《科学》（20190111出版）一周论文导读

Science, 11 JANUARY 2019, VOL 363, ISSUE 6423

《科学》2019年1月11日，第6423期363卷

动物学 Zoology

 

Problem-solving males become more attractive to female budgerigars

能解决问题的雄性对雌性虎皮鹦鹉更有吸引力

▲ 作者：Jiani Chen、Yuqi Zou、Yue-Hua Sun、Carel ten Cate

▲ 链接：

http://science.sciencemag.org/content/363/6423/166

▲ 摘要：

达尔文曾提出配偶选择可能有助于认知能力的进化。

但人们对认知的适合性裨益以及其基础选择机制还不甚理解，对人以外的物种也鲜有研究。

本文表明，显得聪明的雄性虎皮鹦鹉会在雌性同类中变得更具吸引力。

直接看到“聪明行为”（如能解决问题而获取食物）会影响鸟类的择偶偏向，令独擅胜场的雄鸟成为雌性优先考虑的配偶。

但这些结论是有局限性的，它们没有直接论及认知能力对择偶选择的作用。

▲ Abstract

Darwin proposed that mate choice might contribute to the evolution of cognitive abilities. An open question is whether observing the cognitive skills of an individual makes it more attractive as a mate. In this study, we demonstrated that initially less-preferred budgerigar males became preferred after females observed that these males, but not the initially preferred ones, were able to solve extractive foraging problems. This preference shift did not occur in control experiments in which females observed males with free access to food or in which females observed female demonstrators solving these extractive foraging problems. Our results suggest that direct observation of problem-solving skills increases male attractiveness and that this could contribute to the evolution of the cognitive abilities underlying such skills.

Termites mitigate the effects of drought in tropical rainforest

白蚁减轻热带雨林干旱的影响

▲ 作者：L. A. Ashton、H. M. Griffiths、C. L. Parr、T. A. Evans、R. K. Didham、F. Hasan、Y. A. The、H. S. Tin、C. S. Vairappan、P. Eggleton

▲ 链接：

http://science.sciencemag.org/content/363/6423/174

▲ 摘要：

白蚁在热带生态系统中具有重要的生态功能，受降雨量变化的影响较大，对生境扰动的响应较差。

但林木白蚁对总体生态的影响仍然基本上未得到量化；人们对干旱介导的对白蚁群体的变化如何在环境应激时影响热带雨林的生态系统所知甚少。

这里，研究人员发现，与干旱后的情况相比，干旱期间有白蚁群落的土地上的白蚁活性和数量增加了一倍以上，后者导致了落叶分解速率、土壤营养混合及土壤湿度增加。

而在白蚁受到抑制的地区，树苗的存活率下降。

▲ Abstract

Termites perform key ecological functions in tropical ecosystems, are strongly affected by variation in rainfall, and respond negatively to habitat disturbance. However, it is not known how the projected increase in frequency and severity of droughts in tropical rainforests will alter termite communities and the maintenance of ecosystem processes. Using a large-scale termite suppression experiment, we found that termite activity and abundance increased during drought in a Bornean forest. This increase resulted in accelerated litter decomposition, elevated soil moisture, greater soil nutrient heterogeneity, and higher seedling survival rates during the extreme El Niño drought of 2015–2016. Our work shows how an invertebrate group enhances ecosystem resistance to drought, providing evidence that the dual stressors of climate change and anthropogenic shifts in biotic communities will have various negative consequences for the maintenance of rainforest ecosystems.

