title: Genome sequence surveys of Brachiola algerae and Edhazardia aedis reveal microsporidia with low gene densities.
abstract: BACKGROUND
  Microsporidia are well known models of extreme nuclear genome reduction and compaction. The smallest microsporidian genomes have received the most attention, but genomes of different species range in size from 2.3 Mb to 19.5 Mb and the nature of the larger genomes remains unknown.
  
  
  RESULTS
  Here we have undertaken genome sequence surveys of two diverse microsporidia, Brachiola algerae and Edhazardia aedis. In both species we find very large intergenic regions, many transposable elements, and a low gene-density, all in contrast to the small, model microsporidian genomes. We also find no recognizable genes that are not also found in other surveyed or sequenced microsporidian genomes.
  
  
  CONCLUSIONS
  Our results demonstrate that microsporidian genome architecture varies greatly between microsporidia. Much of the genome size difference could be accounted for by non-coding material, such as intergenic spaces and retrotransposons, and this suggests that the forces dictating genome size may vary across the phylum.
authors.affiliation: Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada. B.A.P.Williams@exeter.ac.uk
authors.forename: Bryony A P
authors.initials: BA
authors.lastname: Williams
authors.forename: Renny C H
authors.initials: RC
authors.lastname: Lee
authors.forename: James J
authors.initials: JJ
authors.lastname: Becnel
authors.forename: Louis M
authors.initials: LM
authors.lastname: Weiss
authors.forename: Naomi M
authors.initials: NM
authors.lastname: Fast
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Keeling
mesh_terms: D000330:Aedes / Q000382:microbiology; D000818:Animals; D016817:Apansporoblastina / Q000235:genetics*; D004251:DNA Transposable Elements; D019143:Evolution, Molecular; D023061:Gene Order; D016681:Genome, Fungal; D016814:Microsporidia / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements