Anti-inflammatory and cytotoxicity nitrogenous merosesquiterpenoids from the sponge Pseudoceratina purpurea.

Fourteen undescribed nitrogenous merosesquiterpenoids, purpurols A-D (1-4) and puraminones A-J (5-14), along with three known related compounds (15-17) were isolated from the sponge Pseudoceratina purpurea collected in the South China Sea. Their structures and absolute configurations were unambiguously elucidated by a combination of spectroscopic data, X-ray diffraction analysis, electronic circular dichroism calculations, and chemical derivatization. Purpurols A-D (1-4) incorporated nitrogenous heterocycles, compounds 1 and 2 feature an unusual benzothiazole ring, while 3 and 4 feature benzoxazole ring. Puraminones A-J (5-14) represent sesquiterpenoid aminoquinones with different amine and amino acid side chains at C-20. Additionally, twenty unreported sesquiterpenoid aminoquinone analogues were obtained through chemical derivatization. It is worth noting that all compounds are featured with unusual rearranged 4,9-friedodrimane subunit. In the bioassays, purpurols A and B showed weak anti-inflammation in zebrafish, as well as some compounds showed activities against tumor cells, therefore, preliminary structure-cytotoxicity relationships are also discussed.

Sarcocinerenolides A, an open-loop decarbonizing cembranolide, and sarcocinerenolides B-I, eight polyoxygenated cembranolides with anti-thrombotic activity from the South China Sea soft coral Sarcophyton cinereum.

A previously undescribed open-loop decarbonizing cembranolide, sarcocinerenolide A, and eight undescribed cembranolides, sarcocinerenolides B-I, characterized by poly-membered oxygen ring fragments were isolated from the soft coral Sarcophyton cinereum collected from the South China Sea. The structures and absolute configurations of these previously undescribed compounds were precisely determined by analysis of NMR data, DP4+ and ECD spectra. The bioactivities of the compounds were evaluated using zebrafish models and sarcocinerenolides C and H exhibited anti-thrombotic activity.

Terpenoids from the Soft Coral Stereonephthya bellissima.

A detailed chemical study of the extract from the soft coral Stereonephthya bellissima resulted in the isolation and identification of seven new sesquiterpenoids, bellissinanes A-G (1-7), along with four new diterpenes (8-11). Bellissinane A (1) is the third reported nardosinane-type sesquiterpene bearing a 6/5/6 tricyclic system. Bellissinanes C and D (3, 4) contain a phenylethylamine fragment, which is relatively unusual in marine organisms. Bellissinanes E-G (5-7) belong to the rare class of nornardosinane sesquiterpenoids. Structurally uncommon octahydro-1H-indenyl-type and prenyleudesmane-type skeletons were characterized for herpetopanone B (8) and bellissimain A (9), respectively. Bellissinane E (5) exhibited in vivo angiogenesis-promoting activity.

Long-term warming increased carbon sequestration capacity in a humid subtropical forest.

Tropical and subtropical forests play a crucial role in global carbon (C) pools, and their responses to warming can significantly impact C-climate feedback and predictions of future global warming. Despite earth system models projecting reductions in land C storage with warming, the magnitude of this response varies greatly between models, particularly in tropical and subtropical regions. Here, we conducted a field ecosystem-level warming experiment in a subtropical forest in southern China, by translocating mesocosms (ecosystem composed of soils and plants) across 600 m elevation gradients with temperature gradients of 2.1°C (moderate warming), to explore the response of ecosystem C dynamics of the subtropical forest to continuous 6-year warming. Compared with the control, the ecosystem C stock decreased by 3.8% under the first year of 2.1°C warming; but increased by 13.4% by the sixth year of 2.1°C warming. The increased ecosystem C stock by the sixth year of warming was mainly attributed to a combination of sustained increased plant C stock due to the maintenance of a high plant growth rate and unchanged soil C stock. The unchanged soil C stock was driven by compensating and offsetting thermal adaptation of soil microorganisms (unresponsive soil respiration and enzyme activity, and more stable microbial community), increased plant C input, and inhibitory C loss (decreased C leaching and inhibited temperature sensitivity of soil respiration) from soil drying. These results suggest that the humid subtropical forest C pool would not necessarily diminish consistently under future long-term warming. We highlight that differential and asynchronous responses of plant and soil C processes over relatively long-term periods should be considered when predicting the effects of climate warming on ecosystem C dynamics of subtropical forests.

