brd2 paralogs are maternal transcripts with different patterns of expression in oocytes. Whole mount in situ hybridizations to RNA in zebrafish ovaries with DIG-labelled zf626 (A, C, E, G, I) and zf69 (B, D, F, H, J) cloned sequences. Cross sections through ovaries are shown in E-J. brd2 maternal RNAs are dispersed and abundant in stage I and II oocytes (A, E), and are sometimes found inside the germinal vesicle (gv), as in G (see small oocytes at far right). By stage III,brd2 transcripts accumulate around the outside of the germinal vesicle and rather unevenly around the periphery of the cortex just inside the vitelline envelope (C, E; G, arrowheads). brd2 RNAs then localize around the periphery of the cortex by late stage III, early stage IV (I, arrowheads). brd2 RNAs are also present in follicle cells of stage III/IV oocytes (C; G, I, arrowheads outside oocyte). Although brd2b maternal transcripts are also dispersed throughout stage I and II oocytes, and often found inside the germinal vesicle (B, F, H, J), in contrast to brd2, they become strictly localized to the region surrounding the micropyle (D, mp; H, J, arrowheads), the future animal pole, sometime during stage III, and are not expressed in follicle cells. A,B: 40X; C-F: 80X; G-J, 100X.
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