Complex sentence: Expression of PRR5, PRR7, and PRR9 peaks around midday, though each gene peaks at a slightly different time, and as a group these genes are one part of the three-part repressilator system that governs the biological clock in plants.
Split into simpler sentences: Expression of PRR5, PRR7, and PRR9 peaks around midday, though each gene peaks at a slightly different time. As a group, these genes are one part of the three-part repressilator system that governs the biological clock in plants.