Editors' Choice

Science  08 Jun 2018:
Vol. 360, Issue 6393, pp. 1083
  1. Geophysics

    The San Andreas creeps along the decade

    1. Brent Grocholski

    Aerial view of a section of the San Andreas fault

    PHOTO: KEVIN SCHAFER/ALAMY STOCK PHOTO

    The famous San Andreas fault in California is an excellent place to understand the behavior of faults. Khoshmanesh and Shirzaei used high-resolution satellite measurements to track surface deformation along the central portion of the fault over two decades. Accurate modeling of the deformation requires shifts in the time scale of the fault's aseismic creeping behavior from yearly to decadal. The different modes of creep are important for assessing seismic hazard and may provide some clues about fault rupture.

    Geophys. Res. Lett. 10.1002/2018GL077017 (2018).

  2. Molecular Biology

    The long and short of RNA export

    1. Steve Mao

    Circular RNAs (circRNAs) are back-spliced RNA products that have regulatory roles in gene expression, and most circRNAs are enriched in the cytoplasm. Huang et al. identified protein factors that are required to export circRNAs from the nucleus to the cytoplasm. An RNA interference screen targeting some proteins that are known to export various linear RNAs in Drosophila cells showed that a RNA helicase is required for the cytoplasmic accumulation of circRNAs that are longer than 800 nucleotides. The two human homologs of this Drosophila helicase play similar roles in human cells. Surprisingly, one controls long (>1300-nucleotide) and the other controls short (<350-nucleotide) circRNAs. Future investigation of pathways that measure and export circRNAs of different lengths will shed light on circRNA functions.

    Genes Dev. 10.1101/gad.314856.118 (2018).

  3. Ecological Invasions

    An algal transformation in Lake Baikal

    1. Andrew M. Sugden

    Human-induced changes in Lake Baikal have resulted in the spread of a previously rare filamentous alga.

    PHOTO: ANDREY NEKRASOV/ALAMY STOCK PHOTO

    In central Siberia, Lake Baikal—the world's deepest freshwater lake—is undergoing ecological change. Volkova et al. report that species of the filamentous mat-forming alga Spirogyra, formerly present at low abundance in restricted areas of the lake, have proliferated and diversified in recent years. Spirogyra has invaded shallow-water zones of the lake, and several species have appeared in Baikal for the first time. These changes are likely to have been driven by a combination of factors, some of them anthropogenic, such as agricultural runoff and changing patterns of seasonal temperatures. The consequences may be hard to predict and control.

    Phycologia 57, 298 (2018).

  4. DNA Methylation

    Tissue-specific DNA demethylation after birth

    1. Beverly A. Purnell

    Because of changes in their environment, including the need to repair tissue, cells cannot remain static. They must do their job even if conditions around them vary. One way to accommodate change in gene expression is through DNA methylation. The vast majority of this modification takes place during mammalian embryogenesis. Initially, methyl groups are removed around implantation, and then de novo methylation occurs in specific tissues and at set times during cell differentiation. Using high-throughput and genetic analysis, Reizel et al. show that considerable postnatal demethylation also occurs. For example, hormone signaling triggers DNA demethylation at enhancer-like regions in the liver after birth in mice. These epigenetic changes give access to specific chromatin sites for proper hepatocyte gene expression and function.

    Nat. Comm. 10.1038/s41467-018-04456-6 (2018).

  5. Protein Structure

    Not just a LARK

    1. Valda Vinson

    Many proteins involved in neurodegenerative diseases contain low-complexity domains (LCDs) that frequently exhibit no secondary structure but are implicated in both functional reversible aggregation and pathological irreversible aggregation. Guenther et al. determined the structures of 10 peptide segments from the LCD domain of the RNA binding protein TDP-43. The LCD is implicated in the formation of stress granules, which disaggregate when stress is relieved, and of pathogenic amyloid fibrils. Six of the segments form structures characteristic of amyloid fibrils, whereas four form labile amyloid-like interactions, termed LARKs. Disease variants of TDP-43 convert the LARKs to irreversible aggregates. This raises the possibility that either mutagenesis or protein modifications such as phosphorylation may play a role in switching between functional and pathological aggregation.

    Nat. Struct. Mol. Biol. 10.1038/s41594-018-0064-2 (2018).

  6. Genetics

    Genomic crowdsourcing with privacy

    1. Barbara R. Jasny

    Privacy concerns can be an obstacle to large-scale donation of the genetic material that is essential for understanding how genetic variants are associated with disease. Cho et al. have developed an approach that has the potential to be scalable to as many as a million genomes. Their system is based on dividing genotype and phenotype data from each individual among multiple servers in such a way that no one server can infer the original data. An attacker would have to hack all of the servers to extract the data. Computational approaches that simplified corrections for misleading correlations and sped up the system were used to reproduce three published genome-wide association studies representing 23,000 genomes and could make the process cost-effective.

    Nat. Biotechnol. 10.1038/nbt.4108 (2018).

  7. Climate Change Impacts

    Hurting the most vulnerable

    1. H. Jesse Smith

    The Paris Agreement set a goal of limiting global average anthropogenic climate warming to 1.5°C or less—cooler than the oft-cited target of 2°C that previously had been considered the threshold of dangerous consequences. Is the difference in impacts between the two goals meaningful, and who would be affected most by a failure to stay within the lower limit? King and Harrington find that exceeding the 1.5°C ceiling would affect tropical latitudes—which have a disproportionate share of poor populations—more than higher latitudes. Thus, if ways are not found to meet the global warming targets of the Paris Agreement, then the most vulnerable will experience the greatest consequences.

    Geophys. Res. Lett. 10.1029/2018GL078430 (2018).

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