Chromosome studies of the transplantable Shay chloroleukemia in rats.

Chromosomes obtained from tumors in male Long-Evans rats with transplantable Shay chloroleukemia were counted and analyzed with Giemsa staining and quinacrine fluorescence. Several consistent abnormalities were noted in the 43 cells in metaphase. An interstitial deletion of the distal portion of chromosome No 2 was noted in all cells. Trisomy for No 2 was found in 27 of 43 metaphases; the third No 2 had a terminal deletion, resulting in a chromosome shorter than the other deleted No 2. All cells were missing a No 11 chromosome. Most cells contained a large acrocentric chromosome that appeared to be a No 10 with a terminal addition (10q+). Several markers were also consistently noted. These chromosome abnormalities were compared to previous cytogenic analyses on the transplantable Shay chloroleukemia, in which new fluorescent banding techniques were not utilized. Since all the studies ultimately derived from the original Shay chloroleukemia, karyotypic differences and changes could be viewed over an extended period of time. This study corroborated previous reports on the specificity of involvement of chromosome No 2 in chemically induced tumors and supported the idea that chromosome No 2 may be important in oncogenesis in the rat and in the host response to different etiologic agents.