New structures in complex formation between DNA and cationic liposomes visualized by freeze-fracture electron microscopy.
Structures formed during interaction of cationic liposomes and plasmid DNA were studied by freeze-fracture electron microscopy and their morphology was found to be dependent on incubation time and DNA concentration. These structures were formed with liposomes composed of DC-Chol and DOPE after 30 min incubation at DNA:lipid concentrations encompassing maximal transfection activity. They resembled liposome complexes (meatballs) and additionally bilayer-covered DNA tubules (spaghetti), whereby the DNA-tubules were found to be connected to the liposome complexes as well as occurring free in the suspension. At later times and higher DNA-to-liposome ratios the complexes grow larger while their membranes become discontinuous, allowing the self-encapsulation of the DNA. The relative transfection potency of the various morphologically distinct structures is discussed.
Sternberg
B
B
Institute of Ultrastructure Research, Medical School, Friedrich-Schiller-University Jena, Germany.
Sorgi
F L
FL
Huang
L
L
D001358:Avian Sarcoma Viruses / Q000235:genetics; D002412:Cations; D002784:Cholesterol; D004247:DNA / Q000648:ultrastructure*; D005614:Freeze Fracturing / Q000379:methods; D008081:Liposomes; D008156:Luciferases / Q000235:genetics; D008854:Microscopy, Electron / Q000379:methods; D008961:Models, Structural; D010714:Phosphatidylethanolamines; D010957:Plasmids / Q000648:ultrastructure*; D011401:Promoter Regions, Genetic
D002412:Cations; D008081:Liposomes; D010714:Phosphatidylethanolamines; C020888:1,2-dielaidoylphosphatidylethanolamine; D004247:DNA; D002784:Cholesterol; D008156:Luciferases