来自杂志 Nature 的文献。
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61.
哪有情可长
(2022-06-30 22:52):
#paper 10.1038/s41586-020-03091-w. Nature. Genomic basis of geographical adaptation to soil nitrogen in rice. 推荐理由:这篇文章是水稻里面发现了一个关于适应当地土壤环境相关氮利用效率的基因。本研究课题的试验方式是先通过GWAS在不同区域环境下氮素利用的密切相关的性状进行定位,鉴定发现OsTCP19。后续发现该基因缺失了29bp的插入导致不同水稻品种之间不同的基因表达量和对氮素反应分蘖能力的变化。在野生稻和栽培稻中鉴定该基因29bp位点的变化,且发现现代栽培品种中该位点丢失,丢失的位点导致氮的利用率低。后续又进行全国各个区域试验,证明这个基因能够提高氮利用率,可以减少氮肥的施用,也能改善土壤中过量的氮素对环境的污染。很漂亮的正向遗传研究,从基因定位,得到转基因,转基因验证,大田产量验证,每一步逻辑都很严谨且证明的过程流畅。
Abstract:
The intensive application of inorganic nitrogen underlies marked increases in crop production, but imposes detrimental effects on ecosystems: it is therefore crucial for future sustainable agriculture to improve the nitrogen-use …
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The intensive application of inorganic nitrogen underlies marked increases in crop production, but imposes detrimental effects on ecosystems: it is therefore crucial for future sustainable agriculture to improve the nitrogen-use efficiency of crop plants. Here we report the genetic basis of nitrogen-use efficiency associated with adaptation to local soils in rice (Oryza sativa L.). Using a panel of diverse rice germplasm collected from different ecogeographical regions, we performed a genome-wide association study on the tillering response to nitrogen-the trait that is most closely correlated with nitrogen-use efficiency in rice-and identified OsTCP19 as a modulator of this tillering response through its transcriptional response to nitrogen and its targeting to the tiller-promoting gene DWARF AND LOW-TILLERING (DLT). A 29-bp insertion and/or deletion in the OsTCP19 promoter confers a differential transcriptional response and variation in the tillering response to nitrogen among rice varieties. The allele of OsTCP19 associated with a high tillering response to nitrogen is prevalent in wild rice populations, but has largely been lost in modern cultivars: this loss correlates with increased local soil nitrogen content, which suggests that it might have contributed to geographical adaptation in rice. Introgression of the allele associated with a high tillering response into modern rice cultivars boosts grain yield and nitrogen-use efficiency under low or moderate levels of nitrogen, which demonstrates substantial potential for rice breeding and the amelioration of negative environment effects by reducing the application of nitrogen to crops.
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62.
颜林林
(2022-06-09 07:56):
#paper doi:10.1038/s41586-022-04803-0 Nature, 2022, Cohesin-mediated loop anchors confine the locations of human replication origins. 这篇新发表在Nature上的文章,来自一项大型研究项目,The 4D nucleome project (doi:10.1038/nature23884),该项目旨在开发并应用一系列生物技术方法,研究人类和小鼠基因组在时空上的结构特性,以深入了解细胞核的组织和功能,4D指的正是三维空间结构加上时间动态变化。在这篇文章中,作者们主要对该项目 Phase 1 的 Tier 1 H1 Human hES (hES) 细胞系的 Hi-C 数据进行分析,通过其自研方法,鉴定出全基因组水平上高分辨率的 TADs/subTADs(拓扑关联域/拓扑关联子域),并分析它们与染色质loop、DNA复制起始区(IZ)之间的分布关系,结合这些数据的采集方法及细胞所处周期等信息,提出由cohesin介导的loop挤压和复制推动的相关模型。同时,使用靶向 CRISPR–Cas9 基因组编辑方法,干扰CTCF+cohesin后对复制的影响,也验证了该模型。这项工作展示了如何通过组学数据分析,提出在分子细胞生物学相应概念模型的研究方法,很值得学习。
Abstract:
DNA replication occurs through an intricately regulated series of molecular events and is fundamental for genome stability. At present, it is unknown how the locations of replication origins are determined …
