The GFPT2-O-GlcNAcylation-YBX1 axis promotes IL-18 secretion to regulate the tumor immune microenvironment in pancreatic cancer.

The immunosuppressive microenvironment caused by several intrinsic and extrinsic mechanism has brought great challenges to the immunotherapy of pancreatic cancer. We identified GFPT2, the key enzyme in hexosamine biosynthesis pathway (HBP), as an immune-related prognostic gene in pancreatic cancer using transcriptome sequencing and further confirmed that GFPT2 promoted macrophage M2 polarization and malignant phenotype of pancreatic cancer. HBP is a glucose metabolism pathway leading to the generation of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), which is further utilized for protein O-GlcNAcylation. We confirmed GFPT2-mediated O-GlcNAcylation played an important role in regulating immune microenvironment. Through cellular proteomics, we identified IL-18 as a key downstream of GFPT2 in regulating the immune microenvironment. Through CO-IP and protein mass spectrum, we confirmed that YBX1 was O-GlcNAcylated and nuclear translocated by GFPT2-mediated O-GlcNAcylation. Then, YBX1 functioned as a transcription factor to promote IL-18 transcription. Our study elucidated the relationship between the metabolic pathway of HBP in cancer cells and the immune microenvironment, which might provide some insights into the combination therapy of HBP vulnerability and immunotherapy in pancreatic cancer.

Deubiquitinating PABPC1 by USP10 upregulates CLK2 translation to promote tumor progression in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is extremely malignant with limited treatment options. Deubiquitinases (DUBs), which cleave ubiquitin on substrates, can regulate tumor progression and are appealing therapeutic targets, but there are few related studies in PDAC. In our study, we screened the expression levels and prognostic value of USP family members based on published databases and selected USP10 as the potential interventional target in PDAC. IHC staining of the PDAC microarray revealed that USP10 expression was an adverse clinical feature of PDAC. USP10 promoted tumor growth both in vivo and in vitro in PDAC. Co-IP experiments revealed that USP10 directly interacts with PABPC1. Deubiquitination assays revealed that USP10 decreased the K27/29-linked ubiquitination level of the RRM2 domain of PABPC1. Deubiquitinated PABPC1 was able to couple more CLK2 mRNA and eIF4G1, which increased the translation efficiency. Replacing PABPC1 with a mutant that could not be ubiquitinated impaired USP10 knock-down-mediated tumor suppression in PDAC. Targeting USP10 significantly delayed the growth of cell-derived xenograft and patient-derived xenograft tumors. Collectively, our study first identified USP10 as the DUB of PABPC1 and provided a rationale for potential therapeutic options for PDAC with high USP10 expression.

Inhibition of epithelial-to-mesenchymal transition augments antitumor efficacy of nanotherapeutics in pancreatic ductal adenocarcinoma.

Intrinsic drug resistance mechanisms of tumor cells often reduce intracellular drug concentration to suboptimal levels. Epithelial-to-mesenchymal transition (EMT) is a pivotal process in tumor progression and metastasis that confers an aggressive phenotype as well as resistance to chemotherapeutics. Therefore, it is imperative to develop novel strategies and identify new targets to improve the overall efficacy of cancer treatment. We developed SN38 (active metabolite of irinotecan)-assembled glycol chitosan nanoparticles (cSN38) for the treatment of pancreatic ductal adenocarcinoma (PDAC). Furthermore, cSN38 and the TGF-ß1 inhibitor LY364947 formed composite nanoparticles upon self-assembly (cSN38 + LY), which obviated the poor aqueous solubility of LY364947 and enhanced drug sensitivity. The therapeutic efficacy of cSN38 + LY nanotherapeutics was studied in vitro and in vivo using suitable models. The cSN38 nanoparticles exhibited an antitumor effect that was significantly attenuated by TGF-ß-induced EMT. The cellular uptake of SN38 was impeded during EMT, which affected the therapeutic efficacy. The combination of LY364947 and cSN38 markedly enhanced the cellular uptake of SN38, increased cytotoxic effects, and inhibited EMT in PDAC cells in vitro. Furthermore, cSN38 + LY significantly inhibited PDAC xenograft growth in vivo. The cSN38 + LY nanoparticles increased the therapeutic efficacy of cSN38 via repressing the EMT of PDAC cells. Our findings provide a rationale for designing nanoscale therapeutics to combat PDAC.

