A rodent-human hybrid containing Xq24-qter translocated to a hamster chromosome expresses the Xq27 folate-sensitive fragile site.
A somatic cell hybrid containing a single human X chromosome bearing the Xq27 fragile site was lethally irradiated and re-hybridized to its HPRT- Chinese hamster parent. One of 24 colonies surviving selection for HPRT was found to have retained human G6PD but not PGK. This line, X3000-11, which shows Xq24-qter translocated to a hamster chromosome by trypsin G-banding and a single human chromatin fragment corresponding to this segment of the X by G-11 staining, expresses the fragile site on exposure to 5-fluorodeoxyuridine. Dot blots using total human DNA suggest that X3000-11 retains approximately 0.2% of the human genome. By Southern blotting, X3000-11 retains Factor IX, DXS11 and DXS42 but lacks DXYS1, DXS3 and DXS17. This hybrid is being used to construct a cosmid library in the vector pCOS2 from which a sub-library of 500-1000 clones of human origin will be isolated using in vivo recombination with cloned Alu and Kpn family repeats. Such a sub-library will greatly facilitate chromosome walking to the fragile site as well as the testing of individual clones for their ability to create a folate-sensitive fragile site by DNA transfer into permissive Chinese hamster recipient cells.
D000818:Animals; D006224:Cricetinae; D003412:Cricetulus; D003582:Cytogenetics; D004247:DNA / Q000032:analysis / Q000235:genetics; D005467:Floxuridine / Q000494:pharmacology; D005492:Folic Acid / Q000494:pharmacology; D005600:Fragile X Syndrome / Q000235:genetics*; D006801:Humans; D006822:Hybrid Cells / Q000648:ultrastructure*; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D014178:Translocation, Genetic; D014960:X Chromosome
D005467:Floxuridine; D004247:DNA; D005492:Folic Acid