| 11. |
- Conley, Daniel, et al.
(författare)
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A call to commission more women writers
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 488:7413, s. 590-590
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 12. |
- Conley, Daniel
(författare)
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Ecology: Save the Baltic Sea.
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 486:7404, s. 463-464
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined Comment: Geoengineering efforts to bring oxygen into the deep Baltic should be abandoned, says Daniel J. Conley
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| 13. |
- Contreras, F.-Xabier, et al.
(författare)
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Molecular recognition of a single sphingolipid species by a protein's transmembrane domain
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 481:7382, s. 525-529
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Tidskriftsartikel (refereegranskat)abstract
- Functioning and processing of membrane proteins critically depend on the way their transmembrane segments are embedded in the membrane. Sphingolipids are structural components of membranes and can also act as intracellular second messengers. Not much is known of sphingolipids binding to transmembrane domains (TMDs) of proteins within the hydrophobic bilayer, and how this could affect protein function. Here we show a direct and highly specific interaction of exclusively one sphingomyelin species, SM 18, with the TMD of the COPI machinery protein p24 (ref. 2). Strikingly, the interaction depends on both the headgroup and the backbone of the sphingolipid, and on a signature sequence (VXXTLXXIY) within the TMD. Molecular dynamics simulations show a close interaction of SM 18 with the TMD. We suggest a role of SM 18 in regulating the equilibrium between an inactive monomeric and an active oligomeric state of the p24 protein, which in turn regulates COPI-dependent transport. Bioinformatic analyses predict that the signature sequence represents a conserved sphingolipid-binding cavity in a variety of mammalian membrane proteins. Thus, in addition to a function as second messengers, sphingolipids can act as cofactors to regulate the function of transmembrane proteins. Our discovery of an unprecedented specificity of interaction of a TMD with an individual sphingolipid species adds to our understanding of why biological membranes are assembled from such a large variety of different lipids.
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| 14. |
- Curtis, Bruce A., et al.
(författare)
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Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 492:7427, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host-and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.
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| 15. |
- de Vries, B. L., et al.
(författare)
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Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 490:7418, s. 74-76
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Tidskriftsartikel (refereegranskat)abstract
- Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets(1). Collisions between such bodies produce small dust particles(2), the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg2-2xFe2xSiO4) has been done for the protoplanetary disk HD 100546 (refs 3, 4) and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids(5,6) (x approximate to 0.29). In the cold outskirts of the beta Pictoris system, an analogue to the young Solar System, olivine crystals were detected(7) but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets(8,9). Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of beta Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15-45 astronomical units from the star (one astronomical unit is the Sun-Earth distance), determine their magnesium-rich composition (x = 0.01 +/- 0.001) and show that they make up 3.6 +/- 1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System(8-10), even though beta Pictoris is more massive and more luminous and has a different planetary system architecture.
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| 16. |
- Dethoff, Elizabeth A, et al.
(författare)
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Visualizing transient low-populated structures of RNA
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 491:7426, s. 724-728
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Tidskriftsartikel (refereegranskat)abstract
- The visualization of RNA conformational changes has provided fundamental insights into how regulatory RNAs carry out their biological functions. The RNA structural transitions that have been characterized so far involve long-lived species that can be captured by structure characterization techniques. Here we report the nuclear magnetic resonance visualization of RNA transitions towards 'invisible' excited states (ESs), which exist in too little abundance (2-13%) and for too short a duration (45-250 μs) to allow structural characterization by conventional techniques. Transitions towards ESs result in localized rearrangements in base-pairing that alter building block elements of RNA architecture, including helix-junction-helix motifs and apical loops. The ES can inhibit function by sequestering residues involved in recognition and signalling or promote ATP-independent strand exchange. Thus, RNAs do not adopt a single conformation, but rather exist in rapid equilibrium with alternative ESs, which can be stabilized by cellular cues to affect functional outcomes.
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| 17. |
- Ellegren, Hans, et al.
