Search

The quantification of large-scale leaf-age-dependent leaf area index has been lacking in tropical and subtropical evergreen broadleaved forests (TEFs), despite the recognized importance of leaf age in influencing leaf photosynthetic capacity in this biome. Here, we simplified the canopy leaves of TEFs into three age cohorts (i.e., young, mature, and old, with different photosynthesis capacities; i.e., Vc,max) and proposed a novel neighbor-based approach to develop the first gridded dataset of a monthly leaf-age-dependent leaf area index (LAI) product (referred to as Lad-LAI) at 0.25 ∘ spatial resolution over the continental scale during 2001–2018 from satellite observations of sun-induced chlorophyll fluorescence (SIF) that was reconstructed from MODIS and TROPOMI (the TROPOspheric Monitoring Instrument). The new Lad-LAI products show good performance in capturing the seasonality of three LAI cohorts, i.e., young (LAI young ; the Pearson correlation coefficient of R=0.36), mature (LAI mature ; R=0.77), and old (LAI old ; R=0.59) leaves at eight camera-based observation sites (four in South America, three in subtropical Asia, and one in the Democratic Republic of the Congo (DRC)) and can also represent their interannual dynamics, validated only at the Barro Colorado site, with R being equal to 0.54, 0.64, and 0.49 for LAI young , LAI mature , and LAI old , respectively. Additionally, the abrupt drops in LAI old are mostly consistent with the seasonal litterfall peaks at 53 in situ measurements across the whole tropical region (R=0.82). The LAI seasonality of young and mature leaves also agrees well with the seasonal dynamics of the enhanced vegetation index (EVI; R=0.61), which is a proxy for photosynthetically effective leaves. Spatially, the gridded Lad-LAI data capture a dry-season green-up of canopy leaves across the wet Amazonian areas, where mean annual precipitation exceeds 2000 mm yr -1 , consistent with previous satellite-based analyses. The spatial patterns clustered from the three LAI cohorts also coincide with those clustered from climatic variables over the whole TEF region. Herein, we provide the average seasonality of three LAI cohorts as the main dataset and their time series as a supplementary dataset. These Lad-LAI products are available at 10.6084/m9.figshare.21700955.v4 (Yang et al., 2022). [ABSTRACT FROM AUTHOR]

Author(s): Dexiang Chen (corresponding author) [1]; Ryan L. Endres [1]; Cherie A. Erickson [1]; Kathleen F. Weis [1]; Martha W. McGregor [2]; Yoshihiro Kawaoka [2]; Lendon G. Payne [1] Human [...]

Aims Understanding variation and coordination of leaf traits at multiscales along elevational gradients can help predict the likely responses of dominant species to climate change. We seek to determine the extent to which variation in leaf stomatal, anatomical and morphological traits is associated with environmental factors, and whether ecological strategies of Cyclobalanopsis species shift with elevations. Methods In a tropical forest landscape in Jianfengling, South China, we determined leaf traits related to stomata, anatomy and morphology of six evergreen oak species (Cyclobalanopsis bambusaefolia , C. hui , C. patelliformis , C. fleuryi , C. tiaoloshanica and C. phanera) along a long elevational gradient (400–1400 m above sea level). Important Findings We found that stomatal density and stomatal pore index increased, whereas spongy mesophyll thickness to leaf thickness ratios decreased, significantly with elevation. The leaf area and leaf dry matter content increased and decreased, respectively, with elevation. Variations in stomatal, anatomical and morphological traits were mainly correlated to the mean annual temperature, mean annual sum precipitation and soil pH. At low and high elevations, the oak species exhibited strong stress tolerance combined with competition strategy, while they shifted toward more clearly the competitive strategy at intermediate elevations. And the changes in soil phosphorus concentration and soil pH along the elevation may drive the shift of ecological strategy. The results showed that the dominant oak species in tropical forests respond to environmental change by modulating traits at multiple levels, from that of the individual cell, through tissue and up to the whole leaf scale. [ABSTRACT FROM AUTHOR]

