Pericentric characterization of human chromosome 7 in a melanoma cell line
- Universite de Montreal, Quebec (Canada); and others
Cytogenetic analyses of an established melanoma cell line show structural abnormalities involving mainly chromosome 7. Molecular cytogenetic examination of the different abnormalities (i(7q), i(7p), t(7;12)) was used to pinpoint the site of the break and to analyse the possible mechanisms by which isochromosomes 7 could be formed. Human chromosome 7 has been shown to contain two distinct alpha satellite arrays: D7Z1 and D7Z2 which are separated by 1Mb. We confirm the order to be short-arm- D7Z2 - D7Z1 - long arm. Both probes were then used to characterize two different types of isochromosomes 7 (one of the long arms and one of the short arms) and a translocation (7;12). Isochromosome 7q showed a single D7Z1 signal and loss of D7Z2. The unique centromeric structure of i(7q), with only the D7Z1 signal, suggests that a breakpoint occurred within D7Z1. Isochromosome 7p showed two distinct D7Z1 and D7Z2 hybridization signals. The distance observed between the two signals suggests that the breakpoint is in the proximal part of the long arms. This chromosome might be considered as a dicentric isochromosome 7p. Translocation (7;12) showed the two arrays of chromosome 7 {alpha} satellite DNA. The three derived chromosomes appeared to result from independent rearrangements. This observation shows that a variety of breaks may occur in the juxtacentromeric region of a given chromosome. It also shows that the functional centromere of chromosome 7 does not need the presence of D7Z2, since only D7Z1 was conserved in all cases, suggesting the importance of this sequence for the centromeric function.
- OSTI ID:
- 133494
- Report Number(s):
- CONF-941009--
- Journal Information:
- American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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