Karyological analysis of N-methyl-N'-nitro-N-nitrosoguanidine transformed Syrian hamster cell lines using high resolution G-banding technique

The karyotypes of two Syrian hamster cell lines transformed by N-methyl-N'-nitro-N-nitrosoguanidine have been analyzed using high resolution G-banding technique. The change of gene dosage appears to be the main feature of the chromosome aberrations. One of the cell lines (BHLB4) has been passaged in vitro for 68 times and has a pseudodiploid chromosome number of 44. The most common feature of aberrations of this cell line is monosomy of chromosome 15 and in addition trisomy of chromosome 8. The other cell line (HEC5) was newly transformed, having a modal chromosome number of 50. In spite of the occurrence of trisomy of some autosomes, monosomy of chromosome 15 was still evident. No obvious structural changes were found even in G-banded prophase chromosomes. Our observations support the previous report on the monosomy of chromosome 15, as the most common feature of virally- and chemically-transformed Syrian hamster cell lines.