Au nanodots decorated Cu2O nanooctahedrons were fabricated by a facile liquid-phase process combined with a galvanic replacement reaction for nonenzyme glucose detection. A simple rapid test strip based on the nanooctahedrons was proposed to evaluate the possibility of commercial application in nonenzymatic glucose detection. This test strip shows excellent response toward glucose. Linear response was obtained over a concentration ranging from 0.05 mM to 15 mM, and the detection accuracy is 0.05 mM. The good detection performance in selectivity, stability, and feasibility proving the great potential application in human blood glucose monitoring. This study demonstrated the possibility of a high-performance nonenzyme glucose test strip based on metal-oxide nanostructures decorated by catalysts. [ABSTRACT FROM AUTHOR]

The effects of nitrogen (N) deposition on forests largely depend on its fate after entering the ecosystem. While several studies have addressed the forest fate of N deposition using 15N tracers, the long‐term fate and redistribution of deposited N in tropical forests remains unknown. Here, we applied 15N tracers to examine the fates of deposited ammonium (NH4+) and nitrate (NO3‐) separately over 3 years in a primary and a secondary tropical montane forest in southern China. Three months after 15N tracer addition, over 60% of 15N was retained in the forests studied. Total ecosystem retention did not change over the study period, but between 3 months and 3 years following deposition 15N recovery in plants increased from 10% to 19% and 13% to 22% in the primary and secondary forests, respectively, while 15N recovery in the organic soil declined from 16% to 2% and 9% to 2%. Mineral soil retained 50% and 35% of 15N in the primary and secondary forests, with retention being stable over time. The total ecosystem retention of the two N forms did not differ significantly, but plants retained more 15NO3‐ than 15NH4+ and the organic soil more 15NH4+ than NO3‐. Mineral soil did not differ in 15NH4+ and 15NO3‐ retention. Compared to temperate forests, proportionally more 15N was distributed to mineral soil and plants in these tropical forests. Overall, our results suggest that atmospherically deposited NH4+ and NO3‐ is rapidly lost in the short term (months) but thereafter securely retained within the ecosystem, with retained N becoming redistributed to plants and mineral soil from the organic soil. This long‐term N retention may benefit tropical montane forest growth and enhance ecosystem carbon sequestration. [ABSTRACT FROM AUTHOR]

