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Stability of the "two active X" phenotype in triploid somatic cells
Cell
|November 1, 1979
Summary
Triploid cells with XXY karyotype show stable X chromosome expression, maintaining a consistent G6PD isozyme ratio. Even after cell fusion or SV40 transformation, this X chromosome phenotype remained stable.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- X chromosome inactivation is a key process in mammalian development.
- Understanding X chromosome stability is crucial for genetic research.
Purpose of the Study:
- To investigate the stability of the X chromosome phenotype in triploid cells.
- To determine the influence of autosomal complement on X chromosome expression.
- To analyze X chromosome activity in hybrid cells and SV40-transformed cells.
Main Methods:
- Analysis of glucose 6 phosphate dehydrogenase (G6PD) electrophoretic variants in triploid cells.
- Cell fusion experiments with human diploid fibroblasts.
- Creation of interspecific hybrids with mouse fibroblasts.
- SV40 transformation of triploid cells and subsequent analysis.
Main Results:
- Triploid XXY cells maintained a stable 1:2:1 ratio of G6PD isozymes (A:heteropolymer:B).
- Cell fusion and interspecific hybridization experiments confirmed X chromosome activity maintenance.
- SV40 transformation altered LDH patterns and chromosome number but not the G6PD phenotype.
- No derepression of the inactive X chromosome was observed in fusion experiments.
Conclusions:
- The X chromosome phenotype is stable in triploid cells under various experimental conditions.
- Autosomal complement does not appear to disrupt X chromosome expression stability.
- Segregation of chromosomes or autosomes may occur in hybrid cell lines.
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