Among the many niche communities in the giant enterprise of science, worm experts are a special cadre. Caenorhabditis elegans—the slender and sinuous nematode—may be a model organism, but it also requires model experimental techniques. And in the small guild of C. elegans specialists, Peggy Kroll-Conner is a star.

Judith Kimble, an HHMI investigator at the University of Wisconsin–Madison who studies the fundamental controls of animal development, has for 16 years relied on Kroll-Conner’s finesse. “Peggy is the heart and soul of all our genetics,” says Kimble. “She has become the person who generates some of the most finicky strains in the lab. In the worm community, she is known as being exceptionally fastidious—her strains always have the correct genotype and, just as important, are not contaminated.”

According to Kroll-Conner, the key to ensuring that frozen worm stocks are free of mold and bacteria is good sterile technique. She vigilantly labels items to prevent strain mix-ups. Once the worms are frozen, she thaws a portion to make sure the animals are viable and the stock pristine. She returns test thaws to the scientists who created the worms, so they can validate the strains. She also revalidates her own strains. “In other words,” says Kroll-Conner, “we do a lot of quality control.”

Alongside the ever-present threat of contamination is the challenge of fashioning strains with multiple mutations. “Mother Nature doesn’t give up her secrets easily,” says Kroll-Conner. “I try to figure out a way to balance the mutations in a user-friendly way, to minimize the work needed to maintain the worms.” Certain mutations are more challenging than others, she says. In one experiment, she had to set up a mating with a strain of worms whose reproductive systems quickly developed tumors. “I set up numerous mating plates with large numbers of worms and ended up with only three cross-progeny. Only one of those had the genotype that I was looking for.”

Such perseverance and attention to detail is essential in her role. It’s also about mutual support, she says, a concept that seems to have been bred into the C. elegans world by Janelia Farm senior fellow Sydney Brenner, a molecular biologist who shared the 2002 Nobel Prize in Physiology or Medicine. “When Brenner started this science in the 1970s, he said that the worm community should work together in a spirit of cooperation. He felt that science would advance much faster that way,” she says. “I like that philosophy.”

Illustration: Chris King

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