[FISH-analysis of regional replication in homologous chromosomes in hybrid cells obtained by fusion of embryonic stem cells with somatic cells].

The paper concerns FISH-analysis of regional replication of parental chromosomes 1, 3 and 6 in hybrid cells obtained by fusion between Mus musculus embryonic stem cells (ESC) and M. caroli splenocytes. The data demonstrated that parental chromosomes in the hybrid cells with near-diploid karyotype showed synchronous replication in 70-75% of tested cells that was comparable with diploid ESC and diploid fibroblasts. Synchronous replication of parental chromosomes in hybrid cells with near-triploid karyotype was observed in 46-57% of tested cells. However, it was correct in the case of hybrid cells with three copies of the tested chromosomes whereas the ratio of synchronous replication in triploid cells with two copies was comparable or similar to that in diploid cells. Hybrid cells with near-tetraploid karyotype showed high ratio of asynchronous replication (over 50%) comparable to those tetraploid ESC and tetraploid fibroblasts but significantly distinguished from diploid cells. Thus, most hybrid cells with two copies of tested parental chromosomes showed their synchronous replication. Unfortunately, the FISH-analysis is poor informative when it is used for studying cells with more than two copies of tested chromosomes.