A team of researchers has discovered the mechanisms that help an animal sense and respond to temperature changes. The study, which used fruit flies as model organisms, also showed that a temperature-sensing signal channel was less active when the temperature was raised slowly. The details are in a paper that was just published in the journal Nature Neuroscience.
When animals, including humans, are exposed to very gradual temperature changes, they become less sensitive to those changes. Scientists have known about this phenomenon for a long time but the actual mechanisms involved were unknown. A team of researchers decided to investigate this effect by using Drosophila fruit fly larvae.
The research team first exposed fruit fly larvae to a sudden increase in temperature. This caused the larvae to writhe and try to escape. When the temperature was raised slowly, however, many larvae failed to react at all. The team was able to identify the thermosensory neurons that played an active role in sensing temperature changes. From there, the researchers found that sensitivity to temperatures depended on a transient receptor potential channel. The channel was activated by a protein called TRPA1.
If temperatures increased rapidly, TRPA1 turned on and activated the larvae’s thermosensory neurons. When the temperature was raised very slowly, however, TRPA1 was not as active and failed to properly excite the neurons. The researchers found that in some of these cases, TRPA1 would end up being shut down by other mechanisms before stimulating these neurons. This mechanism explains why animals are so much slower to react to temperature changes when they occur gradually.
The team’s findings provide new insights into how animals sense temperature fluctuations, an ability that can be critical to survival. While the study used fruit fly larvae as models, the authors speculate that TRP channels also control temperature-sensing functions in humans.
Luo J, Shen WL, Montell C. TRPA1 mediates sensing the rate of temperature change in Drosophila larvae. Nature Neuroscience (2016).