In the PNAS Early Edition this week, researchers at Michigan State University and their colleagues show that Pack-Mutator-like transposable elements "specifically acquire GC-rich fragments and preferentially insert into the 5' end of genes" in Arabidopsis, which they say "may influence the conformation of chromatin, the expression level of genes, as well as the recombination rate." These Pack-Mutator-like transposable elements — or Pack-MULEs — "form independent, GC-rich tr