The intrinsic fluorescence of Tetrahymena as a function of temperature

Washed suspensions of Tetrahymena pyriformis GL have an intrinsic fluorescence with an excitation maximum at 291 nm and an emission peaking at 358 nm. These wavelengths are characteristic for protein fluorescence. When suitable optical filters are used to eliminate scattered light, a sharp increase in the fluorescence.is seen on heating the suspensions. The increase in fluorescence at 32°C and peaks at 36°C, with a mid-point at 34°C. The fluorescence-temperature profile does not change during the cell cycle.