Figure 1.
Excision/incision of oxidative DNA substrates by human and rat cellular extracts. TC, testicular cells; SC, spermatocytes; RS, round spermatids; ES, elongating/elongated spermatids; HEP, primary hepatocytes; MNC, mononuclear blood cells. Rat or human samples are indicated with r or h, respectively. (A) Excision of 8-oxo-7,8-dihydroguanine (8-oxoG). Duplex oligonucleotides containing 8-oxoG:C (0.15 fmol), 10 µg extract and endonuclease IV (Nfo, 20 ng) were used in each reaction. The results are presented as mean cleaved substrate (%) ± SD of three to four independent extracts of each cell type (human testis extracts 8–10 and 13). (B) Excision of 5-hydroxycytosine (5-ohC). Duplex oligonucleotides containing 5-ohC:G (1 fmol) and 2 µg extracts were used. The results are presented as mean cleaved substrate (%) ± SD of three to four independent extracts of each cell type (human testis extracts 8–10 and 13). (C) Excision of thymine glycol (TG). Duplex oligonucleotides containing TG:A (10 fmol) and 5 µg extracts were used. The results are presented as mean cleaved substrate (%) ± SD of one to three independent extracts of each cell type (human testis extracts 1–3). (D) Release of 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FaPy) residues. The amount of [3H]FaPy substrate was 0.24 µg. Three independent extracts (25 µg) of each cell type (human testis extracts 8–10) were used and the results are expressed as mean released FaPy (fmol) ± SD.