Multiple specific chromosomal alterations in a rat ascitic histiocytoma 'AK-5'

In the rat ascitic histiocytoma, AK-5, chromosome numbers vary between 33 and 41 with a peak at 40 chromosomes. None of the metaphase spreads showed double minute chromosomes. The karyotype of this tumor was characterized by hypodiploid chromosome constitution. Giemsa banding analysis revealed 12 clonal marker chromosomes (M1-M12). Tentative identification of these markers were: M1 = ins(1q); M2 = t(5;?); M3 = t(8;10); M4 = t(8;?); M5 = t(10;X); M6 - t(15;?); M7 = t(5;6); M8 = del(13p); M9-M12 = unidentified. M3 being a large near metacentric chromosome serves as a characteristic marker for this tumor. All marker chromosomes except M2 and M4 were present in single copy per cell. In some metaphases M2 was present in 2 copies while M4 was present in 2 or 3 copies per cell. The total cell cycle duration of AK-5 cells was 15.5 h and the different phases, G1, S, G2 + M were estimated as 1.2, 12.2, and 2 h, respectively.