翻譯 | 唐一塵
Science, 07 FEBRUARY 2020, VOL 367, ISSUE 6478
《科學》2020年2月7日，第367卷，6478期
生物學Biology
Microglia mediate forgetting via complement-dependent synaptic elimination
小膠質細胞可調節大腦的遺忘
▲ 作者：Chao Wang,Huimin Yue,Zhechun Hu, et al.
▲ 鏈接：
https://science.sciencemag.org/content/367/6478/688
▲ 摘要：
人們認為，大腦會以記憶印跡編碼和存儲記憶。通過這些突觸連接的記憶印跡的再激活令人們能夠回憶特定的記憶；無法重新激活記憶印跡則會導致相關記憶的丟失。
因此，突觸迴路的重新連線可能會通過削弱或切斷連接記憶印跡細胞的網絡而促成先前形成記憶的丟失。
小膠質細胞在腦發育過程中負責修剪過多的突觸，並對突觸動態進行調控。然而，人們尚不清楚小膠質細胞活動是否也能調節成年腦的遺忘和記憶消除。
研究人員在經過記憶力訓練的健康小鼠腦中對小膠質細胞和記憶印跡細胞進行了觀察和操控，以便弄清這些細胞在調控遺忘中的作用。結果顯示，減少小膠質細胞或抑制其活性可防止遺忘。
研究人員表示，完整的小膠質細胞可介導記憶印跡細胞的分離，導致相關記憶的退化及最終的消失。
總之，忘卻記憶（無論好壞）的能力取決於小膠質細胞和其減弱和消除連接記憶痕跡神經元突觸的傾向。
▲ Abstract
Synapses between engram cells are believed to be substrates for memory storage, and the weakening or loss of these synapses leads to the forgetting of related memories. We found engulfment of synaptic components by microglia in the hippocampi of healthy adult mice. Depletion of microglia or inhibition of microglial phagocytosis prevented forgetting and the dissociation of engram cells. By introducing CD55 to inhibit complement pathways, specifically in engram cells, we further demonstrated that microglia regulated forgetting in a complement- and activity-dependent manner. Additionally, microglia were involved in both neurogenesis-related and neurogenesis-unrelated memory degradation. Together, our findings revealed complement-dependent synapse elimination by microglia as a mechanism underlying the forgetting of remote memories.
Mosquito heat seeking is driven by an ancestral cooling receptor
蚊子尋熱是由一種古老的冷卻感受器驅動的
▲ 作者：Chloe Greppi, Willem J. Laursen, Gonzalo Budelli, et al.
▲ 鏈接：
https://science.sciencemag.org/content/367/6478/681
▲ 摘要：
蚊子會傳播多種不同的病原體，而且通過疫苗或使用殺蟲劑的蚊蟲—介體的做法殺滅它們頗為困難。
就像其他傳播疾病的昆蟲一樣，蚊子會用專門的感受器感知宿主體熱，以瞄準其下一餐。然而，其逐熱行為的分子基礎仍屬未知。
研究人員對岡比亞按蚊祖傳性冷卻激活受體是否在感熱中扮演某種角色進行了評估（岡比亞按蚊是撒哈拉以南非洲大部分地區傳播瘧疾的主要蚊媒）。
研究人員確定了在進化上保守的感覺性熱感受器IR21a是蚊子逐熱行為的關鍵驅動因子。在其它昆蟲中，Ir21a是一種冷卻感受器並能介導避熱，令昆蟲能維持最佳體溫。
研究人員表示，雖然阻斷Ir21a不能完全徹底地終止其逐熱行為，但它顯著降低了雌性蚊子尋找血源的能力。
▲ Abstract
Mosquitoes transmit pathogens that kill >700,000 people annually. These insects use body heat to locate and feed on warm-blooded hosts, but the molecular basis of such behavior is unknown. Here, we identify ionotropic receptor IR21a, a receptor conserved throughout insects, as a key mediator of heat seeking in the malaria vector Anopheles gambiae. Although Ir21a mediates heat avoidance in Drosophila, we find it drives heat seeking and heat-stimulated blood feeding in Anopheles. At a cellular level, Ir21a is essential for the detection of cooling, suggesting that during evolution mosquito heat seeking relied on cooling-mediated repulsion. Our data indicate that the evolution of blood feeding in Anopheles involves repurposing an ancestral thermoreceptor from non–blood-feeding Diptera.
