Developmentally regulated protein expression mediated by dimethylsulfoxidein Herpetomonas samuelpessoai

We have analyzed the total cell extract, cell surface, and secretory protei n profiles related to cellular differentiation triggered by dimethylsulfoxi de in the insect trypanosomatid Herpetomonas samuelpessoai. The flagellates were cultivated in chemically defined conditions in the absence or in the presence of 4% DMSO, and the resolved protein bands were detected by SDS-PA GE gels and avidin-Western blotting. The cell-associated proteins showed a complex pattern of around 40 silver staining bands ranging from 15 to 150 k Da. There were generally minor quantitative differences in the protein prof ile between the non-treated and the DMSO-treated cells. The cell-surface pr otein profile revealed by the incubation of live parasites with biotin show ed a decrease in the expression of the 120 kDa biotinylated polypeptide obs erved in the DMSO-treated cells when compared with untreated ones. However, control samples of both systems showed an endogenous biotinylated polypept ide of 63 kDa which also presented gelatinolytic activity. The trypanosomat ids released at least 10 polypeptides to the culture medium. A low molecula r mass exopolypeptide (35 kDa) was found exclusively in untreated cells, wh ereas a high-molecular-mass exopolypetide (250 kDa) was preferentially foun d in DMSO-treated cells.