his protégés made the discoveries that laid the foundations of modern genetics.
September 1, 2013|
COURTESY OF THE ARCHIVES, CALIFORNIA INSTITUTE OF TECHNOLOGY.In 1904, developmental biologist Thomas Hunt Morgan was appointed professor of experimental zoology at Columbia University in New York City, where he began to explore heredity as the key to development. A few years later, he turned to the suitably fecund fruit fly, Drosophila melanogaster, to search for mutations—the spontaneous, heritable changes that had already been observed in plants—and set up a dedicated lab in Schermerhorn Hall’s room 613. Here, hundreds of fly-filled milk bottles cluttered a cramped space that became known as the Fly Room, where Morgan and his students made seminal discoveries about genes and chromosomes that paved the way for modern genetics and transformed biology into an experimental science.
“Morgan’s discoveries made it possible to address a series of questions regarding the function and structure of genes,” wrote neurobiologist Eric Kandel in a 2002 essay in Columbia’s alumni magazine. Some answers came from Morgan and his protégés; others came from the scientists they influenced, added Kandel. “In every case, the discoveries made by these pioneering researchers set the agenda for biology in the twentieth century.”
The first couple of years in the Fly Room were frustrating. Despite subjecting roughly 60 generations of flies to extreme temperatures and exposing them to salts, sugars, acids, alkalis, X-rays, and radium, Morgan and his colleagues failed to detect any visibly mutated flies. Then, in April 1910, they finally spotted one: a fly with white eyes rather than the usual red. With a series of crossbreeding experiments, Morgan determined that the white-eye mutation was recessive and linked to sex. More observations revealed that the allele for eye color lies on the X chromosome—the first time a trait had been linked with a specific chromosome.
The findings, published in Science in 1910 and 1911, confirmed the chromosomal theory of inheritance—an idea derived from Gregor Mendel’s work and one that Morgan had previously doubted. Subsequent work carried out in the Fly Room demonstrated that some genes are grouped together on the same chromosome and almost always inherited together. But the researchers also showed that such “linked” genes can be separated when two paired chromosomes cross over and exchange material. By 1913, Alfred Sturtevant, one of Morgan’s students, had created the first physical map of genes on a chromosome, work that was continued through the 1930s by another Morgan disciple, Calvin Bridges.
For such achievements, Morgan was awarded the 1933 Nobel Prize in Physiology or Medicine. (Although he was the sole laureate, he shared the prize money with Sturtevant and Bridges.) But Morgan’s legacy reached even further: the egalitarian atmosphere he cultivated in the Fly Room—where he encouraged students to develop ideas and execute experiments—became the blueprint for modern American research culture.
“The idea that students could do the research was new,” says Stuart Firestein, a biologist at Columbia who plays Morgan in a forthcoming movie set in the Fly Room. “That’s how we all operate now, of course. So not only did Morgan introduce fly genetics, he also introduced a new kind of lab culture to science.”