The midpoint potentials of the mitochondrial respiratory chain cytochromes of the protozoan Crithidia fasciculata at pH 7.2, Em7.2, show great similarity to those measured in higher organisms. Values of Em7.2 for cytochromes a and a3 are +165 and +340 mV. Both c cytochromes have Em7.2 = +230 mV. There are two b cytochromes with the same spectral characteristics with Em7.2 = -20 and -135 mV. The...

Kinetoplast DNA, the mitochondrial DNA of trypanosomatids, is a remarkable DNA structure that contains, in the species Crithidia fasciculata, 5000 topologically linked duplex DNA minicircles. Their replication initiates at two conserved sequences, a dodecamer, known as the universal minicircle sequence (UMS), and a hexamer, which are located at the replication origins of the minicircle L and H ...

GDP-D-arabinopyranose (GDP-D-Ara) is the precursor of the uncommon D-arabinopyranose residues present in the glycoconjugates of a few trypanosomatid parasites. Biosynthetic labelling experiments with Crithidia fasciculata showed that GDP-D-Ara could be labelled with [3H]D-Ara, [2-3H]D-Glc and [6-3H]D-Glc, but not with [1-3H]D-Glc, suggesting that D-Ara can be either taken up directly by the par...

The conditions for luxuriant axenic cultivation of the trypanosomid flagellate Crithidia fasciculata in chemically-defined media were determined. Improvements over the hitherto published media include higher concentrations of amino acids, folic acid (where this is the sole source of pteridine) and purines and the inclusion of threonine and Tween 80. Increased oxygenation was obtained by incubat...