《科学》（20190426出版）一周论文导读

编译 | 唐一尘

Science, 26 April 2019, Volume 364 Issue 6438

《科学》2019年4月26日，第6438期364卷

细胞生物学Cell biology

 

Identification of a mesenchymal progenitor cell hierarchy inadipose tissue

鉴定脂肪组织间充质祖细胞

▲ 作者：David Merrick、Alexander Sakers、Zhazira Irgebay，et al

▲ 链接：

https://science.sciencemag.org/content/364/6438/eaav2501

▲ 摘要：

白色脂肪组织是一种基本的脂肪组织，它能通过储存多余热卡并同时防止脂肪滴在非脂肪组织中积聚而在代谢健康中起着关键作用。

脂肪组织的生长方式有两种：脂肪细胞增加数目或增加体积，后者是一种已知的促成代谢性疾病（如肥胖症或糖尿病）的因素。

因此，代谢健康以及代谢疾病的驱动因子主要依赖于脂肪组织祖细胞（APCs）成为发育完全的成熟脂肪细胞的能力，但相关细胞机制仍然未知。

本研究用单细胞RNA测序对祖细胞进行识别与分析，这些细胞来自幼年小鼠快速发育的白色脂肪组织。

结果发现了几组新的会产生脂肪组织的多能祖细胞，它们中有些驻留在新近发现的解剖微环境中。其中，新确认的一种APC，即DPP4+，可在网状间质中被发现。

研究人员表示，这些结果或能为研发促进健康脂肪生长及预防代谢疾病的靶向手段提供信息。

▲ Abstract

Metabolic health depends on the capacity of adipose tissue progenitor cells to undergo de novo adipogenesis. The cellular hierarchy and mechanisms governing adipocyte progenitor differentiation are incompletely understood. Through single-cell RNA sequence analyses, we show that the lineage hierarchy of adipocyte progenitors consists of distinct mesenchymal cell types that are present in both mouse and human adipose tissues. Cells marked bydipeptidyl peptidase–4 (DPP4)/CD26 expression are highly proliferative, multipotent progenitors. During the development of subcutaneous adipose tissuein mice, these progenitor cells give rise to intercellular adhesion molecule–1(ICAM1)/CD54–expressing (CD54+) committed preadipocytes and a related adipogenic cell population marked by Clec11a and F3/CD142 expression. Transforming growth factor–β maintains DPP4+ cell identity and inhibits adipogenic commitment of DPP4+ andCD142+ cells. Notably, DPP4+ progenitors reside in the reticular interstitium, a recently appreciated fluid-filled space within and between tissues, including adipose depots.

Cell competition during reprogramming gives rise to dominant clones

在重编程过程中细胞竞争产生优势克隆

▲ 作者：Nika Shakiba、Ahmed Fahmy、Gowtham Jayakumaran，et al

▲ 链接：

https://science.sciencemag.org/content/364/6438/eaan0925

▲ 摘要：

从分化的细胞类型中产生诱导多能干细胞的能力使研究人员能够设计细胞状态。虽然，科学家已经确定了将细胞重新编程为多能细胞的分子网络，但对这些过程的细胞动力学仍然知之甚少。

在这里，通过结合细胞条形码、数学建模和谱系追踪方法，研究人员证明了异种种群中的重编程动力学是由占优势的“精英”克隆驱动的。

这项研究强调了细胞动力学在细胞规划结果中的重要性，揭示了细胞竞争作为一种机制，通过这种机制，具有优势的细胞出现，占据和主导重新规划的利基。

▲ Abstract

The ability to generate induced pluripotent stem cells from differentiated cell types has enabled researchers to engineer cell states. Although studies have identified molecular networks that reprogram cells topluripotency, the cellular dynamics of these processes remain poorly understood. Here, by combining cellular barcoding, mathematical modeling, and lineage tracing approaches, we demonstrate that reprogramming dynamics in heterogeneous populations are driven by dominant “elite” clones. Clones arise apriori from a population of poised mouse embryonic fibroblasts derived from Wnt1-expressing cells that may represent a neural crest–derived population.This work highlights the importance of cellular dynamics in fate programming outcomes and uncovers cell competition as a mechanism by which cells with eliteness emerge to occupy and dominate the reprogramming niche.

 

材料Material

Low–interfacial toughness materials for effective large-scale deicing

低界面韧性材料能有效大规模除冰

▲ 作者：Kevin Golovin、Abhishek Dhyani、M. D. Thouless、Anish Tuteja

▲ 链接：

https://science.sciencemag.org/content/364/6438/371

▲ 摘要：

目前，大多数的除冰材料聚焦于将冰与表面间的粘附强度降至最低。然而，将冰与表面分离所需的力量会随着结冰表面面积的变大而增加。

同样地，将冰从特大表面分离可能需要极高强度的力量，并且十分昂贵且对环境不安全。

这里，研究人员将强度限制性除冰与韧性限制性除冰进行了比较，发现降低冰与表面间的韧性而非强度是研发高度疏冰材料的关键。

研究人员表示，对低界面韧性材料而言，除冰已不再作为冰覆盖函数而受到限制。研究人员展示了，用低界面韧性设计的各种塑胶与橡胶涂层去除大面积冰所需力量的大幅减少。

此外，用低界面韧性所制造的一种基于橡胶的疏冰涂层，能令冰仅用自身的重量就干净彻底地与大面积表面分离。

▲ Abstract

Ice accretion has adverse effects on a range of commercial and residential activities. The force required to remove ice from a surface is typically considered to scale with the iced area. This imparts a scalability limit to the use of icephobic coatings for structures with large surface areas, such as power lines or ship hulls. We describe a class of materials that exhibit a low interfacial toughness with ice, resulting in systems for which the forces required to remove large areas of ice (a few square centimeters or greater) are both low and independent of the iced area. We further demonstrate that coatings made of such materials allow ice to be shed readily from largeareas (~1 square meter) merely by self-weight.

