Fig. 1

Nuclear shape change during mouse embryonic stem cell differentiation in culture. ES cells in culture were treated for 4 days with or without 1 μM retinoic acid (RA). a Confocal immunofluorescence microscopy was performed for immunostaining of lamin B to determine nuclear periphery and Gata4 to indicate differentiated cells, and counterstaining for DNA with DAPI. b The change in nuclear shape in the differentiation of ES cells into primitive endoderm is illustrated. The dimensions are indicated as mean values. Optical sectioning of the cells was performed and the z-stacks were analyzed using the Volocity 3D imaging software (Perkins Elmer) to determine nuclear dimensions. c Shape factors were calculated based on the average of 50 nuclei analyzed. The difference is statistically significant (P < 0.0001). Nuclear volume (d) and nuclear surface area (e) were calculated. The change in surface area is statistically significant (P < 0.0001). f mRNA levels of lamin A/C and emerin were determined in triplicate by qRT-PCR using GAPDH for normalization. The relative expression levels are presented as average and standard deviation with the expression in undifferentiated (−RA) ES cells defined as “1”