Fig. 5. (A) Stem-loop binding activity of lysates of oocytes. Lysates from 10 metaphase II oocytes (lanes 2,3) or 228 GV-stage oocytes (lanes 4,5) were incubated with a radioactive stem-loop RNA and the complexes resolved by native gel electrophoresis. In lanes 3 and 5, the antibody to SLBP was added to the extract prior to electrophoresis. (B) Stem-loop binding activity of lysates of oocytes and 1-cell embryos. Lysates from 20 oocytes or embryos were incubated with a radiolabelled stem-loop RNA and resolved on native polyacrylamide gels. MII, metaphase II oocytes; G1, 1-cell embryos, 18 hours post-hCG; S, 1-cell embryos 24 hours post-hCG; G2, 1-cell embryos 28 hours post-hCG. Presence of the SLBP antibody in the binding reaction is indicated (+). (C) Immunoblot of samples used for stem-loop binding assay. Five oocyte- or embryo-equivalents were immunoblotted using the anti-SLBP antiserum. Stages correspond to those in Fig. 5B. (D) Stem-loop binding activity of blastocysts compared with metaphase II oocytes. Lysates from equal numbers of oocytes or blastocysts were incubated with a radiolabelled stem-loop RNA and resolved on native polyacrylamide gels. MII, metaphase II oocytes; EB, early blastocysts; LB, late blastocysts.