Climate change-related biodiversity fluctuations and composition changes in an old-growth subtropical forest: A 26-yr study.

The detection and attribution of biodiversity change is of great scientific interest and central to policy effects aimed at meeting biodiversity targets. Yet, how such a diverse climate scenarios influence forest biodiversity and composition dynamics remains unclear, particularly in high diversity systems of subtropical forests. Here we used data collected from the permanent sample plot spanning 26 years in an old-growth subtropical forest. Combining various climatic events (extreme drought, subsequent drought, warming, and windstorm), we analyzed long-term dynamics in multiple metrics: richness, turnover, density, abundance, reordering and stability. We did not observe consistent and directional trends in species richness under various climatic scenarios. Still, drought and windstorm events either reduced species gains or increased species loss, ultimately increased species turnover. Tree density increased significantly over time as a result of rapid increase in smaller individuals due to mortality in larger trees. Climate events caused rapid changes in dominant populations due to a handful of species undergoing strong increases or declines in abundance over time simultaneously. Species abundance composition underwent significant changes, particularly in the presence of drought and windstorm events. High variance ratio and species synchrony weaken community stability under various climate stress. Our study demonstrates that all processes underlying forest community composition changes often occur simultaneously and are equally affected by climate events, necessitating a holistic approach to quantifying community changes. By recognizing the interconnected nature of these processes, future research should accelerate comprehensive understanding and predicting of how forest vegetation responds to global climate change.

Soil microbial community structure, function and network along a mangrove forest restoration chronosequence.

Mangrove forests have high ecological, social and economic values, but due to environmental changes and human activities, natural mangrove forests have experienced serious degradations and reductions in distribution area worldwide. In the coastal zones of southern China, an introduced mangrove species, Sonneratia apetala, has been extensively used for mangrove restoration because of its rapid growth and strong environmental adaptability. However, little is known about how soil microorganisms vary with the restoration stages of the afforested mangrove forests. Here, we examined the changes in soil physicochemical properties and microbial biomass, community structure and function, and network in three afforested S. apetala forests with restoration time of 7, 12, and 18 years and compared them with a bare flat and a 60-year-old natural Kandelia obovata forest in a mangrove nature reserve. Our results showed that the contents of soil salinity, organic carbon, total nitrogen, ammonium nitrogen, and microbial biomass increased, while soil pH and bacterial alpha diversity decreased with afforestation age. Soil microbial community structure was significantly affected by soil salinity, organic carbon, pH, total nitrogen, ammonium nitrogen, available phosphorus, and available kalium, and susceptibility to environmental factors was more pronounced in bacterial than fungal community structure. The relative abundances of aerobic chemoheterotrophy were significantly higher in 12- and 18-year-old S. apetala than in K. obovata forest, while that of sulfate-reducing bacteria showed a decreasing trend with afforestation age. The abundance of dung saprotroph was significantly higher in 12- and 18-year-old S. apetala forests than in the natural forest. With the increasing afforestation age, the modularity of microbial networks increased, while stability and robustness decreased. Our results suggest that planting S. apetala contributes to improving soil fertility and microbial biomass but may make soil microbial networks more vulnerable.

Climate change reshapes plant trait spectrum to explain biomass dynamics in an old-growth subtropical forest.

Climate change leads to novel species interactions and continues to reshuffle ecological communities, which significantly declines carbon accumulation rates in mature forests. Still, little is known about the potential influence of multiple global change factors on long-term biomass dynamics and functional trait combinations. We used temporal demographic records spanning 26 years and extensive databases of functional traits to assess how old-growth subtropical forest biomass dynamics respond to various climatic change scenarios (extreme drought, subsequent drought, warming, elevated CO2 concentrations, and windstorm). We found that the initial severe drought, subsequent drought and windstorm events increased biomass loss due to tree mortality, which exceeded the biomass gain produced by survivors and recruits, ultimately resulting in more negative net biomass balances. These drought and windstorm events caused massive biomass loss due to tree mortality that tended towards acquisition species with high hydraulic efficiency, whereas biomass growth from survivors and recruits tended to consist of acquisition species with high hydraulic safety. Compensatory growth in this natural forest provided good explanation for the increase in biomass growth after drought and windstorm events. Notably, these dominant-species transitions reduced carbon storage and residence time, forming a positive carbon-climate feedback loop. Our findings suggest that climate changes could alter functional strategies and cause shifts in new dominant species, which could greatly reduce ecological functions and carbon gains of old-growth subtropical forests.

