Summary
After incorporation of BrdU for one or more replication cycles, the fragile site at Xq27 [fra(X)] was induced by a late pulse with excess thymidine (dT), resulting in the simultaneous visualization of G bands and differentially stained sister chromatids. The degree of BrdU substitution (uni- vs bifilarly substituted DNA) did not affect the expression of the fra(X). Without addition of dT, expression was the same in M1, M2, and M3 cells. With the addition of dT, expression was reduced in M1 cells and increased in M2 and M3 cells. One way to explain this fact would be an increased repair of the fragile site in M1 cells by illegitimate G:BrdU pairing under dCTP-deficient conditions. A preferential depletion of M3 cells, and to a lesser extent also M2 cells, could suggest a synergistic toxic effect of BrdU substitution and dCTP depletion. With this technique, sister chromatid exchanges (SCEs) could be directly localized at band level, facilitating a more detailed study of SCEs at the Xq27 fragile site.
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References
Cantú ES, Jacobs PA (1984) Fragile (X) expression. Relationship to the cell cycle. Hum Genet 67:99–102
Chapelle A de la, Schröder J, Selander R-K, Stenstrand K (1973) Differences in DNA composition along mammalian metaphase chromosomes. Chromosoma 42:365–382
Couturier J, Dutrillaux B, Lejeune J (1973) Etude de fluorescences specifiques des bandes R et des bandes Q des chromosomes humains. C R Acad Sci Paris 276:339–342
Eichenbaum SZ, Krumins EJ (1983) A simple and reliable method of chromosome banding for prenatal cytogenetics using a bromodeoxyuridine pulse. Prenat Diagn 3:291–296
Fonatsch C (1981) A simple method to demonstrate the fragile X chromosome in fibroblasts. Hum Genet 59:186
Gibas Z, Becher R, Sandberg AA, Limon J, Bregula U, Rochowska M (1983) Unusual SCD in cancer cells: a phenomenon related to decreased BrdU incorporation? Cancer Genet Cytogenet 9: 387–389
Glover TW (1981) FUdR induction of the X chromosome fragile site: evidence for the mechanism of folic acid and thymidine inhibition. Am J Hum Genet 33:234–242
Glover TW, Stein CK (1987) Induction of sister chromatid exchanges in common fragile sites. Am J Hum Genet 41:882–890
Holmquist G, Gray M, Porter T, Jordan J (1982) Characterization of Giemsa dark- and light-band DNA. Cell 31:121–129
Hoo J, Parslow MI, Chambers D (1979) Combination of differential sister chromatid staining, G-banding pattern, and X-inactivation pattern. Hum Genet 47:291–295
Iannuzzi L, Di Berardino D, Ferrara L, Gustavsson I, Di Meo GP, Lioi MG (1985) Fluorescent G- and C-bands in mammalian chromosomes by using early BrdU incorporation simultaneous to methotrexate treatment. Hereditas 103:153–160
Jacobs PA, Glover TW, Mayer M, Fox P, Gerrard JW, Dunn HG, Herbst DS (1980) X-linked mental retardation: a study of 7 families. Am J Med Genet 7:471–489
Jennings M, Hall JG, Joehn H (1980) Significance of phenotypic and chromosomal abnormalities in X-linked mental retardation (Martin-Bell or Renpenning syndrome). Am J Med Genet 7: 417–432
Mattei MG, Mattei J-F, Vidal I, Giraud F (1981) Expression in lymphocyte and fibroblast culture of the fragile X chromosome: a new technical approach. Hum Genet 59:166–169
Miller RC, Aronson MM, Nichols WW (1976) Effects of treatment on differential staining of BrdU labeled metaphase chromosomes: three-way differentiation of M3 chromosomes. Chromosoma 55: 1–11
Perry P, Evans HJ (1975) Cytological detection of mutagen-carcinogen exposure by sister chromatid exchange. Nature 258:121–125
Perry P, Wolff S (1974) A new Giemsa method for the differential staining of sister chromatids. Nature 251:156–158
Sutherland GR (1979) Heritable fragile sites on human chromosomes. I. Factors affecting expression in lymphocyte culture. Am J Hum Genet 31:125–135
Sutherland GR, Baker E, Fratini A (1985) Excess thymidine induces folate sensitive fragile sites. Am J Med Genet 22:433–443
Tommerup N, Poulsen H, Brøndum-Nielsen K (1981) 5-Fluoro-2′-deoxyuridine induction of the fragile site on Xq28 associated with X-linked mental retardation. J Med Genet 18:374–376
Wenger SL, Hennessey JC, Steele MW (1987) Increased sister chromatid exchange frequency at Xq27 site in affected fragile X males. Am J Med Genet 26:909–914
Wulf HC (1976) Mechanical preparation of cells for chromosome studies. Chromosomes Today 5:439–443
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Tommerup, N. Induction of the fragile X on BrdU-substituted chromosomes with direct visualization of sister chromatid exchanges on banded chromosomes. Hum Genet 81, 377–381 (1989). https://doi.org/10.1007/BF00283696
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DOI: https://doi.org/10.1007/BF00283696