Splicing defects observed in the absence of MRG15. (A and B) Quantitative expressions of Prm1, Prm2, Tnp1, and Tnp2 were examined by quantitative RT-PCR in (A) testes and (B) spermatid fractions of 22-d-old WT (green) and MRG15 cKO (red) mice. Hprt was used as an internal control. (C) Validation of the size of the PCR products of Prm1, Prm2, Tnp1, and Tnp2 in 4-wk-old testes and spermatid fractions of F/− and cKO males by electrophoresis. (D) Detection of TNP2 protein in F/− and cKO spermatids. Whole-protein extracts of crude spermatid fractions of F/− and cKO were separated by electrophoresis and probed with anti-TNP2 antibody. Arrow and arrowhead indicate a predicted size of TNP2 and a larger size of intron retained TNP2, respectively. Histone H3 was performed as control. (E) Structure of Tnp2 gene. Tnp2 mRNA consists of two exons (391 and 158 bp) and one intron (171 bp). The ORF of Tnp2 is 354 bp. When the intron is retained in the Tnp2 mRNA, the predicted length is 525 bp.