Pseudoceranoids A-J, Sesquiterpene-Based Meroterpenoids with Cytotoxicity from the Sponge Pseudoceratina purpurea.

Pseudoceranoid A (1), a rare merosesquiterpene featuring a rearranged 4,9-friedodrimane-type core with a crotonolactone moiety, two new rearranged 4,9-friedodrimane-type sesquiterpene cyclopentanones (2 and 3), and three new rearranged 4,9-friedodrimane-type sesquiterpene hydroquinones (4-6), along with two new drimane-type sesquiterpene derivatives (7 and 8), as well as two new 4,9-friedodrimane-type sesquiterpene quinones (9 and 10), were isolated from the South China Sea sponge Pseudoceratina purpurea. The structures of compounds were established by analysis of spectroscopic data, as well as by single-crystal X-ray diffraction, DP4+ probability analyses, and calculated electronic circular dichroism. Compound 4 showed weak cytotoxicity against K562, H69AR, and MDAMB-231 cell lines with IC50 values of 3.01, 7.74, and 9.82 µM, respectively. Compound 5 exhibited cytotoxicity against the H69AR cell line with an IC50 value of 2.85 µM.

Cytotoxic Epipolythiodioxopiperazines from the Deep-Sea-Derived Fungus Exophiala mesophila MCCC 3A00939.

Four new aranotin-type epipolythiodioxopiperazines, graphiumins K-N (1-4), along with four known analogues (5-8), were isolated from the deep-sea-derived fungus Exophiala mesophila MCCC 3A00939. Their structures were elucidated by detailed interpretation of NMR and mass spectrometric data. The absolute configuration of the isolates was deduced by a single-crystal X-ray diffraction analysis and the comparisons of experimental electronic circular dichroism (ECD) data with calculated ECD spectra. Graphiumins K (1) and L (2) exhibited cytotoxic activities against the K562, H69AR, and MDA-MB-231 cancer cells with IC50 values ranging from 2.3 to 5.9 µM.

Heterolactone and Heterolactams A-M, Verticillane Diterpenoids with Anti-Inflammatory and Hepatoprotective Activities from the Soft Coral Heteroxenia ghardaqensis.

Fourteen new verticillane diterpenoids, heterolactone (1) and heterolactams A-M (2-14), were isolated from the soft coral Heteroxenia ghardaqensis. They structurally share the same 6/12 bicyclic carbon skeleton that is not commonly encountered in marine organisms. The structures, including the absolute configurations, were determined by extensive spectroscopic analysis, single-crystal X-ray diffraction analysis, calculated ECD spectra, and DP4+ probability analyses. Compounds 5, 8, and 9 showed anti-inflammatory activities, and 2, 8, and 12 displayed hepatoprotective activities in zebrafish assays.

Carbon sequestration and storage capacity of Chinese fir at different stand ages.

In southern China, Chinese fir Cunninghamia lanceolata is one of the most important native conifer trees, widely used in afforestation programs. This area has the largest forestland atmospheric carbon sink, and a relatively young stand age characterizes these forests. However, how C. lanceolata forests evolved regarding their ability to sequester carbon remains unclear. Here we present data on carbon storage and sequestration capacity of C. lanceolata at six stand ages (5-, 10-, 15-, 20-, 30- and 60 - year-old stands). Results show that the carbon stock in trees, understory, vegetation, litter, soil, and ecosystem significantly increased with forest age. The total ecosystem carbon stock increased from 129.11 to 348.43 Mg ha-1 in the 5- and 60 - year-old stands. The carbon sequestration rate of C. lanceolata shows an overall increase in the first two stand intervals (5-10 and 10-15), peaks in the 15-20 stand intervals, and then decreases in the 20-30 and 30-60 stand intervals. Our result revealed that carbon sequestration rate is a matter of tree age, with the highest sequestration rates occurring in the middle age forest (15-20 - year-old). Therefore, this information may be useful for national climate change mitigation actions and afforestation programs, since forests are primarily planted for this purpose.

