Genomic nanos fragment in which the nanos 3'UTR has been replaced with the αTub84B 3'UTR. A fragment of the nanos 3'UTR containing the +1 and +2' localization elements (nucleotides 6-185) has been inserted into the αTub84B 3'UTR; a G to C mutation has been introduced into the first (A) CGUU motif within the nanos +2' element sequence