Beschreibung:
<jats:p>Monomorphic bloodstream forms of <jats:italic>Trypanosoma brucei</jats:italic>, grown in the mammal, are deficient in aconitase and 2‐oxoglutarate dehydrogenase and they do not respire in the presence of the substrates citrate, <jats:italic>cis</jats:italic>‐aconitate, succinate, proline or 2‐oxoglutarate. When grown <jats:italic>in vitro</jats:italic> low levels of aconitase, succinate oxidase and proline oxidase are detected.</jats:p><jats:p>Addition of citrate/<jats:italic>cis</jats:italic>‐aconitate at 37°C to bloodstream forms leads to the formation of aconitase and proline oxidase. Most cells undergo an ‘abortive’ transformation to non‐dividing procyclic‐like cells while some cells adapt to the presence of the citric acid cycle intermediates and continue to multiply as bloodstream forms.</jats:p><jats:p>At 27°C and in the presence of citrate/<jats:italic>cis</jats:italic>‐aconitate bloodstream forms transform synchronously to dividing procyclic cells. Within 72 h the rate of respiration with proline, succinate and 2‐oxoglutarate becomes similar to that in established procyclic cells while the rate of glucose oxidation decreases.</jats:p><jats:p>The possible role of citric acid cycle intermediates in determining whether a trypanosome will retain the properties of a bloodstream trypomastigote or differentiate to a procyclic trypomastigote is discussed.</jats:p>