Nitric oxide induces cell death in Taxus cells

Sodium nitroprusside (SNP), a nitric oxide donor, or centrifugation at 150 times unit gravity, caused a nitric oxide burst in oocyte-derived Taxus bre6ifolia haploid cultures. This burst, visualized by the specific fluorescent probe 4,5-diaminofluorescein diacetate (DAF-2 DA), preceded a significant increase in nuclear DNA fragmentation and cell death. DNA fragmentation was detected in situ by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) of DNA 3%-OH groups. Nitric oxide formation and cell death were significantly decreased by NG-monomethyl-L-arginine (L-NMMA), a nitric oxide-syn-thase (NOS; EC 1.14.13.39) inhibitor. Our results show that nitric oxide leads to irreversible DNA fragmentation and cell deat