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Genome sequence surveys of Brachiola algerae and Edhazardia aedis reveal microsporidia with low gene densities.

Williams BA, Lee RC, Becnel JJ, Weiss LM, Fast NM, Keeling PJ - BMC Genomics (2008)

Bottom Line: Microsporidia are well known models of extreme nuclear genome reduction and compaction.We also find no recognizable genes that are not also found in other surveyed or sequenced microsporidian genomes.Our results demonstrate that microsporidian genome architecture varies greatly between microsporidia.

View Article: PubMed Central - HTML - PubMed

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

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.

Conclusion: 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.

Show MeSH
Schematic consensus of microsporidian phylogenetic relationships. Microsporidian relationships from a consensus of published SSU phylogenies [28, 30, 40] and concatenated tubulin genes (unpublished data). Genome sizes are labeled and the reported presence of Gypsy/Ty transposons is indicated by (Ty).
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Figure 3: Schematic consensus of microsporidian phylogenetic relationships. Microsporidian relationships from a consensus of published SSU phylogenies [28, 30, 40] and concatenated tubulin genes (unpublished data). Genome sizes are labeled and the reported presence of Gypsy/Ty transposons is indicated by (Ty).

Mentions: Though the phylogenetic relationships of major microsporidian lineages are not well resolved, phylogenies of rRNA [28] and concatenated tubulin genes (unpublished data) suggest a relationship between B. algerae and A. locustae to the exclusion of E. aedis or E. cuniculi (Figure 3). This raises interesting questions about whether microsporidian genomes have compacted more than once during the diversification of the phylum, or if some have re-expanded from a compacted state.


Genome sequence surveys of Brachiola algerae and Edhazardia aedis reveal microsporidia with low gene densities.

Williams BA, Lee RC, Becnel JJ, Weiss LM, Fast NM, Keeling PJ - BMC Genomics (2008)

Schematic consensus of microsporidian phylogenetic relationships. Microsporidian relationships from a consensus of published SSU phylogenies [28, 30, 40] and concatenated tubulin genes (unpublished data). Genome sizes are labeled and the reported presence of Gypsy/Ty transposons is indicated by (Ty).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2387174&req=5

Figure 3: Schematic consensus of microsporidian phylogenetic relationships. Microsporidian relationships from a consensus of published SSU phylogenies [28, 30, 40] and concatenated tubulin genes (unpublished data). Genome sizes are labeled and the reported presence of Gypsy/Ty transposons is indicated by (Ty).
Mentions: Though the phylogenetic relationships of major microsporidian lineages are not well resolved, phylogenies of rRNA [28] and concatenated tubulin genes (unpublished data) suggest a relationship between B. algerae and A. locustae to the exclusion of E. aedis or E. cuniculi (Figure 3). This raises interesting questions about whether microsporidian genomes have compacted more than once during the diversification of the phylum, or if some have re-expanded from a compacted state.

Bottom Line: Microsporidia are well known models of extreme nuclear genome reduction and compaction.We also find no recognizable genes that are not also found in other surveyed or sequenced microsporidian genomes.Our results demonstrate that microsporidian genome architecture varies greatly between microsporidia.

View Article: PubMed Central - HTML - PubMed

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

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.

Conclusion: 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.

Show MeSH