Acid-soluble Ribonucleotides in Euglena gracilis Wild-type, and some Apoplastic Mutants

Summary The acid-soluble ribonucleotides of Euglem gracilis Z grown in photo organ otrophic cultures have been determined during four stages of growth, i.e. logarithmic phase (20, 48 h), and stationary phase (66, 96 h). The most marked increase in the contents of all the compounds occurred between 48–66 h. There was a predominance of purine nucleotides throughout culture growth. Adenine and uracil compounds showed a preponderance over those of guanine. Cytosine nucleotides and sugar-nucleotides could not be detected. In nucleotide profile NAD+ was measured with the highest content, UMP could be determined as the only uridine nucleotide. Uracil and adenosine could be detected only as nucleobase resp. nucleoside. — In all apoplastic Euglena mutants investigated free uracil was not detectable. The UMP content was different. — In the late stationary phase (144 h), the UMP content of Euglena gracilis Z is increased, whereas uracil was exhausted. The depletion of uracil could be produced experimentally by preservation of 48 h old cells in a nitrogen- carbon-free medium. By preincubation of stationary phase cells with uracil an accumulation of uracil could be measured.