The Composition of Nucleic Acids Prepared from Rat and Mouse Tumours

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【作者】 Judith A. Butler  E. W. Johns  Jack A. Lucy  P?ivo Simson 

【摘要】DEOXYRIBONUCLEIC acids have been prepared from a number of tumours of various types, using well-known methods which, when applied to calf thymus glands and other normal tissues, usually give a good quality of deoxyribonucleic acid (DNA), free from appreciable proportions of ribonucleic acid (RNA). It has been found that the tumour DNA's so far examined, as prepared by these methods, almost invariably contain appreciable quantities of uracil, a normal constituent of RNA, in the acid hydrolysates. The experiments reported below provide evidence that the uracil is actually a component of ribonucleic acid. If this is so, it would be possible to determine the proportion of RNA present in any given preparation if the ratios of the bases present in the RNA were known. This is not the case, but as an approximation, the ratio of RNA to DNA can be taken as equal to that of uracil to thymine, on the assumption that the proportion of uracil in RNA is the same as that of thymine in DNA.* Table I gives the analyses obtained for a number of these preparations, which can be compared with analyses ofnormal tissues shown in Table II. The proportion of RNA found in the tumour DNA's varies considerably even with one type of tumour. Studies were made of DNA isolated from a transplanted rat sarcoma (which had arisen in a granuloma produced by the repeated subcutaneous injection of xanthine) of different ages, but no clear trend was apparent in the analytical results (Table III). Variations of the preparative procedure were also tried (e.g. variation in number of washings of nucleoproteins, Tables I and III), but it was not found possible to obtain DNA free from RNA by continued washing of the nucleoproteins.

【刊名】British Journal of Cancer