Histone demethylases are promising therapeutic targets as they play fundamental roles for survival of Mixed lineage leukemia rearranged acute leukemia (MLLr AL). Here we focused on the catalytic Jumonji domain of histone H3 lysine 9 (H3K9) demethylase JMJD1C to screen for potential small molecular modulators from 149,519 natural products and 33,765 Chinese medicine components via virtual screening. JMJD1C Jumonji domain inhibitor 4 (JDI‐4) and JDI‐12 that share a common structural backbone were detected within the top 15 compounds. Surface plasmon resonance analysis showed that JDI‐4 and JDI‐12 bind to JMJD1C and its family homolog KDM3B with modest affinity. In vitro demethylation assays showed that JDI‐4 can reverse the H3K9 demethylation conferred by KDM3B. In vivo demethylation assays indicated that JDI‐4 and JDI‐12 could induce the global increase of H3K9 methylation. Cell proliferation and colony formation assays documented that JDI‐4 and JDI‐12 kill MLLr AL and other malignant hematopoietic cells, but not leukemia cells resistant to JMJD1C depletion or cord blood cells. Furthermore, JDI‐16, among multiple compounds structurally akin to JDI‐4/JDI‐12, exhibits superior killing activities against malignant hematopoietic cells compared to JDI‐4/JDI‐12. Mechanistically, JDI‐16 not only induces apoptosis but also differentiation of MLLr AL cells. RNA sequencing and quantitative PCR showed that JDI‐16 induced gene expression associated with cell metabolism; targeted metabolomics revealed that JDI‐16 downregulates lactic acids, NADP+ and other metabolites. Moreover, JDI‐16 collaborates with all‐trans retinoic acid to repress MLLr AML cells. In summary, we identified bona fide JMJD1C inhibitors that induce preferential death of MLLr AL cells. What's new? Histone demethylase JMJD1C represents one of the most promising therapeutic targets for a subtype of acute leukemia with inferior prognosis, MLLr AL. Here, the authors focused on the catalytic Jumonji domain of JMJD1C to screen for potential small molecular modulators from 149,519 natural products and 33,765 Chinese medicine components via virtual screening. They identified structurally‐akin JMJD1C inhibitors with the ability to selectively kill MLLr AL cells, regulate MLLr AL cell metabolism, and collaborate with all‐trans retinoic acid to repress MLLr AL. The findings helped identify the backbone of an inhibitor class that holds promise for the treatment of MLLr AL. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition is projected to substantially increase in the tropics over the coming decades, which is expected to lead to enhanced N saturation and gaseous N emissions from tropical forests (via NO, N 2 O, and N 2). However, it is unclear how N deposition in tropical forests influences both the magnitude of gaseous loss of nitrogen and its partitioning into the N 2 and N 2 O loss mechanisms. Here, for the first time, we employed the acetylene inhibition technique and the 15N-nitrate labeling method to quantify N 2 and N 2 O emission rates for long-term experimentally N-enriched treatments in primary and secondary tropical montane forest. We found that during laboratory incubation under aerobic conditions long-term increased N addition of up to 100 kg N ha−1 yr−1 at Jianfengling forest, China, did not cause a significant increase in either N 2 O or N 2 emissions, or N 2 O/N 2. However, under anaerobic conditions, N 2 O emissions decreased and N 2 emissions increased with increasing N addition in the secondary forest. These changes may be attributed to substantially greater N 2 O reduction to N 2 during denitrification, further supported by the decreased N 2 O/N 2 ratio with increasing N addition. No such effects were observed in the primary forest. In both forests, N addition decreased the contribution of denitrification while increasing the contribution of co-denitrification and heterotrophic nitrification to N 2 O production. Denitrification was the predominant pathway to N 2 production (98–100%) and its contribution was unaffected by N addition. Despite the changes in the contributions of denitrification to N 2 O gas emissions, we detected no change in the abundance of genes associated with denitrification. While the mechanisms for these different responses are not yet clear, our results indicate that the effects of N deposition on gaseous N loss were ecosystem-specific in tropical forests and that the microbial processes responsible for the production of N gases are sensitive to N inputs. Graphical abstract Image 1 Highlights • The effects of N addition on N gas losses were studied for two tropical forests. • The effects on N gas losses was significant in one forest while not in the other. • N addition increased N 2 O reduction to N 2 by denitrification in secondary forest. • Microbial processes contributions to N 2 O productions are sensitive to N additions. • The abundances of denitrification genes did not change after long term N additions. [ABSTRACT FROM AUTHOR]

Bacteria are the highest abundant microorganisms in the soil. To investigate bacteria community structures, diversity, and functions, contrasting them in four different seasons all the year round with/within two different forest type soils of China. We analyzed soil bacterial community based on 16S rRNA gene sequencing via Illumina HiSeq platform at a temperate deciduous broad-leaved forest (Baotianman, BTM) and a tropical rainforest (Jianfengling, JFL). We obtained 51,137 operational taxonomic units (OTUs) and classified them into 44 phyla and 556 known genera, 18.2% of which had a relative abundance >1%. The composition in each phylum was similar between the two forest sites. Proteobacteria and Acidobacteria were the most abundant phyla in the soil samples between the two forest sites. The Shannon index did not significantly differ among the four seasons at BTM or JFL and was higher at BTM than JFL in each season. The bacteria community at both BTM and JFL showed two significant (P < 0.05) predicted functions related to carbon cycle (anoxygenic photoautotrophy sulfur oxidizing and anoxygenic photoautotrophy) and three significant (P < 0.05) predicted functions related to nitrogen cycle (nitrous denitrificaton, nitrite denitrification, and nitrous oxide denitrification). We provide the basis on how changes in bacterial community composition and diversity leading to differences in carbon and nitrogen cycles at the two forests. [ABSTRACT FROM AUTHOR]

