Sea urchin development, calmodulin changes during cell cycle

The interactions between calcium and calmodulin during the cell cycle in a developing sea urchin (Lytechinus pictus). Calcium increases throughout the cell just before mitosis, and at anaphase calcium activates calmodulin, causing it to migrate to the spindle. The false colour indicates the calmodulin activity: the TA calmodulin signal has been ratioed with the signal from the calcium-insensitive analogue FL calmodulin, ensuring that any changes in the signal are not due to accumulation of calmodulin in one area of the cell.