1【生物】Structure of the mitochondrial inner membrane AAA+ protease YME1 gives insight into substrate processing
Cristina Puchades et.al
（导读 严冰）固定于酵母线粒体内膜的AAA+蛋白酶YME1负责线粒体内蛋白质的质量控制，含有ATPase域和蛋白酶域。本文通过冷冻电镜解析出其ATPase域的高分辨率结构，发现ATPase域呈闭合的非对称螺旋阶梯状，将未折叠的底物环绕其中，中央孔道内保守的酪氨酸残基与底物多肽接触，通过ATP水解循环改变酪氨酸位置，从而将底物转运至楼梯底部的环状蛋白酶域中。该转运机制很可能也适用于其他的AAA+ ATPase。
We present an atomic model of a substrate-bound inner mitochondrial membrane AAA+ quality control protease in yeast, YME1. Our ~3.4-angstrom cryo–electron microscopy structure reveals how the adenosine triphosphatases (ATPases) form a closed spiral staircase encircling an unfolded substrate, directing it toward the flat, symmetric protease ring. Three coexisting nucleotide states allosterically induce distinct positioning of tyrosines in the central channel, resulting in substrate engagement and translocation to the negatively charged proteolytic chamber. This tight coordination by a network of conserved residues defines a sequential, around-the-ring adenosine triphosphate hydrolysis cycle that results in stepwise substrate translocation. A hingelike linker accommodates the large-scale nucleotide-driven motions of the ATPase spiral relative to the planar proteolytic base. The translocation mechanism is likely conserved for other AAA+ ATPases.
2【生物】Lattice system of functionally distinct cell types in the neocortex
Hisato Maruoka et.al
The mammalian neocortex contains many cell types, but whether they organize into repeated structures has been unclear. We discovered that major cell types in neocortical layer 5 form a lattice structure in many brain areas. Large-scale three-dimensional imaging revealed that distinct types of excitatory and inhibitory neurons form cell type–specific radial clusters termed microcolumns. Thousands of microcolumns, in turn, are patterned into a hexagonal mosaic tessellating diverse regions of the neocortex. Microcolumn neurons demonstrate synchronized in vivo activity and visual responses with similar orientation preference and ocular dominance. In early postnatal development, microcolumns are coupled by cell type–specific gap junctions and later serve as hubs for convergent synaptic inputs. Thus, layer 5 neurons organize into a brainwide modular system, providing a template for cortical processing.
3 【神经】Topological and modality-specific representation of somatosensory information in the fly brain
Asako Tsubouchi and Tomoko Yano et.al
Insects and mammals share similarities of neural organization underlying the perception of odors, taste, vision, sound, and gravity. We observed that insect somatosensation also corresponds to that of mammals. In Drosophila, the projections of all the somatosensory neuron types to the insect’s equivalent of the spinal cord segregated into modality-specific layers comparable to those in mammals. Some sensory neurons innervate the ventral brain directly to form modality-specific and topological somatosensory maps. Ascending interneurons with dendrites in matching layers of the nerve cord send axons that converge to respective brain regions. Pathways arising from leg somatosensory neurons encode distinct qualities of leg movement information and play different roles in ground detection. Establishment of the ground pattern and genetic tools for neuronal manipulation should provide the basis for elucidating the mechanisms underlying somatosensation.
4 【生物】ER-mitochondria tethering by PDZD8 regulates Ca2+ dynamics in mammalian neurons
Yusuke Hirabayashi and Seok-Kyu Kwon et.al
Interfaces between organelles are emerging as critical platforms for many biological responses in eukaryotic cells. In yeast, the ERMES complex is an endoplasmic reticulum (ER)–mitochondria tether composed of four proteins, three of which contain a SMP (synaptotagmin-like mitochondrial-lipid binding protein) domain. No functional ortholog for any ERMES protein has been identified in metazoans. Here, we identified PDZD8 as an ER protein present at ER-mitochondria contacts. The SMP domain of PDZD8 is functionally orthologous to the SMP domain found in yeast Mmm1. PDZD8 was necessary for the formation of ER-mitochondria contacts in mammalian cells. In neurons, PDZD8 was required for calcium ion (Ca2+) uptake by mitochondria after synaptically induced Ca2+-release from ER and thereby regulated cytoplasmic Ca2+ dynamics. Thus, PDZD8 represents a critical ER-mitochondria tethering protein in metazoans. We suggest that ER-mitochondria coupling is involved in the regulation of dendritic Ca2+ dynamics in mammalian neurons.
