For a long time, scientists with huge questions on biology have discovered solutions in a tiny worm. That worm — a millimeter-long creature known as Caenorhabditis elegans — has helped researchers uncover basic options of how cells and organisms work. The influence of that work is big: Discoveries made utilizing C. elegans have been acknowledged with 4 Nobel Prizes and have led to the event of recent remedies for human illness.
In a perspective piece printed within the November 2025 situation of the journal PNAS, 11 biologists together with Robert Horvitz, the David H. Koch (1962) Professor of Biology at MIT, rejoice Nobel Prize-winning advances made by way of analysis in C. elegans. The authors discuss how that work has led to advances for human well being, and spotlight how a uniquely collaborative group amongst worm researchers has fueled the sector.
MIT scientists are effectively represented in that group: The outstanding worm biologists who coauthored the PNAS paper embody former MIT graduate college students Andrew Fire PhD ’83 and Paul Sternberg PhD ’84, now at Stanford University and Caltech, respectively; and two previous members of Horvitz’s lab, Victor Ambros ’75, PhD ’79, who’s now on the University of Massachusetts Medical School, and former postdoc Gary Ruvkun of Massachusetts General Hospital. Ann Rougvie on the University of Minnesota is the paper’s corresponding creator.
“This tiny worm is beautiful — elegant both in its appearance and in its many contributions to our understanding of the biological universe in which we live,” says Horvitz, who in 2002 was awarded the Nobel Prize in Physiology or Medicine, together with colleagues Sydney Brenner and John Sulston, for discoveries that helped clarify how genes regulate programmed cell demise and organ growth.
Early worm discoveries
Those discoveries had been among the many early successes in C. elegans analysis, made by pioneering scientists who acknowledged the ability of the microscopic roundworm. C. elegans gives many benefits for researchers: The worms are simple to develop and keep in labs; their clear our bodies make cells and inside processes readily seen underneath a microscope; they’re cellularly quite simple (e.g., they’ve solely 302 nerve cells, in contrast with about 100 billion in a human) and their genomes will be readily manipulated to review gene operate.
Most importantly, most of the molecules and processes that function in C. elegans have been retained all through evolution, which means discoveries made utilizing the worm can have direct relevance to different organisms, together with people.
“Many aspects of biology are ancient and evolutionarily conserved,” Horvitz, who can also be a member of MIT’s McGovern Institute for Brain Research and Koch Institute for Integrative Cancer Research, in addition to an investigator on the Howard Hughes Medical Institute. “Such shared mechanisms can be most readily revealed by analyzing organisms that are highly tractable in the laboratory.”
In the Nineteen Sixties, Brenner, a molecular biologist who was interested in how animals’ nervous methods develop and performance, acknowledged that C. elegans supplied distinctive alternatives to review these processes. Once he started growing the worm right into a mannequin for laboratory research, it didn’t take lengthy for different biologists to hitch him to reap the benefits of the brand new system.
In the Nineteen Seventies, the distinctive options of the worm allowed Sulston to trace the transformation of a fertilized egg into an grownup animal, tracing the origins of every of the grownup worm’s 959 cells. His research revealed that in each growing worm, cells divide and mature in predictable methods. He additionally realized that a number of the cells created throughout growth don’t survive into maturity, and are as a substitute eradicated by a course of termed programmed cell demise.
By in search of mutations that perturbed the method of programmed cell demise, Horvitz and his colleagues recognized key regulators of that course of, which is usually known as apoptosis. These regulators, which each promote and oppose apoptosis, turned out to be important for programmed cell demise throughout the animal kingdom.
In people, apoptosis shapes growing organs, refines mind circuits, and optimizes different tissue constructions. It additionally modulates our immune methods and eliminates cells which might be in peril of changing into cancerous. The human model of CED-9, the anti-apoptotic regulator that Horvitz’s crew found in worms, is BCL-2. Researchers have proven that activating apoptotic cell demise by blocking BCL-2 is an efficient therapy for sure blood cancers. Today, researchers are additionally exploring new methods of treating immune issues and neurodegenerative illness by manipulating apoptosis pathways.