The impacts of increasing nitrogen (N) deposition on forest ecosystems, including on carbon (C) sequestration, largely depend on the extent to which forests are N-limited and so whether and where deposited N is retained within the ecosystem. The 15 N tracer method can provide excellent insight into the ecosystem fates of N, but while it has been extensively used in temperate forests it has yet to be sufficiently employed in tropical forests, which are often thought not to be N-limited. Here, we used stable isotope 15 NH 4 + and 15 NO 3 − tracers applied as solutions to the forest floor to examine the fates of different forms of N in a tropical montane primary forest with low background atmospheric N deposition (6 kg N ha −1  yr −1 ) in China. We found that a substantial amount of 15 N was assimilated by plants over time and significantly more 15 N was recovered following 15 NO 3 − addition than following 15 NH 4 + addition: 7% and 16% of 15 N were recovered three months after the respective 15 NH 4 + and 15 NO 3 − tracer additions and 11% and 29% respectively after one year. In contrast to plants, the organic layer was only an important short-term sink for deposited N: while 21% and 12% of the 15 N from 15 NH 4 + and 15 NO 3 − additions were accumulated in the organic layer after three months, more than half of the retained 15 N was lost after one year. Mineral soil was the largest sink for deposited N, and the 15 N retained in soil was relatively stable over time for both N forms, with 39% and 32% of the initial 15 N input recovered after one year for 15 NH 4 + and 15 NO 3 − tracer additions, respectively. Overall, the total ecosystem 15 N recovery one year after the 15 NH 4 + and 15 NO 3 − tracer additions was large (60% and 66% respectively), and not significantly different from total recovery after three months, suggesting that a large proportion of deposited N could be retained in the longer term. Based on the measured fate of 15 N one year after labeling and the C:N ratios of different plant components, this tropical forest’s carbon sequestration efficiency is calculated to be 17 kg C per kg N added, comparable to the values reported for temperate and boreal forests in Europe and North America and indicating substantial N limitation of this tropical forest. Our results suggest that anthropogenic N input in moderate levels may contribute to enhance C sequestration in some tropical forests, without significant long-term loss of N to the environment. [ABSTRACT FROM AUTHOR]

In most real-world planning domains, it is important to have flexible executive time against uncertainty and disturbance of environment. Execution time can be propagated from dispatchable Simple Temporal Network (STN), which is obtained from filtering the distance graph of STN. To minimise the execution latency, computation of dispatchable STN should be improved. In the previous works, all-pairs shortest paths (APSP) algorithm is used to compute distance graph of STN, so the redundant constraints should be processed in the following filtering process. In this paper, an improved algorithm named Dispatchabile Partial Path (DPP) algorithm, which uses the P3C algorithm to replace APSP and compute the shortest distance of vertices, is presented. To ensure the correctness of dispatchable STN, triangulation uses vertices ordering sorted by execute time. The filtering process is also simplified by time-sorting vertices. Experimental evidence confirms that the DPP algorithm outperforms previous algorithms based on APSP. [ABSTRACT FROM AUTHOR]

An influenza pandemic remains a major public health concern. A key strategy to prevent a pandemic is to stockpile and pre-position stable influenza vaccine to allow rapid deployment in response to an outbreak. However, most influenza vaccines today are formulated as liquids that are stable only within a temperature range of 2°C to 8°C and require use of a cold chain, making vaccine transportation, distribution, and storage complicated and expensive, particularly for developing countries. To support the National Strategy for Pandemic Influenza preparedness in the United States and internationally, we developed two lead dry formulations of stable H1N1 influenza subunit vaccines using freeze-drying technology. The stable formulations contain an excipient combination of a disaccharide, such as sucrose or trehalose, and glycine, in addition to a surfactant and phosphate buffer. The freeze-dried vaccines were shown to be safe and remained immunogenic in an in vivo study in mice. Moreover, the lead formulations demonstrated no significant loss of activity after 40 months at storage temperatures of 25°C and 37°C. This stability can be particularly attractive as it could eliminate the need to use a cold chain for vaccine deployment and facilitate integration of vaccine distribution with general drug distribution where appropriate. These freeze-dried thermostable influenza subunit vaccines could also reduce the frequency of vaccine stockpile turnover, offering a cost-effective option for pandemic preparedness. [ABSTRACT FROM AUTHOR]