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Fish Can Recognize Human Faces, According to One New Study

Yale Environment 360 - Thu, 06/09/2016 - 00:43

Fish now join humans, monkeys, primates, and birds as one of the few animals able to distinguish faces, according to new research published in the journal Scientific Reports this week.

James St. John/Wikimedia The skill requires a sophisticated combination of perception and memory— and generally, a neocortex. But scientists at the University of Oxford in England and the University of Queensland in Australia were able to train archerfish to recognize human faces, despite the fact that these tropical fish don’t have complex brain structures. Archerfish typically feed by spitting water at prey, like insects. So the scientists taught the fish to spray water at images of particular human faces in exchange for food. Archerfish identified the correct person 81 percent of the time.

Categories: Environmental News

Sea Ice Hits New Spring Low In the Arctic, Says Federal Agency

Yale Environment 360 - Wed, 06/08/2016 - 11:42

Sea ice extent in the Arctic hit a new record spring low last month, measuring 537,000 square miles below average — an area twice the size of Texas, the National Snow and Ice Data Center announced this week.

NASA/GSFC Sea ice breaking up in the Beaufort Sea in May. Last month’s Arctic sea ice extent was the lowest May sea ice measurement since satellite monitoring began 38 years ago and follows a string of record low ice this winter. “We didn’t just break the old May record, we’re way below the previous one,” NSIDC Director Mark Serreze told Climate Central. The Arctic’s snow cover also hit record lows this year, with April having the lowest snow cover for that month on record and May the fourth lowest. The Arctic has warmed twice as fast as the rest of the world in recent decades, but scientists say that this year’s strong El Niño in the Pacific Ocean could be ramping up temperatures even more. Temperatures at the pole have been 4 to 11 degrees F above average this winter. “Will we end up with very low sea ice extent this September?” Serreze said. “I think pretty much absolutely.”

Categories: Environmental News

Books in brief

Nature - Wed, 06/08/2016 - 00:00

Books in brief

Nature 534, 7608 (2016). doi:10.1038/534473a

Author: Barbara Kiser

Barbara Kiser reviews five of the week's best science picks.

Categories: Literature

Genomics: The language of flowers

Nature - Wed, 06/08/2016 - 00:00

Genomics: The language of flowers

Nature 534, 7607 (2016). doi:10.1038/nature18445

Authors: Sandra Knapp & Dani Zamir

The complete DNA sequences of the two wild parents of the garden petunia provide valuable genetic insights into this model plant, and will improve the optimization of other crop plants for agriculture.

Categories: Literature

Cell reprogramming: Brain versus brawn

Nature - Wed, 06/08/2016 - 00:00

Cell reprogramming: Brain versus brawn

Nature 534, 7607 (2016). doi:10.1038/nature18444

Authors: Bruno Di Stefano & Konrad Hochedlinger

The mechanisms that underlie enforced transitions between mature cell lineages are poorly understood. Profiling single skin cells that are induced to become neurons reveals that, unexpectedly, they often become muscle. See Letter p.391

Categories: Literature

Dual targeting of p53 and c-MYC selectively eliminates leukaemic stem cells

Nature - Wed, 06/08/2016 - 00:00

Dual targeting of p53 and c-MYC selectively eliminates leukaemic stem cells

Nature 534, 7607 (2016). doi:10.1038/nature18288

Authors: Sheela A. Abraham, Lisa E. M. Hopcroft, Emma Carrick, Mark E. Drotar, Karen Dunn, Andrew J. K. Williamson, Koorosh Korfi, Pablo Baquero, Laura E. Park, Mary T. Scott, Francesca Pellicano, Andrew Pierce, Mhairi Copland, Craig Nourse, Sean M. Grimmond, David Vetrie, Anthony D. Whetton & Tessa L. Holyoake

Chronic myeloid leukaemia (CML) arises after transformation of a haemopoietic stem cell (HSC) by the protein-tyrosine kinase BCR–ABL. Direct inhibition of BCR–ABL kinase has revolutionized disease management, but fails to eradicate leukaemic stem cells (LSCs), which maintain CML. LSCs are independent of BCR–ABL for survival,

