Culture form and tsetse fly midgut form procyclic Trypanosoma brucei express common proteins.

Proteins expressed by culture form and tsetse fly midgut form procyclic trypanosomes were examined by polyacrylamide gel electrophoretic techniques. Analysis of the proteins of the two forms of procyclic organisms was performed by comparison of autoradiographs of high resolution two-dimensional polyacrylamide gels prepared using [35S]methionine-labelled parasites. Only eight spots were found to differ between autoradiographs of culture form and tsetse fly midgut form parasites. Seven of these differences were attributable to 35S-labelled non-trypanosomal proteins from the tsetse midgut. The other single spot difference was seen in one of two experiments and was present only in the autoradiograph of the material from trypanosome-infected tsetse fly midgut. Thus the cultivated procyclic organisms did not differ significantly from their tsetse-derived counterparts in protein composition and therefore their use as models for the natural stage is probably justified for most studies.