Bursts and horizontal evolution of DNA transposons in the speciation of pseudotetraploid salmonids
Date
2007-11-16
Authors
de Boer, Johan G
Yazawa, Ryosuke
Davidson, William S
Koop, Ben F
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: Several genome duplications have occurred in the evolutionary history of teleost
fish. In returning to a stable diploid state, the polyploid genome reorganized, and large portions are
lost, while the fish lines evolved to numerous species. Large scale transposon movement has been
postulated to play an important role in the genome reorganization process. We analyzed the DNA
sequence of several large loci in Salmo salar and other species for the presence of DNA transposon
families.
Results: We have identified bursts of activity of 14 families of DNA transposons (12 Tc1-like and
2 piggyBac-like families, including 11 novel ones) in genome sequences of Salmo salar. Several of
these families have similar sequences in a number of closely and distantly related fish, lamprey, and
frog species as well as in the parasite Schistosoma japonicum. Analysis of sequence similarities
between copies within the families of these bursts demonstrates several waves of transposition
activities coinciding with salmonid species divergence. Tc1-like families show a master gene-like
copying process, illustrated by extensive but short burst of copying activity, while the piggyBac-like
families show a more random copying pattern. Recent families may include copies with an open
reading frame for an active transposase enzyme.
Conclusion: We have identified defined bursts of transposon activity that make use of masterslave
and random mechanisms. The bursts occur well after hypothesized polyploidy events and
coincide with speciation events. Parasite-mediated lateral transfer of transposons are implicated
Description
BioMed Central
Keywords
Citation
deBoer et al. Bursts and horizontal evolution of DNA transposons in the speciation of pseudotetraploid salmonids. BMC Genomics 2007, 8 :422