Unravelling intrinsic descriptors based on a two-stage activity regulation of bimetallic 2D c-MOFs for CO2RR.

The bimetallic 2D conductive MOFs of M1Pc-M2-O, possessing dual metal sites to realize flexible molecular-level structural modification, are brilliant catalysts for electrochemical CO2 reduction. However, the bimetallic centers bring about the complex regulatory mechanism of catalytic activity and obscure principles for catalyst design. Herein, systematical theoretical investigation unravels intrinsic descriptors to design favorable M1Pc-M2-O catalysts based on the discovered coarse-fine two-stage activity regulation mechanism. The reaction site controls the M-COOH distance of the key intermediate and therefore affects the reaction kinetics for the first stage of coarse regulation. The other metal site influents the d-band center of the reaction site and thus constitutes the second stage of fine regulation. The coarse and fine regulation are related to the valence electrons (V), electronegativity (E), and bond length (LM-N/O) between the metal and coordination atoms. The intrinsic descriptor ϕ = (4 × VM1 × (EM1 + EN/O)/EN/O + VM2 × (EM2 + EN/O)/EN/O) × LM1-N/O (with a coefficient ratio of 4 : 1) was eventually established and correlated well with the reported experiments. On this basis, the favorable catalysts CoPc-Zn-O and CoPc-Co-O were located. The research results could contribute to the diversity of bimetallic 2D c-MOFs in CO2RR.

Structural length-scale of ß relaxation in metallic glass.

Establishing the structure-property relationship is an important goal of glassy materials, but it is usually impeded by their disordered structure and non-equilibrium nature. Recent studies have illustrated that secondary (ß) relaxation is closely correlated with several properties in a range of glassy materials. However, it has been challenging to identify the pertinent structural features that govern it. In this work, we show that the so-called polyamorphous transition in metallic glasses offers an opportunity to distinguish the structural length scale of ß relaxation. We find that, while the glass transition temperature and medium-range orders (MROs) change rapidly across the polyamorphous transition, the intensity of ß relaxation and the short-range orders (SROs) evolve in a way similar to those in an ordinary reference glass without polyamorphous transition. Our findings suggest that the MRO accounts mainly for the global stiffening of the materials and the glass transition, while the SRO contributes more to ß relaxation per se.

Intrinsic Regularity of Catalytic Cobalt Chalcogenides in Lithium-Sulfur Battery: Theoretical Study Delivers New Insights.

Cobalt chalcogenides CoX2 (X=S, Se, Te) render great performance of lithium-sulfur batteries based on catalytic capacity to alleviate shuttle effect. Given that S/Se/Te belong to the same main group, the outstanding cycling stability delivered by CoTe2 aroused the curiosity about the uniqueness of CoTe2 and intrinsic laws of cobalt chalcogenide. Herein, comprehensive theoretical study delivers new insights into the intrinsic laws of CoX2 : the relative vertical distance of two X atomic layers (rather than atom electronegativity) mainly controls adsorption; CoX2 mainly regulates the charging process (rather than discharging process) thus contributes to great cycling stability. On this basis, the advantages of CoTe2 are three-fold: moderate polysulfide adsorption, facile ion transport capacity, and surprisingly great promotion of charging process. It is hope the results will facilitate the development of cobalt chalcogenides, especially tellurides as catalytic material in lithium sulfur batteries.

Binding properties of odorant-binding protein 4 from bean bug Riptortus pedestris to soybean volatiles.

The bean bug Riptortus pedestris is a notorious insect pest that can damage various crops, especially soybean, in East Asia. In insects, the olfactory system plays a crucial role in host finding and feeding behaviour in which the odorant-binding proteins (OBPs) are believed to be involved in initial step in this system. In this study, we produced the R. pedestris adult antennae-expressed RpedOBP4 protein using a recombinant expression system in E. coli. Fluorescence competitive binding confirmed that RpedOBP4 has binding affinities to 7 of 20 soybean volatiles (ligands), and that a neutral condition is the best environment for it. The binding property of RpedOBP4 to these ligands was further revealed by integrating data from molecular docking, site-directed mutagenesis and ligand binding assays. This demonstrated that five amino acid residues (I30, L33, Y47, I57 and Y121) are involved in the binding process of RpedOBP4 to corresponding ligands. These findings will not only help us to more thoroughly explore the olfactory mechanism of R. pedestris during feeding on soybean, but also lead to the identification of key candidate targets for developing environmental and efficient behaviour inhibitors to prevent population expansion of R. pedestris in the future.

