Involvement of L-DNase II in nuclear degeneration during chick retina development

During the development of the neural retina, 50 % of the neurons die physio logically by apoptosis. Tn the chick embryo, the apoptotic wave starts at E 8 and ends at E18, with a peak at E11. The onset of apoptosis is accompanie d by the activation of several degradative enzymes. Among these, the activa tion of the endonucleases leads to the degradation of tho genomic DNA of th e cell which is thought to he the final event in apoptosis. Here, we have i nvestigated the endonucleases activated during apoptosis associated with re tinal development. We have found that Ca2+-Mg2+-dependant endonucleases, as well as acid endonucleases are activated. The results obtained in vitro us ing purified nuclei from chicken retina indicate that the endonuclease acti vity resulting From the activation of L-DNase II, an acid DNase is responsi ble for most of the DNA degradation observed in these cells. (C) 2001 Acade mic Press.