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DNA replication occurs through an intricately regulated series of molecular events and is fundamental for genome stability. At present, it is unknown how the locations of replication origins are determined in the human genome. Here we dissect the role of topologically associating domains (TADs), subTADs and loops in the positioning of replication initiation zones (IZs). We stratify TADs and subTADs by the presence of corner-dots indicative of loops and the orientation of CTCF motifs. We find that high-efficiency, early replicating IZs localize to boundaries between adjacent corner-dot TADs anchored by high-density arrays of divergently and convergently oriented CTCF motifs. By contrast, low-efficiency IZs localize to weaker dotless boundaries. Following ablation of cohesin-mediated loop extrusion during G1, high-efficiency IZs become diffuse and delocalized at boundaries with complex CTCF motif orientations. Moreover, G1 knockdown of the cohesin unloading factor WAPL results in gained long-range loops and narrowed localization of IZs at the same boundaries. Finally, targeted deletion or insertion of specific boundaries causes local replication timing shifts consistent with IZ loss or gain, respectively. Our data support a model in which cohesin-mediated loop extrusion and stalling at a subset of genetically encoded TAD and subTAD boundaries is an essential determinant of the locations of replication origins in human S phase.
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63.
颜林林
(2022-06-03 12:22):
#paper doi:10.1038/s41586-022-04759-1 Nature 2022, Fast and efficient DNA replication with purified human proteins. 这篇新发表的Nature文章,是还原论研究方法的典范。通过人工合成的方法,用43个多肽,从头构建了体外的多个DNA合成因子,并组装成具有生物活性的复合物,重现了快速高效的DNA合成过程。由于是完全人工合成,所以通过这个体系,可以研究各个组分在DNA复制过程中的必要性,以及组分之间的相互关系,并确认可以不需要其他更多额外分子。这项研究重点研究了人体DNA合成中的PCNA、CLASPIN、TIMELESS-TIPIN、AND-1等组分在相应合成步骤中的作用。
Abstract:
Chromosome replication is performed by a complex and intricate ensemble of proteins termed the replisome, where the DNA polymerases Polδ and Polε, DNA polymerase α-primase (Polα) and accessory proteins including …
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Chromosome replication is performed by a complex and intricate ensemble of proteins termed the replisome, where the DNA polymerases Polδ and Polε, DNA polymerase α-primase (Polα) and accessory proteins including AND-1, CLASPIN and TIMELESS-TIPIN (respectively known as Ctf4, Mrc1 and Tof1-Csm3 in Saccharomyces cerevisiae) are organized around the CDC45-MCM-GINS (CMG) replicative helicase. Because a functional human replisome has not been reconstituted from purified proteins, how these factors contribute to human DNA replication and whether additional proteins are required for optimal DNA synthesis are poorly understood. Here we report the biochemical reconstitution of human replisomes that perform fast and efficient DNA replication using 11 purified human replication factors made from 43 polypeptides. Polε, but not Polδ, is crucial for optimal leading-strand synthesis. Unexpectedly, Polε-mediated leading-strand replication is highly dependent on the sliding-clamp processivity factor PCNA and the alternative clamp loader complex CTF18-RFC. We show how CLASPIN and TIMELESS-TIPIN contribute to replisome progression and demonstrate that, in contrast to the budding yeast replisome, AND-1 directly augments leading-strand replication. Moreover, although AND-1 binds to Polα, the interaction is dispensable for lagging-strand replication, indicating that Polα is functionally recruited via an AND-1-independent mechanism for priming in the human replisome. Collectively, our work reveals how the human replisome achieves fast and efficient leading-strand and lagging-strand DNA replication, and provides a powerful system for future studies of the human replisome and its interactions with other DNA metabolic processes.