Two new spongian diterpene derivatives from the aquaculture sponge Spongia officinalis Linnaeus, 1759.

2ß,3α,19-Triacetoxy-17-hydroxyspongia-13(16),14-diene (1), a novel acetoxy diterpenoid, and 18-nor-2,17-hydroxyspongia-1,4,13(16),14-quaien-3-one (2), belonging to the rare 18-nor-spongian carbon skeleton, together with six related known metabolites (3‒8), were isolated from the aquaculture Spongia officinalis Linnaeus, 1759. Their structures were elucidated by comprehensive spectroscopic analysis, quantum chemical calculation of NMR parameters, and electronic circular dichroism (ECD). Compounds 3, 4, and 5 exhibited moderate inhibition against STAT3/NF-κB, HIF-1, Wnt signalling pathways. Compounds 1, 3, and 5 showed cytotoxicity activities against K562 cell line with IC50 values of 7.3, 3.5, and 6.4 µM, respectively.

Tracking biomedical articles along the translational continuum: a measure based on biomedical knowledge representation.

Keeping track of translational research is essential to evaluating the performance of programs on translational medicine. Despite several indicators in previous studies, a consensus measure is still needed to represent the translational features of biomedical research at the article level. In this study, we first trained semantic representations of biomedical entities and documents (i.e., bio-entity2vec and bio-doc2vec) based on over 30 million PubMed articles. With these vectors, we then developed a new measure called Translational Progression (TP) for tracking biomedical articles along the translational continuum. We validated the effectiveness of TP from two perspectives (Clinical trial phase identification and ACH classification), which showed excellent consistency between TP and other indicators. Meanwhile, TP has several advantages. First, it can track the degree of translation of biomedical research dynamically and in real-time. Second, it is straightforward to interpret and operationalize. Third, it doesn't require labor-intensive MeSH labeling and it is suitable for big scholarly data as well as papers that are not indexed in PubMed. In addition, we examined the translational progressions of biomedical research from three dimensions (including overall distribution, time, and research topic), which revealed three significant findings. The proposed measure in this study could be used by policymakers to monitor biomedical research with high translational potential in real-time and make better decisions. It can also be adopted and improved for other domains, such as physics or computer science, to assess the application value of scientific discoveries.

Subergorgines A-E, five new suberosanone-purine hybrids from the South China Sea gorgonian Subergorgia suberosa.

Five new suberosanone-purine hybrids, namely subergorgines A-E (1-5), were isolated from the South China Sea gorgonian Subergorgia suberosa. Their structures were elucidated on the basis of extensive spectroscopic data and the absolute configurations were clarified by the theoretical ECD calculation. Compounds 1-5 were rare purine alkaloids merged with the same suberosanone moiety via different C (6)-N bridges. Cytotoxic activities of the isolates were tested. Compound 4 was found to be the most active against the HL-60 cancer cell line with an IC50 value of 14.3 µM. A plausible biosynthetic pathway for suberosanone-purine hybrids was also discussed.

Sarcoeleganolides C-G, Five New Cembranes from the South China Sea Soft Coral Sarcophyton elegans.

Five new cembranes, named sarcoeleganolides C-G (1-5), along with three known analogs (6-8) were isolated from soft coral Sarcophyton elegans collected from the Yagong Island, South China Sea. Their structures and absolute configurations were determined by extensive spectroscopic analysis, QM-NMR, and TDDFT-ECD calculations. In addition, compound 3 exhibited better anti-inflammation activity compared to the indomethacin as a positive control in zebrafish at 20 µM.

Tree species richness as an important biotic factor regulates the soil phosphorus density in China's mature natural forests.

