编译|李言

Nature, 16 January 2025, Volume 637 Issue 8046

《自然》2025年1月16日，第637卷，8046期

材料科学Material Sciences

Janus graphene nanoribbons with localized states on a single zigzag edge

单之字形边缘局域态的Janus石墨烯纳米带

▲ 作者：Shaotang Song, Yu Teng et al.

▲链接：

https://www.nature.com/articles/s41586-024-08296-x

▲摘要：

在此，我们报告设计和制造具有两种不同边缘结构的雅努斯石墨烯纳米带（JGNRs）的方法。在Lieb定理和拓扑分类理论的指导下，我们在一个锯齿形边缘不对称地引入苯基序的拓扑缺陷阵列，同时另一条之字形边缘不变，设计出两种JGNRs。这打破了结构对称性，并在每个晶胞内产生子晶格不平衡，引发自旋对称性破缺。

我们设计了三个之字形前驱体，用于制造母本之字形石墨烯纳米带和两条具有最优缺陷阵列晶格间距的JGNRs，以完全淬灭“缺陷”边缘的磁边缘态。通过扫描探针显微镜和光谱学以及第一性原理密度泛函理论的表征，我们成功制造了JGNRs，其铁磁基态沿未受干扰的之字形边缘局域。

▲ Abstract：

Here we report a general approach for designing and fabricating such ferromagnetic GNRs in the form of Janus GNRs (JGNRs) with two distinct edge configurations. Guided by Lieb’s theorem and topological classification theory, we devised two JGNRs by asymmetrically introducing a topological defect array of benzene motifs to one zigzag edge, while keeping the opposing zigzag edge unchanged. This breaks the structural symmetry and creates a sublattice imbalance within each unit cell, initiating a spin-symmetry breaking. Three Z-shaped precursors are designed to fabricate one parent ZGNR and two JGNRs with an optimal lattice spacing of the defect array for a complete quench of the magnetic edge states at the ‘defective’ edge. Characterization by scanning probe microscopy and spectroscopy and first-principles density functional theory confirms the successful fabrication of JGNRs with a ferromagnetic ground-state localized along the pristine zigzag edge.

地球科学Earth Science

Sulfide-rich continental roots at cratonic margins formed by carbonated melts

碳酸盐熔体在克拉通边缘形成的富含硫化物的大陆根

▲ 作者：Chunfei Chen, Michael W. F?rster et al.

▲链接：

https://www.nature.com/articles/s41586-024-08316-w

▲摘要：

在此，我们整理了全球克拉通橄榄岩的硫和铜含量，确定了克拉通边缘深度160—190公里的富硫化物和富铜大陆根。新的高压实验表明，源自软流圈的碳酸硅酸盐熔体在与岩石圈橄榄岩的反应过程中失去了硅酸盐成分，演化为碳酸盐岩熔体，并集中在克拉通边缘。

这一过程中，随着熔体SiO₂含量的降低，硫在熔体中的溶解度大幅降低，迫使硫化物沉淀，并在地幔岩石圈底部形成富硫化物的大陆根。碳酸化熔体向克拉通边缘的迁移为那里的大陆根补充了硫，解释了岩浆金属矿床与靠近克拉通边缘的碳酸盐岩共存的原因。

这些发现突出了碳酸化熔体在成矿作用中的重要作用，为金属矿勘查提供了潜在途径。

▲ Abstract：

Here we compile sulfur and copper contents of global cratonic peridotites, identifying sulfide-rich and copper-rich continental roots at depths of 160–190?km at cratonic margins. Our new high-pressure experiments show that carbonated silicate melts originating from the asthenosphere lose silicate components during reaction with lithospheric peridotite, evolving to carbonatite melts that become concentrated at cratonic margins. Sulfur solubility in melts substantially decreases as the SiO₂content of melts decreases during this process, forcing sulfide precipitation and the formation of sulfide-rich continental roots at the base of the mantle lithosphere. The migration of carbonated melts towards cratonic margins replenishes the continental roots there with sulfur, explaining the co-location of magmatic metal deposits with carbonatites close to cratonic margins. These findings highlight the notable role of carbonated melts in metallogenesis and provide a potential platform for metal ore exploration.

Diversity and biogeography of the bacterial microbiome in glacier-fed streams

冰川补给河流中细菌微生物群的多样性和生物地理学

▲ 作者：Le?la Ezzat, Hannes Peter et al.

▲链接：

https://www.nature.com/articles/s41586-024-08313-z

▲摘要：

在此，通过利用元条形码和宏基因组学，我们对地球主要山脉的152个冰川补给河流（GFSs）的底栖微生物群细菌进行了全面调查。我们发现GFS细菌微生物组在分类和功能上与其他冰冻圈微生物组不同。

GFS细菌种类繁多，其中一半以上是某些山脉特有的，一些是单一GFS所特有的，还有一些是世界性的，含菌量众多。我们展示了地理隔离和环境选择如何塑造其生物地理，其特征是在山脉和半球之间具有独特的组成模式。系统发育分析进一步揭示了环境选择导致的微多样性分支，可能促进了功能恢复能力，并有助于GFS细菌多样性和生物地理学。

气候导致的冰川消融使这种独特的微生物群处于危险之中。我们的研究为未来可能消失的GFS生态系统上开展气候变化微生物学研究提供了全球性的参考。

▲ Abstract：

Here, by leveraging metabarcoding and metagenomics, we provide a comprehensive survey of bacteria in the benthic microbiome across 152? Glacier-fed streams (GFSs) draining the Earth’s major mountain ranges. We find that the GFS bacterial microbiome is taxonomically and functionally distinct from other cryospheric microbiomes. GFS bacteria are diverse, with more than half being specific to a given mountain range, some unique to single GFSs and a few cosmopolitan and abundant. We show how geographic isolation and environmental selection shape their biogeography, which is characterized by distinct compositional patterns between mountain ranges and hemispheres. Phylogenetic analyses furthermore uncovered microdiverse clades resulting from environmental selection, probably promoting functional resilience and contributing to GFS bacterial biodiversity and biogeography. Climate-induced glacier shrinkage puts this unique microbiome at risk. Our study provides a global reference for future climate-change microbiology studies on the vanishing GFS ecosystem.

