Glucose-6-phosphate dehydrogenase activity in a hepatoma cell line: preliminary evidence for negative genetic control

A line of cells, positive for glucose-6-phosphate dehydrogenase activity, has been separated from a negative parental stock derived from the H4-II-E-3C rat hepatoma line. Cytogenetic analyses showed specific marker chromsomes of the parent line were present in the variant. On the other hand, cells of the variant line contained three chromosomes less, on the average, than the total present in parent cells. Karyotypic analyses indicated the diminution in chromosome numbers to be in the subacrocentric group. The appearance of glucose-6-phosphate dehydrogenase associated with loss of chromosomes suggests this enzyme is suppressed or under negative control in the parental stock. The consistent loss of chromosomes of the subacrocentric group suggests that the locus bearing regulatory activity is in this specific group.