Preparation of Medical 228Th-224Ra Radionuclide Generator Based on SiO2@TiO2 Microspheres.

224Ra (T1/2 = 3.63 d), an α-emitting radionuclide, holds significant promise in cancer endoradiotherapy. Current 224Ra-related therapy is still scarce because of the lack of reliable radionuclide supply. The 228Th-224Ra radionuclide generator can undoubtedly introduce continuous and sustainable availability of 224Ra for advanced nuclear medicine. However, conventional metal oxides for such radionuclide generators manifest suboptimal adsorption capacities for the parent nuclide, primarily attributable to their limited surface area. In this work, core-shell SiO2@TiO2 microspheres were proposed to develop as column materials for the construction of a 228Th-224Ra generator. SiO2@TiO2 microspheres were well prepared and systematically characterized, which has also been demonstrated to have good adsorption capacity to 228Th and very weak binding affinity toward 224Ra via simulated chemical separation. Upon introducing 228Th-containing solution onto the SiO2@TiO2 functional column, a 228Th-224Ra generator with excellent retention of the parent radionuclide and ideal elution efficiency of daughter radionuclide was obtained. The prepared 228Th-224Ra generator can produce 224Ra with high purity and medical usability in good elution efficiency (98.72%) even over five cycles. To the best of our knowledge, this is the first time that the core-shell mesoporous materials have been applied in a radionuclide generator, which can offer valuable insights for materials chemistry, radiochemical separation, and biological medicine.

Deep metagenomic characterization of the gut virome in pregnant women with preeclampsia.

Preeclampsia (PE), a pregnancy-specific syndrome, has been associated with the gut bacteriome. Here, to investigate the impact of the gut virome on the development of PE, we identified over 8,000 nonredundant viruses from the fecal metagenomes of 40 early-onset PE and 37 healthy pregnant women and profiled their abundances. Comparison and correlation analysis showed that PE-enriched viruses frequently connected to Blautia species enriched in PE. By contrast, bacteria linked to PE-depleted viruses were often the Bacteroidaceae members such as Bacteroides spp., Phocaeicola spp., Parabacteroides spp., and Alistipes shahii. In terms of viral function, PE-depleted viruses had auxiliary metabolic genes that participated in the metabolism of simple and complex polysaccharides, sulfur metabolism, lipopolysaccharide biosynthesis, and peptidoglycan biosynthesis, while PE-enriched viruses had a gene encoding cyclic pyranopterin monophosphate synthase, which seemed to be special, that participates in the biosynthesis of the molybdenum cofactor. Furthermore, the classification model based on gut viral signatures was developed to discriminate PE patients from healthy controls and showed an area under the receiver operating characteristic curve of 0.922 that was better than that of the bacterium-based model. This study opens up new avenues for further research, providing valuable insights into the PE gut virome and offering potential directions for future mechanistic and therapeutic investigations, with the ultimate goal of improving the diagnosis and management of PE.IMPORTANCEThe importance of this study lies in its exploration of the previously overlooked but potentially critical role of the gut virome in preeclampsia (PE). While the association between PE and the gut bacteriome has been recognized, this research takes a pioneering step into understanding how the gut virome, represented by over 8,000 nonredundant viruses, contributes to this condition. The findings reveal intriguing connections between PE-enriched viruses and specific gut bacteria, such as the prevalence of Blautia species in individuals with PE, contrasting with bacteria linked to PE-depleted viruses, including members of the Bacteroidaceae family. These viral interactions and associations provide a deeper understanding of the complex dynamics at play in PE.

Absorbed Bioactive Compounds Replicate Guanxin II-Induced Endothelium-Associated in/ex vivo Vasodilation.

