In PLoS Genetics this week, researchers at the Gregor Mendel Institute of Molecular Plant Biology and their colleagues report their "analysis of chromatin structure and RNA transcription at chromosome termini in Arabidopsis." They found telomeric repeat-containing transcripts, some of which "are processed into small interfering RNAs." Telomeric siRNAs promote methylation of asymmetric cytosines in telomeric repeats, contributing to telomeric chromatin maintenance, the authors write.
Investigators at the University of Texas, Austin, report "mechanisms used for genomic proliferation by thermophilic group II Introns" in PLoS Biology this week. Using a combination of bionformatic approaches and mobility assays, the authors "identified mechanisms that contribute to the proliferation of [Thermosynechococcus] elongatus group II introns," including divergence of DNA target specificity, adaptation to some intron-encoded reverse transcriptases, and preferential insertion among other mobile introns or insertion elements.
Meanwhile, in PLoS Computational Biology, three researchers suggest that the rate of auto-regulation of transcription factors in E. coli is controlled by additional TFs. "In these cases, the way the expression of the auto-regulator responds to changes in the concentrations of the 'input' regulators — the response function — is obviously affected by the auto-regulation," the authors write, adding that when they tested their hypothesis with an evolutionary algorithm, they found that auto-regulation can evolve, so long as it provides a functional benefit.
And in PLoS One, researchers at the University of Sydney and their colleagues report the deregulation of neuronal miRNAs in response to amyloid-β in Alzheimer’s disease. Using TaqMan arrays on mouse hippocampal cultures, the team shows that "about half of all miRNAs tested were down-regulated in response to Aβ peptides," which, they write, suggests it may be "an important factor contributing to the cascade of events leading to AD."