UTILIZATION OF CARBOHYDRATES BY THE MOSQUITO FLAGELLATE, CRITHIDIA FASCICULATA

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Abstract
The trypanosomid flagellate, Crithidia fasciculata, has been shown to have, in the absence of exogenous substrate, a long-sustained oxygen consumption (R.Q. 0.85) accompanied by the production of ammonia. Ribose, xylose, fructose, glucose, galactose, mannose, maltose, cellobiose, sucrose, raffinose, glycerol, and dihydroxyacetone abolish this oxygen consumption while increasing the rate of respiration up to fivefold. Glucose is incompletely oxidized (R.Q. 1.06) with the consumption of 2.6 moles of oxygen and production of 0.6 moles succinate and 0.4 moles ethanol and traces of pyruvate per mole of glucose consumed. Ethanol and a variety of other alcohols can be metabolized when presented as the only exogenous substrate. These results are discussed with respect to the metabolic activities of other members of the family Trypanosomatidae and to the hypothesis that the end products accumulate as a result of limiting amounts, rather than complete absence, of certain enzymes.