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Genome reduction of the aphid endosymbiont Buchnera aphidicola in a recent evolutionary time scale

Authors :
Gómez-Valero, Laura
Silva, Francisco J.
Christophe Simon, Jean
Latorre, Amparo
Source :
Gene. Mar2007, Vol. 389 Issue 1, p87-95. 9p.
Publication Year :
2007

Abstract

Abstract: Genome reduction, a typical feature of symbiotic bacteria, was analyzed in the last stages of evolution of Buchnera aphidicola, the primary aphid endosymbiont, in two neutrally evolving regions: the pseudogene cmk and an intergenic region. These two regions were examined in endosymbionts from several lineages of their aphid host Rhopalosiphum padi, and different species of the same genus, whose divergence times ranged from 0.62 to 19.51 million years. Estimates of nucleotide substitution rates were between 4.3 and 6.7×10−9 substitution/site/year, with G or C nucleotides being substituted around four times more frequently than A or T. Two different types of indel events were detected, of which many were small (1–10 nt) but one was large (about 200 nucleotides).With respect to the large one and considering the proportion and size of the deletions and insertions, the reduction rate was 1.3×10−8 lost nucleotides/site/year. We propose a stepwise scenario for the last stages of evolution in B. aphidicola: together with a very slow and gradual degradation, considerable indels would punctually emerge. The only restriction to large deletion fixation is that the lost fragment does not contain essential genes. [Copyright &y& Elsevier]

Details

Language :
English
ISSN :
03781119
Volume :
389
Issue :
1
Database :
Academic Search Index
Journal :
Gene
Publication Type :
Academic Journal
Accession number :
23740824
Full Text :
https://doi.org/10.1016/j.gene.2006.10.001