Internucleosomal DNA fragmentation during deprived and non-deprived olfactory development

DNA fragmentation is a key marker of neuronal death during development, yet little is known about the size, pattern or quantities of fragments generated during normal and sensory-deprived development. Since there are few neurons dying at any particular time, it has not been possible to obtain sufficient quantities of material to make such a determination. By using a highly sensitive Taq polymerase-based technique, we revealed DNA fragments of 180 base pairs and multiples thereof both in bulbs and cortex of young rats (P4-P31). The bulbs subjected to olfactory deprivation at P1 had higher levels of internucleosomal DNA fragmentation at P16 than the contra-lateral, non-deprived bulbs. Interestingly, the DNA fragmentation induced by olfactory deprivation displayed a characteristic internucleosomal fragmentation pattern, suggesting that the cells induced to die may do so by apoptosis. A significant inverse correlation between DNA fragmentation and the natural variation in normal bulb size was found, suggesting that bulb size may be related to cell death. (C) 2002 Elsevier Science B.V. All rights reserved.