Fig. 9. Effect of temperature on synergy and cell sorting. Twenty-five per cent DH1 cells expressing red-shifted GFP under the control of the actin 15 promoter were mixed with 75% tsaca2 cells and allowed to develop to the slug stage at either 22°C (A and B) or 28°C (C and D). (A) and (C) are bright field images; (B) and (D) are fluorescence images of the structures shown in (A) and (C) to show the localization of the labelled DH1 cells. The black arrows in (A) and (C) point towards the tips of the slugs.