Masafumi Ayata, Juerg Leuthold et al.
Plasmonics provides a possible route to overcome both the speed limitations of electronics and the critical dimensions of photonics. We present an all-plasmonic 116–gigabits per second electro-optical modulator in which all the elements—the vertical grating couplers, splitters, polarization rotators, and active section with phase shifters—are included in a single metal layer. The device can be realized on any smooth substrate surface and operates with low energy consumption. Our results show that plasmonics is indeed a viable path to an ultracompact, highest-speed, and low-cost technology that might find many applications in a wide range of fields of sensing and communications because it is compatible with and can be placed on a wide variety of materials.
6 【化学】Self-assembled three-dimensional chiral colloidal architecture
Matan Yah Ben Zion et.al
Although stereochemistry has been a central focus of the molecular sciences since Pasteur, its province has previously been restricted to the nanometric scale. We have programmed the self-assembly of micron-sized colloidal clusters with structural information stemming from a nanometric arrangement. This was done by combining DNA nanotechnology with colloidal science. Using the functional flexibility of DNA origami in conjunction with the structural rigidity of colloidal particles, we demonstrate the parallel self-assembly of three-dimensional microconstructs, evincing highly specific geometry that includes control over position, dihedral angles, and cluster chirality.
7 【物理】Nonreciprocal lasing in topological cavities of arbitrary geometries
Babak Bahari, et.al
Resonant cavities are essential building blocks governing many wave-based phenomena, but their geometry and reciprocity fundamentally limit the integration of optical devices. We report, at telecommunication wavelengths, geometry-independent and integrated nonreciprocal topological cavities that couple stimulated emission from one-way photonic edge states to a selected waveguide output with an isolation ratio in excess of 10 decibels. Nonreciprocity originates from unidirectional edge states at the boundary between photonic structures with distinct topological invariants. Our experimental demonstration of lasing from topological cavities provides the opportunity to develop complex topological circuitry of arbitrary geometries for the integrated and robust generation and transport of photons in classical and quantum regimes.
8 【物理】Femtosecond laser reshaping yields gold nanorods with ultranarrow surface plasmon resonances
Guillermo González-Rubio et.al
The irradiation of gold nanorod colloids with a femtosecond laser can be tuned to induce controlled nanorod reshaping, yielding colloids with exceptionally narrow localized surface plasmon resonance bands. The process relies on a regime characterized by a gentle multishot reduction of the aspect ratio, whereas the rod shape and volume are barely affected. Successful reshaping can only occur within a narrow window of the heat dissipation rate: Low cooling rates lead to drastic morphological changes, and fast cooling has nearly no effect. Hence, a delicate balance must be achieved between irradiation fluence and surface density of the surfactant on the nanorods. This perfection process is appealing because it provides a simple, fast, reproducible, and scalable route toward gold nanorods with an optical response of exceptional quality, near the theoretical limit.
9 【物理】A cryofuge for cold-collision experiments with slow polar molecules
Xing Wu， et.al
（导读 阿金）超冷分子作为前沿研究项目，在低速下制备其高密度样品仍具挑战。本研究通过使用非常规的冷冻离心机技术，将低温冷却的分子动能调控至1 K × kB (波尔兹曼常数)，使氟代甲烷和氘代氨样品密度高于每立方厘米109，相互作用时间超过25毫秒，并观察到分子间的低温偶极碰撞，确定了它们的碰撞截面。
Ultracold molecules represent a fascinating research frontier in physics and chemistry, but it has proven challenging to prepare dense samples at low velocities. Here, we present a solution to this goal by means of a nonconventional approach dubbed cryofuge. It uses centrifugal force to bring cryogenically cooled molecules to kinetic energies below 1 K × kB in the laboratory frame, where kB is the Boltzmann constant, with corresponding fluxes exceeding 1010 per second at velocities below 20 meters per second. By attaining densities higher than 109 per cubic centimeter and interaction times longer than 25 milliseconds in samples of fluoromethane as well as deuterated ammonia, we observed cold dipolar collisions between molecules and determined their collision cross sections.