SIGLEC15 amplifies immunosuppressive properties of tumor-associated macrophages in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) usually presents infrequent infiltration of T lymphocytes. The known immune-checkpoint inhibitors to date focus on activating T cells and manifest limited effectiveness in PDAC. SIGLEC15 was identified as a novel tumor-associated macrophage (TAM)-related immune-checkpoint in other cancer types, while its immunosuppressive role and clinical significance remained unclear in PDAC. In our study, SIGLEC15 presented immunosuppressive relevance in PDAC via bioinformatic analysis and expressed on TAM and PDAC cells. SIGLEC15+ TAM, rather than SIGLEC15+ PDAC cells or SIGLEC15- TAM, correlated with poor prognosis and immunosuppressive microenvironment in the PDAC microarray cohort. Compared with SIGLEC15- TAM, SIGLEC15+ TAM presented an M2-like phenotype that could be modulated by SIGLEC15 in a tumor cell-dependent manner. In mechanism, SIGLEC15 interacted with PDAC-expressed sialic acid, preferentially α-2, 3 sialic acids, to stimulate SYK phosphorylation in TAM, which further promoted its immunoregulatory cytokines and chemokines production. In vivo, SIGLEC15+ TAM also presented an M2-like phenotype, accelerated tumor growth, and facilitated immunosuppressive microenvironment, which was greatly abolished by SYK inhibitor. Our study highlighted a novel M2-promoting function of SIGLEC15 and strongly suggested SIGLEC15 as a potential immunotherapeutic target for PDAC.

Ligand-binding properties of odorant-binding protein 6 in Athetis lepigone to sex pheromones and maize volatiles.

BACKGROUND: Athetis lepigone, a noctuid moth feeding on more than 30 different crops worldwide, has evolved a sophisticated, sensitive, and specific chemosensory system to detect and discriminate exogenous chemicals. Odorant-binding proteins (OBPs) are the most important agent in insect chemosensory systems to be explored as an alternative target for environmentally friendly approaches to pest management. RESULTS: To investigate the olfactory function of A. lepigone OBPs (AlepOBPs), AlepOBP6 was identified and expressed in Escherichia coli. The binding affinity of the recombinant OBP to 20 different ligands was then examined using a competitive binding approach. The results revealed that AlepOBP6 can bind to two sex pheromones and ten maize volatiles, and its conformation stability is pH dependent. We also carried out a structure-function study using different molecular approaches, including structure modeling, molecular docking, and a mutation functional assay to identify amino acid residues (M39, V68, W106, Q107, and Y114) involved in the binding of AlepOBP6 to both sex pheromones and maize volatiles in A. lepigone. CONCLUSION: These results suggest that AlepOBP6 is likely involved in mediating the responses of A. lepigone to sex pheromones and maize volatiles, which may play a pivotal function in mating, feeding, and oviposition behaviors. This study not only provides new insight into the binding mechanism of OBPs to sex pheromones and host volatiles in moths, but also contributes to the discovery of novel target candidates for developing efficient behavior disruptors to control A. lepigone in the future. © 2021 Society of Chemical Industry.

Cascade Wolff Rearrangement/Acylation: A Metal-Free and Eco-Friendly Approach for 4-Hydroxy-pyrazolo[3,4-b]pyridin-6-ones and N-Pyrazole Amides Synthesis from 5-Aminopyrazoles and α-Diazoketones.

