Fig. 3.

—Distribution of long introns across microsporidia. Presence of the Poly-A (blue) and S23 (red) long introns are indicated by predicted folding of the released intron. Absence of the structure indicates absence of the intron in the genome. The stem–loop structure in the internal conserved region is highlighted. Microsporidian relationships follow Pombert et al. (2015) with more recent modifications suggested by Luallen et al. (2016), Ndikumana et al. (2017), Mikhailov et al. (2017), and Quandt et al. (2017). Enterocytozoonidae/Vittaforma and Nematocida have no long introns and have been collapsed. Nematocida spp. and Edhazardia aedis do not have identified ORFs homologous to the Poly-A ORF of Encephalitozoon cuniculi. Enterocytozoonidae and Vittaforma have Poly-A ORFs without introns (supplementary fig. 3, Supplementary Material online).