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64.
李翛然
(2022-05-31 23:45):
#paper doi:10.1038/s41586-022-04463-0 nature FSH blockade improves cognition in mice with Alzheimer’s disease FSH,2022年3月发表在Nature正刊,用于治疗老年痴呆症,调控 beta蛋白和Tau蛋白.本文是多个描述AZ疾病的论文中比较肯定的这个荷尔蒙作用。目前是一个潜在的重要靶点
Abstract:
Alzheimer's disease has a higher incidence in older women, with a spike in cognitive decline that tracks with visceral adiposity, dysregulated energy homeostasis and bone loss during the menopausal transition. …
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Alzheimer's disease has a higher incidence in older women, with a spike in cognitive decline that tracks with visceral adiposity, dysregulated energy homeostasis and bone loss during the menopausal transition. Inhibiting the action of follicle-stimulating hormone (FSH) reduces body fat, enhances thermogenesis, increases bone mass and lowers serum cholesterol in mice. Here we show that FSH acts directly on hippocampal and cortical neurons to accelerate amyloid-β and Tau deposition and impair cognition in mice displaying features of Alzheimer's disease. Blocking FSH action in these mice abrogates the Alzheimer's disease-like phenotype by inhibiting the neuronal C/EBPβ-δ-secretase pathway. These data not only suggest a causal role for rising serum FSH levels in the exaggerated Alzheimer's disease pathophysiology during menopause, but also reveal an opportunity for treating Alzheimer's disease, obesity, osteoporosis and dyslipidaemia with a single FSH-blocking agent.
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65.
颜林林
(2022-05-31 07:28):
#paper doi:10.1038/s41586-021-03583-3 Nature 2021, Swarm Learning for decentralized and confidential clinical machine learning. 精准医学的发展得益于数据的快速积累,然而数据共享却始终是数据充分使用的重大障碍。本文提出一种群体学习方法,它结合了边缘计算、区块链等技术,使数据拥有者可以在不违反隐私法规的情况下,让数据可以在全球范围被集成使用,从而解决药物靶标发现、诊断标志物发现等精准医学研究目标所亟需的大规模数据整合需求。为验证该方法的可行性,本文选取了四种疾病,新冠、结核、白血病和肺病,包括血液转录组和胸部X光片数据,且这些数据存在普遍的异质性和对照分布不均匀等问题,对这些数据进行此群体学习的分析。通过将数据分散到不同网络节点,并让这些节点动态加入计算,最终实现对这些疾病的识别或亚型鉴定,并与传统机器学习方法结果进行对比。本文最近在Nature Reviews Immunology的一篇comment上被再次提及,并介绍了其白血病临床诊断已被欧盟成功标准化并随后商业化,进一步验证了该方法的实际价值。同时,由于它以“共享见解而非共享数据(sharing insights, not data)”的方式进行协作,对于当下诸如医学免疫学等复杂研究,也将起到更大作用。
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Fast and reliable detection of patients with severe and heterogeneous illnesses is a major goal of precision medicine. Patients with leukaemia can be identified using machine learning on the basis …
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Fast and reliable detection of patients with severe and heterogeneous illnesses is a major goal of precision medicine. Patients with leukaemia can be identified using machine learning on the basis of their blood transcriptomes. However, there is an increasing divide between what is technically possible and what is allowed, because of privacy legislation. Here, to facilitate the integration of any medical data from any data owner worldwide without violating privacy laws, we introduce Swarm Learning-a decentralized machine-learning approach that unites edge computing, blockchain-based peer-to-peer networking and coordination while maintaining confidentiality without the need for a central coordinator, thereby going beyond federated learning. To illustrate the feasibility of using Swarm Learning to develop disease classifiers using distributed data, we chose four use cases of heterogeneous diseases (COVID-19, tuberculosis, leukaemia and lung pathologies). With more than 16,400 blood transcriptomes derived from 127 clinical studies with non-uniform distributions of cases and controls and substantial study biases, as well as more than 95,000 chest X-ray images, we show that Swarm Learning classifiers outperform those developed at individual sites. In addition, Swarm Learning completely fulfils local confidentiality regulations by design. We believe that this approach will notably accelerate the introduction of precision medicine.
