In Science this week, researchers from the University of Massachusetts and the University of Oxford report on the discovery that transposons are more mobile in certain neurons than others in the Drosophila brain. Fly cells typically use the piwi-interacting proteins Aubergine and Argonaute 3 to suppress transposable elements. However, in mushroom body neurons, where transposon expression is more abundant, these two proteins are less abundant. The team suggests that the greater level of transposons in this part of the brain helps ensure genomic heterogeneity.
Also in Science, investigators from the UK's Medical Research Council present a paper indicating that translational inhibition is the primary event required for microRNA-mediated mRNA degradation, and that the process relies on impairing the function of the eIF4F initiation complex. Additionally, the scientists report a "correlation between the presence of miRNA target sites in the 3' untranslated region of mRNAs and secondary structure in the 5' UTR and show that mRNAs with unstructured 5' UTRs are refractory to miRNA repression."