Promotes adaption to elevated temperatures by regulating expression of the lipid desaturase, fat-7. Binds selectively and with high affinity to fatty acids with chain lengths from C10 to C12 and prevents them from activating fat-7 expression mediated by the nuclear hormone receptor nhr-49, leading to low levels of membrane lipid desaturation and membrane fluidity for adaption to heat. Homotetramer; dimer of dimers. By heat. Two-fold induction at 25 degrees Celsius compared with 15 degrees Celsius. Temperature-sensitive mutants in which embryos develop to adulthood at 15 and 20 degrees Celsius, but have a poor survival incidence at 25 degrees Celsius. Mutants have increased membrane fluidity and abnormal compositions of fatty acid species. Belongs to the acyl-CoA dehydrogenase family.