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Cytogenetic analysis of spontaneous and 2‐cyanoethylene oxide‐induced tk —/— mutants in TK6 human lymphoblastoid cultures
Author(s) -
Kodama Yoshiaki,
Boreiko Craig J.,
Skopek Thomas R.,
Recio Leslie
Publication year - 1989
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/em.2850140304
Subject(s) - mutant , biology , microbiology and biotechnology , genetics , locus (genetics) , lymphoblast , allele , marker chromosome , reversion , chromosome , cell culture , karyotype , phenotype , gene
Two phenotypic classes of selectable tk —/— mutants have been isolated from the TK6 human lymphoblast cell line; one has a normal growth rate ( tk n ) relative to the parental cell line; the other has a slow growth rate ( tk s ). Complete karyotypes of metaphase chromosomes were prepared and analyzed from 16 tk s mutants (eight spontaneous and eight 2‐cyanoethylene oxide [CNEtO]‐induced), two spontaneous tk n mutants, and the parental TK6 cell line. Southern blot analysis of these tk —/— mutants indicated that all had lost a 14.8 kb polymorphic band corresponding to the active tk allele. No chromosome abnormalities with respect to the parental cell line TK6 were observed in eight spontaneous tk s mutants. Chromosome abnormalities that may have been related to CNEtO treatment were observed in four of eight CNEtO mutants. However, chromosome 17, containing the tk locus in man, was cytologically normal with respect to the parental TK6 cell line in 15 of 16 tk s mutants. A visible abnormality of chromosome 17 was present in one CNEtO‐induced tk s mutant. The abnormality was a duplication of the long arm of the chromosome 17, with break points at q11 and q21. The latter break point is close to the site of the tk locus, suggesting that the aberration observed may be associated with tk —/— phenotype. These observations contrast with the relatively high incidence (>59%) of chromosome 11 abnormalities reported in tk s (small colony) mouse lymphoma L5178Y/TK + / — mutants.