編譯|李言
Science, 14 FEB 2025, VOL 387, ISSUE 6735
《科學》2025年2月14日，第387卷，6735期
醫學Medicine
Thalamic opioids from POMC satiety neurons switch on sugar appetite
POMC神經元的丘腦阿片類物質調控嗜甜水平
▲ 作者：MARIELLE MINèRE, HANNAH WILHELMS et al.
▲鏈接：
https://www.science.org/doi/10.1126/science.adp1510
▲摘要：
即使在餐后吃飽的情況下，人們也很容易攝入高糖食物。盡管對美味食物的獎勵驅動會激發過度進食，但在飽腹狀態下對甜食有偏好的神經生物學機制仍不明確。
下丘腦前阿片黑皮質素（POMC）神經元是飽腹感的主要調節者，因為它們通過興奮性黑皮質素神經肽減少食物攝入。我們發現POMC神經元不僅在進食條件下促進飽腹感，同時開啟了對甜食的食欲，導致過度進食。
POMC神經元向室旁丘腦的投射通過μ-阿片受體信號選擇性地抑制了突觸后神經元。這一阿片回路在甜食的攝入過程中被強烈激活，在飽腹狀態下尤為顯著。相應地，抑制其活動減少了飽腹小鼠對高糖飲食的攝入。
▲ Abstract：
High sugar–containing foods are readily consumed, even after meals and beyond fullness sensation (e.g., as desserts). Although reward-driven processing of palatable foods can promote overeating, the neurobiological mechanisms that underlie the selective appetite for sugar in states of satiety remain unclear. Hypothalamic pro-opiomelanocortin (POMC) neurons are principal regulators of satiety because they decrease food intake through excitatory melanocortin neuropeptides. We discovered that POMC neurons not only promote satiety in fed conditions but concomitantly switch on sugar appetite, which drives overconsumption. POMC neuron projections to the paraventricular thalamus selectively inhibited postsynaptic neurons through mu-opioid receptor signaling. This opioid circuit was strongly activated during sugar consumption, which was most notable in satiety states. Correspondingly, inhibiting its activity diminished high-sugar diet intake in sated mice.
材料科學Materials Science
Ultrastable supported oxygen evolution electrocatalyst formed by ripening-induced embedding
熟化誘導嵌入形成的超穩定析氧反應電催化劑
▲ 作者：WENJUAN SHI, TONGHAO SHEN et al.
▲鏈接：
https://www.science.org/doi/10.1126/science.adr3149
▲摘要：
在此，我們提出一種能將銥催化劑穩固地嵌入氧化鈰載體中的成熟誘導嵌入策略。低溫電子斷層掃描和全原子動力學蒙特卡羅模擬揭示了通過超聲調節載體生長速率與銥成核速率的同步對于成功合成至關重要。
使用這種催化劑的質子交換膜水電解池（PEMWE）在每平方厘米3安培的電流密度下實現了1.72伏的電池電壓，而銥的負載量僅為每平方厘米0.3毫克，經過6000小時的加速老化測試，其電壓退化率為每小時1.33微伏。
▲ Abstract：
Here we present a ripening-induced embedding strategy that securely embeds the Ir catalyst in a cerium oxide support. Cryogenic electron tomography and all-atom kinetic Monte Carlo simulations reveal that synchronizing the growth rate of the support with the nucleation rate of Ir, regulated by sonication, is pivotal for successful synthesis. A PEMWE using this catalyst achieves a cell voltage of 1.72 volts at a current density of 3 amperes per square centimeter with an Ir loading of just 0.3 milligrams per square centimeter and a voltage degradation rate of 1.33 microvolts per hour, as demonstrated by a 6000-hour accelerated aging test.
化學Chemistry
Thermal catalytic reforming for hydrogen production with zero CO2 emission
二氧化碳零排放的熱催化重整制氫技術
▲ 作者：MI PENG, YUZHEN GE et al.
▲鏈接：
https://www.science.org/doi/10.1126/science.adt0682
▲摘要：
碳中性氫氣生產對于未來化學工業至關重要。我們展示了一種新的熱催化途徑，用于將乙醇部分重整為氫氣和乙酸，且幾乎不產生二氧化碳排放。這一反應通過一種催化劑實現。
該催化劑含有高密度的原子級Pt1和Ir1物種，負載在反應性α-碳化鉬基底上，在270°C下實現了每小時每克催化劑331.3毫摩爾氫氣的產率和84.5%的乙酸選擇性，因此與標準重整相比更加節能。對乙醇部分重整的技術經濟分析展示了在工業規模上潛在的盈利能力，為生產氫氣和乙酸提供了大幅減少二氧化碳排放的機會。
▲ Abstract：
Carbon-neutral hydrogen production is of key importance for the chemical industry of the future. We demonstrate a new thermal catalytic route for the partial reforming of ethanol into hydrogen and acetic acid with near-zero carbon dioxide emissions. This reaction is enabled by a catalyst containing a high density of atomic Pt1 and Ir1 species supported on a reactive alpha-molybdenum carbide substrate, achieving a hydrogen production rate of 331.3 millimoles of hydrogen per gram catalyst per hour and an acetic acid selectivity of 84.5% at 270°C, and is therefore more energy-efficient compared with standard reforming. Techno-economic analysis of partial ethanol reforming demonstrates the potential profitability for operation at an industrial scale, presenting the opportunity to produce hydrogen and acetic acid with a substantially reduced carbon dioxide footprint.
