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Analysis by FISH of the spectrum of chromosome aberrations induced by X‐rays in G 0 human lymphocytes and their fate through mitotic divisions in culture
Author(s) -
Hoffmann George R.,
Sayer Anne M.,
Joiner Eugene E.,
McFee Alfred F.,
Littlefield L. Gayle
Publication year - 1999
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/(sici)1098-2280(1999)33:2<94::aid-em2>3.0.co;2-e
Subject(s) - chromosomal translocation , chromatid , metaphase , biology , chromosome , mitosis , karyotype , microbiology and biotechnology , genetics , fluorescence in situ hybridization , aneuploidy , differential staining , cytogenetics , staining , gene
The induction, distribution, and persistence of chromosome aberrations in human lymphocytes exposed to X‐rays in G 0 were analyzed in 48‐, 70‐, and 94‐hr cultures by conventional metaphase analysis and painting of chromosomes 1, 2, and 4 by FISH. All cells that had been scored by FISH were relocated to determine by differential staining of chromatids whether they had passed through 1, 2, or ≥3 divisions. FISH revealed a dose‐dependent induction of stable and unstable aberrations, while chromatid labeling showed mitotic lag caused by irradiation in G 0 . Relative to their DNA contents, there was a small but significant overrepresentation of chromosome 4 and underrepresentation of chromosome 2 among the aberrations involving chromosomes 1, 2, and 4. FISH slightly underestimated the genomic frequency of unstable aberrations measured by conventional metaphase analysis. There was a slight excess of translocations relative to dicentrics, but the data are compatible with the 1:1 ratio expected from cytogenetic theory. Many of the translocations were apparently incomplete (i.e., nonreciprocal). Incomplete translocations were more frequent at higher X‐ray dose and in first division, suggesting that they may be associated with complex damage and are more apt to be lost in mitosis than complete translocations. Among the incomplete translocations, t(Ab) outnumbered t(Ba) — a difference ascribable to the FISH technique. Aberration frequencies declined as the cells divided in culture. The overall decline in the frequency of aberrant cells (≈29% per cell generation) reflects a rapid decline in dicentrics and fragments (≈60% per cell generation) and the relative stability of translocations. The frequency of translocation‐bearing cells underwent a modest decline in culture (≈13% per cell generation). Environ. Mol. Mutagen. 33:94–110, 1999 © 1999 Wiley‐Liss, Inc.