A highly chemoselective cascade Wolff rearrangement/acylation reaction between 5-aminopyrazoles and diazo compounds has been developed. The protocol can facilitate the switchable synthesis of 4-hydroxy-pyrazolo[3,4-b]pyridin-6-ones and N-pyrazole amides with the merits of a broad substrate scope, high functional group compatibility, and green and sustainable performance manner. All reactions proceeded efficiently without any catalyst and additives (acid and base) and resulted in the release of benign N2, wherein diethyl carbonate served as a green benign solvent.

[Spatial distribution and associations of dead woods in natural spruce-fir secondary forests]. / äº‘å†·æ‰å¤©ç„¶æ¬¡ç”Ÿæž—æ­»æœ¨åˆ†å¸ƒæ ¼å±€åŠç©ºé—´å ³è”æ€§.

To reveal the community succession rule of natural secondary forest, we investigated basic characteristics and coordinates of each tree (DBH≥1 cm) within a plot (100 m×100 m) using the adjacent grid method and examined the distribution pattern and spatial associations of dead woods in a natural spruce-fir secondary forest in Jingouling Forest Farm, Wangqing Forestry Bureau, Jilin Province, China. The results showed that the diameter class distribution of dead woods showed the pattern of left single-peak curve, while the logs showed the pattern of multi-peak curve. The relationship between the abundance of dead woods and the standing individuals of a particular species was inconsistent. There was a significant negative exponential relationship between the number of dead woods and mixing degree of trees. The distribution of dead woods was concentrated at the 0-8 m scale. With the increases of scale, it gradually changed to random or uniform, with the random distribution being dominant. The aggregation distribution of dead woods with middle (10 cm≤DBH＜20 cm) and small (1 cm≤DBH＜10 cm) DBH was the main reason for the aggregation distribution of dead woods at small scale below 8 m. The spatial associations between dead woods and stan-ding trees at different diameter classes were significantly different. The relationship between dead woods and saplings (1 cm≤DBH＜5 cm) was closely correlated. The dead woods with large DBH and saplings showed a significant positive association at 2-25 m scale. There was no spatial association between dead woods and small trees (5 cm≤DBH＜15 cm). At the 0-3 m scale, there was a positive association between the middle trees (15 cm≤DBH＜25 cm) and dead woods of small and middle DBH. At the 9, 11-14 and 15, 42-45 m scales, dead woods of small and middle DBH were significantly negatively associated with large trees (DBH≥25 cm). In conclusion, biological traits, diameter class distribution, and spatial distribution affected the abundance and diameter class distribution of dead woods. The species with low mixing degree tended to have more dead woods. The diameter and scale would affect the spatial distribution of dead woods. The spatial correlation between dead woods and standing trees varied across diameter classes and scales.

One-Pot Synthesis of Chromone-Fused Pyrrolo[2,1-a]isoquinolines and Indolizino[8,7-b]indoles: Iodine-Promoted Oxidative [2 + 2 + 1] Annulation of O-Acetylphenoxyacrylates with Tetrahydroisoquinolines and Noreleagnines.

An iodine-promoted one-pot cascade oxidative annulation reaction has been developed for the synthesis of chromone-fused-pyrrolo[2,1-a]isoquinolines and indolizino[8,7-b]indoles from o-acetylphenoxyacrylates, tetrahydroisoquinolines, and noreleagnines. This process underwent a logical approach to both chromone-fused-pyrrolo[2,1-a]isoquinolines and chromone-fused-indolizino[8,7-b]indoles isolamellarin derivatives. Manipulations of l-menthol and dl-α-tocopherol demonstrate the applications of this strategy.

Dual Enzyme-Like Performances of PLGA Grafted Maghemite Nanocrystals and Their Synergistic Chemo/Chemodynamic Treatment for Human Lung Adenocarcinoma A549 Cells.

