SYNOPSIS. Crithidia deanei from the reduviid hemipteron, Zelus leucogrammus, unlike most lower trypanosomatids cultivated in defined medium, required only 2 amino acids, methionine and tyrosine; only 4 vitamins, folk acid, thiamine, biotin, and nicotinamide; and neither hemin nor a purine source. Electron microscopy reveals an endosymbiont, probably bacterial, which presumably provides the other basic trypanosomatid essential nutrients.
SYNOPSIS. Chloramphenicol cured Crithidia deanei of its endosymbiote. The derived aposymbiotic strain had additional growth requirements: purin (as adenine), heme, arginine, histidine, isoleucine, leucine, phenylalanine, threonine, tryptophan, valine, pyridoxine, riboflavin, and pantothenate and liver infusion (replaceable by high nicotinamide).
Purine nucleotide biosynthesis was studied in culture forms of Trypanosoma cruzi strain Y, Crithidia deanei (a reduviid trypanosomatid with an endosymbiote) and an aposymbiotic strain of C. deanei (obtained by curing C. deanei with chloramphenicol). Trypanosoma cruzi was found to synthesize purine nucleotides only fring incorporated into both adenine and guanine nucleotides. Similar results were obtained with guanine, indicating that this flagellate has a system for the interconversion of purine nucleotides. Crithidia deanei was able to synthesize purine and pyrimidine nucleotides from glycine ("de novo" pathway) and purine nucleotides from adenine and guanine ("salvage" pathway). Adenine was incorporated into both adenine and guanine nucleotides, while guanine was incorporated into guanine nucleotides only, indicating the presence of a metabolic block at the level of GMP reductase. The aposymbiotic C. deanei strain was unable to utilize glycine for the synthesis of purine nucleotides, although glycine was utilized for synthesizing pyrimidine nucleotides. These results suggest that the endosymbiote is implicated in the de novo purine nucleotide pathway of the C. deanei-endosymbiote complex. The incorporation of adenine and guanine by aposymbiotic C. deanei strain followed a pattern similar to that observed for C. deanei.
SYNOPSIS. Crithidia hutneri sp. n. and Crithidia luciliae thermophila s. sp. n. are described. Both flagellates can be grown in a defined medium over a temperature range of 15–37°C. The requirements for amino acids, vitamins, purine and hemin, and pH range were similar to those established for Crithidia fasciculata, although threonine was required as a growth factor for C. luciliae thermophila at high temperatures. Adenosine could be used by the 2 Crithidia as a purine source at 28 but not at 37 C.
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