Redistribution of DNA loop domains in human lymphocytes under blast transformation with interleukin 2.

At higher order levels chromatin fibers in interphase nuclei are organized into loop domains. Gene regulatory elements (promoters and enhancers) are often located near the sites of loop attachments. Therefore, loop domains play a key role in regulation of cell transcriptional activity. We investigated the kinetics of DNA loop exit during single cell gel electrophoresis (the comet assay) of nucleoids obtained from two cell types that differ in their synthetic activity ­ human lymphocytes and lymphoblasts. Lymphocyte activation and transformation into lymphoblasts (blast transformation) was performed with interleukin 2. The results obtained suggest that a rearrangement of the loops occurs after lymphocyte activation. After blast transformation we observed an increase of the amount of loop domains on the surface of nucleoids against a decrease of the inner loop fraction. Therefore, the comet assay can be used for detection of large-scale changes in the cell nucleus that follow changes in cell functional state.

C60 fullerene prevents genotoxic effects of doxorubicin in human lymphocytes in vitro.

The self-ordering of C60 fullerene, doxorubicin and their mixture precipitated from aqueous solutions was investigated using atomic-force microscopy. The results suggest the complexation between the two compounds. The genotoxicity of doxorubicin in complex with C60 fullerene (C 60+Dox) was evaluated in vitro with comet assay using human lymphocytes. The obtained results show that the C60 fullerene prevents the toxic effect of Dox in normal cells and, thus, C60+Dox complex might be proposed for biomedical application.