Fig. 5.

Expansion of the sex loci to acquire the adjacent RNA helicase gene. (A) Alignment of the 3′ ends of sexM and sexP with the start of sequence similarity, just prior to the start codon of the RNA helicase genes. The stop codons are in gray boxes, and the start codons are in black boxes. *, the position corresponding to where the poly(A) tail is attached to the sexP transcript, determined on the basis of 3′ RACE. Lowercase nucleotides represent the first intron in the rnhA homologs. (B) Overlapping transcripts for sexM and rnhA genes. Ends were amplified by 5′ or 3′ RACE, cloned, and sequenced. The poly(A) tail sequences for the sexM transcripts have been removed for clarity in alignment. Four different transcripts for each gene are illustrated.