Since these cells originate from dicentric
chromosomes in which the centromeres are pulled to the opposite poles (FENECH, 2000), there is a traction force during this process and the chromosome can suffer breakage in any point, which can form a chromosomal fragment that can be transformed into MN (VRAL et al.
During the progression of the cell cycle, these dicentric
chromosomes will be competitively pulled towards the opposite poles of the mitotic spindle (each centromere towards one pole), and their stretching will result in the formation of bridges during anaphase (the step that precedes cell division).
The "cat eye syndrome": Dicentric
small marker chromosome probably derived from a no.
Different configurations of dicentric
bridges and fragments at anaphase I and II are expected and depend on the types of crossovers within the inversion loop (Singh, 1993).
The kind of aberrations detected were acentric fragments, dicentric
chromosomes, rings, gaps and breaks.
In the 20-wk-old callus cells, nearly 10% of the diploid and tetraploid cells counted had structural changes with acrocentric, telocentric and/ or dicentric
chromosomes (unpublished data).
However, they took only dicentric
and ring chromosomes into account, which were not findings reported in our study.
a) Normal metaphase, (b) chromatid-type gap, (c) isochromatid gaps, (d) chromosome fragments, (e) chromosome with dicentrics
and the accompanying fragments, (f) Robertsonian translocation, (g) chromosome deletion, and (h) chromosomes with exchanged fragments.
The chromosomal aberrations (CAs) mainly observed were gaps, breakes, fragments and dicentrics
& Rings Deletions DONOR 400 cGy (5 + 400) cGy 400 cGy (5+400) cGy #1 136 92 52 51 #2 178 120 62 46 #3 79 50 39 15 #4 172 42 46 34 #5 134 106 58 41 Table 2.
Non-overlapping and well spread metaphase plates were selected for scoring chromosomal aberrations such as chromatid breaks, rings, chromatid exchanges, intrachromatid deletions, minutes, achromatic lesions, chromosome breaks, dicentrics
, triradials and RBI complexes.
Chromatid-type aberrations such as breaks and exchanges and chromosome-type aberrations such as deletions and dicentrics