ROLE OF VITAMIN-B12 IN REDUCTION OF RIBONUCLEOTIDES INTO DEOXYRIBONUCLEOTIDES IN DROSOPHILA CELLS GROWN INVITRO

Adenosine inhibited growth of D. melanogaster cells in culture. This toxic effect was prevented by the addition of uridine + deoxyuridine, or uridine + deoxycytidine. In the presence of vitamin B12, uridine alone was sufficient to sustain proliferation of Drosophila cells inhibited by adenosine. Vitamin B12 increased the incorporation of [3H]uridine into DNA, and decreased the incorporation of [3H]thymidine. No modification of the incorporation of [14C]adenine, [14C]adenosine or [3H]cytosine into DNA was found in the presence of vitamin B12. Vitamin B12 was involved in an enhanced conversion of uridine ribonucleotides into deoxyribonucleotides derived from uridine.