Redistribution of HP1α under heat shock conditions did not lead to decompaction of centromeric DNA. (A) Human MCF-7 cells, both untreated and heat shock-treated, were double immunostained with a human antibody against CENP-A (column 1) and a mouse monoclonal antibody against HP1α (column 2). Human and mouse primary antibodies were visualized by incubation with secondary antibodies conjugated to FITC and Alexa Fluor 555, respectively. Co-localization of CENP-A foci with HP1α is shown as yellow in the merged images (column 4). (B) Human MCF-7 cells, both untreated and heat shock-treated, were double immunostained with a human antibody against CENP-A (column 1) and a rabbit polyclonal antibody against histone H3 tri-methylated at lysine 9 (H3K9me3, column 2). Human and rabbit primary antibodies were visualized by incubation with secondary antibodies conjugated to FITC and Alexa Fluor 594, respectively. Co-localization of CENP-A foci with H3K9me3 is shown as yellow in the merged images (column 4). In (A and B) DNA was stained with DAPI fluorescent dye (column 3). Images were collected using a Zeiss LSM 510 META NLO multiphoton microscope. Only one representative section is shown in each case. Bar scale: 5 µm.