生物学Biology

A combinatorial neural code for long-term motor memory

长期运动记忆的组合神经代码

▲ 作者：Jae-Hyun Kim, Kayvon Daie & Nuo Li

▲链接：

https://www.nature.com/articles/s41586-024-08193-3

▲摘要：

在此，我们追踪了老鼠生命周期中学习到的动作的神经表征，并表明学习到的动作在与环境的结合中被稳定地保留，这保护了现有的记忆在新的运动学习中不被抹去。我们建立了一个持续的学习范式。

在这个范式中，老鼠学会了在不同的任务背景下进行定向舔舐。同时我们使用双光子成像跟踪了老鼠长达六个月的运动皮层活动。在相同的任务背景下，驱动定向舔舐的活动随着时间的推移是稳定的，几乎没有代表性漂移。当学习新的任务情境时，新的准备活动出现以驱动相同的舔舐动作。学习创造了新的运动记忆，而不是修改现有的表征。甚至几个月后，在之前的任务环境中重新学习做出同样的动作，也会重新激活之前的准备活动。

对新任务背景的持续学习不断创造新的准备活动模式。正如我们在运动系统中观察到的那样，情境特定记忆可能在持续学习过程中为稳定的记忆存储提供了一种解决方案。

▲ Abstract：

Here we tracked neural representation of learned actions throughout a significant portion of the lifespan of a mouse and show that learned actions are stably retained in combination with context, which protects existing memories from erasure during new motor learning. We established a continual learning paradigm in which mice learned to perform directional licking in different task contexts while we tracked motor cortex activity for up to six months using two-photon imaging. Within the same task context, activity driving directional licking was stable over time with little representational drift. When learning new task contexts, new preparatory activity emerged to drive the same licking actions. Learning created parallel new motor memories instead of modifying existing representations. Re-learning to make the same actions in the previous task context re-activated the previous preparatory activity, even months later. Continual learning of new task contexts kept creating new preparatory activity patterns. Context-specific memories, as we observed in the motor system, may provide a solution for stable memory storage throughout continual learning.

Diatom phytochromes integrate the underwater light spectrum to sense depth

硅藻光敏色素整合水下光谱来感知深度

▲ 作者：Carole Duchêne, Jean-Pierre Bouly et al.

▲链接：

https://www.nature.com/articles/s41586-024-08301-3

▲摘要：

在此，通过对硅藻光敏色素（DPH）介导的光谱变化进行体内剂量响应分析，我们发现DPH可以在整个光谱中触发光可逆反应，导致DPH光平衡随深度的变化。通过在硅藻Thalassiosira pseudonana中产生DPH突变体，我们还证明了在模拟海洋深度的低蓝光条件下，DPH调节光合作用适应，从而将光学深度检测与功能响应联系起来。

从永久分层区到季节混合区含DPH硅藻的纬度分布表明，DPH功能在应对水体垂直位移方面具有一定的适应性。通过将DPH作为光学深度探测器，我们的研究提供了一种新的视角，即嵌入在水下光场的信息如何被硅藻利用以调节其在光区的生理作用。

▲ Abstract：

Here, by developing an in vivo dose–response assay to light spectral variations mediated by DPH, we show that DPH can trigger photoreversible responses across the entire light spectrum, resulting in a change in DPH photoequilibrium with depth. By generating dph mutants in the diatom Thalassiosira pseudonana, we also demonstrate that under simulated low-blue-light conditions of ocean depth, DPH regulates photosynthesis acclimation, thus linking optical depth detection with a functional response. The latitudinal distribution of DPH-containing diatoms from permanently stratified regions to seasonally mixed regions suggests an adaptive value of DPH functions in coping with vertical displacements in the water column. By establishing DPH as a detector of optical depth, this study provides a new view of how information embedded in the underwater light field can be exploited by diatoms to modulate their physiology throughout the photic zone.

古生物学Paleontology

New Silurian aculiferan fossils reveal complex early history of Mollusca

新志留纪甲壳纲化石揭示了软体动物复杂的早期历史

▲ 作者：Mark D. Sutton, Julia D. Sigwart et al.

▲链接：

https://www.nature.com/articles/s41586-024-08312-0

▲摘要：

在此，我们描述了两种新的三维保存的甲壳纲物种，它们来自志留纪的赫里福德郡，大大扩展了该分支的形态和生态范围。系统发育分析表明它们在一个复杂的类群关系中的位置，显示基本特征状态会发生逆转，如瓣膜的存在和脚的性质。

与先前的形态保守性假设相反，早期甲壳纲物种的进化产生了大量不寻常的形式，与其他冠类软体动物的多样化相当。

▲ Abstract：

Here we describe two new three-dimensionally preserved aculiferan species from the Silurian Herefordshire Lagerst?tte, which substantially extend the morphological and ecological range of the clade. Phylogenetic analyses indicate positions within a complex nexus of taxa and suggest reversals in the states of fundamental characters such as the presence of valves and the nature of the foot. In contrast to previous hypotheses of morphological conservatism, evolution in early aculiferans generated a profusion of unusual forms comparable to the diversification of other crown-group molluscs.