Induction of stress proteins in the plant trypanosome Phytomonas characias

The present study of the synthesis of new proteins in plant trypanosomatids in the genus Phytomonas as a response to different types of stress demonstrates the production of a number of proteins that can be grouped into four families similar to those that appear in other organisms (heat-shock proteins). In the study of stress, Phytomonas cultures were subjected to changes in temperature from 22° to 37 °C, deprived of glucose, grown in the presence of sodium arsenite, and treated with calcium ionophore. In addition, the culture medium was changed from Grace's medium (330 mosmol/l) to a plant-culture medium with an osmolarity of 286 mosmol/l, implying the exertion of stress during the parasite's normal biological cycle of passage from the insect vector to the plant host. The treatment with actinomycin D demonstrated that some of the mRNAs that codify these proteins are found in normal presynthesized conditions. To measure the effect of temperature on the macromolecule biosynthesis we compared the incorporation of labeled analogues ([ 3 H]-thymidine, [ 3 H]-uridine, and [ 3 H]-leucine) by flagellates cultured at 22 °C with that by parasites cultivated at 37 °C.