Alternative splicing of MDH orthologs in the Saccharomycotina and A. fumigatus. (A) Splicing pattern is shown for each of the species analyzed, along with the species phylogeny as in Figure 1A. In addition, the black asterisks indicate a change of splicing pattern. Specifically, the ancestor likely used both intron retention and alternative 3′ splice sites. (*) Loss of alternative 3′ splice sites in L. starkeyi, loss of intron retention in Y. lipolytica, and the conversion of the peroxisomal gene into a pseudogene in O. polymorpha. (B) Intron retention and alternative 3′ splice sites in the A. fumigatus MDH gene. The light gray box indicates a reading frame that is different from the dark gray boxes. PTS indicates a peroxisomal targeting signal. (C) Intron retention (likely coupled with an intronic polyadenylation site) in the L. starkeyi MDH gene. (D) Alternative 3′ splice sites in the Y. lipolytica MDH gene. (E,F) Duplicated MDH genes in S. cerevisiae lack introns. In panels B–D, only the 3′ end of the gene is shown.
