TRANSIENT ADENYLATE-CYCLASE ACTIVATION ACCOMPANIES DIFFERENTIATION OFTRYPANOSOMA-BRUCEI FROM BLOOD-STREAM TO PROCYCLIC FORMS

Pleomorphic bloodstream forms of Trypanosoma brucei differentiate sync hronously into procyclic forms when cultivated at 27-degrees-C in the presence of citrate/cis-aconitate [22]. The activity of adenylate cycl ase was monitored during this process. Two phases of transient stimula tion were observed. The first phase occurred 6-10 h after the triggeri ng of differentiation, a period which immediately follows the release of the bulk of the VSG and immediately precedes both the first cell di vision and the loss of the bloodstream-specific ESAG 4 transmembrane a denylate cyclase, The second phase occurred between 20 and 40 h, when the cells that emerged from the first division began to proliferate. T hese observations suggest that cAMP may be involved in differentiation /proliferation of the parasite.