生物学 Biology

Emergence of preconfigured and plastic time-compressed sequences in early postnatal development

在出生后早期的时空记忆发育

▲ 作者：U. Farooq、G. Dragoi

▲ 链接：

http://science.sciencemag.org/content/363/6423/168

▲ 摘要：

海马神经元系统何时以及如何首先组织起来，以支持记忆片段的编码和巩固是大脑的一项关键认知功能，目前相关机制尚不清楚。

研究人员在新生大鼠睁开眼睛并开始探索其周遭环境时开始记录其神经活动，并确认了3个神经元集合发育的依赖年龄且独特的阶段。

这些神经元序列的形成会在睡眠时自发启动，且有可能受到从发育中脑子的其他部位发出的信号的控制。

到出生后4周时，大鼠会展现出成年样的情景样记忆功能。

▲ Abstract

When and how hippocampal neuronal ensembles first organize to support encoding and consolidation of memory episodes, a critical cognitive function of the brain, are unknown. We recorded electrophysiological activity from large ensembles of hippocampal neurons starting on the first day after eye opening as naïve rats navigated linear environments and slept. We found a gradual age-dependent, navigational experience–independent assembly of preconfigured trajectory-like sequences from persistent, location-depicting ensembles during postnatal week 3. Adult-like compressed binding of adjacent locations into trajectories during navigation and their navigational experience–dependent replay during sleep emerged in concert from spontaneous preconfigured sequences only during early postnatal week 4. Our findings reveal ethologically relevant distinct phases in the development of hippocampal preconfigured and experience-dependent sequential patterns thought to be important for episodic memory formation.

An evolutionary perspective on immunometabolism

免疫代谢的演化观点

▲ 作者：Andrew Wang、Harding H. Luan、Ruslan Medzhitov

▲ 链接：

http://science.sciencemag.org/content/363/6423/eaar3932

▲ 摘要：

新陈代谢是所有生物功能的核心。

合成代谢利用衍生自营养物质等的构建块产生生物基础构造，而分解代谢产生能量来为所有生物过程提供燃料。

不同的生物功能需要不同的代谢程序。

因此，最近的研究揭示了调节细胞静息、增殖和分化的信号是如何诱导适当的代谢程序的。

特别是，在免疫代谢领域的大量新研究揭示了代谢、细胞命运决定和组织生理学之间的联系的许多例子。

我们从生命历史理论的进化和生态原理出发，在一个统一的框架下讨论这些发现。

▲ Abstract

Metabolism is at the core of all biological functions. Anabolic metabolism uses building blocks that are either derived from nutrients or synthesized de novo to produce the biological infrastructure, whereas catabolic metabolism generates energy to fuel all biological processes. Distinct metabolic programs are required to support different biological functions. Thus, recent studies have revealed how signals regulating cell quiescence, proliferation, and differentiation also induce the appropriate metabolic programs. In particular, a wealth of new studies in the field of immunometabolism has unveiled many examples of the connection among metabolism, cell fate decisions, and organismal physiology. We discuss these findings under a unifying framework derived from the evolutionary and ecological principles of life history theory.

Cell-autonomous clock of astrocytes drives circadian behavior in mammals

星形胶质细胞的细胞自主时钟驱动哺乳动物的昼夜节律行为

▲ 作者：Marco Brancaccio、Mathew D. Edwards、Andrew P. Patton、Nicola J. Smyllie、Johanna E. Chesham、Elizabeth S. Maywood、Michael H. Hastings

▲ 链接：

http://science.sciencemag.org/content/363/6423/187

▲ 摘要：

昼夜节律依赖于细胞内转录—翻译负反馈回路（TTFLs）。

这些自我维持的细胞时钟是如何实现多细胞融合从而指导动物的日常行为节奏的，这在很大程度上还不清楚。

视交叉上核（SCN）是哺乳动物从基因到细胞再到神经回路再到行为的这一通路的支点。

我们描述了SCN神经元和星形胶质细胞中细胞类型特异性、功能特异性的TTFLs，并表明在缺乏其他细胞时钟的情况下，细胞自主星形胶质细胞TTFL可以单独驱动SCN中的分子振动和小鼠的昼夜节律行为。