動物學Zoology
Elephant seals as ecosystem sentinels for the northeast Pacific Ocean twilight zone
象海豹是東北太平洋暮光帶生態系統哨兵
▲ 作者：ROXANNE S. BELTRAN, ALLISON R. PAYNE et al.
▲鏈接：
https://www.science.org/doi/10.1126/science.adp2244
▲摘要：
開闊海洋的暮光帶擁有全球大部分的魚類生物量，但由于難以大規模測量次表層生態系統過程，人們對這一區域的情況知之甚少。
我們證明了一種廣泛分布的肉食性動物——北方象海豹——可以成為暮光帶的生態系統哨兵。我們將海洋盆地尺度的覓食成功與海洋學指數聯系起來，以估算過去五十年及未來暮光帶魚類的豐度。
我們發現，母體覓食成功的小幅變化會放大為后代體重的較大變化，并造成第一年存活率和補充量的巨大差異。惡化的海洋學條件可能會使捕食者種群軌跡從目前的增長轉變為急劇下降。作為海洋的整合者，廣泛分布的捕食者可以揭示未來人為變化對開闊海洋生態系統的影響。
▲ Abstract：
The open ocean twilight zone holds most of the global fish biomass but is poorly understood owing to difficulties of measuring subsurface ecosystem processes at scale. We demonstrate that a wide-ranging carnivore—the northern elephant seal—can serve as an ecosystem sentinel for the twilight zone. We link ocean basin–scale foraging success with oceanographic indices to estimate twilight zone fish abundance five decades into the past, and into the future. We discovered that a small variation in maternal foraging success amplified into larger changes in offspring body mass and enormous variation in first-year survival and recruitment. Worsening oceanographic conditions could shift predator population trajectories from current growth to sharp declines. As ocean integrators, wide-ranging predators could reveal impacts of future anthropogenic change on open ocean ecosystems.
地球科學Earth Science
Depth-dependent seismic sensing of groundwater recovery from the atmospheric-river storms of 2023
對2023年大氣層河流風暴后地下水恢復的深度依賴性地震傳感
▲ 作者：SHUJUAN MAO, WILLIAM L. ELLSWORTH et al.
▲鏈接：
https://www.science.org/doi/10.1126/science.adr6139
▲摘要：
2023年初，一系列強烈的大氣層河流風暴緩解了加利福尼亞州的歷史性干旱，然而人們對地下水恢復的時空范圍仍然知之甚少。
我們利用地震環境場干涉測量法追蹤了大洛杉磯地區二十年來地下水的變遷。所得到的地震水文圖揭示了地下水和地表水干旱的明顯表現：盡管在2023年的雨季中，地表和近地表水儲存幾乎完全恢復，但自2006年以來流失的地下水僅有約25%得到補充。
在十年尺度上，我們發現50米深度以下的含水層存在顯著枯竭，僅有有限的風暴相關恢復。我們的分析強調了使用高分辨率工具如地震傳感來監測深層含水層，以更全面地評估總水虧缺的必要性。
▲ Abstract：
In early 2023, a series of intense atmospheric-river storms eased California’s historic drought, yet the spatiotemporal extent of groundwater recovery remains poorly understood. We tracked two-decadal changes in groundwater in Greater Los Angeles using seismic ambient-field interferometry. The derived seismic hydrographs reveal distinct expressions of groundwater and surficial water droughts: Whereas surface and near-surface water storage nearly fully recovered in the epic wet season of 2023, only about 25% of the groundwater lost since 2006 was restored. On a decadal scale, we find substantial depletion in aquifers below 50-meter depth, with only limited storm-related recovery. Our analysis underscores the need to monitor deep aquifers for a more complete assessment of total water deficits, using high-resolution tools such as seismic sensing.
Variability of flowing stream network length across the US
美國流動溪流網絡長度的變化
▲ 作者：JEFF P. PRANCEVIC, HANSJ?RG SEYBOLD, AND JAMES W. KIRCHNER
▲鏈接：
https://www.science.org/doi/10.1126/science.ado2860
▲摘要：
排水網絡中流動溪流的總長度會隨著地表變得濕潤或干燥，相應變長或縮短。然而，直接測量溪流網絡變化的研究僅限于少數小型排水流域。
我們利用測量的流量分布和基于地形的估算，評估了美國本土14765個已測量流域的溪流網絡長度變化。這些估算反映了每個溪流網絡對景觀濕度變化的敏感性（網絡的彈性）。
我們發現，美國溪流網絡在年度高流量條件下的中位長度是年度低流量條件下的五倍。溪流網絡在某些地區比其他地區更具動態性，這主要是由于各地區水文氣候學的差異以及網絡對水文氣候強迫的彈性反應不同所致。
▲ Abstract：
The aggregate length of flowing streams in a drainage network lengthens and shortens as landscapes become wetter and drier. However, direct measurements of stream network variability have been limited to a handful of small drainage basins. We estimated the variability of stream network length for 14,765 gauged basins across the contiguous United States using measured streamflow distributions and topography-based estimates of how sensitive each stream network is to changing landscape wetness (the network’s elasticity). We find that the median US stream network is five times longer during annual high-flow conditions than during annual low-flow conditions. Stream networks are more dynamic in some regions than in others, driven by regional differences in both hydroclimatology and the networks’ elasticity in response to hydroclimatic forcing.
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