A Histoautoradiographic Study of Deoxyribonucleic Acid Synthesis in Tissue Cultures of Chicken Embryo Liver Cells Infected with RPL-12 Lymphomatosis Virus

The growth of RPL-12 lymphomatosis virus in tissue cultures of chick embryo liver (1, 2) induces the appearance of large intranudear inclusions which exhibit a strongly positive Feulgen reaction (Fig. 1). After t reatment with DNase the Feulgen reaction in the inclusion is negative. Other cytochemical characteristics of these inclusions have been reported elsewhere (2). To study the localization and synthesis of D N A in these preparations histoautoradiographic experiments with thymidine-H 3 were carried out. Thymidine was the compound of choice for these studies because of its specific incorporation into D N A (3, 4) and because of the high resolution which can be obtained (5). I t is the purpose of this report to demonstrate: (a) that tritiated thymidine is incorporated in the intranuclear inclusions produced by the RPL-12 virus and (b) that the chromosoma D N A does not play any major role in the formation of the inclusions, confirming the fact that a large portion of the D N A of the inclusions is synthesized de novo under the influence of the virus.