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Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells

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ABSTRACT

Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

No MeSH data available.


FCNTs located inside plant cells. a Prepared FCNT; b TEM image of FCNTs located inside the vacuole; c Fluorescent microscope image of FCNTS inside the vacuole; e TEM picture of FCNTs inside nucleus, d fluorescent microscope image of FCNTs inside nucleus.
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Figure 3: FCNTs located inside plant cells. a Prepared FCNT; b TEM image of FCNTs located inside the vacuole; c Fluorescent microscope image of FCNTS inside the vacuole; e TEM picture of FCNTs inside nucleus, d fluorescent microscope image of FCNTs inside nucleus.

Mentions: As shown in Figure 2a–d, a few SWCNTs attached to the surface of plant cell wall, a lot of SWCNTs penetrated cell wall to enter inside the plant cell. Figure 2a ① showed the SWCNTs located in mitochondria, Figure 2a ② showed the SWCNTs located in nucleus, the inset was the magnified picture that clearly showed the existences of SCWNTs, Figure 2a ③, c ⑦ and d ⑨ showed the SWCNTs inside the chloroplast, Figure 2a ④ showed the SWCNTs just got through cell wall, Figure 2b ⑤, and c ⑥ and d ⑧ showed the SWCNTs inside the vacuole. In order to confirm that SWCNTs could penetrate cell wall to enter into the inner of plant cell, we used FITC-labeled SWCNTs (FCNTs) to incubate with plant cells. Figure 3a showed the prepared FCNTs, Figure 3b, c showed the FCNTs inside the vacuole, Figure 3d, e clearly showed the FCNTs inside the nucleus. All these data mentioned above fully demonstrate that SWCNTs can enter into Arabidopsis mesophyll cells. It is the first to report that SWCNTs was confirmed to get through the Arabidopsis mesophyll cell wall, and enter into the inner organelles of the mesophyll cell. We also put the Arabidopsis mesophyll cells into different temperature solution such as 4, 25 and 40°C, and observed the fluorescent signal intensity, we did not observe the obvious changes of fluorescent intensity (data not shown), which highly suggest that SWCNTs likely get through plant cell wall and membrane by non-energy dependent endocytosis manner.


Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells
FCNTs located inside plant cells. a Prepared FCNT; b TEM image of FCNTs located inside the vacuole; c Fluorescent microscope image of FCNTS inside the vacuole; e TEM picture of FCNTs inside nucleus, d fluorescent microscope image of FCNTs inside nucleus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211858&req=5

Figure 3: FCNTs located inside plant cells. a Prepared FCNT; b TEM image of FCNTs located inside the vacuole; c Fluorescent microscope image of FCNTS inside the vacuole; e TEM picture of FCNTs inside nucleus, d fluorescent microscope image of FCNTs inside nucleus.
Mentions: As shown in Figure 2a–d, a few SWCNTs attached to the surface of plant cell wall, a lot of SWCNTs penetrated cell wall to enter inside the plant cell. Figure 2a ① showed the SWCNTs located in mitochondria, Figure 2a ② showed the SWCNTs located in nucleus, the inset was the magnified picture that clearly showed the existences of SCWNTs, Figure 2a ③, c ⑦ and d ⑨ showed the SWCNTs inside the chloroplast, Figure 2a ④ showed the SWCNTs just got through cell wall, Figure 2b ⑤, and c ⑥ and d ⑧ showed the SWCNTs inside the vacuole. In order to confirm that SWCNTs could penetrate cell wall to enter into the inner of plant cell, we used FITC-labeled SWCNTs (FCNTs) to incubate with plant cells. Figure 3a showed the prepared FCNTs, Figure 3b, c showed the FCNTs inside the vacuole, Figure 3d, e clearly showed the FCNTs inside the nucleus. All these data mentioned above fully demonstrate that SWCNTs can enter into Arabidopsis mesophyll cells. It is the first to report that SWCNTs was confirmed to get through the Arabidopsis mesophyll cell wall, and enter into the inner organelles of the mesophyll cell. We also put the Arabidopsis mesophyll cells into different temperature solution such as 4, 25 and 40°C, and observed the fluorescent signal intensity, we did not observe the obvious changes of fluorescent intensity (data not shown), which highly suggest that SWCNTs likely get through plant cell wall and membrane by non-energy dependent endocytosis manner.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

No MeSH data available.