UV-induced growth inhibition in the trypanosomatid Crithidia fasciculata

The effects of short ultraviolet (253 mm) radiation on the growth of the trypanosomatid flagellate Crithidia fasciculada were studied in liquid medium and nutrient agar plates. Cell duplication was completely inhibited after exposure of the flagellates to doses equal to or higher than 50 J/m2. The UV-induced lag period was dose-dependent. Survival was reduced to 1% after exposure of the parasites to 200 J/m2. Ultrastructural changes after the lag period were studied by transmission electron microscopy. Changes of the kinetoplast network structure and sometimes of the mitochondrial matrix were observed. The existence of DNA repair mechanisms in this protozoan is discussed