OBJECTIVE: To develop an interference-free and rapid method to elucidate Guanxin II (GX II)'s representative vasodilator absorbed bioactive compounds (ABCs) among enormous phytochemicals. METHODS: The contents of ferulic acid, tanshinol, and hydroxysafflor yellow A (FTA) in GX II/rat serum after the oral administration of GX II (30 g/kg) were detected using ultra-performance liquid chromatography-mass spectrometry. Totally 18 rats were randomly assigned to the control group (0.9% normal saline), GX II (30 g/kg) and FTA (5, 28 and 77 mg/kg) by random number table method. Diastolic coronary flow velocity-time integral (VTI), i.e., coronary flow or coronary flow-mediated dilation (CFMD), and endothelium-intact vascular tension of isolated aortic rings were measured. After 12 h of exposure to blank medium or 0.5 mmol/L H2O2, endothelial cells (ECs) were treated with post-dose GX II of supernatant from deproteinized serum (PGSDS, 300 µL PGSDS per 1 mL of culture medium) or FTA (237, 1539, and 1510 mg/mL) for 10 min as control, H2O2, PGSDS and FTA groups. Nitric oxide (NO), vascular endothelial growth factor (VEGF), endothelin-1 (ET-1), superoxide dismutase (SOD), malondialdehyde (MDA) and phosphorylated phosphoinositide 3 kinase (p-PI3K), phosphorylated protein kinase B (p-AKT), phosphorylated endothelial nitric oxide synthase (p-eNOS) were analyzed. PGSDS was developed as a GX II proxy of ex vivo herbal crude extracts. RESULTS: PGSDS effectively eliminates false responses caused by crude GX II preparations. When doses equaled the contents in GX II/its post-dose serum, FTA accounted for 98.17% of GX II -added CFMD and 92.99% of PGSDS-reduced vascular tension. In ECs, FTA/PGSDS was found to have significant antioxidant (lower MDA and higher SOD, P<0.01) and endothelial function-protective (lower VEGF, ET-1, P<0.01) effects. The increases in aortic relaxation, endothelial NO levels and phosphorylated PI3K/Akt/eNOS protein induced by FTA/PGSDS were markedly abolished by NG-nitro-L-arginine methyl ester (L-NA, eNOS inhibitor) and wortmannin (PI3K/AKT inhibitor), respectively, indicating an endothelium-dependent vasodilation via the PI3K/AKT-eNOS pathway (P<0.01). CONCLUSION: This study provides a strategy for rapidly and precisely elucidating GX II's representative in/ex vivo cardioprotective absorbed bioactive compounds (ABCs)-FTA, suggesting its potential in advancing precision ethnomedicine.

Chemically Cross-Linked Hammerhead Ribozyme as an Efficient RNA Interference Tool.

RNA-cleaving ribozymes are promising candidates as general tools of RNA interference (RNAi) in gene manipulation. However, compared with other RNA systems, such as siRNA and CRISPR technologies, the ribozyme tools are still far from broad applications on RNAi due to their poor performance in the cellular context. In this work, we report an efficient RNAi tool based on chemically modified hammerhead ribozyme (HHR). By the introduction of an intramolecular linkage into the minimal HHR to reconstruct the distal interaction within the tertiary ribozyme structure, this cross-linked HHR exhibits efficient RNA substrate cleavage activities with almost no sequence constraint. Cellular experiments suggest that both exogenous and endogenous RNA expression can be dramatically knocked down by this HHR tool with levels comparable to those of siRNA. Unlike the widely applied protein-recruiting RNA systems (siRNA and CRISPR), this ribozyme tool functions solely on RNA itself with great simplicity, which may provide a new approach for gene manipulation in both fundamental and translational studies.

Harnessing Catalytic RNA Circuits for Construction of Artificial Signaling Pathways in Mammalian Cells.

