Genome sequence surveys of Brachiola algerae and Edhazardia aedis reveal microsporidia with low gene densities.
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.
Williams
Bryony A P
BA
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
Lee
Renny C H
RC
Becnel
James J
JJ
Weiss
Louis M
LM
Fast
Naomi M
NM
Keeling
Patrick J
PJ
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*
D004251:DNA Transposable Elements