The frequency of spontaneous transformation, defined as the acquisition of the ability to form colonies in soft agar (anchorage independence) was compared in rat fibroblasts of recently established lines possessing pseudodiploid to pseudotetraploid numbers of chromosomes. Transformation frequency appeared to be independent on the ploidy level. The effect of colcemid on the transformation frequency of pseudodiploid fibroblasts was also examined. Colcemid treatment resulted in an increased frequency of transformation. In addition, most of the transformed clones, either derived from colcemid-treated cells, or derived from untreated cells, were characterized by significant changes in chromosome number. These results cannot be easily reconciled with the hypothesis that the main cause of spontaneous transformation is the appearance of recessive mutations. They rather support the idea that this conversion is the consequence of alterations in the number of certain chromosomes.
ASJC Scopus subject areas
- Cell Biology