Trypanosoma congolense: differentiation to metacyclic trypanosomes in culture depends on the concentration of glutamine or proline.

The effect of glutamine on the number of metacyclic trypanosomes produced in insect form cultures of Trypanosoma congolense TREU 1457 was investigated. When cultured in the absence of glutamine, trypanosomes did not develop to metacyclic forms. While metacyclics were produced in all cultures maintained with glutamine in the concentration range 2-20 mM, optimum numbers were obtained between 4 and 12 mM glutamine. This pattern was constant in flasks cultured for over two months. The substitution of glutamine by proline in culture medium did not influence the number of metacyclic forms produced. Removal of proline or glutamine from cultures producing metacyclics caused a rapid fall in production of metacyclic forms which could be reversed by re-introduction of either nutrient. Cultures of another stock of T. congolense responded similarly when maintained in different concentrations of glutamine, showing that the effect may be a general one.