環境研究與監測
Environment Research and monitoring
Climate change contributes to widespread declines among bumble bees across continents
氣候變化導致大黃蜂數量普遍減少
▲ 作者：Peter Soroye, Tim Newbold, Jeremy Kerr
▲ 鏈接：
https://science.sciencemag.org/content/367/6478/685
▲ 摘要：
氣候變化可能會增加物種滅絕的風險，因為溫度和降水量開始超過歷史上觀察到的物種承受能力。
利用北美和歐洲66種大黃蜂的長期數據，研究人員測試了這種機制是否改變了大黃蜂物種滅絕或發展新“殖民地”的可能性。
氣溫升高的頻率影響了物種的局部滅絕風險、移居新地區的機會，以及物種豐富度的變化。而且，這些影響與土地用途的變化無關。
利用新方法，研究人員在空間上預測了物種內部對與氣候變化相關的種群滅絕—定殖動力學，從而解釋所觀察到的地理範圍消失和跨大陸擴張的模式。
結果顯示，目前氣溫升高的頻率超過了歷史上觀察到的大黃蜂的耐受範圍，這有助於解釋大黃蜂物種的普遍減少。
研究人員認為，這一機制也可能導致更普遍的生物多樣性喪失。
▲ Abstract
Climate change could increase species’ extinction risk as temperatures and precipitation begin to exceed species’ historically observed tolerances. Using long-term data for 66 bumble bee species across North America and Europe, we tested whether this mechanism altered likelihoods of bumble bee species’ extinction or colonization. Increasing frequency of hotter temperatures predicts species’ local extinction risk, chances of colonizing a new area, and changing species richness. Effects are independent of changing land uses. The method developed in this study permits spatially explicit predictions of climate change–related population extinction-colonization dynamics within species that explains observed patterns of geographical range loss and expansion across continents. Increasing frequencies of temperatures that exceed historically observed tolerances help explain widespread bumble bee species decline. This mechanism may also contribute to biodiversity loss more generally.
Using sewage for surveillance of antimicrobial resistance
利用汙水監測抗菌素耐藥性
▲ 作者：Frank M. Aarestrup, Mark E. J. Woolhouse
▲ 鏈接：
https://science.sciencemag.org/content/367/6478/630
▲ 摘要：
目前大多數抗菌素耐藥性（AMR）的監測方法都聚焦於臨床環境中的住院患者，這些方法可能導致對健康人或絕大多數常用抗菌藥物治療中AMR的擴散的偏頗理解和低估。
未經處理的汙物或能提供一種具強大潛力的、伴隨臨床AMR監測的工具。它能將來自大型、多元人群的材料合併在一起。
研究人員表示，宏基因組學研究證明，可以通過檢測汙水來描述人群中AMR基因的概貌。基於汙水的AMR監測將是目前對抗全球範圍內AMR舉措的一個有價值的補充。
他們提議，這樣的系統還可用於識別和追蹤其他重大的公共衛生問題，其中包括新型的和緊急的腸道及食源性病原體。
研究人員估計，在全球範圍內建立一個有效的連續監測系統的年度花費不到100萬美元，這比常規監測的年度成本要便宜得多。
▲ Abstract
Antimicrobial resistance (AMR), a cross-cutting and increasing threat to global health (1–3), is a complex problem with multiple and interconnected drivers. Reliable surveillance data that accurately describe and characterize the global occurrence and distribution of AMR are essential for tracking changes in resistance over time, setting national and global priorities, assessing the impacts of interventions, identifying new kinds of resistance, and supporting investigation of (international) outbreaks of resistant pathogens. AMR surveillance data can also inform development of treatment guidelines. Yet it has proven difficult to achieve these objectives on a global scale, and especially in low- and middle-income countries (LMICs), largely because current surveillance systems deliver data that are extremely variable in quality and quantity and highly heterogeneous in terms of which population is sampled (usually a category of hospital patients) and what drug-bug combinations are included (1). Here, we outline a plan for a global AMR surveillance system based on applying next-generation sequencing (NGS) to human sewage that will be especially helpful for community AMR surveillance, which is difficult to achieve in other ways, and will provide an affordable surveillance option in resource-poor settings.
