Metabolism of nucleic acids during regeneration of wound tissue. III. The rate of formation of DNA.

The formation of regenerating wound tissue involves not only production of new cells but also synthesis of relatively large amounts of protein (l-5). From these facts, it may be inferred that while this new tissue is being formed, nucleic acid metabolism is probably different from that observed in normal animals. There has been some indication that this may be the situation for ribonucleic acid during limb regeneration in amphibia (6). The problem of the formation and metabolism of both types of nucleic acid during regeneration of liver has been investigated extensively (7-13). As the liver is a more versatile and active tissue than the skin, in the metabolic sense, it might be expected that the metabolism of nucleic acids in regenerating skin tissue should be on a different level from that in regenerating liver. As yet, no basis for comparison exists, inasmuch as there appears to be no literature even on the nucleic acid content of such regenerating tissue. However, there are several reports indicating that specific nucleotides affect the formation of regenerating wound tissue (14-18). The earliest work on nucleic acids was in connection with exudates from regenerating wound tissue (19). More recent work on such exudates still does not definitely establish whether the nucleic acids originate in the damaged cells, extraneous body tissue, leukocytes, or by synthesis in cells of the regenerating tissue (20-22). The demonstration of great changes in the protein metabolism of injured animals as compared to normal animals (1, 2, 23, 24) points to the possibility that there also may be some change in the nucleic acid metabolism of the wounded animals. It seems quite probable that some further clue to the metabolism of the nucleic acids may be obtained from consideration of the nucleotide content of the regenerating tissue. The present report considers the metabolism of nucleic acids in regenerating wound tissue and in the nonregenerating tissues of wounded animals.