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Oligonucleotides targeting mRNA are promising therapeutic agents but suffer from poor bioavailability. Here, the authors develop reduced-charge oligonucleotides with artificial LNA-amide linkages with improved cell uptake and minimal structural deviation to the DNA:RNA duplex.

The relationship between regulatory elements, chromatin interactions and gene expression during development remains poorly understood. Here the authors present Tiled-C, a low-input 3C approach to study genome architecture at high resolution, and apply it to mouse erythroid differentiation in vivo, finding that enhancer-promoter interactions are formed gradually during differentiation, concomitant with progressive upregulation of gene activity.

For CRISPR-Cas9 genome editing, Cas9 protein is guided to its target by single guide (sg) RNA. Here, the authors synthesised sgRNAs via convergent ‘click’ ligation of variable 20-mer RNAs that target the genome and a Cas9-binding 79-mer chimeric RNA/2´-OMe RNA of fixed sequence in a single tube.

Abstract Fluorescent base analogues (FBAs) have emerged as a powerful class of molecular reporters of location and environment for nucleic acids. In our overall mission to develop bright and useful FBAs for all natural nucleobases, herein we describe the synthesis and thorough characterization of bicyclic thymidine (bT), both as a monomer and when incorporated into DNA. We have developed a robust synthetic route for the preparation of the bT DNA monomer and the corresponding protected phosphoramidite for solid-phase DNA synthesis. The bT deoxyribonucleoside has a brightness value of 790 M−1cm−1 in water, which is comparable or higher than most fluorescent thymine analogues reported. When incorporated into DNA, bT pairs selectively with adenine without perturbing the B-form structure, keeping the melting thermodynamics of the B-form duplex DNA virtually unchanged. As for most fluorescent base analogues, the emission of bT is reduced inside DNA (4.5- and 13-fold in single- and double-stranded DNA, respectively). Overall, these properties make bT an interesting thymine analogue for studying DNA and an excellent starting point for the development of brighter bT derivatives.