If you then consider that these Nardonella strains co-evolved with their present weevil hosts, that is, 'survived' the speciation of the latter from their common ancestor, it is mind-blowing how stable these genomes are over millions of years of constant 'editing' despite ongoing genome reduction.įigure 2.1. This high degree of synteny makes it intuitively clear that the four Nardonellas are isolates ‒ or if you wish: strains ‒ of one single bacterial species irrespective of how you prefer to define a 'bacterial species' (see our post on ' bacterial species'). Figure 2.1 shows that today the four genomes are still almost completely syntenic, that is, have much the same gene order that is only interrupted by very few indels (=insertions/deletions), inversions and transpositions (see legend to Fig. A similar process of losing more than 90% of the genome of an enterobacterial ancestor was ‒ and probably still is ‒ underway in Nardonella. Earlier, Moran and Mira had partially reconstructed the ~4 Mb genome of a hypothetical enterobacterial ancestor of the small Buchnera genomes (0.45‒0.65 Mb) by what could be aptly called ' in silico molecular archaeology'. As said in part 1, the genomes are tiny (0.2‒0.23 Mb) and contain ~200 open reading frames. paper (Figure 1.2 in part 1, or here), is so stuffed with information about the weevils' Nardonella endosymbiont genomes that I better tear it apart a little to show you that it is actually possible to observe genome reduction 'at work'. Yet, do not take this as peer-reviewed scientific work, it's just a finger exercise.įigure 2 in the Anbutsu et al. Here now I give you a summary of what I read. When I was drafting part 1 of the weevil–Nardonella story, the symbiosis aspect, I could hardly wait to take a deeper look at the endosymbiont genomes, literally 'reading' the annotated genomes.
0 kommentar(er)
