Loss of RNA-dependent RNA Polymerase 2 (RDR2) Function Causes Widespread and Unexpected Changes in the Expression of Transposons, Genes, and 24-nt Small RNAs
Jia Y, Lisch DR, Ohtsu K, Scanlon MJ, Nettleton D, et al.
Jia et al. focus on a mechanism by which the activity of genes and transposons alike are reined in or left to run free. The mechanism, involving small RNA molecules and their interactions with chromatin, is known to regulate transposons. Based on these findings, it now appears to influence gene activity as well.
Mu Transposon Insertion Sites and Meiotic Recombination Events Co-localize with Epigenetic Marks for Open Chromatin across the Maize Genome
Liu S, Yeh C-T, Ji T, Ying K, Wu H, et al.
Eighty-five percent of the newly sequenced maize genome consists of transposable elements, restless chunks of DNA that restructure the genome, generate genetic diversity, and influence gene expression patterns. Liu et al. debut a new PCR-based strategy for identifying Mu transposon insertion sites using highly conserved signature sequences from these elements. The finding that both Mu insertions and meiotic recombination sites concentrate in genomic regions decorated with epigenetic marks of open chromatin provides support for the hypothesis that open chromatin enhances rates of both Mu insertion and meiotic recombination.
Exceptional Diversity, Non-Random Distribution, and Rapid Evolution of Retroelements in the B73 Maize Genome
Baucom RS, Estill JC, Chapparro C, Upshaw N, Jogi A, et al.
Baucom et al. report results showing that the maize genome provides a great number of different niches for the survival and generation of a wide variety of retroelements that have evolved differentially to occupy and exploit this genomic diversity. "This research breaks a lot of new ground in the understanding of what drives the evolution o
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