Unconventional Fermi surface in an insulating state

Insulators occur in more than one guise, a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. The quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behaviour

Ribo-Pop: simple, cost-effective, and widely applicable ribosomal RNA depletion

The measurement of RNA abundance derived from massively parallel sequencing experiments is an essential technique. Methods that reduce ribosomal RNA levels are usually required prior to sequencing library construction because ribosomal RNA typically comprises the vast majority of a total RNA sample. For some experiments, ribosomal RNA depletion is favored over poly(A) selection because it offers a more inclusive representation of the transcriptome. However, methods to deplete ribosomal RNA are generally proprietary, complex, inefficient, applicable to only specific species, or compatible with only a narrow range of RNA input levels. Here, we describe Ribo-Pop (ribosomal RNA depletion for popular use), a simple workflow and antisense oligo design strategy that we demonstrate works over a wide input range and can be easily adapted to any organism with a sequenced genome. We provide a computational pipeline for probe selection, a streamlined 20-min protocol, and ready-to-use oligo sequences for several organisms. We anticipate that our simple and generalizable “open source” design strategy would enable virtually any laboratory to pursue full transcriptome sequencing in their organism of interest with minimal time and resource investment

Systematic analysis of YFP traps reveals common mRNA/protein discordance in neural tissues

While post-transcriptional control is thought to be required at the periphery of neurons and glia, its extent is unclear. Here, we investigate systematically the spatial distribution and expression of mRNA at single molecule sensitivity and their corresponding proteins of 200 YFP trap lines across the intact Drosophila nervous system. 97.5% of the genes studied showed discordance between the distribution of mRNA and the proteins they encode in at least one region of the nervous system. These data suggest that post-transcriptional regulation is very common, helping to explain the complexity of the nervous system. We also discovered that 68.5% of these genes have transcripts present at the periphery of neurons, with 9.5% at the glial periphery. Peripheral transcripts include many potential new regulators of neurons, glia, and their interactions. Our approach is applicable to most genes and tissues and includes powerful novel data annotation and visualization tools for post transcriptional regulation.Acknowledgments. We are very grateful to the Bloomington, Vienna, and Kyoto Drosophila Stock Centres (fly stocks), Flybase and Flymine (Lyne et al., 2007) for their reagents and open data, which were invaluable to this work. We are grateful to David Ish-Horowicz, Alfredo Castello, and members of the Davis laboratory for critical reading of the manuscript and feedback on the project. We thank Zegami Ltd. for their help, advice, and hosting the collection. This work was generously supported by a Wellcome Senior Research Fellowship (096144) and Wellcome Investigator Award (209412) to I. Davis, which funded A.I. Jarvelin, R.M. Parton, J.S. Titlow, and M.K. Thompson. Advanced microscopy facilities and technical advice as well as support to D.M. Susano Pinto were provided by Micron Oxford (https://micronoxford.com), supported by Wellcome Strategic Awards (091911 and 107457) and a Medical Research Council/Engineering and Physical Sciences Research Council/Biotechnology and Biological Sciences Research Council next-generation imaging award to I. Davis as the principal investigator. J.S. Titlolw and M.K. Thompson were supported by a Leverhulme Trust grant to I. Davis. Department of Biochemistry DPhil studentships supported J.Y. Lee and D.S. Gala. M. Kiourlappou was supported by the Biotechnology and Biosciences Research Council, grant numbers: BB/M011224/1 and BB/S507623/1, by A.G. Leventis Foundation, and by Zegami Ltd