Fruit Flies Are Important to Science. So Are the Employees Who Hold Them Alive.
The rooms of the Bloomington Drosophila Stock Center at Indiana University are lined with identical shelves from wall to wall. Each shelf is filled with uniform frames and each frame with indistinguishable glass bottles.
However, the tens of thousands of fruit fly species in the vials are each very different. Some have eyes that fluoresce pink. Some will jump if you throw a red light on them. Some have short bodies and iridescent curly wings and look “like little ballet flats,” said Carol Sylvester, who helps with grooming. Each strain is also a unique research tool, and it has taken decades to introduce the traits that make them useful. If left unattended, the flies will die in a few weeks and destroy entire scientific disciplines.
During the Covid-19 pandemic, workers from different industries held the world together and took great personal risk to care for sick patients, maintain supply chains, and feed people. However, other important professions are less well known. Dozens of employees come to work at the Stock Center every day to serve the flies that support scientific research.
Small beetle, big impact
For most casual watchers, fruit flies are tiny dots with wings that hang near old bananas. Over the past century, researchers have turned the insect – known in science as Drosophila melanogaster – into something of a genetic switchboard. Biologists regularly develop new “fly strains” in which certain genes are switched on or off.
Studying these light mutants can show how these genes work – including in humans, as we share more than half of our genes with Drosophila. For example, researchers discovered what is now known as the hippopotamus gene – which helps regulate organ size in both fruit flies and vertebrates – after flies with a defect in them became unusually large and wrinkled. Further work with the gene has shown that such defects can contribute to the uncontrolled cell growth that leads to cancer in humans.
Other work with the flies has shed light on diseases from Alzheimer’s to Zika, taught scientists about decision making and circadian rhythms, and helped researchers win six Nobel Prizes. Over a century of optimizing fruit flies and cataloging the results has made Drosophila the best characterized animal model we have.
It’s a big part of a humble mistake. “When I try to tell people what I’m doing, the first thing they usually say is, ‘Why should you keep fruit flies alive? I’m trying to kill her! “Said Ms. Sylvester, who has been a Bloomington warehouse keeper since 2014.
When a couple of hitchhikers come to her house from the grocery store and their children rape her, she added, “Mom, you brought your coworkers home from work.”
The Bloomington Drosophila Stock Center is the only facility of its kind in the United States and the largest in the world. It is currently home to over 77,000 different types of fruit flies, most of which are in high demand. In 2019, the center shipped 204,672 fly vials to 49 laboratories States and 54 countries, said Annette Parks, one of the center’s five lead investigators.
It’s “one of the jewels we have in the community,” said Pamela Geyer, a University of Iowa stem cell biologist who has been ordering flies from the storage center for 30 years.
Other model organisms can be frozen for long-term storage in certain life stages. Laboratory freezers around the world hold mouse embryos and E. coli cultures. But fruit flies cannot go on ice. Taking care of the creatures means turning them over regularly: they are transferred from an old vial to a clean vial that has been supplied with plenty of food. Under quarantine with other members of their species, the flies mate and lay eggs that hatch, pupate and reproduce and continue the cycle.
“We have strains in our collection that have been continuously propagated this way since about 1909,” said Cale Whitworth, another senior investigator at the camp center, across generations and institutions. To keep the millions of Drosophila on their toes, the center employs 64 storekeepers plus a media preparer – think fly food cook – as well as a kitchen assistant and five dishwashers.
In the camp center, as everywhere, the first movements of the pandemic felt threatening. “I remember joking with people:” We are the people at the beginning of the dystopian novel, and we still don’t know what’s coming, “said Ms. Sylvester.
As the number of cases increased, Dr. Whitworth got a bag with a pillow and a toothbrush and imagined the worst. “I was in the ‘everyone is sick, last man on earth’ business,” he said. “How ‘How many flies can I fly in a period of 20 hours, sleep for four hours and keep turning the next day?'”
When Indiana University closed on March 15, the warehouse center remained open.
Kevin Gabbard, the fly food chef, made an emergency shop. Although they eat the same thing every day – a yeast puree made primarily from corn products – flies can be picky. Risking nothing, Mr Gabbard ordered two months of her favorite brands. “They think cornmeal is cornmeal,” he said. “But it’s not when it’s not right.”
The co-directors developed a more robust Hail Mary plan that would enable them, if necessary, to “keep most flies alive with just eight people,” said Dr. Whitworth. They also decided to stop all supplies and focus their energies on looking after flies.
On March 26th, the flies stopped leaving the building – and news of support came in almost immediately. “You are all amazing,” read an email. “The fly community is strong because of the phenomenal work you do.”
At around the same time, employees had a choice. They were considered essential workers and were allowed to come on campus. The university guaranteed them full pay even if they decided to stay home or an hour and a half to get in. (The center covers its costs through a combination of federal grants from the National Institutes of Health and its own income from sales of flies.)
The vast majority chose to keep working, said Dr. Whitworth – although suddenly the job was very different. The center is usually a very social place to work with birthday parties and group lunches. Working hours are usually flexible, a big selling point for employees, many of whom are parents, students, or have retired from full-time work.
Now people work in masks, often in separate rooms. Relocations in one of the buildings in the center were strictly planned to avoid overlap. “You can work alone for quite a while, maybe all day,” said Roxy Bertsch, who has been a warehouse keeper since 2018.
And for the first few weeks, the warehouse keepers – many of whom do additional duties like packing, shipping, and training – spent all of their time turning flies, which is monotonous and tough on the hands. “We just came in, fed flies and left,” said Ms. Bertsch.
But she kept going back. After her son may have been exposed to the coronavirus and she had to quarantine herself, she counted down the 14 days before she could return.
“There’s no way to keep me from work when I could be here,” she said.
Ms. Sylvester specializes in caring for flies whose mutations mean they will need additional DC. She also worked full time during the entire shutdown, borne by the care for her protégés. “Most of the time, I just love the flies and don’t want them to die,” she said. “I never thought I would love larvae so much.”
Back to the ship shape
In mid-May, the center began shipping inventory again. Dr. Parks relayed another series of messages, many of which were now relieved.
“Feels like Christmas,” tweeted a laboratory at Aarhus University in Denmark with a photo of a box of vials.
A message in the spring from Tony Parkes, a biologist at Nipissing University in Ontario, had praised those “who do their job with few awards, but on which everyone counts as a basic backbone”.
When Dr. Parkes’ laboratory paused, he spent some of his unexpected downtime thinking about the storage center. It is a balance, he said, that enables even small laboratories to answer big questions “without using large resources”.
Plus, researchers can literally share their discoveries with one another. “You don’t need to have your own library to access all of this information,” he said, since the storage center is “there whenever you want.”
The people who keep the center going are also thinking about it. “It means a lot to know that you are part of it,” said Ms. Bertsch.
But it increases the pressure. “We all feel this great weight in making sure the storage center is there for everyone,” said Dr. Whitworth.
The pandemic continues, of course, and further obstacles loom. Although the fall semester has passed without incident, cases are increasing in the region, increasing the potential for another shutdown. Post delays at home and abroad have led the center to point out that their customers are turning to private freight forwarders – flies die if they’re on the road too long.
Although they are no longer paid extra, they all keep coming back to work. And even if things change, Dr. Whitworth ready. “I never unpacked my bag,” he said. “It’s still in the closet.”