| Abstract |
Mouse m5S cells were subjected to soft X-ray irradiation. Twenty-four
transformants were separated as indicators of focus formation. Two clones,
cl.4103 and cl.6310, were chosen for the analysis of chromosome
alterations in transformants. A parent strain, m5S/1M, served as the
control. Anchorage independence (AG) was not detected in the control
strain, irrespective of culture conditions and population doubling number
(PDN). In the case of transformants, the frequency of AG was increased
with increasing PDN for cl.4103, and was constant for cl.6310,
irrespective of PDN. Karyotype of m5S/1M was 42, X, -Y, +der(6) t(6;13),
t(8;8), +8, +15. In addition, -13, der(10) and -der(6)t(6;13), der(5),
+mar occurred as karyotype alterations for cl.4103 and cl. 6310,
respectively. The present experiment indicated that chromosome alterations
secondary to primary alterations occur in a high frequency in the
transforming process of X-ray irradiated cells, and that the secondary
chromosome alterations result in selective proliferation of transformed
clones.
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