Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/29/2008
Publication Date: 4/29/2008
Citation: Williams, B.A.P., Lee, R.C.H., Becnell, J.J., Weiss, L.M., Fast, N.M., Keeling, P.J. 2008. Genome sequence surveys of Brachiola algerae and Edhazardia aedis reveal microsporidia with low gene densities. BMC Genomics. 9:200. Interpretive Summary: Naturally occurring protozoan parasites (Microsporidia) of mosquitoes are under study to evaluate and develop these disease causing organisms as biological control agents. Microsporidian parasites are known to cause mortality in mosquitoes worldwide, but fundamental knowledge on the genomes of mosquito microsporidia is unknown. This genomic investigation conducts an analysis, for the first time, on the genomes of 2 microsporidia from mosquitoes, Brachiola algerae and Edhazardia aedis. The new information obtained here contributes to our basic understanding of the organization of the genomes of these parasites which will assist in the evaluation and development of microsporidia as biocontrol agents.
Technical Abstract: Microsporidia are well known models of extreme nuclear genome reduction and compaction. The smallest microsporidian genomes have received the most attention, but with a size range of 2.3 Mb to 19.5 Mb the nature of the larger genomes remains unknown. Here we have undertaken genome sequence surveys of two diverse microsporidia, Brachiola algerae and Edhazardia aedis. In both we find very large intergenic regions, an abundance of transposable elements, a low gene-density and no recognizable genes that are not also found in smaller genomes. Our results demonstrate that microsporidian genome architecture varies greatly between microsporidia with varying genome size. Much of the genome size difference can 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. Our data suggests that either compaction or decompaction has occurred more than once within the phylum.