In recent years, the emergence of non-toxic but catalytically active inorganic nanoparticles has attracted great attention for cancer treatment, but the therapeutic effect has been affected by the limited reactive oxygen species in tumors. Therefore, the combination of chemotherapy and chemodynamic therapy is regarded as a promising therapeutic strategy. In this paper, we reported the preparation and bioactivity evaluation of poly(lactic acid-co-glycolic acid) (PLGA) grafted-γ-Fe2O3 nanoparticles with dual response of endogenous peroxidase and catalase like activities. Our hypothesis is that PLGAgrafted γ-Fe2O3 nanoparticles could be used as a drug delivery system for the anti-tumor drug doxorubicin to inhibit the growth of lung adenocarcinoma A549 cells; meanwhile, based on its mimic enzyme properties, this kind of nanoparticles could be combined with doxorubicin in the treatment of A549 cells. Our experimental results showed that the PLGAgrafted γ-Fe2O3 nanoparticles could simulate the activity of catalase and decompose hydrogen peroxide into H2O and oxygen in neutral tumor microenvironment, thus reducing the oxidative damage caused by hydrogenperoxide to lung adenocarcinoma A549 cells. In acidic microenvironment, PLGA grafted γ-Fe2O3 nanoparticles could simulate the activity of peroxidase and effectively catalyze the decomposition of hydrogen peroxide to generate highly toxic hydroxyl radicals, which could cause the death of A549 cells. Furthermore, the synergistic effect of peroxidase-like activity of PLGA-grafted γ-Fe2O3 nanoparticles and doxorubicin could accelerate the apoptosisand destruction of A549 cells, thus enhancing the antitumor effect of doxorubicin-loaded PLGA-grafted γ-Fe2O3 nanoparticles. Therefore, this study provides an effective nanoplatform based on dual inorganic biomimetic nanozymes for the treatment of lung cancer.

Biodiversity increased both productivity and its spatial stability in temperate forests in northeastern China.

Although the relationship between biodiversity and ecosystem functioning has been extensively studied, it remains unclear if the relationships of biodiversity with productivity and its spatial stability vary along productivity gradients in natural ecosystems. Based on a large dataset from 2324 permanent forest inventory plots across northeastern China, we examined the intensity of species richness (SR) and tree size diversity (Hd) effects on aboveground wood productivity (AWP) and its spatial stability among different productivity levels. Structural equation modeling was applied, integrating abiotic (climate and soil) and biotic (stand density) factors. Our results demonstrated that both SR and Hd positively affected AWP and its spatial stability, and the intensity of these positive effects decreased with increasing productivity. At low productivity levels, SR and Hd increased spatial stability by reducing spatial variability and increasing mean AWP. At high productivity levels, stability increased only through mean AWP increase. Moreover, temperature and stand density affected the AWP directly and indirectly via biodiversity, and the strength and direction of these effects varied among different productivity levels. We concluded that biodiversity could simultaneously enhance productivity and its spatial stability in temperate forests, and that the effect intensity was uniform along productivity gradients, which provided a new perspective on relationships within biodiversity-ecosystem functioning.

[Spatial distribution of carbon storage in natural secondary forest based on geographically weighted regression expansion model.] / åŸºäºŽåœ°ç†åŠ æƒå›žå½’æ‹“å±•æ¨¡åž‹çš„å¤©ç„¶æ¬¡ç”Ÿæž—ç¢³å‚¨é‡ç©ºé—´åˆ†å¸ƒ.

To accurately assess carbon storage and its spatial distribution in natural secondary forest at the regional scale, we constructed seven expansion models by modifying the geographically weighted regression (GWR) in aspects of spatial dimension, parameter heterogeneity and residual spatial autocorrelation, based on data collected from 165 bureau level permanent plots in Langxi Forest Farm of Wangqing Forestry Bureau in Jilin Province. Stand factor, topography factor, and soil factor were selected as the influencing factors. The expansion models included geographically and altitudinal weighted regression (GAWR), semiparametric geographically weighted regression (SGWR), semiparametric geographically and altitudinal weighted regression (SGAWR), geographically weighted regression Kriging (GWRK), geographically and altitudinal weighted regression Kriging (GAWRK), semiparametric geographically weighted regression Kriging (SGWRK), and semiparametric geographically and altitudinal weighted regression Kriging (SGAWRK). Coefficient of determination (R2), mean square error (MSE) and Akaike's Information Criterion (AIC) were used to evaluate the fitness of these models. Finally, the spatial distribution diagram of forest carbon storage was drawn with the fitting results of the optimal regression model, and the distribution pattern of forest carbon storage in the research area was analyzed. The stand factor and topographic factor had strong influence on carbon storage of natural secondary forests, among which the average diameter at breast height (DBH) of stands was the dominant variable. There was positive correlation between stand factor and topographic factor. SGWR and SGAWR model could reduce the spatial autocorrelation of the GWR model residual. The geographically regression expansion model could improve the fitting effect of GWR model. Among them, the SGWRK model had the highest R2 and the lowest MSE and AIC. The method with altitude as the spatial weight did not effectively improve the fitting effect of the model. The total forest carbon storage of Langxi Forest Farm was 205×104 t, and the carbon density ranged from 8.56 to 145.74 t·hm-2, with a mean value of 57.98 t·hm-2. Overall, the distribution pattern of carbon storage was high in the northwest and low in the southeast, while high in the edge and low in the interior. By improving the parameter heterogeneity and residual spatial autocorrelation in the GWR model, we can accurately assess the spatial relationship between forest carbon storage and relevant variables in the study area, and improve the estimation accuracy of the forest carbon storage and its spatial distribution at the regional scale.