Categories: Literature

Self-assembly of microcapsules via colloidal bond hybridization and anisotropy

Nature - Wed, 06/08/2016 - 00:00

Self-assembly of microcapsules via colloidal bond hybridization and anisotropy

Nature 534, 7607 (2016). doi:10.1038/nature17956

Authors: Chris H. J. Evers, Jurriaan A. Luiken, Peter G. Bolhuis & Willem K. Kegel

Particles with directional interactions are promising building blocks for new functional materials and may serve as models for biological structures. Mutually attractive nanoparticles that are deformable owing to flexible surface groups, for example, may spontaneously order themselves into strings, sheets and large vesicles. Furthermore, anisotropic colloids with attractive patches can self-assemble into open lattices and the colloidal equivalents of molecules and micelles. However, model systems that combine mutual attraction, anisotropy and deformability have not yet been realized. Here we synthesize colloidal particles that combine these three characteristics and obtain self-assembled microcapsules. We propose that mutual attraction and deformability induce directional interactions via colloidal bond hybridization. Our particles contain both mutually attractive and repulsive surface groups that are flexible. Analogously to the simplest chemical bond—in which two isotropic orbitals hybridize into the molecular orbital of H2—these flexible groups redistribute on binding. Via colloidal bond hybridization, isotropic spheres self-assemble into planar monolayers, whereas anisotropic snowman-shaped particles self-assemble into hollow monolayer microcapsules. A modest change in the building blocks thus results in much greater complexity of the self-assembled structures. In other words, these relatively simple building blocks self-assemble into markedly more complex structures than do similar particles that are isotropic or non-deformable.

Categories: Literature

Towards clinical application of pronuclear transfer to prevent mitochondrial DNA disease

Nature - Wed, 06/08/2016 - 00:00

Towards clinical application of pronuclear transfer to prevent mitochondrial DNA disease

Nature 534, 7607 (2016). doi:10.1038/nature18303

Authors: Louise A. Hyslop, Paul Blakeley, Lyndsey Craven, Jessica Richardson, Norah M. E. Fogarty, Elpida Fragouli, Mahdi Lamb, Sissy E. Wamaitha, Nilendran Prathalingam, Qi Zhang, Hannah O’Keefe, Yuko Takeda, Lucia Arizzi, Samer Alfarawati, Helen A. Tuppen, Laura Irving, Dimitrios Kalleas, Meenakshi Choudhary, Dagan Wells, Alison P. Murdoch, Douglass M. Turnbull, Kathy K. Niakan & Mary Herbert

Mitochondrial DNA (mtDNA) mutations are maternally inherited and are associated with a broad range of debilitating and fatal diseases. Reproductive technologies designed to uncouple the inheritance of mtDNA from nuclear DNA may enable affected women to have a genetically related child with a greatly reduced risk of mtDNA disease. Here we report the first preclinical studies on pronuclear transplantation (PNT). Surprisingly, techniques used in proof-of-concept studies involving abnormally fertilized human zygotes were not well tolerated by normally fertilized zygotes. We have therefore developed an alternative approach based on transplanting pronuclei shortly after completion of meiosis rather than shortly before the first mitotic division. This promotes efficient development to the blastocyst stage with no detectable effect on aneuploidy or gene expression. After optimization, mtDNA carryover was reduced to <2% in the majority (79%) of PNT blastocysts. The importance of reducing carryover to the lowest possible levels is highlighted by a progressive increase in heteroplasmy in a stem cell line derived from a PNT blastocyst with 4% mtDNA carryover. We conclude that PNT has the potential to reduce the risk of mtDNA disease, but it may not guarantee prevention.