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66.
笑对人生
(2022-04-30 21:43):
#paper The single-cell transcriptional landscape of mammalian organogenesis Cao J, et al. Nature. 2019 Feb;566(7745):496-502. doi: 10.1038/s41586-019-0969-x
该文章是利用一种名为sci-RNA-seq3超高通量单细胞测序技术,该技术一次实验可完成大约200万个细胞转录组测序建库,单人完成的时间为1周,成本为每个细胞0.01美元。该研究主要是对小鼠不同发育阶段的61个胚胎(E9.5到E13.5)的单细胞转录图谱进行了描述,该图谱命名为MOCA(mouse organogenesis cell altas)。文章虽然不是很新,但这是monocle3首次在scRNAseq(单细胞转录组测序)的应用案例,提供monocle3详尽的基本原理和分析思路。从文章的作者列表来看,也发现有monocle3软件开发者的名字。monocle3是一款用于scRNAseq拟时序分析的工具,为monocle2更新版本。虽然,monocle2是目前已发表文章的应用较为广泛的一款版本,但是它在实际使用时存在一些问题,第一,monocle2使用的细胞降维方式与seurat(一款流行的,能独立完成从细胞-基因表达矩阵到细胞降维聚类分群的scRNAseq工具)并不兼容;第二,该版本已被作者弃用并停止维护,实际应用中发现一些bug,却难以找到解决的方案。在生信分析中,如何选择软件往往是一个难题(这可能也是很多评测文章出现的原因)。作为一名工具的使用者,可以在充分理解算法原理的基础上,结合自己的研究,并通过调试,最终做出适当的选择。
Abstract:
Mammalian organogenesis is a remarkable process. Within a short timeframe, the cells of the three germ layers transform into an embryo that includes most of the major internal and external …
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Mammalian organogenesis is a remarkable process. Within a short timeframe, the cells of the three germ layers transform into an embryo that includes most of the major internal and external organs. Here we investigate the transcriptional dynamics of mouse organogenesis at single-cell resolution. Using single-cell combinatorial indexing, we profiled the transcriptomes of around 2 million cells derived from 61 embryos staged between 9.5 and 13.5 days of gestation, in a single experiment. The resulting 'mouse organogenesis cell atlas' (MOCA) provides a global view of developmental processes during this critical window. We use Monocle 3 to identify hundreds of cell types and 56 trajectories, many of which are detected only because of the depth of cellular coverage, and collectively define thousands of corresponding marker genes. We explore the dynamics of gene expression within cell types and trajectories over time, including focused analyses of the apical ectodermal ridge, limb mesenchyme and skeletal muscle.
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67.
