FIZ1 is associated with photoreceptor gene promoters in photoreceptor neurons. Combined agarose gel images. A) Chromatin immunoprecipitation (ChIP) assays were performed using the anti-bFIZ1 antibody. Normal IgG and no chromatin (mock) samples served as negative controls, whereas input DNA (without IP) served as positive controls. ChIP DNA was analyzed using PCR amplicons corresponding to the proximal promoter regions of the indicated photoreceptor-specific genes (Sop, Mop, Rho, Pde6b and Rbp3) and a non-photoreceptor gene (Alb, liver gene). B) ChIP assays were performed using the anti-FIZ1-1 antibody, and retinas of the following mouse strains: Wild-type (C57BL/6J), and Rodless/Coneless (Rd1). ChIP DNA was analyzed by PCR for promoter regions of key photoreceptor-specific genes (Sop, Mop, Rho, Pde6b and Rbp3) and non-photoreceptor genes (mGluR6, bipolar cells).