Engineering of genetic networks with artificial signaling pathways (ASPs) can reprogram cellular responses and phenotypes under different circumstances for a variety of diagnostic and therapeutic purposes. However, construction of ASPs between originally independent endogenous genes in mammalian cells is highly challenging. Here we report an amplifiable RNA circuit that can theoretically build regulatory connections between any endogenous genes in mammalian cells. We harness the system of catalytic hairpin assembly with combination of controllable CRISPR-Cas9 function to transduce the signals from distinct messenger RNA expression of trigger genes into manipulation of target genes. Through introduction of these RNA-based genetic circuits, mammalian cells are endowed with autonomous capabilities to sense the changes of RNA expression either induced by ligand stimuli or from various cell types and control the cellular responses and fates via apoptosis-related ASPs. Our design provides a generalized platform for construction of ASPs inside the genetic networks of mammalian cells based on differentiated RNA expression.

meHOLMES: A CRISPR-cas12a-based method for rapid detection of DNA methylation in a sequence-independent manner.

Aberrant DNA methylation is closely associated with various diseases, particularly cancer, and its precise detection plays an essential role in disease diagnosis and monitoring. In this study, we present a novel DNA methylation detection method (namely meHOLMES), which integrates both the TET2/APOBEC-mediated cytosine deamination step and the CRISPR-Cas12a-based signal readout step. TET2/APOBEC efficiently converts unmethylated cytosine to uracil, which is subsequently changed to thymine after PCR amplification. Utilizing a rationally designed crRNA, Cas12a specifically identifies unconverted methylated cytosines and generates detectable signals using either fluorescent reporters or lateral flow test strips. meHOLMES quantitatively detects methylated CpG sites with or without Protospacer Adjacent Motif (PAM) sequences in both artificial and real biological samples. In addition, meHOLMES can complete the whole detection process within 6 h, which is much faster than traditional bisulfite-based sample pre-treatment method. Above all, meHOLMES provides a simpler, faster, more accurate, and cost-effective approach for quantitation of DNA methylation levels in a sequence-independent manner.

NR5A2 promotes malignancy progression and mediates the effect of cisplatin in cutaneous squamous cell carcinoma.

INTRODUCTION: Nuclear receptor subfamily five group A member two (NR5A2) plays a key role in the development of many tumor types, while it is uncertain in cutaneous squamous cell carcinoma (cSCC). The aim of this work was to determine the role of NR5A2 in cSCC proliferation, and to determine whether NR5A2 mediates the effect of cisplatin in cSCC. METHODS: We performed a systematic study of existing data and conducted a preliminary bioinformatics analysis of NR5A2 expression in cSCC using bioinformatics databases. Immunohistochemical staining was performed on cSCC tissues of seven patients to study NR5A2 expression. NR5A2 expression was examined in human keratin-forming cells (HaCaT) and human cSCC cells (A431, Colo-16, SCL-1, SCL-2, and HSC-5). Stable A431 and SCL-2 cell lines consisting of sh-RNA-NR5A2 were constructed to detect changes in cell proliferation, cell cycle, apoptosis, and to determine the key proteins in the Wnt/ß-catenin pathway. We also investigated changes in the effects of cisplatin on cSCC cells by CCK-8, clone formation assay, and Flow apoptosis assay after NR5A2 knockdown. RESULTS: NR5A2 showed enhanced expression in cSCC tissues than in healthy tissues. Downregulation of NR5A2 in cSCC cells led to the formation of a less malignant phenotype. In contrast, the proliferative capacity of the cSCC cells was enhanced posttreatment with RJW100, an NR5A2 agonist. Additionally, NR5A2 knockdown led to a decrease in the expression level of the proteins in the Wnt/ß-catenin pathway, and this inhibition was reversed by LiCl and recombinant antibody, Wnt3a. Moreover, NR5A2 knockdown resulted in diminished proliferative capacity and increased apoptotic cells after the addition of cisplatin. CONCLUSION: NR5A2 plays a crucial role in the progression of cSCC, and the Wnt/ß-catenin signaling pathway may be involved in the regulation of NR5A2-mediated cSCC. Knockdown of NR5A2 enhanced both the proliferation inhibiting and apoptosis promoting effects of cisplatin on cSCC.

Effect of TCM rehabilitation program on activities of daily living in patients with post-stroke limb spasticity: An observational study.

