Expression pattern of the Fugu Epo gene. (A) RT-PCR analysis. The Fugu Epo cDNA (fEpo) was amplified by RT-PCR using primers complementary to exons 2 and 3. The kidney tissue used for RNA extraction includes the head and the tail kidney. Actin was amplified as an internal control for the quality of Fugu cDNA. (B) Northern blot analysis. Each lane contains about 20 μg (brain, heart, kidney, ovary) or 10 μg (liver) of Fugu total RNA. The Epo transcript in the brain (1.54 kb) is shorter than that in the heart and liver (1.73 kb). A larger transcript of 3.1 kb is also found in these tissues. The sequence of this transcript is not clear from the exon-intron structure of Epo predicted by us.