10 【物理】Even-denominator fractional quantum Hall states in bilayer graphene
J. I. A. Li， et.al
The distinct Landau level spectrum of bilayer graphene (BLG) is predicted to support a non-abelian even-denominator fractional quantum Hall (FQH) state similar to the Embedded Image state first identified in GaAs. However, the nature of this state has remained difficult to characterize. Here, we report transport measurements of a robust sequence of even-denominator FQH in dual-gated BLG devices. Parallel field measurement confirms the spin-polarized nature of the ground state, which is consistent with the Pfaffian/anti-Pfaffian description. The sensitivity of the even-denominator states to both filling fraction and transverse displacement field provides new opportunities for tunability. Our results suggest that BLG is a platform in which topological ground states with possible non-abelian excitations can be manipulated and controlled.
11 【进化】Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago
Carina M. Schlebusch and Helena Malmström， et.al
Southern Africa is consistently placed as a potential region for the evolution of Homo sapiens. We present genome sequences, up to 13x coverage, from seven ancient individuals from KwaZulu-Natal, South Africa. The remains of three Stone Age hunter-gatherers (about 2000 years old) were genetically similar to current-day southern San groups, and those of four Iron Age farmers (300 to 500 years old) were genetically similar to present-day Bantu-language speakers. We estimate that all modern-day Khoe-San groups have been influenced by 9 to 30% genetic admixture from East Africans/Eurasians. Using traditional and new approaches, we estimate the first modern human population divergence time to between 350,000 and 260,000 years ago. This estimate increases the deepest divergence among modern humans, coinciding with anatomical developments of archaic humans into modern humans, as represented in the local fossil record.
12 【进化】A high-coverage Neandertal genome from Vindija Cave in Croatia
Kay Prüfer， et.al
（导读 陈月欣） 迄今为止，唯一一份高质量尼安德特人基因组样本来自于南西伯利亚。本研究对约50,000年前克罗地亚Vindija洞穴的一位女性尼安德特人进行了高质量基因组测序，发现他们的群体应该较小，并推测现代人可能拥有比此前估计更多的尼安德特人基因。
To date, the only Neandertal genome that has been sequenced to high quality is from an individual found in Southern Siberia. We sequenced the genome of a female Neandertal from ~50,000 years ago from Vindija Cave, Croatia, to ~30-fold genomic coverage. She carried 1.6 differences per 10,000 base pairs between the two copies of her genome, fewer than present-day humans, suggesting that Neandertal populations were of small size. Our analyses indicate that she was more closely related to the Neandertals that mixed with the ancestors of present-day humans living outside of sub-Saharan Africa than the previously sequenced Neandertal from Siberia, allowing 10 to 20% more Neandertal DNA to be identified in present-day humans, including variants involved in low-density lipoprotein cholesterol concentrations, schizophrenia, and other diseases.
Martin Sikora1 ， et.al
Present-day hunter-gatherers (HGs) live in multilevel social groups essential to sustain a population structure characterized by limited levels of within-band relatedness and inbreeding. When these wider social networks evolved among HGs is unknown. To investigate whether the contemporary HG strategy was already present in the Upper Paleolithic, we used complete genome sequences from Sunghir, a site dated to ~34,000 years before the present, containing multiple anatomically modern human individuals. We show that individuals at Sunghir derive from a population of small effective size, with limited kinship and levels of inbreeding similar to HG populations. Our findings suggest that Upper Paleolithic social organization was similar to that of living HGs, with limited relatedness within residential groups embedded in a larger mating network.