Tree species richness has been recognized as an underlying driving factor for regulating soil phosphorus (P) status in many site-specific studies. However, it remains poorly understood whether this is true at broad scales where soil P strongly rely on climate, soil type and vegetation type. Here, based on the data of 946 mature natural forest sites from a nationwide field survey in China, we analyzed the impact of tree species richness on soil P density of China's mature natural forests (deciduous coniferous forest, DCF; evergreen coniferous forest, ECF; deciduous broad-leaved forest, DBF; evergreen broad-leaved forest, EBF; and mixed coniferous and broad-leaved forest, MF). Our results showed that tree species richness had a negative effect on soil P density in China's mature natural forests. The Random Forest regression model showed that the relative importance of tree species richness to soil P density was second only to the climate factors (mean annual temperature, MAT; mean annual precipitation, MAP). In addition, the structural equation model (SEM) results showed that the goodness fit of SEM increased when the tree species richness was included into the model. These results suggested that tree species richness was an important factor in regulating the China's mature natural forests soil P density. Furthermore, the SEM results showed that the decreased soil P density was related to the increase in ANPP and the decrease in litter P concentration induced by tree species richness. This result indicates that tree species richness could facilitate plant P absorption and inhibit plant P return into the soil, and thus reducing the soil P density in China's mature natural forests. In conclusion, we found tree species richness was an important biotic factor in regulating soil P density at broad scales, which should be fully considered in Earth models that represent P cycle.

Four bioactive new steroids from the soft coral Lobophytum pauciflorum collected in South China Sea.

Four new polyhydroxylated steroids lobophysterols E-H (1-4), together with three known compounds (5-7), were isolated from the soft coral Lobophytum pauciflorum collected at Xisha Island, China. The structures of the new compounds were elucidated by extensive spectroscopic analysis and comparison with NMR data of structurally related compounds reported in the literature. The absolute configuration of 1-3 was determined by X-ray diffraction. All the compounds have assessed the cytotoxicity against HL-60, K562, and Hela cells. Compound 1 showed weak cytotoxicity against K562 cells with an IC50 value of 19.03 µM. In addition, compound 1 also showed a moderate anti-inflammatory effect in zebrafish.

Guaiane sesquiterpenes from the gorgonian Echinogorgia flora collected in the South China Sea.

Echinoflorine (1), a new dimethylamino-substituted guaipyridine alkaloid with a novel γ-lactone-cyclohepta[c]pyridine fused skeleton, and three new guaiane sesquiterpene lactones, echinofloranolides A-C (2-4), together with eight known guaiane sesquiterpenes were isolated from the gorgonian Echinogorgia flora collected in the South China Sea. Their structures were elucidated by 1D and 2D NMR, HRESIMS, calculated ECD and DP4+ probability analyses.

Dolabellane Diterpenes and Elemane Alkaloids from the Soft Coral Clavularia inflata Collected in the South China Sea.

Five new dolabellane diterpenes, clavularinlides A-E (1-5), and four new racemic elemane alkaloids, clavulacylides A-D (7-10), together with one known compound (6), were isolated from the soft coral Clavularia inflata collected in the South China Sea. Their structures were elucidated by 1D and 2D NMR, HRESIMS, calculated ECD, and DP4+ probability analyses. Compounds 1-7 showed anti-inflammatory activity in the zebrafish assay.

Internationalizing AI: evolution and impact of distance factors.

International collaboration has become imperative in the field of AI. However, few studies exist concerning how distance factors have affected the international collaboration in AI research. In this study, we investigate this problem by using 1,294,644 AI related collaborative papers harvested from the Microsoft Academic Graph dataset. A framework including 13 indicators to quantify the distance factors between countries from 5 perspectives (i.e., geographic distance, economic distance, cultural distance, academic distance, and industrial distance) is proposed. The relationships were conducted by the methods of descriptive analysis and regression analysis. The results show that international collaboration in the field of AI today is not prevalent (only 15.7%). All the separations in international collaborations have increased over years, except for the cultural distance in masculinity/felinity dimension and the industrial distance. The geographic distance, economic distance and academic distances have shown significantly negative relationships with the degree of international collaborations in the field of AI. The industrial distance has a significant positive relationship with the degree of international collaboration in the field of AI. Also, the results demonstrate that the participation of the United States and China have promoted the international collaboration in the field of AI. This study provides a comprehensive understanding of internationalizing AI research in geographic, economic, cultural, academic, and industrial aspects. Supplementary Information: The online version contains supplementary material available at 10.1007/s11192-021-04207-3.