Scientists studying how animals survive winter have found that fruit flies completely rebuild their internal biological clocks to switch to a different seasonal mode. For reference, a fruit fly is a small insect that feeds on ripe, rotten, or fermented fruits and vegetables. They are typically about 2–4 millimeters long, have a brown or yellowish-brown body, red eyes and clear wings.People use this term in two common ways: Domestic Fruit Flies and Laboratory Fruit FliesThe discovery reveals a genetic winter lock that keeps the insects in a state of low activity until warm weather returns. The study, led by researchers at Washington State University, found that the biological clock doesn’t just run slower in cold weather. Instead, it changes its molecular structure to run on a completely different seasonal schedule.The findings, published in the journal Science Advances, could lead to new ways to target agricultural pests and help researchers understand why some human health conditions change with the seasons.
dividing internal clock
To understand seasonal variation, the research team focused on a core gene within the circadian clock called Timeless, which regulates daily circadian rhythms.As winter approaches, genes undergo a process called alternative splicing. This mechanism allows a gene to arrange its code differently and produce completely different proteins depending on environmental signals. The winter-specific version of the protein reshapes the fly’s daily activity patterns and completely shuts down its reproductive system, effectively keeping the insect dormant.The discovery solves a long-standing mystery about how animals process seasonal changes, said Sergio Hidalgo, assistant professor in the College of Veterinary Medicine at Washington State University and lead author of the study.“We have long known that animals use environmental cues to prepare for seasonal changes, but we have not understood how this information is integrated by the biological clock,” Hidalgo said. “What we found is that the clock can be reset to a winter state which helps animals stay there until conditions become favorable to go back into summer mode.”For decades, scientific models of the circadian clock were based almost entirely on how organisms function during the warmer months. This new evidence shows that organisms are not tied to a single, rigid internal clock that runs the same way throughout the year.“For years, we’ve been studying what is essentially a summer version of the watch,” Hidalgo said. “This work shows that the clock can be reprogrammed in winter, creating a system that works differently and helps animals maintain winter schedules.”
Sergio Hidalgo, left, a professor works with research intern Audrey Berry in his laboratory (Credit: College of Veterinary Medicine/Ted S. Warren)
a blueprint for survival
Adapting to changing climates is a basic necessity for survival in nature. Microbes, complex plants, and large animals all rely on external factors such as changes in temperature and shorter day length to anticipate the arrival of winter.These environmental changes induce physical survival strategies, including long-distance migration, hibernation, halted reproduction, and deep dormancy. While scientists understood what was causing these reactions, the exact biological pathways coordinating these whole-body changes remained unclear.Winter Lock’s discovery shows that the fruit fly’s genetic machinery directly integrates these external signals to rebuild its internal clock. The fly remains locked in this low-power state until environmental conditions improve significantly, giving a clear signal that it is safe to return to summer mode.The research project was a collaborative effort, combining genetic data and resources from both Washington State University and the University of California, Davis. Co-authors included Audrey Berry, a former university student and research intern who worked in Hidalgo’s laboratory.
Targeting insect and human rhythms
The discovery of this seasonal genetic switch opens up practical possibilities for the management of destructive insects. Hidalgo suspects that the same or similar molecular mechanisms control the seasonal timing of major agricultural pests and disease-carrying insects such as mosquitoes.Most modern pest control strategies focus on direct, immediate eradication. Understanding winter lock could help scientists develop methods that disrupt the biological clock itself. By interfering with the genetic splicing that allows insects to survive winter or dry periods, researchers could potentially destroy insect populations before they become active in the spring.The study also provides new clues for researchers studying human biology. Many medical conditions, including seasonal affective disorder, along with various neurological and psychiatric conditions, follow distinct seasonal patterns. The precise biological processes driving these changes in human health are still poorly understood.The biological systems of fruit flies and humans are very different, but the discovery that a core clock gene can radically reorganize itself every season gives medical researchers a solid molecular starting point. Scientists can now investigate whether similar genetic changes occur in the human biological clock during the dark months of the year.