• ArtsandLectures twitter avatar
    In @ManualCinema 's family-friendly multimedia theater, projections, shadow puppets, live actors, miniature toys an… https://t.co/ZJVMQnVozV
    2 hours 49 min ago
  • UCSBgauchos twitter avatar
    https://t.co/gBQwcqu8DH https://t.co/vS9ykF5PY9
    10 hours 23 min ago
  • UCSBgauchos twitter avatar
    UCSB Tops Fordham, Falls to No. 5 UCLA on Opening Day of Mary Nutter Classic https://t.co/eF70BJWFrw
    10 hours 26 min ago
  • UCSBgauchos twitter avatar
    https://t.co/j2uLYNr3O4 https://t.co/tzwHnTo7jU
    11 hours 6 min ago
  • UCSBgauchos twitter avatar
    Pair of Gauchos Tally Double-Doubles in Big 82-55 Win over UC Irvine https://t.co/u2wlVpQhCJ
    11 hours 10 min ago
  • UCSBgauchos twitter avatar
    Clay Fisher goes 2-4 to continue his hot start, but @UCSB_Baseball drops middle game to SDSU on Saturday night. REC… https://t.co/l7Hl7v5YI4
    11 hours 34 min ago
  • UCSBgauchos twitter avatar
    Women's Tennis: UC Santa Barb. 0, St. Mary's (Cal.) 4 (Final) UCSB Gets Blanked in Return to Courts Against St. Mar… https://t.co/8VPPLXzowH
    15 hours 36 min ago

Adapting to the Heat

Biologist Craig Montell uncovers the molecular mechanism that regulates an animal’s ability to sense the rate of temperature change
Monday, October 17, 2016 - 08:00
Santa Barbara, CA

Frog on pot handle.jpeg

Photo Credit: 

© 2010 J. Ronald Lee

Craig Montell and Junjie Luo.jpg

Montell and Luo

Craig Montell and Junjie Luo

Photo Credit: 

Sonia Fernandez

In classic experiments on frogs, scientists found that the amphibians’ urge to escape from dangerously hot water decreased significantly when the water temperature rose very gradually. 

In fact, sensitivity of many animals to temperature — including humans — is similarly affected by the rate of increase. Exactly why, however, has not been understood.

Hoping to shed light on this phenomenon, UC Santa Barbara professor Craig Montell and graduate students Junjie Luo and Wei Shen developed fruit fly larvae as a model to reveal a mechanism through which the animal shows different behavioral responses to fast and slow rises in temperature.

The researchers discovered that a rapid 25-degree Fahrenheit temperature change caused a writhing response in fruit fly larvae. However, when the temperature was raised gradually, far fewer animals reacted, and for those that did, the average threshold temperature was significantly higher. The team’s findings appear in the journal Nature Neuroscience.

“We know a lot about how animals sense large and sudden increases in temperature,” said Montell, the Patricia and Robert Duggan Professor of Neuroscience in UCSB’s Department of Molecular, Cellular, and Developmental Biology. “They respond to noxious heat by initiating an escape response. But how is it that animals are so much less sensitive to the same hot temperature when the change is really slow?” 

The answer to that question turned out to have two parts. First, Montell and his team identified the thermosensory neurons in the brain responsible for sensing the rate of temperature change, which helped to define the underlying molecular mechanism.

“When there is a really rapid change in temperature, you want to protect the brain, particularly in fly larvae because they’re cold-blooded and their body temperature equilibrates to the outside,” explained Montell. “If their brains feel a rapid increase in temperature, that stimulates the writhing response.”

Second, the researchers discovered that the fast response to rapidly increasing heat depended on a transient receptor potential (TRP) channel. The activation of the cellular temperature sensor, a protein called TRPA1, was not simply a function of the absolute temperature but rather depended on the rate of temperature change. If the temperature increase was rapid, TRPA1 turned on quickly and excited those thermosensory brain neurons. When the temperature increased slowly, TRPA1 was less active.

“There’s a feedback mechanism that turns off this protein as quickly as it’s turned on,” Montell said. “When it’s turned on quickly, it stimulates the pathway to cause the writhing response. But when the process occurs slowly, the on and off mechanisms cancel each other out.”

The scientists posit that the ability to sense the rate of temperature change is a critical survival mechanism that allows an animal to quickly respond to and escape from a noxious thermal landscape before it is too late.

“We think similar mechanisms occur in other animals — for example, the frog,” Montell said. “It could be that related mechanisms affect temperature-sensitive TRP channels in humans as well. Ultimately, if a common mechanism is conserved across species, our findings may provide insight into how different animals adapt to the rate of temperature change.” 

Contact Info: 

Julie Cohen
(805) 893-7220