Observation of second sound in graphite at temperatures above 100 K

石墨在100 K以上温度下的第二种声观察

▲ 作者：S. Huberman、R. A. Duncan、K. Chen、B. Song，et al

▲ 链接：

https://science.sciencemag.org/content/364/6438/375

▲ 摘要：

固体中的波状热传输，被称为第二种声，这是一种奇特的现象，以前仅在低温下的少数材料中被发现。这种效应的罕见发生，限制了它的科学和实际意义。

利用微米尺度上的热输运时间分辨光学测量方法，研究人员直接观测了石墨在100K（开尔文）以上温度下的第二种声。

研究人员认为，结果表明，在大温度范围内，第二种声对二维和层状材料的微尺度瞬态热传输具有重要的作用。

▲ Abstract

Wavelike thermal transport in solids, referred to as second sound, is an exotic phenomenon previously limited to a handful of materials at low temperatures. The rare occurrence of this effect restricted its scientific and practical importance. We directly observed second sound in graphite attemperatures above 100 kelvins by using time-resolved optical measurements of thermal transport on the micrometer-length scale. Our experimental results are in qualitative agreement with ab initio calculations that predict wavelike phonon hydrodynamics. We believe that these results potentially indicate animportant role of second sound in microscale transient heat transport in two-dimensional and layered materials in a wide temperature range.

环境Environment

Nitrogen isotope evidence for expanded ocean suboxia in the early Cenozoic

新生代早期海洋扩张的氮同位素证据

▲ 作者：Emma R. Kast、DanielA. Stolper、Alexandra Auderset，etal

▲ 链接：

https://science.sciencemag.org/content/364/6438/386

▲ 摘要：

人们对海洋氮循环的百万年变异性知之甚少。

在新生代早期，现在的印度与欧亚板块相撞时，海洋环流发生了变化，对全球海洋生物地球化学产生了巨大的影响——包括反硝化速率的变化——这种影响持续了数百万年。

本研究测定了浮游有孔虫化石氮同位素的变化，分析了7000万至3000万年前全球变冷期间海的洋氮循环。与其他可能被污染的来源不同，有孔虫能受其碳酸盐外壳的保护。

分析显示，随着时间的推移，海洋硝酸盐含量发生了巨大的变化，揭示了一个与今天根本不同的海洋。

此外，δ¹⁵N 的变化与改变海洋环流的大规模事件相一致，例如构造板块碰撞和极地冰盖的扩张。这些结果揭示了海洋环流在调节过去和未来海洋内部氮和氧含量平衡方面的重要性。

▲ Abstract

The million-year variability of the marine nitrogen cycle is poorly understood. Before 57 million years (Ma) ago, the ¹⁵N/¹⁴N ratio (δ¹⁵N) of for aminifera shell-bound organic matter from three sediment cores was high, indicating expanded water column suboxia and denitrification. Between 57 and 50 Ma ago, δ¹⁵N declined by 13 to 16per mil in the North Pacific and by 3 to 8 per mil in the Atlantic. The decline preceded global cooling and appears to have coincided with the early stages ofthe Asia-India collision. Warm, salty intermediate-depth water forming along the Tethys Sea margins may have caused the expanded suboxia, ending with the collision. From 50 to 35 Ma ago, δ¹⁵N was lower than modern values, suggesting widespread sedimentary denitrification on broad continental shelves. δ¹⁵N rose at 35 Ma ago, as ice sheets grew, sea level fell, and continental shelves narrowed.

Rewilding complex ecosystems

再野生化复杂生态系统

▲ 作者：Andrea Perino、Henrique M. Pereira、Laetitia M. Navarro，et al

▲ 链接：

https://science.sciencemag.org/content/364/6438/eaav5570

▲ 摘要：

近年来，再野生化的做法受到了提倡和批评。

支持者认为，这有助于灵活应对环境变化和促进社会与自然重新联系。而批评意见包括对再野生化缺乏清晰的概念，对可能造成的结果缺乏足够了解，以及认为再野生化将人类排除在景观之外。

在这里，研究人员提出了一个解决这些问题的再野生化框架。

他们建议，再野生化的努力应以营养复杂性、自然干扰和散布为目标，将其作为能够提高生态系统恢复力和维持生物多样性的相互作用过程。

研究人员提出了一种结构化的方法，包括评估自然对人类的贡献和对社会生态恢复的约束。

▲ Abstract

The practice of rewilding has been both promoted and criticized in recent years. Benefits include flexibility to react to environmental change and the promotion of opportunities for society to reconnect with nature. Criticisms include the lack of a clear conceptualization of rewilding, insufficient knowledge about possible outcomes, and the perception that rewilding excludes people from landscapes. Here, we present a framework for rewilding that addresses these concerns. We suggest that rewilding efforts should target trophic complexity, natural disturbances, and dispersal as interacting processes that can improve ecosystem resilience and maintain biodiversity. We propose a structured approach to rewilding projects that includes assessment of the contributions of nature to people and the social-ecological constraints on restoration.

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