[Community structure characteristics and spatial distribution of dominant species of secondary Quercus mongolica forest in Changbai Mountains, China.] / é•¿ç™½å±±è’™å¤æ Žæ¬¡ç”Ÿæž—ç¾¤è½ç»“æž„ç‰¹å¾åŠä¼˜åŠ¿æ ‘ç§ç©ºé—´åˆ†å¸ƒæ ¼å±€.

Understanding forest community structure is the basis for revealing community maintenance mechanism and succession dynamics, and the premise forest management activities. Taking two permanent 1-hm2 plots of Quercus mongolica broadleaved mixed forest located in Wangqing Fore-st Bureau in Jilin Province as objects, we analyzed the community structure characteristics of secondary Q. mongolica forest and spatial distribution of dominant species with the point pattern analysis method (the O-ring statistics). The results showed that both plots were dominated by Q. mongo-lica with distinct hierarchy character. The co-dominated trees in plot I were Populus ussuriensis, Be-tula platyphylla, and Pinus koraiensis, which were different from plot II (Tilia amurensis, Acer mono, and Pinus koraiensis). The richness and Shannon index of plot I were higher than that of plot II. The DBH class distribution of trees in both plots were reverse-J-shaped. Individuals of Q. mongolica exhibited a normal distribution and P. koraiensis showed a reverse-J-shaped. There were differences in the diameter structure of other co-dominant tree species. The spatial distribution of Q. mongolica in two plots was aggregation distribution at small scale and random distribution in medium and large scales. P. koraiensis showed aggregation-random distribution at 0-50 m scale, while its aggregation degree in plot I were higher than that of plot II. B. platyphylla and P. ussuriensis in plot I were aggregated at the scale of 0-17 m, and the aggregation intensity was significantly higher than other tree species, and showed random distribution and uniform-random distribution at the scale of 18-50 m, respectively. Random or uniform distribution at the medium-large scale, and aggregate distribution at small scale of T. amurensis were observed in plot II. These results demonstrated that both plots were at the primary stage of succession with different growth stages. The succession stage of plot II was more progressed than that of plot I and the community of plot II was relatively more stable. Our results provide references for the precise management of Q. mongolica secondary forests at different developmental stages.

Delivery of bevacizumab by intracranial injection: assessment in glioma model.

BACKGROUND: Many reports have indicated that the intravenous administration of bevacizumab produces a number of systemic side effects. Therefore, we investigated the therapeutic effects of intratumoral bevacizumab administration using a glioma animal model. METHODS: The glioma cell lines U251 and U87 that carried luciferase were implanted into the brains of mice to develop glioma models. Glioma-bearing mice were treated with bevacizumab intravenously or intratumorally by Alzet micro-osmotic pumps, and the survival time of mice was monitored. Tumor volumes and location were observed by fluorescence imaging and histological analysis. Levels of microvessel marker, cancer stem cell marker as well as angiogenesis-, invasion-, and inflammation-related factors in tumors were examined by immunohistochemical staining. RESULTS: Mice treated with intratumoral low-dose bevacizumab had smaller tumor volumes, longer survival time, lower microvessel density, and fewer cancer stem cells as compared with untreated and intravenously treated mice. Furthermore, expression levels of inflammation-related factors increased signifiwhereas that of angiogenesis- and invasion-related factors decreased in intratumorally treated animals, compared with intravenously treated mice. CONCLUSION: These results implied bevacizumab delivery by intratumoral injection via Alzet micro-osmotic pumps may be a more effective and safer protocol for treating gliomas.

