Detection of Silver Nanoparticles Internalization into Petunia, Petunia hybrida, Isolated Protoplasts

The use of nanoparticles has spannded many divisions of biological fields including sensors, drug delivery and clinical diagnosis. These functions all based on the most important action in cells called Endocytosis. The study of endocytosis in higher order plants remained inactive for a long period of time. In this work we use Silver Nano Particles (S.N.Ps) as a endocytosic substances were incubated by isolated protoplast of petunia .Concurrently, with the study of internalization, their appear aggregation inter and intracellular were investigated by Transmissions Electron Microscopy (TEM). Results and observations showed that the S.N.Ps crossed the cell membrane and internalized in to the cells. It can be assumed that the particles with the organic functionality – PEG coated – were internalized by the petunia protoplasts.

Regulation of Activator/Dissociation Transposition by Replication and DNA Methylation

In maize the transposable elements Activator/Dissociation (Ac/Ds) transpose shortly after replication from one of the two resulting chromatids (“chromatid selectivity”). A model has been suggested that explains this phenomenon as a consequence of different affinity for Ac transposase binding to holo-, hemi-, and unmethylated transposon ends. Here we demonstrate that in petunia cells a holomethylated Ds is unable to excise from a nonreplicating vector and that replication restores excision. A Ds element hemi-methylated on one DNA strand transposes in the absence of replication, whereas hemi-methylation of the complementary strand causes a >6.3-fold inhibition of Ds excision. Consistently in the active hemi-methylated state, the Ds ends have a high binding affinity for the transposase, whereas binding to inactive ends is strongly reduced. These results provide strong evidence for the above-mentioned model. Moreover, in the absence of DNA methylation, replication enhances Ds transposition in petunia protoplasts >8-fold and promotes formation of a predominant excision footprint. Accordingly, replication also has a methylation-independent regulatory effect on transposition.