吴增丁
(2022-04-02 11:39):
#paper Sahin, U., Oehm, P., Derhovanessian, E. et al. An RNA vaccine drives immunity in checkpoint-inhibitor-treated melanoma. Nature 585, 107–112 (2020). doi:org/10.1038/s41586-020-2537-9
这篇2020年发表在Nautre文章介绍了BioNtech关于FixVac BNT111的I期临床结果,它是2016年pre-clinical 研究( doi.org/10.1038/nature18300)的clinical 研究的延续。该文章首先介绍了临床研究设计:
1.药物核心还是用临川前验证有效的RNA-LPX载体递送四个TAA (NY-ESO-1/Tyrosinase/MAGE-A3/TPTE); 2.通过总共纳入了89例黑色素瘤患者,做了 a.剂量爬坡 、b.剂量范围(7.2-400ug totalRNA)、c. 单用及联合PD-1 抑制剂分别进行cohort验证药效和安全性分析。
最终结果显示单独或与PD1抑制剂联用,都可以介导晚期无法手术的患者产生客观缓解(OR)。通过进一步研究分析产生客观缓解的患者体内伴随着很强的CD4+和CD8+ T 细胞,这个水平几乎和T-cell治疗的水平相当,并且有持久效果。综合显示,TAA BNT111对治疗黑色素瘤取得较好效果。
Abstract:
Treating patients who have cancer with vaccines that stimulate a targeted immune response is conceptually appealing, but cancer vaccine trials have not been successful in late-stage patients with treatment-refractory tumours. …
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Treating patients who have cancer with vaccines that stimulate a targeted immune response is conceptually appealing, but cancer vaccine trials have not been successful in late-stage patients with treatment-refractory tumours. We are testing melanoma FixVac (BNT111)-an intravenously administered liposomal RNA (RNA-LPX) vaccine, which targets four non-mutated, tumour-associated antigens that are prevalent in melanoma-in an ongoing, first-in-human, dose-escalation phase I trial in patients with advanced melanoma (Lipo-MERIT trial, ClinicalTrials.gov identifier NCT02410733). We report here data from an exploratory interim analysis that show that melanoma FixVac, alone or in combination with blockade of the checkpoint inhibitor PD1, mediates durable objective responses in checkpoint-inhibitor (CPI)-experienced patients with unresectable melanoma. Clinical responses are accompanied by the induction of strong CD4 and CD8 T cell immunity against the vaccine antigens. The antigen-specific cytotoxic T-cell responses in some responders reach magnitudes typically reported for adoptive T-cell therapy, and are durable. Our findings indicate that RNA-LPX vaccination is a potent immunotherapy in patients with CPI-experienced melanoma, and suggest the general utility of non-mutant shared tumour antigens as targets for cancer vaccination.
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68.
吴增丁
(2022-04-01 16:41):
#paper Kranz, L., Diken, M., Haas, H. et al. Systemic RNA delivery to dendritic cells exploits antiviral defence for cancer immunotherapy. Nature 534, 396–401 (2016). DOI:10.1038/nature18300 该文章是BioNtech在2016年发表的,展示了其公司开发的RNA-LPX递送载体技术,以及利用该提送技术成功地将包含四个Tumor associate antigen (NY-SYO-1,MAGE-A3,tyrosinase,TPTE)的FixVac panel,成功推到了临床研究阶段。1.该研究在pre-clinical阶段:a.探索了LPX载体的生产工艺,包括其电荷比,mRNA:Lipid比例等关键参数等。b.探索了mRNA在老鼠体内的表达位置,通过调整DOTAM/DOPE比例,将mRNA的表达主要局限在spleen和骨髓中;c.通过注射能表达流感免疫原的mRNA,评估确定了mRNA能正常表达,且在老鼠体内产生了免疫反应;d.在小鼠体内也能对肿瘤产生免疫反应;2. 在clinical阶段,采用了四个在黑色素瘤中特异高表达的Tumor associate antigen (NY-SYO-1,MAGE-A3,tyrosinase,TPTE),并对纳入临床研究的几例patien分析评估其产生了免疫反应。
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Lymphoid organs, in which antigen presenting cells (APCs) are in close proximity to T cells, are the ideal microenvironment for efficient priming and amplification of T-cell responses. However, the systemic …
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Lymphoid organs, in which antigen presenting cells (APCs) are in close proximity to T cells, are the ideal microenvironment for efficient priming and amplification of T-cell responses. However, the systemic delivery of vaccine antigens into dendritic cells (DCs) is hampered by various technical challenges. Here we show that DCs can be targeted precisely and effectively in vivo using intravenously administered RNA-lipoplexes (RNA-LPX) based on well-known lipid carriers by optimally adjusting net charge, without the need for functionalization of particles with molecular ligands. The LPX protects RNA from extracellular ribonucleases and mediates its efficient uptake and expression of the encoded antigen by DC populations and macrophages in various lymphoid compartments. RNA-LPX triggers interferon-α (IFNα) release by plasmacytoid DCs and macrophages. Consequently, DC maturation in situ and inflammatory immune mechanisms reminiscent of those in the early systemic phase of viral infection are activated. We show that RNA-LPX encoding viral or mutant neo-antigens or endogenous self-antigens induce strong effector and memory T-cell responses, and mediate potent IFNα-dependent rejection of progressive tumours. A phase I dose-escalation trial testing RNA-LPX that encode shared tumour antigens is ongoing. In the first three melanoma patients treated at a low-dose level, IFNα and strong antigen-specific T-cell responses were induced, supporting the identified mode of action and potency. As any polypeptide-based antigen can be encoded as RNA, RNA-LPX represent a universally applicable vaccine class for systemic DC targeting and synchronized induction of both highly potent adaptive as well as type-I-IFN-mediated innate immune mechanisms for cancer immunotherapy.