[Geostatistical analysis on the spatial pattern of Quercus mongolica population in different communities.] / ä¸åŒç¾¤è½è’™å¤æ Žç§ç¾¤ç©ºé—´æ ¼å±€çš„åœ°ç»Ÿè®¡å­¦åˆ†æž.

Taking Quercus mongolica population in the secondary forest of Q. mongolica as the research object, two plots in different stages of succession (A and B) were set up in Tazigou Forest Farm of Wangqing Forestry Bureau, Jilin Province. By applying the method of adjacent grid survey, each plot was divided into 100 units of 10 m×10 m and the spatial coordinates of each tree in the unit were accurately located to survey all the basic information of trees with diameter at breast height (DBH)≥1 cm. The degree, composition, scale and pattern of spatial heterogeneity of individual tree of Q. mongolica were analyzed by means of semi-variance function and fractal dimension of geostatistics. By using Kriging interpolation method, unbiased estimation of tree attribute with spatial autocorrelation was carried out, distribution map was drawn and spatial distribution pattern was analyzed. The results showed that the best semi-variance function of tree attributes in two plots was mainly distributed in an exponential model and a spherical model with an aggregated distribution. The degree of spatial autocorrelation and continuity of plot A were higher than that of plot B. The DBH and the east-west crown (CEW) had strong spatial heterogeneity and autocorrelation in the two plots. The tree attributes of both plots showed strong spatial heterogeneity in the north-south direction. In addition, there was strong spatial heterogeneity in the northwest-southeast direction of plot A and in the northeast-southwest of plot B. The strength of the spatial heterogeneity was higher and the scale being larger in plot A. The variations of DBH and CEW were obvious in plot A, while the variations of CEW and south-north crown (CSN) were obvious in plot B. The fractal dimension and semi-variogram function showed the same result. The tree attributes of plot A were mainly patchy and stripe, and the variation trend of spatial distribution pattern was obvious. The tree attributes of plot B was broken, with complex pattern. Those results indicated that the characteristics of population, community development, spatial scale and spatial horizontal direction might affect the spatial pattern of populations. The geostatistical analysis method is helpful to quantitatively and directly describe population growth and development trend, which can provide a theoretical basis for the sustainable management of Q. mongolica secondary forests in Northeast China.

Molecular Design, Structural Analysis and Antifungal Activity of Derivatives of Peptide CGA-N46.

Chromogranin A (CGA)-N46, a derived peptide of human chromogranin A, has antifungal activity. To further research the active domain of CGA-N46, a series of derivatives were designed by successively deleting amino acid from both terminus of CGA-N46, and the amino acid sequence of each derivative was analyzed by bioinformatic software. Based on the predicted physicochemical properties of the peptides, including half-life time in mammalian reticulocytes (in vitro), yeast (in vivo) and E. coli (in vivo), instability index, aliphatic index and grand average of hydropathicity (GRAVY), the secondary structure, net charge, the distribution of hydrophobic residues and hydrophilic residues, the final derivatives CGA-N15, CGA-N16, CGA-N12 and CGA-N8 were synthesized by solid-phase peptide synthesis. The results of bioinformatic analysis showed that CGA-N46 and its derivatives were α-helix, neutral or weak positive charge, hydrophilic, and CGA-N12 and CGA-N8 were more stable than the other derivatives. The results of circular dichroism confirmed that CGA-N46 and its derived peptides displayed α-helical structure in an aqueous solution and 30 mM sodium dodecylsulfate, but α-helical contents decreased in hydrophobic lipid vesicles. CGA-N15, CGA-N16, CGA-N12 and CGA-N8 had higher antifungal activities than their mother peptide CGA-N46. Among of the derived peptides, CGA-N12 showed the least hemolytic activity. In conclusion, we have successfully identified the active domain of CGA-N46 with strong antifungal activity and weak hemolytic activity, which provides the possibility to develop a new class of antibiotics.