Telomere length measurements by Q-FISH in different cell types used. Frequency distributions of telomere fluorescence in mTERC+/+ and mTERC-/- MEFs from Q-FISH studies on metaphases prepared from surviving cells following treatment with PARP inhibitor and arsenite. Average telomere fluorescence intensity was significantly lower (+p < 0.05) in untreated mTERC-/- as compared to untreated mTERC+/+ cells. Arsenite treatment led to significant decrease (*p < 0.05) in average mean telomere florescence intensity in both mTERC+/+ cells and mTERC-/- cell as compared to respective untreated controls. Changes in distribution of frequency of cells with shorter telomere fluorescence intensity observed following treatment with 3-AB and arsenite in both mTERC+/+ and mTERC-/- cells.