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69.
李翛然
(2022-03-31 00:44):
#paper doi: 10.1038/s41586-022-04654-9 Nature,2022 Design of protein binding proteins from target structure alone.
这篇文章我是一定要吐槽一下的!!!!上周5居然被Nature 接受了?!?!这个是我最我无法理解的,去年DeepMind投了预印本开始,我们就开始跟踪这个文章了。其中的所有方法我们已经复现并加以改进,但是团队的所有人都不认为应该被Nature接收。
原因是以下几点:
1,其原理非常简单易懂,就是利用现有的一些氨基酸序列,逐渐地解析靶点结构,然后拼出来新的氨基酸序列。
2,根据AlphaFlod将靶点结构拆解出来,找到相关的合适位置,然后通过检索的方式找到合适的小氨基酸序列(这一步也没有问题,AI生成模型也会这么做)
3,但是下一步就太扯了!因为最关键的步骤来了,就是如何评判找到和生成的氨基酸与靶点的对接亲和力?以及如何评价对接强度? 也是强化学习的关键Q函数到底是啥
他居然用了DeepMind 和华盛顿大学的历史遗留工具集:RoseTTA!!!!最最关键的评分函数居然用自己团队曾经的开源工具集!(大分子准确度也就撑死20%不到)
太不可思议了!!完全没有试验验证和支持的文章居然被Nature 主刊接收了?!?!天啊,这可和ALphaFLod开创性是比不了的,人家是引入了全新的数学工具和解决问题的思路,这文章完全是蹭出来的。
只能说Google,DeepMind 以及华盛顿大学 背后的学术公关和关系网太庞大了!
不过另一方面,只能说的是,生物学过去的发展太慢了,AI行业内卷外溢之后,真的是降维打击!
Abstract:
The design of proteins that bind to a specific site on the surface of a target protein using no information other than the three-dimensional structure of the target remains a …
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The design of proteins that bind to a specific site on the surface of a target protein using no information other than the three-dimensional structure of the target remains a challenge. Here we describe a general solution to this problem that starts with a broad exploration of the vast space of possible binding modes to a selected region of a protein surface, and then intensifies the search in the vicinity of the most promising binding modes. We demonstrate the broad applicability of this approach through the de novo design of binding proteins to 12 diverse protein targets with different shapes and surface properties. Biophysical characterization shows that the binders, which are all smaller than 65 amino acids, are hyperstable and, following experimental optimization, bind their targets with nanomolar to picomolar affinities. We succeeded in solving crystal structures of five of the binder-target complexes, and all five closely match the corresponding computational design models. Experimental data on nearly half a million computational designs and hundreds of thousands of point mutants provide detailed feedback on the strengths and limitations of the method and of our current understanding of protein-protein interactions, and should guide improvements of both. Our approach enables the targeted design of binders to sites of interest on a wide variety of proteins for therapeutic and diagnostic applications.
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70.
