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+[[!meta title="Laboratory evolution of the bacterial genome structure through insertion sequence activation."]]
+[[!tag variants]]
+
+Kanai Y, Shibai A, Yokoi N, Tsuru S, Furusawa C.
+
+Nucleic Acids Res. 2025 May 10;53(9):gkaf331. doi:10.1093/nar/gkaf331
+
+Laboratory evolution of the bacterial genome structure through insertion sequence activation.
+
+[[!pmid 40347137 desc="“we developed an E. coli strain with high IS activity and demonstrated rapid IS-mediated genome evolution under relaxed selection in the laboratory, simulating the natural evolution of symbionts and pathogens. In just ten weeks, we observed numerous IS insertions, IS-mediated duplications, and deletions, contributing to at most −4.4% to 9.2% genome size changes (Fig. 4).” “We detected a total of 457 large-scale rearrangements, including 54 inversions, 363 deletions, and 40 duplications. [...] The median size of inversions was 84 kbp (range: 2.2 kbp–1.7 Mbp). All three inversions exceeding 1 Mbp were nearly symmetric to the ori-ter axis, consistent with observations of large inversions in nature. [...] Deletions ranged from 102 bp to 163 kbp (Fig. 3C), with the largest deletion being a deletion of a duplicated region. [...] Duplications had a median size of 40 kbp (range: 4830 bp–372 kbp). Surprisingly, the majority of the duplications resulted from transpositions of composite transposons with a copy of IS at each end (25/40), rather than tandem duplications. [...] The rearrangements led to genome size changes ranging from 174 kbp reduction to 369 kbp increase or −4.4% to 9.2%. However, overall, deletions were offset by the genome size increase from duplications and IS insertions, resulting in negligible changes in the median genome sizes”"]]

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@@ -23,6 +23,10 @@ vicinity.  [[Donelly and coll., 2010|biblio/20116045]] gave a radically lower
 time estimate of 13,600 to 108,400 years, but an ancient origin was again
 supported by [[Steinberg and coll in 2012|biblio/22751100]].
 
+[[Kanai and coll., 2025|biblio/40347137]] engeneered _E. coli_ strains for high
+transposon activity accumulated hundreds of rearrangements in 10 weeks,
+including 54 inversions (range: 2.2 kbp–1.7 Mbp).
+
 ### Between-species
 
 ~1100 small-scale inversions are estimated to have happened between _S.