An Analysis of the Uncoiling Effect of a BHT-Tween 80/Absolute Ethanol Mixture on Velban^R Arrested Human Metaphase Cells

Abstract

Phytohemagglutinin stimulated human small lymphocyte cultures exposed to a final milliliter media concentration of 50 and 100μg of butylated hydroxytoluene (BHT) dissolved in a 1:4 (v/v) solution of Tween 80/absolute ethanol, displayed an uncoiling of the chromatids in a percentage of Velban^R arrested metaphase cells. These uncoiled chromosomes revealed areas of condensed staining knots along the lengths of the chromatids, with the larger chromosomes displaying a much greater degree of uncoiling than those of the smaller groups. In chromosomes with severe uncoiling, the centromere region revealed two highly condensed areas on each chromatid, giving a characteristic box formation. In some of these chromosomes, the chromatids seemed to have two strands parallel to each other, with condensed areas lying side by side along each of these strands. A remarkable degree of consistency existed in the average number of knots seen on the chromosomes of each chromosome group karyotyped in the different cells examined, with each chromosome group having a characteristic average number of knots/chromosome. There was also a high degree of correlation between the number of knots counted on sister chromatids on one chromosome, and the number of knots seen in the chromatids of homologous chromosome.