Extrachromosomal Circular DNA are composed of chromatin and replicate in the nucleus of the cell during cell division. Unlike typical chromosomes, they are composed of circular fragments of DNA, up to only a few million base pairs in size and contain no centromere or telomere. Extrachromosomal Circular DNA Extrachromosomal circular DNA (eccDNA) is circular DNA found in the nuclei of plant and animal cells, including human cells, in addition to chromosomal DNA. eccDNA can be from 200 up to 5 million base pairs in length. eccDNA has been found in the nuclei of human cancer cells and shown to carry many copies of
Host-Cell Reactivation damage is used as mutagen, the cell uses nucleotide excision repair NER pathway, that is activated by distortion in the DNA helix. The Host-Cell Reactivation Assay or HCR is a technique used to measure the DNA repair capacity of cell of a particular DNA alteration. In the HCR assay the ability of an intact cell to repair exogenous DNA is measured The host cell is transfected with a damaged plasmid containing a reporter gene, usually luciferase, which has been deactivated due to the damage. The ability of the cell to repair the damage in the plasmid, after it has been