Principal component analysis (PCA) of expression profiles reveals distinct developmental patterns of a wild type and knockout model
The stages of development — time points 1, 2, and 3 — are separated and temporally ordered by the first principal component, or horizontal axis. This time dimension explains nearly half of all the variance in global expression profiles across the samples. The second principal component, or vertical axis, represents the difference between the knockout and wild type, accounting for approximately one fifth of the overall variance. The three replicates in each sample group cluster together, indicating good quality of both the biological samples and the measurement.