14 【生物】A glycerophospholipid-specific pocket in the RVFV class II fusion protein drives target membrane insertion
P. Guardado-Calvo， et.al
（导读 陈月欣） 在非洲，RVF病毒通过蚊子叮咬在人类和畜类间传播疾病。本研究通过分析RVF病毒 II类融合蛋白Gc融合后的结构，发现蛋白内置的模块将数个融合环同时插入细胞膜改变膜结构并与甘油磷脂（GPL）结合。这样的融合蛋白结构在虫媒病毒中高度保守。
The Rift Valley fever virus (RVFV) is transmitted by infected mosquitoes, causing severe disease in humans and livestock across Africa. We determined the x-ray structure of the RVFV class II fusion protein Gc in its postfusion form and in complex with a glycerophospholipid (GPL) bound in a conserved cavity next to the fusion loop. Site-directed mutagenesis and molecular dynamics simulations further revealed a built-in motif allowing en bloc insertion of the fusion loop into membranes, making few nonpolar side-chain interactions with the aliphatic moiety and multiple polar interactions with lipid head groups upon membrane restructuring. The GPL head-group recognition pocket is conserved in the fusion proteins of other arthropod-borne viruses, such as Zika and chikungunya viruses, which have recently caused major epidemics worldwide.
15 【生物】Spindle asymmetry drives non-Mendelian chromosome segregation
Takashi Akera ， et.al
Genetic elements compete for transmission through meiosis, when haploid gametes are created from a diploid parent. Selfish elements can enhance their transmission through a process known as meiotic drive. In female meiosis, selfish elements drive by preferentially attaching to the egg side of the spindle. This implies some asymmetry between the two sides of the spindle, but the molecular mechanisms underlying spindle asymmetry are unknown. Here we found that CDC42 signaling from the cell cortex regulated microtubule tyrosination to induce spindle asymmetry and that non-Mendelian segregation depended on this asymmetry. Cortical CDC42 depends on polarization directed by chromosomes, which are positioned near the cortex to allow the asymmetric cell division. Thus, selfish meiotic drivers exploit the asymmetry inherent in female meiosis to bias their transmission.
（导读 郭怿暄）女性减数分裂中，一些自私因子通过结合在卵细胞一侧的纺锤体，利用纺锤体的不对称来增强自身传递 。本研究发现位于细胞皮层的CDC42信号通过调节微管酪氨酸化诱导纺锤体的不对称，进而导致染色体的非孟德尔分离，而皮层CDC42依赖由染色体引起的极化。这一发现揭示自私因子利用女性减数分裂过程中内在不对称性增强自身传递的机制。
16 【生物】The condensin complex is a mechanochemical motor that translocates along DNA
Tsuyoshi Terakawa， Shveta Bisht, Jorine M. Eeftens ， et.al
Condensin plays crucial roles in chromosome organization and compaction, but the mechanistic basis for its functions remains obscure. We used single-molecule imaging to demonstrate that Saccharomyces cerevisiae condensin is a molecular motor capable of adenosine triphosphate hydrolysis–dependent translocation along double-stranded DNA. Condensin’s translocation activity is rapid and highly processive, with individual complexes traveling an average distance of ≥10 kilobases at a velocity of ~60 base pairs per second. Our results suggest that condensin may take steps comparable in length to its ~50-nanometer coiled-coil subunits, indicative of a translocation mechanism that is distinct from any reported for a DNA motor protein. The finding that condensin is a mechanochemical motor has important implications for understanding the mechanisms of chromosome organization and condensation.
- Nature论文导读 11092017-11-20 09:54:50
- Nature论文导读 11022017-11-14 11:33:15
- Science论文导读 10272017-11-06 10:39:19
- Nature论文导读 10262017-11-06 10:37:41
- Science论文导读 10202017-10-30 14:56:50
- 2015/06/01 读完这篇文章，再决定做不做博后
- 2015/04/15 Nature上“一分钟充满电”的超级铝
- 2015/04/02 nature中文摘要 2015.3.26
- 2015/04/20 神经科学：电子游戏似乎会改变大
- 2015/04/15 nature中文摘要 2015.4.9
- 2016/03/01 Nature 中文摘要 | 18 June 2015
- 2015/04/10 nature中文摘要 2015.4.2
- 2015/04/13 新研究引发化学周期表位置之争
- 2016/10/12 Nature 中文摘要 | 28 July 2016
- 2015/06/01 科学家发明“制毒酵母”：“黑科