BACKGROUND: Spliceosomal introns are a common feature of eukaryotic genomes. To approach a comprehensive understanding of intron evolution on Earth, studies should look beyond repeatedly studied groups such as animals, plants, and fungi. The slime mold @entity32118 belongs to a supergroup of eukaryotes not covered in previous studies. RESULTS: We found 441 precise intron losses in @entity4328 and 202 precise intron losses in @entity32118 . Consistent with these observations, @entity4328 was found to have significantly more copies of reverse transcriptase genes than @entity32118 . We also found that the lost introns are significantly further from the 5' end of genes than the conserved introns. Adjacent introns were prone to be lost simultaneously in @entity4328 . In both @entity32118 species, the exonic sequences flanking lost introns were found to have a significantly higher GC content than those flanking conserved introns. Together, these observations support a reverse-transcription model of intron loss in which intron losses were caused by gene conversion between genomic DNA and cDNA reverse transcribed from mature mRNA. We also identified two imprecise intron losses in @entity4328 that may have resulted from genomic deletions. Ninety-eight putative intron gains were also observed. Consistent with previous studies of other lineages, the source sequences were found in only a small number of cases, with only two instances of intron gain identified in @entity4328 . CONCLUSIONS: Although they diverged very early from animals and fungi, @entity32118 species have similar mechanisms of intron loss.

Evaluation of the mechanisms of intron loss and gain in the social amoebae XXXX .

@entity4328 :: ('44689', 'Species') :: ['Dictyostelium discoideum'] @entity32118 :: ('5786', 'Species') :: ['Dictyostelium purpureum', 'Dictyostelium']
@entity32118 :: (5786,Species) :: ['Dictyostelium']
