title: Induction of programmed cell death in Arabidopsis and rice by single-wall carbon nanotubes.
abstract: OBJECTIVE
  Single-walled carbon nanotubes (SWCNTs) have many unique structural and mechanical properties. Their potential applications, especially in biomedical engineering and medical chemistry, have been increasing in recent years, but the toxicological impact of nanoparticles has rarely been studied in plants. •
  
  
  METHODS
  We exposed Arabidopsis and rice leaf protoplasts to SWCNTs and examined cell viability, DNA damage, reactive oxygen species generation, and related gene expression. We also tested the effects of nanoparticles on Arabidopsis leaves after injecting a SWCNT solution. EM-TUNEL (electron-microscopic terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling) and a cerium chloride staining method were used. •
  
  
  RESULTS
  SWCNTs caused adverse cellular responses including cell aggregation, chromatin condensation along with a TUNEL-positive reaction, plasma membrane deposition, and H(2)O(2) accumulation. The effect of SWCNTs on the survival of cells was dose dependent, with 25 μg/mL inducing 25% cell death in 6 h. In contrast, activated carbon, which is not a nano-sized carbon particle, did not induce cell death even 24 h after treatments. The data indicated that the nano-size of the particle is a critical factor for toxicity. Moreover, endocytosis-like structures with cerium chloride deposits formed after SWCNT treatment, suggesting a possible pathway for nanoparticles to traverse the cell membrane. •
  
  
  CONCLUSIONS
  Consequently, SWCNTs have an adverse effect on protoplasts and leaves through oxidative stress, leading to a certain amount of programmed cell death. Although nanomaterials have great advantages in many respects, the benefits and side effects still need to be assessed carefully.
authors: State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510006, P.R. China.
authors: Cong-Xiang
authors: CX
authors: Shen
authors: Quan-Fang
authors: QF
authors: Zhang
authors: Jian
authors: J
authors: Li
authors: Fang-Cheng
authors: FC
authors: Bi
authors: Nan
authors: N
authors: Yao