Chromosomal evolution in the Ehrlich-Lettré complex of hyperdiploid mouse ascites tumors: Results from seven laboratory strains

Abstract

NIELS~N, K. 1976. Chromosomal evolution in the Ehrlich-Lettre complex of hyperdiploid mouse ascites tumors: Results from seven laboratory strains. -Heredim 84: 77-108. Lund, Sweden,The chromosomes of 7 strains of the hyperdiploid Ehrlich-Lettre mouse ascites tumor (ELD) were analyzed by conventional stainings and by Gand C-bandings. A tendency to slow decrease in chromosome number during a 20-year period was revealed in the 7 strains and in the ELD complex in general. A G-band idiogram of the normal mouse chromosomes was elaborated with numbering of regions and bands. By G-band analysis the following average composition of the ELD karyotypes was indicated: unchanged mouse chromosomes (30",), marA, marB, minutes ( I I " o ) , marl -marl2, telocentric markers ( IOU<), anonymous telocentric markers, often strongly rearranged (50%). Great differences were revealed among normal chromosomes and markers in their capacity to persist in the tumor stemline as structurally stable units. The presence of some unchanged chromosomes in most cells of all 7 strains indicated that they involved selective advantage. Evidently chromosomal evolution has operated by preferably maintaining certain elements unchanged and by submitting other elements to heavy rearrangement. The C-band analysis showed that, in addition to the centromeric C-heterochromatin present in all chromosomes, some had interstitial C-bands, as marA in all strains, mar5 and mar7 in specific single strains, and others in numbers varying among the strains.

Chromosome band patterns of near tetraploid Ehrlich-Lettré mouse ascites cells (ELT Bonn) in vivo and in vitro

“…-Among the other markers regularly identified in the present study, some regions showed good resemblance with regions of markers identified earlier (NIELSEN 1976~). Thus, the proximal part (bands qlI-q21) of mar2 of the ELT Bonn was apparently identical with region 1 of mar2 as described in the paper quoted.…”

“…The number of biarmed markers per total chromosome number showed a tremendous increase in comparison with the hyperdiploid Ehrlich-Lettre sublines, in which mostly only one or two biarmed chromosomes per cell are observed (NIELSEN 1976~). The number of the biarmed chromosomes of the present ascites cells varied between 5 and 12 per cell in vivo, and 7 and 12 in vitro.…”