BACKGROUND: Stroke is a neurological disease with many common complications that reduce the activities of daily living and the quality of life of patients. Traditional Chinese medicine (TCM) rehabilitation techniques, scalp acupuncture, and TCM can relieve spasticity symptoms and recovery from physical obstacles is significant. METHODS: Three hundred twenty-one patients with post-stroke limb spasticity were randomly divided into trial and control groups, with 159 and 162 patients in the trial and control groups, respectively. The control group received basic treatment combined with modern rehabilitation techniques, whereas the trial group received basic treatment combined with TCM, Tuina, and scalp acupuncture with kinesiotherapy. The treatment course in both groups was 4 weeks. The Modified Ashworth Scale, magnetic resonance imaging, and Stroke Specific Quality of Life Scale were used to evaluate limb spasticity, activities of daily living, and quality of life, respectively. PASW 18.0 was used for statistical analysis. RESULTS: With a longer treatment period, the improvement in limb spasticity was greater in the trial group than in the control group (P < .05). Similarly, improvements in activities of daily living and quality of life were better in the trial group than in the control group (P < .05). CONCLUSION: The TCM rehabilitation program using Tongjing Tiaoxing combined with scalp acupuncture and kinesiotherapy can effectively treat spasticity symptoms in stroke patients and improve their activities of daily living and quality of life.

Integrating Ligands into Nucleic Acid Systems.

Signal transduction from non-nucleic acid ligands (small molecules and proteins) to structural changes of nucleic acids plays a crucial role in both biomedical analysis and cellular regulations. However, how to bridge between these two types of molecules without compromising the expandable complexity and programmability of the nucleic acid nanomachines is a critical challenge. Compared with the previously most widely applied transduction strategies, we review the latest advances of a kinetically controlled approach for ligand-oligonucleotide transduction in this Concept article. This new design works through an intrinsic conformational alteration of the nucleic acid aptamer upon the ligand binding as a governing factor for nucleic acid strand displacement reactions. The functionalities and applications of this transduction system as a ligand converter on biosensing and DNA computation are described and discussed. Furthermore, we propose some potential scenarios for utilization of this ligand transduction design to regulate gene expression through synthetic RNA switches in the cellular contexts. Finally, future perspectives regarding this ligand-oligonucleotide transduction platform are also discussed.

Understanding the origin of the improved sodium ion storage performance of the transition metal oxide@carbon nanocomposite anodes.

Transition metal oxide (TMO) anodes show inferior sodium ion storage performance compared with that of lithium ion storage owing to the larger radium size and heavier elemental mass of Na+ than Li+. Effective strategies are highly desired to improve the Na+ storage performance of TMOs for applications. In this work, using ZnFe2O4@xC nanocomposites as model materials for investigation, we found that by manipulating the particle sizes of the inner TMOs core and the features of outer carbon coating, the Na+ storage performance can be significantly improved. The ZnFe2O4@1C with a diameter of the inner ZnFe2O4 core of around 200 nm coated by a thin carbon layer of around 3 nm shows a specific capacity of only 120 mA h g-1. The ZnFe2O4@6.5C with a diameter of the inner ZnFe2O4 core of around 110 nm embedding in a porous interconnected carbon matrix displays a significantly improved specific capacity of 420 mA h g-1 at the same specific current. Furthermore, the latter shows an excellent cycling stability of 1000 cycles with a capacity retention of 90% of the initial 220 mA h g-1 specific capacity at 1.0 A g-1. TEM, electrochemical impedance spectroscopy, and kinetic analysis show that the inner ZnFe2O4 core with reduced particle size and the outer thicker and interconnected carbon matrix synergistically improve the active reaction sites, integrity, electric conductivity, and pseudocapacitive-controlled contribution of ZnFe2O4@xC nanocomposites, thus leading to an overall enhanced Na+ storage performance. Our findings create a universal, facile, and effective method to enhance the Na+ storage performance of the TMO@C nanomaterials.

