Isolation of the human chromosomal band Xq28 within somatic cell hybrids by fragile X site breakage

Journal Article · Tue May 01 04:00:00 EDT 1990 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.87.10.3856· OSTI ID:5324082

Warren, S T; Knight, S J.L.; Peters, J F; Stayton, C L; Consalez, G G; Zhang, F ^[1]

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1. Emory Univ. School of Medicine, Atlanta, GA (USA)

The chromosomal fragile-site mapping to Xq27.3 is associated with a frequent form of mental retardation and is prone to breakage after induced deoxyribonucleotide pool perturbation. The human hypoxanthine phosphoribosyltransferase (HPRT) and glucose-6-phosphate dehydrogenase (G6PD) genes flank the fragile X chromosome site and can be used to monitor integrity of the site in human-hamster somatic cell hybrids deficient in the rodent forms of these activities. After induction of the fragile X site, negative selection for HPRT and positive enrichment for G6PD resulted in 31 independent colonies of HPRT{sup {minus}}, G6PD{sup +} phenotype. Southern blot analysis demonstrated the loss of all tested markers proximal to the fragile X site with retention of all tested human Xq28 loci in a majority of the hybrids. In situ hybridization with a human-specific probe demonstrated the translocation of a small amount of human DNA to rodent chromosomes in these hybrids, suggesting chromosome breakage at the fragile X site and the subsequent translocation of Xq28. Southern blot hybridization of hybrid-cell DNA, resolved by pulsed-field gel electrophoresis, for human-specific repetitive sequences revealed abundant CpG-islands within Xq28, consistent with its known gene density. The electrophoretic banding patterns of human DNA among the hybrids were remarkably consistent, suggesting that fragile X site breakage is limited to a relatively small region in Xq27-28.

• OSTI ID: 5324082
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Journal Issue: 10 Vol. 87:10; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
CHROMOSOMAL ABERRATIONS
CHROMOSOMES
DISEASES
DNA HYBRIDIZATION
ENZYMES
ETIOLOGY
GENETIC MAPPING
GLYCOSYL TRANSFERASES
HAMSTERS
HEMIACETAL DEHYDROGENASES
HEREDITARY DISEASES
HETEROCHROMOSOMES
HUMAN X CHROMOSOME
HYBRIDIZATION
HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE
MAMMALS
MAPPING
MUTATIONS
OXIDOREDUCTASES
PENTOSYL TRANSFERASES
RODENTS
TRANSFERASES
VERTEBRATES
X CHROMOSOME