Chromosome Patterns in the AKR Mouse: Spontaneous Leukemia, Ascites Transfers, and Tissue Culture Cell Lines23

Abstract

Chromosomes were analyzed from various tissues of 14 AKR mice with spontaneous leukemia. Only 4 mice showed an apparently normal pattern and a modal diploid number of 40 chromosomes. In the remaining animals abnormal markers were present or the modal chromosome number was 41. Ascites lines established from leukemic lymph nodes and thymus tissues or from a tissue culture line showed predominantly aneuploid cells with modes of 41, 42, and 43 chromosomes. One ascites line transformed to hypotetraploidy by the 40th transfer and has retained this mode ever since. Two or 3 types of marker chromosomes (metacentrics, trans-locations, and minute) have been noted in the different ascites lines and sometimes have persisted through 40 or more transfers. Tissue-cultured cell lines have been grown on 3 or 4 different media and have given rise to lines with various chromosome complements. Most tissue culture lines range from 39 to 42 chromosomes, and one line has retained a mode of 40 chromosomes for more than 130 subcultures. Other lines have transformed so that the modal chromosome number ranges from 70 to 80. The type of growth media used seems to influence the chromosome numbers in these tissue culture lines.