Non-linear dynamics of chromosome condensation induced by colcemid

Abstract

This study investigated the dynamical process of chromosome condensation after colcemid treatment. Two pairs of human chromosomes, #2 and #3, were highlighted for the accurate identification by fluorescence in situ hybridization (FISH). A computerized image analysis system was used to measure the lengths of the two pairs of chromosomes averaged over 50 metaphases of different cultures with colcemid (0.5 µg/mL) added either at 3 or 48 h of a total 72 h culture period. For determining whether the process of chromosome condensation was chaotic or random, the algorithm of Detrended Fluctuation Analysis (DFA) was used. In order to evaluate the power of the method, the data were shuffled and DFA was performed again. It was found that colcemid prolonged treatment induced a significantly greater chromosome condensation (p<0.05), and the dynamics of this process was determined by the DFA and showed to be chaotic, with scaling exponents with range values 0.5< α<1.0. When the data were shuffled, the scaling exponent αreduced around to 0.5, which was characteristic of random events. These findings reinforced the idea that colcemid could interfere in some manner with the structure of chromosomes and the dynamics of chromosome condensation was non-linear.