Collaborative worm group
Horvitz and his colleagues’ discoveries about apoptosis helped show that understanding C. elegans biology has direct relevance to human biology and illness. Since then, a vibrant and carefully related group of worm biologists — together with many who skilled in Horvitz’s lab — has continued to hold out impactful work. In their PNAS article, Horvitz and his coauthors spotlight that early work, in addition to the Nobel Prize-winning work of:
- Andrew Fire and Craig Mello, whose discovery of an RNA-based system of gene silencing led to highly effective new instruments to control gene exercise. The innate course of they found in worms, often called RNA interference, is now used as the idea of six FDA-approved therapeutics for genetic issues, silencing defective genes to cease their dangerous results.
- Martin Chalfie, who used a fluorescent protein made by jellyfish to visualise and monitor particular cells in C. elegans, serving to launch the event of a set of instruments that remodeled biologists’ skill to look at molecules and processes which might be necessary for each well being and illness.
- Victor Ambros and Gary Ruvkun, who found a category of molecules known as microRNAs that regulate gene exercise not simply in worms, however in all multicellular organisms. This prize-winning work was started when Ambros and Ruvkun were postdocs in Horvitz’s lab. Humans depend on greater than 1,000 microRNAs to make sure our genes are used on the proper instances and locations. Disruptions to microRNAs have been linked to neurological issues, most cancers, heart problems, and autoimmune illness, and researchers at the moment are exploring how these small molecules could be used for analysis or therapy.
Horvitz and his coauthors stress that whereas the worm itself made these discoveries potential, so too did a bunch of sources that facilitate collaboration inside the worm group and allow its scientists to construct upon the work of others. Scientists who examine C. elegans have embraced this open, collaborative spirit for the reason that discipline’s earliest days, Horvitz says, citing the Worm Breeder’s Gazette, an early publication the place scientists shared their observations, strategies, and concepts.
Today, scientists who examine C. elegans — whether or not the organism is the centerpiece of their lab or they need to complement research of different methods — contribute to and depend on on-line sources like WormAtlas and WormBase, in addition to the Caenorhabditis Genetics Center, to share information and genetic instruments. Horvitz says these sources have been essential to his personal lab’s work; his crew makes use of them on daily basis.
Just as molecules and processes found in C. elegans have pointed researchers towards necessary pathways in human cells, the worm has additionally been a significant proving floor for growing strategies and approaches later deployed to review extra complicated organisms. For instance, C. elegans, with its 302 neurons, was the primary animal for which neuroscientists efficiently mapped all the connections of the nervous system. The ensuing wiring diagram, or connectome, has guided numerous experiments exploring how neurons work collectively to course of data and management conduct. Informed by each the ability and limitations of the C. elegans’ connectome, scientists at the moment are mapping extra complicated circuitry, such because the 139,000-neuron mind of the fruit fly, whose connectome was accomplished in 2024.
C. elegans stays a mainstay of organic analysis, together with in neuroscience. Scientists worldwide are utilizing the worm to discover new questions on neural circuits, neurodegeneration, growth, and illness. Horvitz’s lab continues to show to C. elegans to analyze the genes that management animal growth and conduct. His crew is now utilizing the worm to discover how animals develop a way of time and transmit that data to their offspring.
Also at MIT, Steven Flavell’s crew within the Department of Brain and Cognitive Sciences and The Picower Institute for Learning and Memory is utilizing the worm to analyze how neural connectivity, exercise, and modulation combine inside states, comparable to starvation, with sensory data, such because the odor of meals, to supply generally long-lasting behaviors. (Flavell is Horvitz’s educational grandson, as Flavell skilled with certainly one of Horvitz’s postdoctoral trainees.)
As new applied sciences speed up the tempo of scientific discovery, Horvitz and his colleagues are assured that the common-or-garden worm will carry extra sudden insights.