SOME OBSERVATIONS ON THE INCORPORATION OF PRECURSORS INTO RIBONUCLEIC ACID OF RAT BRAIN

IN COMMON with other organs, brain utilises precursors such as [14C]formate (MANELL and ROSSITER, 1955), [14C]adenine and [14C]orotic acid (KOENIG, 1958) and [14C]glycine (HENDERSON and LEPAGE, 1959) for the synthesis of acid-soluble nucleotides and RNA. More recently, during an investigation into the effects of 6-azauridine on pyrimidine metabolism in the central nervous system, WELLS, GAINES and KOENIG (1963) suggested that the orotic acid pathway provided a significant portion of the pyrimidine nucleotides in the neuraxis of the cat. They also suggested that the maintenance of the RNA concentration in azauridine-treated brain indicated that preformed pyrimidines derived from the blood stream may supplement the in situ biogenesis of pyrimidines under certain conditions. So far, however, there appears to have been little direct study of the relative efficiencies of the de nouo and the preformed base pathways for the production of brain RNA or of possible effects of the blood-brain barrier on the availability of such precursors. This paper represents an effort to answer some of the questions as a preliminary to studies on the metabolic effects of the incorporation of abnormal bases into cerebral nucleic acid.

[1]  J. Watts.  Turnover of nucleic acids in a multiplying animal cell. 2. Retention studies. , 1964, The Biochemical journal.

[2]  P. Mandel,et al.  DISTRIBUTION AND METABOLISM OF RIBONUCLEIC ACID IN THE VERTEBRATE CENTRAL NERVOUS SYSTEM , 1964 .

[3]  H. Koenig,et al.  STUDIES OF PYRIMIDINE NUCLEOTIDE METABOLISM IN THE CENTRAL NERVOUS SYSTEM—I , 1963, Journal of neurochemistry.

[4]  Mandel Hg,et al.  The depression of the incorporation of sulfur amino acids into Bacillus cereus by 8-Azaguanine. , 1960 .

[5]  Henderson Jf,et al.  Purine biosynthesis de novo in mouse tissues and a mouse tumor. , 1959 .

[6]  H. Koenig.  Uptake of Adenine-8-C14 and Orotic-6-C14 Acid into Nuclear DNA of Non-Dividing Cells in the Adult Feline Neuraxis , 1958, The Journal of biophysical and biochemical cytology.

[7]  G. Lepage,et al.  Purine biosynthesis and inhibitors in ascites cell tumors. , 1956, Cancer research.

[8]  Canellakis Es.  Pyrimidine metabolism. I. Enzymatic pathways of uracil and thymine degradation. , 1956 .

[9]  G. Lepage,et al.  STUDIES OF NUCLEIC ACID SYNTHESIS IN ASCITES TUMOR CELLS , 1955, Annals of the New York Academy of Sciences.

[10]  R. Rossiter,et al.  [14C] Formate labelling of bases of nucleic acids in respiring slices of rat tissues. , 1955, The Biochemical journal.

[11]  V. Potter,et al.  Nucleotide metabolism. II. Chromatographic separation of acid-soluble nucleotides. , 1954, The Journal of biological chemistry.

[12]  V. Potter,et al.  Nucleotide metabolism. I. The conversion of orotic acid-6-C14 to uridine nucleotides. , 1954, The Journal of biological chemistry.

[13]  C. Heidelberger,et al.  Intracellular distribution of radioactivity in nucleic acid nucleotides and proteins following simultaneous administration of P32 and glycine-2-C14. , 1953, Cancer research.