张贝
(2022-03-31 00:05):
#paper doi: 10.1038/s41586-021-03828-1 Nature, 2021, Highly accurate protein structure prediction for the human proteome. AlphaFold2是由DeepMind公司开发的人工智能系统,能够基于氨基酸序列,精确预测蛋白质的3D结构。预测的准确性可以与使用冷冻电镜、X射线衍射等手段解析的3D结构相媲美。AlphaFold2与基础版本相比,在蛋白结构解析的速度方面提升约16倍。本文利用AlphaFold2对98.5%的人类蛋白进行结构预测,并将预测的结果免费向公众开放。AlphaFold2能对人类蛋白质组58%的氨基酸的结构位置给出可信预测,且能对蛋白复合体的结构进行较好预测,其中低置信度的预测结果可能代表蛋白结构的无序状态。AlphaFold的出现代表人工智能驱动的生物学研究时代的来临。
Abstract:
Protein structures can provide invaluable information, both for reasoning about biological processes and for enabling interventions such as structure-based drug development or targeted mutagenesis. After decades of effort, 17% of …
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Protein structures can provide invaluable information, both for reasoning about biological processes and for enabling interventions such as structure-based drug development or targeted mutagenesis. After decades of effort, 17% of the total residues in human protein sequences are covered by an experimentally determined structure. Here we markedly expand the structural coverage of the proteome by applying the state-of-the-art machine learning method, AlphaFold, at a scale that covers almost the entire human proteome (98.5% of human proteins). The resulting dataset covers 58% of residues with a confident prediction, of which a subset (36% of all residues) have very high confidence. We introduce several metrics developed by building on the AlphaFold model and use them to interpret the dataset, identifying strong multi-domain predictions as well as regions that are likely to be disordered. Finally, we provide some case studies to illustrate how high-quality predictions could be used to generate biological hypotheses. We are making our predictions freely available to the community and anticipate that routine large-scale and high-accuracy structure prediction will become an important tool that will allow new questions to be addressed from a structural perspective.
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71.
masion
(2022-02-28 22:39):
#paper doi.org/10.1038/nature11681 Nature volume 492, pages59–65 (2012),Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs
通过对以吞没某些真核藻类而获得光合作用的内共生体中的过渡形式吉氏藻Guillardia theta和纳氏毕氏藻Bigelowiella natans的核基因组进行测序,揭示了单细胞生物体(纳氏毕氏藻)前所未有的选择性剪接以及广泛的遗传和生化镶嵌现象,揭示了为什么会在这些物种中存在,而不存在于其他藻类中。
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 …
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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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72.
傅宇蕾
(2022-02-28 18:08):
#paper Dexterous magnetic manipulation of conductive non-magnetic objects. #DOI: 10.1038/s41586-021-03966-6 这是一篇通过对非磁性材料进行操控的文章,利用磁场(由永磁、电磁或超导产生)和感生的磁场(由感生或,或铁磁材料产生),相互做哟个形成的里进行操控。区别于小轩,操控用到的是三自由度的过程。优点在于针对导电材料可以实现非接触操控,缺点在于力小,速度慢,实时性差。针对空间场景来说,目前离应用较远。
Abstract:
Dexterous magnetic manipulation of ferromagnetic objects is well established, with three to six degrees of freedom possible depending on object geometry. There are objects for which non-contact dexterous manipulation is …
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Dexterous magnetic manipulation of ferromagnetic objects is well established, with three to six degrees of freedom possible depending on object geometry. There are objects for which non-contact dexterous manipulation is desirable that do not contain an appreciable amount of ferromagnetic material but do contain electrically conductive material. Time-varying magnetic fields generate eddy currents in conductive materials, with resulting forces and torques due to the interaction of the eddy currents with the magnetic field. This phenomenon has previously been used to induce drag to reduce the motion of objects as they pass through a static field, or to apply force on an object in a single direction using a dynamic field, but has not been used to perform the type of dexterous manipulation of conductive objects that has been demonstrated with ferromagnetic objects. Here we show that manipulation, with six degrees of freedom, of conductive objects is possible by using multiple rotating magnetic dipole fields. Using dimensional analysis, combined with multiphysics numerical simulations and experimental verification, we characterize the forces and torques generated on a conductive sphere in a rotating magnetic dipole field. With the resulting model, we perform dexterous manipulation in simulations and physical experiments.
