Cumulative macromolecule penetration as a function of time following the administration of 0.55pmol/cell Triton-X100. (a) The time-course of AlexaFluor647 IgG accumulation in the cytoplasm and nucleus of live 1483 cells, averaged over 5 trials. Cells are permeabilized rapidly, with both the cytoplasm (◊) and nucleus (▪) achieving a mean fluorescence intensity equal to that of the extracellular space at approximately 5 minutes. Cells treated with IgG in the absence of Triton-X100 showed no significant uptake of fluorescence. All samples were normalized relative to the extracellular fluorescence. Error bars were removed for clarity; the error ranged from ± 0.01 to 0.10 AU for one standard deviation. (b) The mean fluorescence intensity of each cell compartment relative to that of the extracellular space one hour after Triton-X100 addition. (c) The time required for greater than 98% macromolecule accumulation in the cytoplasm (▪) and nucleus (○) of Triton-X100 treated cells. The time required for macromolecule uptake appears to be dependent on macromolecule size. No significant differences are observed between the cell compartments. The error bars represent 1 standard deviation.

Detection of intra-nuclear markers by immunofluorescence following Triton-X100 treatment. DIC and confocal fluorescence images of 1483 cells labeled with the PC563-hTERT antibody (red) and NCL-hTERT antibody (green) or IgG control antibodies (left panels). We observe enhanced availability of the PC563 target for labeling following treatment with 0.55 pmol/cell Triton-X100 in both fixed and live cells. In contrast, there is a slight decrease in the availability of the NCL target after treatment in live cells, possibly due to washing effects. No labeling is observed in live cells which are not treated with Triton-X100 or cells labeled with IgG antibodies.

Permeabilization of 1483 cell monolayers treated with different concentrations of Triton-X100, as measured by MTT reduction and 3kDa rhodamine-dextran uptake. Cells were treated with Triton-X100 for 10 minutes, incubated in media for 4 hours, and then assayed for cell viability and membrane integrity. The percentage of cells permeabilized (▲) appears to have a threshold concentration above which nearly all cells admit 3kDa rhodamine-dextran. Little to no dextran uptake occurs at lower Triton-X100 concentrations. The viability of cells after treatment (◊) is dependent on the amount of Triton-X100 used. The error bars represent 1 standard deviation.

Macromolecule penetration into the cytoplasm and nucleus as a function of Triton-X100 concentration. Subconfluent monolayers of 1483 cells were pre-treated with different concentrations of Triton-X100 for 10 minutes, and then probed with a 1:1:1 mixture of 3kDa rhodamine-dextran, 40kDa fluorescein-dextran, and AlexaFluor647 IgG. Macromolecule penetration of the cytoplasm appears to be independent of size, with no significant difference observed within each treatment group. Macromolecule penetration of the nucleus shows a stronger dependence on Triton-X100 concentration. Cells required a higher concentration of Triton-X100 permit nuclear entry of 40kDa and 150kDa molecules. At 1.10 pmol/cell, all macromolecules successfully penetrated both the cytoplasm and nucleus of treated cells. The error bars represent 1 standard deviation.

Cell recovery after treatment with Triton-X100. (a) Metabolic activity of 1483 cells 24 hours after treatment with different concentrations of Triton-X100, as measured by the MTT assay. A dose-dependent decrease in the metabolic activity (◊) was observed for each treatment group. When corrected for the number of cells remaining after treatment, changes in the mean metabolic activity per cell (▲) were only observed at Triton-X100 concentrations above 1.1 pmol/cell. (b) Cell proliferation after treatment with 0.55 pmol/cell Triton-X100. Approximately 80% of the cells remained after Triton-X100 treatment (○) compared to the PBS control (▪). Both cell populations continued to proliferate after treatment. (c) Recovery of membrane integrity in metabolically active cells. The percentage of cells with intact membranes (◆) increases progressively with time. Membrane recovery was mostly restored at 24 hours. (d) Confocal images of cells probed with MTT and fluorescent macromolecules 24 hours after treatment with 0.55 pmol/cell Triton-X100. Of the cells that show metabolic activity, less than 10% of cells exhibit permeability to 3kDA rhodamine-dextran (orange), 40kDa fluorescein-dextran (green), or 150kDa AlexaFluor 647 IgG (red). The arrows indicate cells which are permeable to macromolecules. The error bars represent 1 standard deviation.