Rapid metaphase and interphase detection of radiation-induced chromosome aberrations in human lymphocytes by chromosomal suppression in situ hybridization

Chromosomal in situ suppression (CISS)-hybridization of
biotinylated phage DNA-library inserts from sorted human
chromosomes was used to decorate chromosomes 1 and 7 specifically
from pter to qter and to detect structural aberrations of these
chromosomes in irradiated human peripheral lymphocytes. In
addition, probe pUC1.77 was used to mark the Iq12 subregion in
normal and aberrant chromosomes 1. Low LET radiation (60Co--rays;
1.17 and 1.33 MeV) of lymphocyte cultures was performed with
various doses (D = 0, 2, 4, 8 Gy) 5 h after stimulation with
phytohaemagglutinin. Irradiated cells were cultivated for an
additional 67 h before Colcemid arrested metaphase spreads were
obtained. Aberrations of the specifically stained chromosomes, such
as deletions, dicentrics, and rings, were readily scored after in
situ hybridization with either the 1q12 specific probe or
DNA-library inserts. By the latter approach, translocations of the
specifically stained chromosomes could also be reliably assessed. A
linear increase of the percentage of specifically stained aberrant
chromosomes was observed when plotted as a function of the square
of the dose D. A particular advantage of this new approach is
provided by the possibility to delineate numerical and structural
chromosome aberrations directly in interphase nuclei. These results
indicate that cytogenetic monitoring of ionizing radiation may be
considerably facilitated by CISS-hybridization.