Categories: Literature

Co-repressor CBFA2T2 regulates pluripotency and germline development

Nature - Wed, 06/08/2016 - 00:00

Co-repressor CBFA2T2 regulates pluripotency and germline development

Nature 534, 7607 (2016). doi:10.1038/nature18004

Authors: Shengjiang Tu, Varun Narendra, Masashi Yamaji, Simon E. Vidal, Luis Alejandro Rojas, Xiaoshi Wang, Sang Yong Kim, Benjamin A. Garcia, Thomas Tuschl, Matthias Stadtfeld & Danny Reinberg

Developmental specification of germ cells lies at the heart of inheritance, as germ cells contain all of the genetic and epigenetic information transmitted between generations. The critical developmental event distinguishing germline from somatic lineages is the differentiation of primordial germ cells (PGCs), precursors of sex-specific gametes that produce an entire organism upon fertilization. Germ cells toggle between uni- and pluripotent states as they exhibit their own ‘latent’ form of pluripotency. For example, PGCs express a number of transcription factors in common with embryonic stem (ES) cells, including OCT4 (encoded by Pou5f1), SOX2, NANOG and PRDM14 (refs 2, 3, 4). A biochemical mechanism by which these transcription factors converge on chromatin to produce the dramatic rearrangements underlying ES-cell- and PGC-specific transcriptional programs remains poorly understood. Here we identify a novel co-repressor protein, CBFA2T2, that regulates pluripotency and germline specification in mice. Cbfa2t2−/− mice display severe defects in PGC maturation and epigenetic reprogramming. CBFA2T2 forms a biochemical complex with PRDM14, a germline-specific transcription factor. Mechanistically, CBFA2T2 oligomerizes to form a scaffold upon which PRDM14 and OCT4 are stabilized on chromatin. Thus, in contrast to the traditional ‘passenger’ role of a co-repressor, CBFA2T2 functions synergistically with transcription factors at the crossroads of the fundamental developmental plasticity between uni- and pluripotency.

Categories: Literature

Dissecting direct reprogramming from fibroblast to neuron using single-cell RNA-seq

Nature - Wed, 06/08/2016 - 00:00

Dissecting direct reprogramming from fibroblast to neuron using single-cell RNA-seq

Nature 534, 7607 (2016). doi:10.1038/nature18323

Authors: Barbara Treutlein, Qian Yi Lee, J. Gray Camp, Moritz Mall, Winston Koh, Seyed Ali Mohammad Shariati, Sopheak Sim, Norma F. Neff, Jan M. Skotheim, Marius Wernig & Stephen R. Quake

Direct lineage reprogramming represents a remarkable conversion of cellular and transcriptome states. However, the intermediate stages through which individual cells progress during reprogramming are largely undefined. Here we use single-cell RNA sequencing at multiple time points to dissect direct reprogramming from mouse embryonic fibroblasts to induced neuronal cells. By deconstructing heterogeneity at each time point and ordering cells by transcriptome similarity, we find that the molecular reprogramming path is remarkably continuous. Overexpression of the proneural pioneer factor Ascl1 results in a well-defined initialization, causing cells to exit the cell cycle and re-focus gene expression through distinct neural transcription factors. The initial transcriptional response is relatively homogeneous among fibroblasts, suggesting that the early steps are not limiting for productive reprogramming. Instead, the later emergence of a competing myogenic program and variable transgene dynamics over time appear to be the major efficiency limits of direct reprogramming. Moreover, a transcriptional state, distinct from donor and target cell programs, is transiently induced in cells undergoing productive reprogramming. Our data provide a high-resolution approach for understanding transcriptome states during lineage differentiation.

Categories: Literature

The bacterial DnaA-trio replication origin element specifies single-stranded DNA initiator binding

Nature - Wed, 06/08/2016 - 00:00

The bacterial DnaA-trio replication origin element specifies single-stranded DNA initiator binding

Nature 534, 7607 (2016). doi:10.1038/nature17962

Authors: Tomas T. Richardson, Omar Harran & Heath Murray

DNA replication is tightly controlled to ensure accurate inheritance of genetic information. In all organisms, initiator proteins possessing AAA+ (ATPases associated with various cellular activities) domains bind replication origins to license new rounds of DNA synthesis. In bacteria the master initiator protein, DnaA, is highly conserved and has two crucial DNA binding activities. DnaA monomers recognize the replication origin (oriC) by binding double-stranded DNA sequences (DnaA-boxes); subsequently, DnaA filaments assemble and promote duplex unwinding by engaging and stretching a single DNA strand. While the specificity for duplex DnaA-boxes by DnaA has been appreciated for over 30 years, the sequence specificity for single-strand DNA binding has remained unknown. Here we identify a new indispensable bacterial replication origin element composed of a repeating trinucleotide motif that we term the DnaA-trio. We show that the function of the DnaA-trio is to stabilize DnaA filaments on a single DNA strand, thus providing essential precision to this binding mechanism. Bioinformatic analysis detects DnaA-trios in replication origins throughout the bacterial kingdom, indicating that this element is part of the core oriC structure. The discovery and characterization of the novel DnaA-trio extends our fundamental understanding of bacterial DNA replication initiation, and because of the conserved structure of AAA+ initiator proteins these findings raise the possibility of specific recognition motifs within replication origins of higher organisms.