星形细胞时钟通过谷氨酸能信号恢复SCN神经元的时钟基因表达和昼夜节律功能来达到这一目的。

我们的结果表明星形胶质细胞可以自主启动和维持复杂的哺乳动物行为。

▲ Abstract

Circadian (~24-hour) rhythms depend on intracellular transcription-translation negative feedback loops (TTFLs). How these self-sustained cellular clocks achieve multicellular integration and thereby direct daily rhythms of behavior in animals is largely obscure. The suprachiasmatic nucleus (SCN) is the fulcrum of this pathway from gene to cell to circuit to behavior in mammals. We describe cell type–specific, functionally distinct TTFLs in neurons and astrocytes of the SCN and show that, in the absence of other cellular clocks, the cell-autonomous astrocytic TTFL alone can drive molecular oscillations in the SCN and circadian behavior in mice. Astrocytic clocks achieve this by reinstating clock gene expression and circadian function of SCN neurons via glutamatergic signals. Our results demonstrate that astrocytes can autonomously initiate and sustain complex mammalian behavior.

古生态学 Paleoecology

A 90000-year record of Afromontane forest responses to climate change

非洲森林对气候变化的9万年记录

▲ 作者：Anne-Marie Lézine、Kenji Izumi、Masa Kageyama、Gaston Achoundong

▲ 链接：

http://science.sciencemag.org/content/363/6423/177

▲ 摘要：

来自非洲高地的花粉记录很少，因此，非洲Afromontane森林的古生态学及其对冰川循环的反应鲜为人知。Bambili湖（喀麦隆）提供了非洲热带山区在过去9万年间植被变化的记录，且时间分辨率很高。花粉数据和生物群落重建表明，森林对气候变化的响应存在差异。上层林木线极不稳定，随着冰川期—间冰期气候变化而发生了大幅度的变化，而山地森林与低地森林之间的过渡却保持着显著的稳定。这种生态不稳定可能对非洲森林的物种丰富度有重要影响。

▲ Abstract

Pollen records from African highlands are scarce; hence, the paleoecology of the Afromontane forest and its responses to glacial cycles are poorly known. Lake Bambili (Cameroon) provides a record of vegetation changes in the tropical mountains of Africa over the past 90,000 years, with high temporal resolution. Pollen data and biome reconstructions show a diverging response of forests to climate changes; the upper tree line was extremely unstable, shifting substantially in response to glacial-interglacial climate alternation, whereas the transition between the montane and lowland forests remained remarkably stable. Such ecological instability may have had a critical influence on species richness in the Afromontane forests.

纳米 Nanometer

Finite phenine nanotubes with periodic vacancy defects

具有周期性空位缺陷的有限苯类纳米管

▲ 作者：Zhe Sun、Koki Ikemoto、Toshiya M. Fukunaga、Takashi Koretsune、Ryotaro Arita、Sota Sato、Hiroyuki Isobe

▲ 链接：

http://science.sciencemag.org/content/363/6423/151

▲ 摘要：

离散石墨碳化合物可作为纳米管等扩展的大分子结构性能的可调模型。在这里，研究人员报告了一个圆柱形C304H264分子的合成和表征，该分子由40个苯（phenine）单元在1、3、5位置上相互结合而成。利用简单的九步合成法，苯—苯键的平均生成率为91%。研究人员进行了光谱和晶体分析，确定了具有周期性空位缺陷的纳米圆柱体的分子结构。该化合物的纳米孔性质进一步使其能够包含多个富勒烯客体。计算结果表明，将多个碳纳米管熔合在一起，可以产生周期性空位缺陷调制的具有电子特性的碳纳米管。

▲ Abstract

Discrete graphitic carbon compounds serve as tunable models for the properties of extended macromolecular structures such as nanotubes. Here, we report synthesis and characterization of a cylindrical C304H264 molecule composed of 40 benzene (phenine) units mutually bonded at the 1, 3, and 5 positions. The concise nine-step synthesis featuring successive borylations and couplings proceeded with an average yield for each benzene-benzene bond formation of 91%. The molecular structure of the nanometer-sized cylinder with periodic vacancy defects was confirmed spectroscopically and crystallographically. The nanoporous nature of the compound further enabled inclusion of multiple fullerene guests. Computations suggest that fusing many such cylinders could produce carbon nanotubes with electronic properties modulated by the periodic vacancy defects.

（唐一尘）

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