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73.
十年
(2022-02-12 20:00):
#paper doi:10.1038/s41586-021-04223-6 Wright et al., Deep physical neural networks trained with backpropagation. Nature 601,549-555(2022) 传说中的万物皆可神经网络,作者提出PNN(physical neutral network),在机械、光学、电子方面效果贼好。万物皆可神经网络,牛逼格拉斯。
Abstract:
Deep-learning models have become pervasive tools in science and engineering. However, their energy requirements now increasingly limit their scalability. Deep-learning accelerators aim to perform deep learning energy-efficiently, usually targeting the …
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Deep-learning models have become pervasive tools in science and engineering. However, their energy requirements now increasingly limit their scalability. Deep-learning accelerators aim to perform deep learning energy-efficiently, usually targeting the inference phase and often by exploiting physical substrates beyond conventional electronics. Approaches so far have been unable to apply the backpropagation algorithm to train unconventional novel hardware in situ. The advantages of backpropagation have made it the de facto training method for large-scale neural networks, so this deficiency constitutes a major impediment. Here we introduce a hybrid in situ-in silico algorithm, called physics-aware training, that applies backpropagation to train controllable physical systems. Just as deep learning realizes computations with deep neural networks made from layers of mathematical functions, our approach allows us to train deep physical neural networks made from layers of controllable physical systems, even when the physical layers lack any mathematical isomorphism to conventional artificial neural network layers. To demonstrate the universality of our approach, we train diverse physical neural networks based on optics, mechanics and electronics to experimentally perform audio and image classification tasks. Physics-aware training combines the scalability of backpropagation with the automatic mitigation of imperfections and noise achievable with in situ algorithms. Physical neural networks have the potential to perform machine learning faster and more energy-efficiently than conventional electronic processors and, more broadly, can endow physical systems with automatically designed physical functionalities, for example, for robotics, materials and smart sensors.
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74.
尹志
(2022-01-31 12:53):
#paper doi:10.1038/nature14539 LeCun, Y., Bengio, Y. & Hinton, G. Deep learning. Nature 521, 436–444 (2015). 这是深度学习三巨头于2015年写的一篇nature综述。也是nature纪念AI60周年的一系列综述paper里的一篇。这篇paper综述了深度学习这一热门主题。当然,作为深度学习的几位奠基人,确实把深度学习的概念原理应用写的深入浅出。本文从监督学习一直介绍到反向传播,主要综述了CNN和RNN的原理及其应用,很适合初学者全面了解(当时)的深度学习的概貌。在最后一段深度学习的未来一节,作者对无监督学习的未来报以热烈的期望,看看这几年,特别是yann lecun大力推动的自监督成为显学,也算是念念不忘必有回响了。
Abstract:
Deep learning allows computational models that are composed of multiple processing layers to learn representations of data with multiple levels of abstraction. These methods have dramatically improved the state-of-the-art in …
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Deep learning allows computational models that are composed of multiple processing layers to learn representations of data with multiple levels of abstraction. These methods have dramatically improved the state-of-the-art in speech recognition, visual object recognition, object detection and many other domains such as drug discovery and genomics. Deep learning discovers intricate structure in large data sets by using the backpropagation algorithm to indicate how a machine should change its internal parameters that are used to compute the representation in each layer from the representation in the previous layer. Deep convolutional nets have brought about breakthroughs in processing images, video, speech and audio, whereas recurrent nets have shone light on sequential data such as text and speech.
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