[Response of Soil Organic Carbon Accumulation in Paddy Fields in Fujian Province to Future Temperature Increases].

Understanding the effect of the soil carbon "source-sink" in cropland in China under future warming scenarios is the basis for making reasonable carbon neutralization policies. This study focused on the paddy soil in Fujian Province, a typical subtropical region in China including 84 counties (cities and districts). We employed the 1:50000 soil database and biogeochemical process model (DNDC) to simulate the dynamic changes in paddy soil organic carbon under different warming scenarios for the period of 2017-2053. The results indicated that in the context of normal temperature (control run) and 2, 4, and 6℃ of warming, the total amounts of carbon sequestration of paddy soil in Fujian Province were 11.56,9.44, 7.08, and 4.91 Tg, respectively; accordingly, the average annual carbon sequestration rates (expressed by C) were 173, 141, 106, and 74 kg·(hm2·a)-1, indicating that the rate of carbon sequestration was decreasing with the increase in future temperature. However, overall, the paddy field soil in the province was still a "carbon sink" under the warming of 6 (C. We also found that the gleyed paddy soil was mostly affected by the increase in temperature, and the decrease in carbon sequestration rate ranged from 20% to 69% using different treatments. In contrast, the salinized paddy soil was slightly affected, with a 14%-43% decrease in carbon sequestration rates. As for the different administrative regions, Sanming City was the most affected by temperature increase, with the rate of carbon sequestration decreasing by 27%-83% using different treatments. However, it was reduced by only 10%-41% and 14%-42% in Quanzhou and Putian (coastal areas), respectively. Overall, due to different soil properties, fertilization management, and climatic environment, there was a strong variability in the carbon sequestration rates of paddy soil for different soil subtypes and administrative regions in Fujian in response to future climatic warming.

Programming Non-Nucleic Acid Molecules into Computational Nucleic Acid Systems.

Nucleic acid (NA) computation has been widely developed in the past years to solve kinds of logic and mathematic issues in both information technologies and biomedical analysis. However, the difficulty to integrate non-NA molecules limits its power as a universal platform for molecular computation. Here, we report a versatile prototype of hybridized computation integrated with both nucleic acids and non-NA molecules. Employing the conformationally controlled ligand converters, we demonstrate that non-NA molecules, including both small molecules and proteins, can be computed as nucleic acid strands to construct the circuitry with increased complexity and scalability, and can be even programmed to solve arithmetical calculations within the computational nucleic acid system. This study opens a new door for molecular computation in which all-NA circuits can be expanded with integration of various ligands, and meanwhile, ligands can be precisely programmed by the nuclei acid computation.

Anti-cutaneous squamous cell carcinoma effect and mechanism of dihydrochromone-spliced polycyclic pyrrole-spiroepoxidole compound 3m / 中国药房

OBJECTIVE To study the effect and mechanism of dihydrochromone-spliced polycyclic pyrrole-spiroepoxidole compound 3m on cutaneous squamous cell carcinoma. METHODS Using human cutaneous squamous cell carcinoma A431 and Colo-16 cells as research subjects， CCK-8 assay was used to detect the effects of different concentrations of 3m （5， 10， 20， 40， 80 μmol/L） on the proliferation of A431 and Colo-16 cells after 24， 48 and 72 hours； the median inhibitory concentration （IC50） was calculated at 48 h of treatment. A431 and Colo-16 cells were divided into control group， 3m low-concentration and high- concentration groups （15， 30 μmol/L）. After treated with relevant drugs or culture medium for 48 h， the morphological changes of cells in each group were observed by inverted microscope. Clone formation rate， migration rate and number of cell invasions， cell cycle distribution and apoptosis rate were detected. The phosphorylation， or expression of Janus kinase 2/signal transducer and activator of transcription 3 （JAK2/STAT3） signaling pathway related proteins [JAK2， STAT3， B-cell lymphocyte-2 （Bcl-2）， Bcl-2- associated X protein （Bax）]， and their mRNA expression in cells were detected. RESULTS 3m could significantly inhibit the proliferation of A431 and Colo-16 cells after treated for 24， 48， 72 h （P＜0.01）， and IC50 of them were 20.36， 23.72 μmol/L， respectively. After 48 hours of treatment， compared with control group， A431 and Colo-16 cells arranged sparsely and loosely connected in 3m low-concentration and high-concentration groups. The clone formation rate， migration rate， number of cell invasions， mRNA expressions of JAK2， STAT3 and Bcl-2， the phosphorylation of JAK2 and STAT3， protein expression of Bcl-2 were significantly decreased/weakened （P＜0.01）. Proportion of cell cycle in G2 phase， apoptosis rate， protein and mRNA expression of Bax were increased significantly （P＜0.01）； and all the above effects were in dose-dependent manner. CONCLUSIONS 3m can inhibit the proliferation， clone formation， migration and invasion abilities of cutaneous squamous cell carcinoma A431 and Colo-16 cells in a dose-dependent manner， the mechanism of which may be associated with inhibiting the activity of JAK2/STAT3 signaling pathway， and inducing cell apoptosis.

