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. 2009 Apr 8;4(4):e5118. doi: 10.1371/journal.pone.0005118

Figure 6. Mitotic defects after HP1gamma reduction in human cells.

Figure 6

(A) HeLa cells transfected with siRNAs against the HP1 isoforms were grown on coverslips were incubated for 2 hours in colcemid and then in 60 mM KCl for 30 min, fixed and stained with DAPI (blue), anti- SMC2 condensin subunit (green) and anti-Aurora B (red). Representative examples of a normal metaphase cell (top row), and of the two types of abnormalities scored, labeled “1” and “2” (see text for details). Scale bar, 10 micrometers and 2 micrometers for the inset. The white arrowhead points to a chromosome that has lost the centromeric localization of Aurora B. (B) Cells treated as in A were fixed and stained with DAPI (blue) anti-alpha tubulin (red) and CREST serum (green). In a typical metaphase cell, chromosomes are at the spindle equator, forming a tight metaphase plate (top row). Deviations form this phenotype are: multipolar spindles (“3”, second row), pseudoanaphase (“4”, third row) or bipolar spindles in which a number of chromosomes (from one to five, asterisks) had not yet congressed to the metaphase plate (“5”, bottom row). Scale bar, 10 micrometers. (C) Quantitation of the different phenotypes among the mitotic cell population of control and HP1 knock down cells. More than 200 mitotic cells were scored in two or more independent experiments.