Figure 4
Comparing nuclei of different cell lines. (a) Example images from immunofluorescence staining against Lamin B with Hoechst staining for DNA in isolated IMR5, HEK293T, HeLa and MCF7 nuclei. Scale bar = 10 µm. (b) Diameter of the isolated nuclei determined from the immunofluorescence staining. 8.9 ± 0.2 (n = 33), 11.4 ± 0.4 µm (n = 18), 11.6 ± 0.4 µm (n = 20) and 15.6 ± 0.3 µm (n = 20), IMR5, HeLa, HEK293T and MCF7 respectively. Error bars are s.e.m. (c) The thickness of lamin B layer, estimated from the deconvoluted images. 0.99 ± 0.05 (n = 18), 0.62 ± 0.04 (n = 33), 0.85 ± 0.04 (n = 20) and 0.68 ± 0.02 (n = 20), IMR5, HeLa, HEK293T and MCF7 respectively. Error bars are s.e.m. (d) Western blot against lamin B in the nuclear extract from the cell lines used in the study. Samples were normalised to total protein content in the nuclear extract. (e) E* scales with the inverse of the nucleus size as shown by the fit (\({E}^{\ast }\equiv {r}^{\alpha }\) with \(\alpha =-2.21\) and −2.16 at 1 nN and 15 nN respectively). Nuclei appear always softer when subjected to smaller deformations. Individual responses can found in Supplementary Figure S1. The number of nuclei investigated per cell line is indicated in Table 1. (f) All nuclei show a slope α of the modulus vs. frequency response that only increased when probed at small deformations at high frequency. (g) All nuclei show a loss-tangent that only increased when probed at small deformations at high frequency.