[Community structure and species composition of typical Quercus variabilis natural secondary forest at the northern foothills of the Qinling Mountains, China]. / ç§¦å²­åŒ—éº“å ¸åž‹æ “çš®æ Žå¤©ç„¶æ¬¡ç”Ÿæž—ç¾¤è½ç»“æž„ä¸Žç‰©ç§ç»„æˆ.

We investigated species composition and community structure of a typical Quercus variabilis natural secondary forest in the northern foothills of the Qinling Mountains, within the dynamic monitoring plot of deciduous broad-leaved forest at the Louguantai experimental forest farm in Zhouzhi County, Shaanxi Province. The results showed that there were 3162 individual woody plants with diameter at breast height ≥1 cm in the plot, which were belonged to 42 species, 36 genera, and 25 families. The community genus's areal type was dominated by the temperate component, which accounted for 44.4%, and followed by the tropical component. The community was dominated by several tree species. The top three species with respect to importance value were Q. variabilis, Pinus tabuliformis, and Quercus aliena, with the sum of their importance value being 64.7%. The average DBH of all woody plants was 7.58 cm. The distribution of all individuals and dominant species in the tree layer was approximately normal, with more medium-size individuals. The community structure was stable. The community was poorly renewed, with a trend of population decline. Biodiversity indices varied considerably among different plots, being lower than those of subtropical broad-leaved evergreen forests. There was a significant correlation between community species distribution and environmental factors. Soil and topography explained 42.4% of the variation in community distribution. Altitude and soil alkali hydrolysable nitrogen had a significant effect on community distribution. Altitude, soil total phosphorus, and organic matter content significantly affected the species diversity of Q. variabilis communities. The stronger adaptability of Q. variabilis populations allowed them to become dominant in low-nutrient environments, which limited species diversity in the community.

A Catalog of over 5,000 Metagenome-Assembled Microbial Genomes from the Caprinae Gut Microbiota.

Most microbiome studies regarding the ruminant digestive tract have focused on the rumen microbiota, whereas only a few studies were performed on investigating the gut microbiota of ruminants, which limits our understanding of this important component. Herein, the gut microbiota of 30 Caprinae animals (sheep and goats) from six provinces in China was characterized using ultradeep (>100 Gbp per sample) metagenome shotgun sequencing. An inventory of Caprinae gut microbial species containing 5,046 metagenomic assembly genomes (MAGs) was constructed. Particularly, 2,530 of the genomes belonged to uncultured candidate species. These genomes largely expanded the genomic repository of the current microbes in the Caprinae gut. Several enzymes and biosynthetic gene clusters encoded by these Caprinae gut species were identified. In summary, our study extends the gut microbiota characteristics of Caprinae and provides a basis for future studies on animal production and animal health. IMPORTANCE We constructed a microbiota catalog containing 5,046 MAGs from Caprinae gut from six regions of China. Most of the MAGs do not overlap known databases and appear to be potentially new species. We also characterized the functional spectrum of these MAGs and analyzed the differences between different regions. Our study enriches the understanding of taxonomic, functional, and metabolic diversity of Caprinae gut microbiota. We are confident that the manuscript will be of utmost interest to a wide range of readers and be widely applied in future research.

