Banding patterns and late replication in HeLa cells.

Abstract

The modal chromosome number of the HeLa HEI was determined as 71. About 80% of these chromosomes are intact normal human chromosomes, judging from their banding patterns. Up to 18 marker chromosomes were found. The composition of several of them was elucidated. If the chromosome constitution of the HeLa is calculated including the analyzed markers, most chromosomes are present in 3 copies per cell. Chromosome No. 8 is present only in one copy per cell whereas there are usually 4 copies of chromosome No. 9. The late 3H-thymidine incorporation patterns of the apparently normal chromosomes of the HeLa cells are identical to those of normal cells. However, the incorporation rates of the secondary constrictions of chromosomes Nos. 1 and 9 are strikingly enhanced in contrast to normal blood cultures. Typical late replication patterns are also observed in the marker chromosomes. The replication patterns of identifiable normal segments of the markers are no different from the corresponding segments of normal chromosomes.