Constitutively increased micronuclei are predominantly caused by acentric fragments.
The frequency of kinetochore (centromere)-positive micronuclei (MN) was determined in 32 fibroblast cell lines. We tested 16 probands with spontaneously high MN levels (greater than or equal to 20 MN/500 cells (4%] and 8 probands (controls) with low MN levels (less than or equal to 13 MN/500 cells (2.6%]. To study whether the elevation of MN levels is due to increased chromosomal breakage we used the antikinetochore antibody fluorescent staining method. Probands with spontaneously high MN had kinetochore-positive MN increased by a factor 2.1 compared to the controls whereas the kinetochore-negative MN were increased by a factor 6.14. This shows that spontaneous elevation of MN is mainly caused by increased chromosomal breakage and only in a minor proportion by chromosome segregation errors as a consequence of spindle defects.
Kratochvil
M
M
Department of Occupational Medicine, University of Hamburg, F.R.G.
Rümmelein
B
B
Reimers
U
U
Ehlert
U
U
Weichenthal
M
M
Mensing
H
H
Breitbart
E W
EW
Rüdiger
H W
HW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002460:Cell Line; D002869:Chromosome Aberrations; D005347:Fibroblasts / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D006801:Humans; D015162:Micronucleus Tests; D008875:Middle Aged; D008941:Spindle Apparatus