Deep metagenomic characterization of gut microbial community and function in preeclampsia.

Preeclampsia (PE) is a pregnancy complication characterized by severe hypertension and multiple organ damage. Gut microbiota has been linked to PE by previous amplicon sequencing studies. To resolve the PE gut microbiota in a higher taxonomy resolution, we performed shotgun metagenomic sequencing on the fecal samples from 40 early-onset PE and 37 healthy pregnant women. We recovered 1,750 metagenome-assembled genomes (representing 406 species) from the metagenomic dataset and profiled their abundances. We found that PE gut microbiota had enriched in some species belonging to Blautia, Pauljensenia, Ruminococcus, and Collinsella and microbial functions such as the bacitracin/lantibiotics transport system, maltooligosaccharide transport system, multidrug efflux pump, and rhamnose transport system. Conversely, the gut microbiome of healthy pregnant women was enriched in species of Bacteroides and Phocaeicola and microbial functions including the porphyrin and chlorophyll metabolism, pyridoxal-P biosynthesis, riboflavin metabolism, and folate biosynthesis pathway. PE diagnostic potential of gut microbial biomarkers was developed using both species and function profile data. These results will help to explore the relationships between gut bacteria and PE and provide new insights into PE early warning.

Controllable DNA hybridization by host-guest complexation-mediated ligand invasion.

Dynamic regulation of nucleic acid hybridization is fundamental for switchable nanostructures and controllable functionalities of nucleic acids in both material developments and biological regulations. In this work, we report a ligand-invasion pathway to regulate DNA hybridization based on host-guest interactions. We propose a concept of recognition handle as the ligand binding site to disrupt Watson-Crick base pairs and induce the direct dissociation of DNA duplex structures. Taking cucurbit[7]uril as the invading ligand and its guest molecules that are integrated into the nucleobase as recognition handles, we successfully achieve orthogonal and reversible manipulation of DNA duplex dissociation and recovery. Moreover, we further apply this approach of ligand-controlled nucleic acid hybridization for functional regulations of both the RNA-cleaving DNAzyme in test tubes and the antisense oligonucleotide in living cells. This ligand-invasion strategy establishes a general pathway toward dynamic control of nucleic acid structures and functionalities by supramolecular interactions.

[Shrub layer structure and species diversity of warm temperate deciduous broadleaved forests of the Qinling Mountains Huangguan plot in China]. / ç§¦å²­çš‡å† æš–æ¸©å¸¦è½å¶é˜”å¶æž—çŒæœ¨å±‚ç»“æž„ä¸Žç‰©ç§å¤šæ ·æ€§.

Shrub is an important part of forest ecosystem. Exploring the species composition, structure and spatial distribution of shrub layer can lay an important foundation for further clarifying the mechanisms underlying species coexistence, biodiversity maintenance and community succession. In this study, species composition, spatial distribution, and species diversity of shrub layer were analyzed in 25 hm2 of Huangguan forest plot. A total of 20716 individual shrubs (with 10463 branches) were recorded in the plot, belonging to 54 species, 45 genera, 28 families. The status of dominant species in the shrub layer was not obvious, with all the importance values being less than 10. The diameter structure of shrub layer vegetation was inverted 'J' type. Shrubs showed aggregated distribution in the plot, with obvious altitude differences in spatial distribution. The diameter structure and spatial distribution of the nine shrub species with the largest abundance in the plot were consistent with the overall situation of shrub layer. With increasing altitude, the Shannon diversity index (H) and Simpson dominance index (D) did not change significantly, while the Pielou evenness index (E) decreased. Those indices decreased with the increases of the abundance of dominant species in tree layer, and E increased with the increase of the number of dominant species in sub-tree layer. The indices of H, D, E were significantly negatively correlated with soil total phosphorus (TP). The H index was significantly positively correlated with soil pH, and the E index was significantly positively correlated with soil total potassium. The shrub layer was rich in species, stable in community structure and well regenerated. The species diversity of shrub layer was mainly affected by the number of dominant species in the tree layer, soil pH, and TP.

