Fig. 4. The localization and concentration of utrophin in mdx^3cv spermatozoa. (A) Spermatozoa from wild-type and mdx^3cv strains were analyzed by indirect immunofluorescence and western blotting using DRP-1 anti-utrophin antibody. Utrophin immunostaining was exclusively observed in the postacrosomal region of wild-type whole spermatozoa (A1). In mdx^3cv spermatozoa, DRP-1 staining was localized in the whole head and flagellar middle piece (A2). (B) In protein extracts of sperm-isolated membranes from wild-type and mdx^3cv spermatozoa, only one protein band corresponding to Up71 was detected in both membrane protein extracts. Up71 was more concentrated in membranes from mdx^3cv spermatozoa (B2) than in membranes from wild-type spermatozoa (B1). A similar concentration of ß-actin was detected in membrane fractions from wild-type (C1) and mdx^3cv mice (C2). Bar, 6 µm.