Temperature effects in photodynamic processes

摘要

Photodynamic activity of several dyes on Drosophila melanogaster at different temperatures (15-35℃) inside of test-tubes was investigated. Both phototoxic sensitizers (chlorin e_6, methylene blue, etc. -group A) and non active compounds (hemoglobin, brilliant green, pyronine, etc.-group B) were used. Dyes of 10~(-5)-10~(-3) M concentration were added to the food for drosophila 24 hours before irradiation. Solar radiation, narrow -band halogen lamps, LEDs and laser were used as a photo-stimulator. Irradiation parameters: I≤ 45mW/cm~2 and 0.2 < t_(irr) < 1.5 h. Without using dyes in the control test-tubes at all doses of irradiation and temperatures applied percentage of survived insects was approximately 100%. In the darkness with the use of all dyes observations also indicated no damage to the insects. At the temperatures up to 25℃ when using dyes of group B the insects were not affected at all, while with the dyes of group A findings showed dose-dependent insect mortality. At high temperatures (30 -35℃) when using group B dyes the flies were losing their mobility and in the case of group A dyes the drosophila's survival value sharply dropped. Combination of dyes from A group with some dyes from B group leads to the partial disappearance of photodynamic effect. This, probably, is concerned with the toxic photoproduct suppression by the inactive dye. Experimental model of drosophila allows to investigate photosensitization impact within wide temperature range, to find out the processes, when using combination of dyes, as well as to study photodynamic effect on reproductive functions of insects.