(författare)
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The genomic landscape of species divergence in Ficedula flycatchers
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 491:7426, s. 756-760
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Tidskriftsartikel (refereegranskat)abstract
- Unravelling the genomic landscape of divergence between lineages is key to understanding speciation. The naturally hybridizing collared flycatcher and pied flycatcher are important avian speciation models that show pre-as well as postzygotic isolation. We sequenced and assembled the 1.1-Gb flycatcher genome, physically mapped the assembly to chromosomes using a low-density linkage map and re-sequenced population samples of each species. Here we show that the genomic landscape of species differentiation is highly heterogeneous with approximately 50 'divergence islands' showing up to 50-fold higher sequence divergence than the genomic background. These non-randomly distributed islands, with between one and three regions of elevated divergence per chromosome irrespective of chromosome size, are characterized by reduced levels of nucleotide diversity, skewed allele-frequency spectra, elevated levels of linkage disequilibrium and reduced proportions of shared polymorphisms in both species, indicative of parallel episodes of selection. Proximity of divergence peaks to genomic regions resistant to sequence assembly, potentially including centromeres and telomeres, indicate that complex repeat structures may drive species divergence. A much higher background level of species divergence of the Z chromosome, and a lower proportion of shared polymorphisms, indicate that sex chromosomes and autosomes are at different stages of speciation. This study provides a roadmap to the emerging field of speciation genomics.
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| 18. |
- Elmgren, Ragnar, 1944-
(författare)
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Political backing to save the Baltic sea
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 487:7408, s. 432-432
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 19. |
- Garrouste, Romain, et al.
(författare)
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A complete insect from the Late Devonian period
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 488:7409, s. 82-85
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Tidskriftsartikel (refereegranskat)abstract
- After terrestrialization, the diversification of arthropods and vertebrates is thought to have occurred in two distinct phases(1), the first between the Silurian and the Frasnian stages (Late Devonian period) (425-385 million years (Myr) ago), and the second characterized by the emergence of numerous new major taxa, during the Late Carboniferous period (after 345 Myr ago). These two diversification periods bracket the depauperate vertebrate Romer's gap (360-345 Myr ago) and arthropod gap (385-325 Myr ago)(1), which could be due to preservational artefact(2,3). Although a recent molecular dating has given an age of 390 Myr for the Holometabola(4), the record of hexapods during the Early-Middle Devonian (411.5-391 Myr ago, Pragian to Givetian stages) is exceptionally sparse and based on fragmentary remains, which hinders the timing of this diversification. Indeed, although Devonian Archaeognatha are problematic(5,6), the Pragian of Scotland has given some Collembola and the incomplete insect Rhyniognatha, with its diagnostic dicondylic, metapterygotan mandibles(5,7). The oldest, definitively winged insects are from the Serpukhovian stage (latest Early Carboniferous period)(8). Here we report the first complete Late Devonian insect, which was probably a terrestrial species. Its 'orthopteroid' mandibles are of an omnivorous type, clearly not modified for a solely carnivorous diet. This discovery narrows the 45-Myr gap in the fossil record of Hexapoda, and demonstrates [GRAPHICS] further a first Devonian phase of diversification for the Hexapoda, as in vertebrates, and suggests that the Pterygota diversified before and during Romer's gap.
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| 20. |
- Groenen, M. A., et al.
(författare)
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Analyses of pig genomes provide insight into porcine demography and evolution
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 491:7424, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- For 10,000 years pigs and humans have shared a close and complex relationship. From domestication to modern breeding practices, humans have shaped the genomes of domestic pigs. Here we present the assembly and analysis of the genome sequence of a female domestic Duroc pig (Sus scrofa) and a comparison with the genomes of wild and domestic pigs from Europe and Asia. Wild pigs emerged in South East Asia and subsequently spread across Eurasia. Our results reveal a deep phylogenetic split between European and Asian wild boars approximately 1 million years ago, and a selective sweep analysis indicates selection on genes involved in RNA processing and regulation. Genes associated with immune response and olfaction exhibit fast evolution. Pigs have the largest repertoire of functional olfactory receptor genes, reflecting the importance of smell in this scavenging animal. The pig genome sequence provides an important resource for further improvements of this important livestock species, and our identification of many putative disease-causing variants extends the potential of the pig as a biomedical model.
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