Fig. 3. The 5'-UTR of XNIF contains a vegetal localization element. lacZ-tagged RNAs were injected into stage II-III albino oocytes and visualized by whole-mount in-situ hybridization after culturing in vitellogenin-enriched L15 medium. Vegetal localization was observed in oocytes injected with transcripts containing the 5'-UTR (A) and with fragments containing nucleotides 252-551 (C) and 252-381 (D), but not with the coding region or 3'-UTR (B). Scale bar: 500 µm. The section in (E) shows the wedge and cortical staining of a stage II oocyte that has been injected with a transcript containing the nucleotides 252-551 as shown in (C). (F) Schematic representation of the constructs used for XNIF localization element mapping experiments. 5'-UTR, ORF and 3'-UTR are represented by yellow, blue and red, respectively. Corresponding nucleotide positions of the XNIF cDNA are indicated. Capability of vegetal localization is marked with (+), absence of vegetal localization by (-). A weak and not always reproducible localizing activity was also observed for the fragment nt 1002-1308 and is marked by an asterisk.