Genetic determination of fragile-site expression.
To explore genetic effects on the expression of chromosomal fragile sites in vitro, we studied the expression of common fragile sites (c-fra) in cultured lymphocytes of a human chimera (Chi46,XX/46,XY). Since the two cell lines in the chimera share the same environment in vitro and in vivo on cell culture preceding chromosome analysis, differences in the expression of c-fra must be due to genetic factors. The peripheral lymphocytes were cultured in medium 199 and in medium RPMI 1640 with and without aphidicolin. All lesions were localized after GTG-banding and mapped to the human idiogram. In the cultures with aphidicolin the XX cells showed, at high (0.4 microM) APC levels, a significantly higher expression of c-fra than did the XY cells. This difference between cell lineages was not confined to certain individual c-fra; rather it was seen for practically all of them. Therefore, we conclude that there are genetic factors which influence the propensity of c-fra to be expressed. Whether sex is one of these factors, or perhaps even the most important one, still has to be elucidated.
Smeets
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Department of Human Genetics, University of Nijmegen, The Netherlands.
Arets
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D016590:Aphidicolin; D002460:Cell Line; D002678:Chimera; D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D003470:Culture Media; D004224:Diterpenes / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D005819:Genetic Markers; D005838:Genotype; D006801:Humans; D008297:Male
D003470:Culture Media; D004224:Diterpenes; D005819:Genetic Markers; D016590:Aphidicolin