Illumination of KR-expressing heart bleaches KR and causes cardiac edema.(A-B) KR expression in the 3dpf beating heart of SqKR15 was reduced to 21% after 5 min of exposure to intense green light. (A) Expression of GFP and KR in the ET33-mi3A:SqKR15 double transgenic embryo prior to illumination and (B) after illumination. (C-D) Larvae at 4 dpf, one day after illumination: C - ET33-mi3A (control), D - ET33-mi3A:SqKR15 (experimental sample). Cardiac edema developed in ET33-mi3A:SqKR15 larvae one day after illumination (D). Apoptosis in the heart of SqKR15 is similar to that in control.