[Spatial distribution patterns and intraspecific and interspecific associations of dominant shrub species Lonicera fragrantissima var. lancifolia in Huangguan of Qinling Mountains, China]. / ç§¦å²­çš‡å† ä¼˜åŠ¿çŒæœ¨è‹¦ç³–æžœçš„ç©ºé—´åˆ†å¸ƒæ ¼å±€åŠç§å† ç§é—´å ³è”.

In this study, the spatial distribution patterns of individuals with different diameter classes of dominant shrub Lonicera fragrantissima var. lancifolia and the intraspecific and interspecific relationships were analyzed in Qinling Huangguan Plot. The results showed that the diameter class structure of L. fragrantissima var. lancifolia showed a pyramid shape, with a wide bottom and a narrow top. The number of small-diameter class individuals was the largest, showing a good state of renewal and a stable growth, which was conducive to community renewal and succession. Based on Ripley's K function, using univariate and bivariate paired correlation functions, under complete spatial randomness model, heterogeneous Poisson model and antecedent condition model, all individual of the species and their diameter-dividing classes were mainly aggregated, and the aggregation degree decreased with the increases of research scale, and gradually tended to random distribution. Affected by habitat heterogeneity, diffusion restriction and negative density dependence, there was a positive correlation among different intraspecific dia-meter classes, and also a certain degree of no correlation, but without negative correlation. The interspecific relationship was complex. All types of association (no, positive and negative) were observed, but negative association and no association were dominated.

[Spatial distribution pattern and intraspecific association of dominant species Quercus aliena var. acu-tiserrata in Qinling Mountains, China]. / ç§¦å²­ä¼˜åŠ¿ä¹”æœ¨é”é½¿æ§²æ Žçš„ç©ºé—´åˆ†å¸ƒæ ¼å±€åŠç§å† å ³è”.

To explore the spatial distribution and intraspecific correlation of Quercus aliena var. acutiserrata, a domi-nant tree species in a 25 hm2 plot of warm temperate deciduous broadleaved forest in Qinling Mountains, the pair-correlation function g(r) was used to study the spatial pattern and intraspecific association. The results showed that the diameter class structure of Q. aliena var. acutiserrata was bimodal, with a large proportion of young trees (1 cm≤DBH＜5 cm), indicating an increase population structure with good capability of regeneration. The abundance of middle trees (15 cm≤DBH＜25 cm) was slightly more than that of big trees (25 cm≤DBH＜35 cm) and old trees (DBH≥35 cm), but far less than that of young trees and small trees. The spatial distribution of Q. aliena var. acuteserrata was obviously altitude dependent, which mainly distributed in the middle and high altitude areas. Results of complete spatial randomness (CSR) model analysis showed that young trees, small trees, adult trees, big trees, and old trees were aggregated in the large scale (＜60 m). Heterogeneous Poisson (HP) model was used to eliminate habitat heterogeneity. The results of HP model showed that the individual aggregation degree of each diameter class decreased, indicating that the distribution was affected by habitat heterogeneity. At the small scale (＜40 m), spatial correlation was positively correlated between individuals with small diameter gap, whereas the spatial correlation was negative correlation and no correlation between individuals with large diameter gap. At large scale (>40 m), the spatial correlation was positively correlated between large-diameter individuals, but negatively correlated and unrelated between saplings and other diameter individuals. Our results indicated that biological cha-racteristics of Q. aliena var. acutiserrata and habitat heterogeneity were important drivers for the formation of population spatial pattern.