The Utilization of Nucleic Acid Derivatives by Neurospora

Abstract

The utilization of 34 nucleic acid derivatives and related compounds has been studied in Neurospora sitophila. All of the pyrimidines tested (cytosine, 5-methyl cytosine, thymine, uracil, orotic acid, barbituric acid, alloxan, thiouracil, and the pyrimidine moiety of thiamine) were very poor nitrogen sources for growth of this fungus. The purines adenine, guanine, hypoxanthine, xanthine and uric acid, as well as allantoin and urea were excellent nitrogen sources for N. sitophila. Growth was poor upon the methylated purines, caffeine and theophylline. N. sitophila utilizes certain of the purine and pyrimidine nucleosides and nucleotides (adenosine, adenylic acid, guanosine, guanylic acid, cytidine, cytidylic acid) for growth to a greater extent than is the case with the corresponding free bases. Comparable differences were not found between hypoxanthine and inosine, or between xanthine and xanthosine, all of which were excellent as sources of nitrogen for growth, nor among uracil, uridine and uridylic acid, which were poor nitrogen sources. Both ribonucleic acid and desoxyribonucleic acid are favorable nitrogen sources for growth of N. sitophila. N. sitophila is unable to utilize the purine antimetabolites benzimidazole or 2,6-diaminopurine as a source of nitrogen, while 8-azaguanine is a poor nitrogen source.