Figure 4.

AP endonuclease in male germ cell extracts. (A) Incision of linear double-stranded oligonucleotide containing one THF residue calculated as percent cleaved substrate (mean ± SD). Three independent extract preparations (1 ng each) of each cell type were tested; human testicular extracts (donors 1–4). Nfo (5 ng) was used as a positive control. (B) Rat APEX (upper panel) and human HAP1 (lower panel) detected by western analysis. Purified HAP1 (20 ng) was used as positive control. Human testis biopsies are denoted with numbers and human MNCs with letters. Abbreviations are as described in the legend to Figure 1.