Categories: Literature

Humanity’s forgotten family

Nature - Wed, 06/08/2016 - 00:00

Humanity’s forgotten family

Nature 534, 7606 (2016). doi:10.1038/534151a

Hominin fossils discovered near the site of the ‘hobbit’ Homo floresiensis provide yet more evidence that the human lineage is more diverse than was ever imagined.

Categories: Literature

Energy hit

Nature - Wed, 06/08/2016 - 00:00

Energy hit

Nature 534, 7606 (2016). doi:10.1038/534152a

Germany’s decision to slow the expansion of green-energy production is a reasonable move.

Categories: Literature

Second chances

Nature - Wed, 06/08/2016 - 00:00

Second chances

Nature 534, 7606 (2016). doi:10.1038/534152b

The line between compliance and misconduct is finer than you might think.

Categories: Literature

Gene editing can drive science to openness

Nature - Wed, 06/08/2016 - 00:00

Gene editing can drive science to openness

Nature 534, 7606 (2016). http://www.nature.com/doifinder/10.1038/534153a

Author: Kevin Esvelt

The fast-moving field of gene-drive research provides an opportunity to rewrite the rules of the science, says Kevin Esvelt.

Categories: Literature

Glaciology: Early signs of ice retreat

Nature - Wed, 06/08/2016 - 00:00

Glaciology: Early signs of ice retreat

Nature 534, 7606 (2016). doi:10.1038/534154a

Two studies show that Antarctica has been losing ice for longer than previously thought.A team led by Shujie Wang at the University of Cincinnati in Ohio studied recently declassified images taken by US spy satellites. They found that glaciers feeding the Antarctic Peninsula's Larsen

Categories: Literature

Molecular biology: CRISPR tweaked to edit RNA

Nature - Wed, 06/08/2016 - 00:00

Molecular biology: CRISPR tweaked to edit RNA

Nature 534, 7606 (2016). doi:10.1038/534154b

The CRISPR–Cas9 gene-editing system snips DNA, but a newly characterized version targets RNA instead.The CRISPR–Cas system is used by many bacteria to combat viruses. Feng Zhang of the Broad Institute of MIT and Harvard in Cambridge, Massachusetts, Eugene Koonin of the US National Institutes

Categories: Literature

Geology: Magma pool under New Zealand

Nature - Wed, 06/08/2016 - 00:00

Geology: Magma pool under New Zealand

Nature 534, 7606 (2016). doi:10.1038/534154c

Molten rock is accumulating in a magma chamber beneath New Zealand, raising questions about volcanic hazards.Ian Hamling and his colleagues at GNS Science in Lower Hutt, New Zealand, used satellite radar data to study ground motions in the Taupo Volcanic Zone, an area of

Categories: Literature

Ageing: Chemical extends worm lifespan

Nature - Wed, 06/08/2016 - 00:00

Ageing: Chemical extends worm lifespan

Nature 534, 7606 (2016). doi:10.1038/534154d

A chemical lengthens the nematode worm's lifespan by interfering with its perception of whether food is present.Model organisms are known to live longer when they are fed a restricted diet. Mark Lucanic and Gordon Lithgow at the Buck Institute for Research on Aging in

Categories: Literature

Astrophysics: Relativity passes black-hole test

Nature - Wed, 06/08/2016 - 00:00

Astrophysics: Relativity passes black-hole test

Nature 534, 7606 (2016). doi:10.1038/534154e

General relativity holds true, even under the extreme conditions of colliding black holes.In 2015, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) saw the first evidence of gravitational waves, which had been created by two merging black holes. Walter Del Pozzo at the University of

Categories: Literature

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