TY  - JOUR
A1  - Kirchner, S.
A1  - Stopper, Helga
A1  - Papp, T.
A1  - Eckert, I.
A1  - Yoo, H. J.
A1  - Vig, B. K.
A1  - Schiffmann, D.
T1  - Cytogenetic changes in primary, immortalized and malignant mammalian cells
N2  - Some chromosomes in transformed rat cells and somatic cell hybrids fail to display the presence of kinetochore proteins as detected by antikinetochore antibodies. Suchchromosomes (K- Chromosomes) may constitute a novel mechanism for the genesis of aneuploidy. Wehave analyzed primary~ immortalized and malignant marnmalian cells for the presence of kinetochore proteins and micronuclei. Our resuJts suggest a correlation of the K- chromosome and micronucleus frequency with the variability in chromosome number. Upon in situ hybridization with the minor satellite and alpha satellite sequences some Kchromosomes showed a signal. This indicates that the observed lack of kinetocbores is not necessarily due to a lack of centromeric DNA. We conclude that dislocated K- chromosomes may become incorporated into micronuclei which are prone to loss. Such events would be associated with the generation of aneuploidy.
KW  - Toxikologie
KW  - Micronuclei
KW  - Kinetochore
KW  - Chromosome distribution
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63439
ER  - 
TY  - JOUR
A1  - Stopper, Helga
A1  - Eckert, I.
A1  - Schiffmann, D.
A1  - Spencer, D. L.
A1  - Caspary, W. J.
T1  - Is micronucleus induction by aneugens an early event leading to mutagenesis?
N2  - This study was designed to investigate a previously unidentified potential mechanism for mutation induction as well as to clarify a biological comequence of micronucleus formation. We compared the induction of micronuclei with mutation inductioo as measured by trißuorothymidine (TFI') resistance in mouse L5178Y cells using four aneugens: colcemid, diethylstilbestrol, griseofulvin and vioblastine. AU four compounds induced micronuclei which appeared in the first cell cycle after treatment. More than 85% of the micronuclei induced by each compound stained positive for the presence of kinetochores implying that the micronuclei contained wbole cbromosomes. However, these same compounds were unable to induce TFf resistance under tbree different treatment regimes. We concluded that tbese compounds, under conditions where tbey induce primarily kinetochore positive micronuclel, were not able to induce mutations. Thus, the induction of micronuclei containing wbole chromosomes barborlog a select.able gene is not an early event leadlog to mutations in these cells.
KW  - Toxikologie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63390
ER  -