化學Chemistry
Na+-gated water-conducting nanochannels for boosting CO2 conversion to liquid fuels
Na+門控水傳導納米通道促進CO2轉化為液體燃料
▲ 作者：Huazheng Li, Chenglong Qiu, Shoujie Ren, et al.
▲ 鏈接：
https://science.sciencemag.org/content/367/6478/667
▲ 摘要：
在高溫高壓下，可以從氫(H2)等小氣體分子中篩出水分的堅固的、阻礙氣體傳導的水納米通道。疏氣導水納米通道可以通過除去水，保留反應氣體和產物的同時，可以提高反應速率，使平衡向產物生成方向轉移。
研究人員組裝成新的釐米級膜，其具有可忽略不計的缺陷、阻氣水傳導性的NaA沸石納米通道。他們在高溫和高壓下實驗證實了水的傳導，並認為可能是由於Na+的門控效應的結果。該Na+位於8個氧環孔中，調節了其有效尺寸。
這種導水膜在高溫和壓力（21至35 bar）下大幅的提高了CO2轉化率和甲醇生產中CO2加氫催化合成中甲醇產率。
▲ Abstract
Robust, gas-impeding water-conduction nanochannels that can sieve water from small gas molecules such as hydrogen (H2), particularly at high temperature and pressure, are desirable for boosting many important reactions severely restricted by water (the major by-product) both thermodynamically and kinetically. Identifying and constructing such nanochannels into large-area separation membranes without introducing extra defects is challenging. We found that sodium ion (Na+)–gated water-conduction nanochannels could be created by assembling NaA zeolite crystals into a continuous, defect-free separation membrane through a rationally designed method. Highly efficient in situ water removal through water-conduction nanochannels led to a substantial increase in carbon dioxide (CO2) conversion and methanol yield in CO2 hydrogenation for methanol production.
CO2 electrolysis to multicarbon products at activities greater than 1 A
cm−2
新方法將CO2電解成多碳產物
▲ 作者：F. Pelayo García de Arquer,Cao-Thang Dinh,Adnan Ozden,et al.
▲ 鏈接：
https://science.sciencemag.org/content/367/6478/661
▲ 摘要：
電解為將二氧化碳等溫室氣體轉化為有價值的燃料和原料提供了一條有吸引力的途徑。然而，氣體通過液體電解質擴散到催化劑表面會限制生產率。
在這裡，研究人員提出了一種催化劑：CIBH結構，它可以解耦氣體、離子和電子的傳輸。CIBH由金屬和具有疏/親水功能的超細離子層組成，可將氣體和離子的輸運範圍從數十納米擴展到微米級。
應用該設計策略，研究人員在7 M氫氧化鉀電解液（pH≈15）中實現了銅的CO2電還原，在45%陰極能量效率下，乙烯偏電流密度為1.3安培/平方釐米。
▲ Abstract
Electrolysis offers an attractive route to upgrade greenhouse gases such as carbon dioxide (CO2) to valuable fuels and feedstocks; however, productivity is often limited by gas diffusion through a liquid electrolyte to the surface of the catalyst. Here, we present a catalyst:ionomer bulk heterojunction (CIBH) architecture that decouples gas, ion, and electron transport. The CIBH comprises a metal and a superfine ionomer layer with hydrophobic and hydrophilic functionalities that extend gas and ion transport from tens of nanometers to the micrometer scale. By applying this design strategy, we achieved CO2 electroreduction on copper in 7 M potassium hydroxide electrolyte (pH ≈ 15) with an ethylene partial current density of 1.3 amperes per square centimeter at 45% cathodic energy efficiency.
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