Animals can adapt to small temperature differences

July 30th, 2008 - 2:10 pm ICT by IANS  

Washington, July 30 (IANS) Animals can sense large changes in temperatures and either move away or die. Now researchers have found they can perceive small variations in temperature as well, and adjust accordingly. Johns Hopkins researchers have discovered that the fruit fly uses heat sensor proteins known as TRPA1 to sense single degree changes in the comfortable range.

However, TRPA1 works as the last step of a multi-step process in temperature detection that allows animals to adapt to different mercury levels in the comfortable range as well, the researchers write in this week’s edition of Nature Neuroscience.

“It’s an exciting discovery, yet in a lot of ways it just makes a lot of sense,” said Craig Montell, member of Johns Hopkins’ new Centre for Sensory Biology.

“You clearly don’t want to hang around or adapt to a temperature that could kill you, but on the other hand, if you can’t find your favourite temperature, it is OK to adapt to another comfortable temperature.”

Montell and his team used fruit flies as their experimental model because it is easy to perform genetic manipulations on these animals.

Temperatures colder than 16 degrees Celsius or warmer than 26 degrees C are known to trigger an avoidance response. Fruit fly maggots (larvae), explained Montell, prefer 18 degrees C, but are comfortable at temperatures ranging from 18 to 24 degrees C.

Since TRP channels are known to open in response to changes in temperature, Montell’s team then tested flies containing mutations in 12 fruit fly TRP genes to see if any were required for the ability to sense temperature changes within the comfort zone.

Eleven of the 12 TRP mutants still preferred 18 degrees to other temperatures in this range. Only the TRPA1 mutant larvae showed no temperature preference, suggesting to the researchers that only TRPA1 is required for comfort zone temperature sensing.

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