In order to view my cells, Confocal laser scanning microscopy(CLSM) is used. The CLSM used is LSM 5 LIVE, the latest edition for imaging of living cells from ZEISS technology. CLSM uses laser to excite the fluorochromes, unlike fluorescence microscope(FM) which uses fluorescence light.
If you wanna know the principle of CLSM and FM, just give me a comment, as it is more like ‘physics’, afraid some of you might not understand.
One important precaution: sample preparations must be done in the dark, once exposed to light, the fluoresce intensity can greatly decrease, especially for FITC.
GREEN(FITC): polymer ( note: DNA is still bound to the polymer, but cannot be seen as it is not labeled)
The following pictures are a bit blurry because I magnify them 8-12 times from the original one.
1 hr after Transfection: on the cell membrane
Q: Why do the polymers 'stick' onto the membrane?
A: My polymers are cationic(+vely charged), and the cell membrane has proteoglycans(-vely charged), hence the ATTRACTION!
2.5 hr after Transfection: in the cytoplasm
Q: How does my polymer enters the cytoplasm?
A: Based on other science papers, it is known that polymer-DNA complexes enter the cells via endocytosis. However the actual mechanism(type of endocytosis) is still a BIG question, and no one knows.
4.5 hr after transfection: in the nucleus!!
Q: How can the polymers(size: 100-200nm) go into the nucleus, when nuclear pores only allow molecules of less than 10 nm to pass through?
A: This is also a another BIG question that many scientists are still finding. However based on latest papers, it is known that cationic polymers do interact with the anionic phospholipids on the cell membrane and eventually coat the polymer-DNA complexes. These coated complexes then fuse with the nulear envelope, and release the complexes.
Anyway, frankly, i hate 'Live' confocal studies, because it is very tedious, and u will spend the entire day on it, plus TIME is a GREAT factor. Also usually, there will be cells that do not show similiar pattern like others under the microcope, hence, I have to search and search. :(
But still, research is FUN! :))))
Nisha
TGo2
0503254E