[Shelterbelt construction in the scenario of coordinated development of mountain, river, forest, farmland, lake, grassland, and sandy land ecosystems in semi-arid wind-sand areas: Principles and methods]. / 半干旱风沙区"山水林田湖草沙"建设中防护林营建的原理与方法.

We established the systematic concept framework of shelterbelt construction, with "shelterbelts" as the core concern in the construction of integrated ecosystems including mountain, river, forest, farmland, lake, grassland and sandy-land in semi-arid wind-sand areas. In the construction of shelterbelts, it is necessary to adhere to the principles of scientific coordination and systematic management, considering the carrying capacity of water resources, the demand for dust control, the greening and beautification effects, as well as the principle of improving economic benefits. In practice, the construction methods should base on the types and temporal-spatial distribution of shelterbelts, following the shelterbelts construction theory and technology to form different structure and service functions, achieving the functional goals of shelterbelts. By focusing on the key elements including people, forests, grass, fields, water, and sand, we put forward the timeliness, practicality, and scientificity of shelterbelt construction, proposing construction methods for farmland shelterbelts, pastureland shelterbelts, windbreak and sand-fixing forests and protective forest around village (city), which might provide production technical support for the high-quality construction of green ecological barrier in northern China.

Xylem hydraulics strongly influence the niche differentiation of tree species along the slope of a river valley in a water-limited area.

Xylem hydraulic characteristics govern plant water transport, affecting both drought resistance and photosynthetic gas exchange. Therefore, they play critical roles in determining the adaptation of different species to environments with various water regimes. Here, we tested the hypothesis that variation in xylem traits associated with a trade-off between hydraulic efficiency and safety against drought-induced embolism contributes to niche differentiation of tree species along a sharp water availability gradient on the slope of a unique river valley located in a semi-humid area. We found that tree species showed clear niche differentiation with decreasing water availability from the bottom towards the top of the valley. Tree species occupying different positions, in terms of vertical distribution distance from the bottom of the valley, showed a strong trade-off between xylem water transport efficiency and safety, as evidenced by variations in xylem structural traits at both the tissue and pit levels. This optimized their xylem hydraulics in their respective water regimes. Thus, the trade-off between hydraulic efficiency and safety contributes to clear niche differentiation and, thereby, to the coexistence of tree species in the valley with heterogeneous water availability.

Inhibitory effect and mechanism of action of juniper essential oil on gray mold in cherry tomatoes.

Juniper essential oil (JEO), which is mostly known as an immune system booster and effective detoxifier, has substantial antimicrobial activity. A comparison of the inhibitory effects of three plant essential oils from juniper (Juniperus rigida), cedarwood (Juniperus virginiana), and cypress (Crupressus sempervirens) on four plant pathogenic fungi indicated that JEO was the most effective at inhibiting the growth of gray mold (Botrytis cinerea). Additional studies were subsequently conducted to explore the in vivo and in vitro antifungal activity and possible mechanism of JEO against B. cinerea. The results show that JEO inhibited the germination of spores and mycelial growth of B. cinerea in a concentration-dependent manner and exhibited strong inhibition when its concentration exceeded 10 µL/mL. JEO also significantly inhibited the incidence of disease and diameters of gray mold lesions on cherry tomato fruit (Solanum lycopersicum). After 12 h of treatment with JEO, the extracellular conductivity, and the contents of soluble protein, malondialdehyde, and hydrogen peroxide were 3.1, 1.2, 7.2, and 4.7 folds higher than those of the control group, respectively (P < 0.05), which indicated that JEO can damage membranes. Scanning electron microscopy observations revealed that JEO affected the morphology of mycelia, causing them to shrivel, twist and distort. Furthermore, JEO significantly improved the activities of the antioxidant-related enzymes superoxide dismutase and catalase but reduced the pathogenicity-related enzymes polygalacturonase (PG), pectin lyase and endoglucanase of B. cinerea (P < 0.05). In particular, PG was reduced by 93% after treatment with JEO for 12 h. Moreover, the 18 constituents of JEO were identified by gas chromatography/mass spectrometry (GC-MS) analysis, mainly limonene (15.17%), γ-terpinene (8.3%), ß-myrcene (4.56%), terpinen-4-ol (24.26%), linalool (8.73%), α-terpineol (1.03%), o-cymene (8.35%) and other substances with antimicrobial activity. Therefore, JEO can be an effective alternative to prevent and control gray mold on cherry tomato fruit.

Greater hydraulic safety contributes to higher growth resilience to drought across seven pine species in a semi-arid environment.

Quantifying inter-specific variations of tree resilience to drought and revealing the underlying mechanisms are of great importance to the understanding of forest functionality, particularly in water-limited regions. So far, comprehensive studies incorporating investigations in inter-specific variations of long-term growth patterns of trees and the underlying physiological mechanisms are very limited. Here, in a semi-arid site of northern China, tree radial growth rate, inter-annual tree-ring growth responses to climate variability, as well as physiological characteristics pertinent to xylem hydraulics, carbon assimilation and drought tolerance were analyzed in seven pine species growing in a common environment. Considerable inter-specific variations in radial growth rate, growth response to drought and physiological characteristics were observed among the studied species. Differently, the studied species exhibited similar degrees of resistance to drought-induced branch xylem embolism, with water potential corresponding to 50% loss hydraulic conductivity ranging from -2.31 to -2.96 MPa. We found that higher branch hydraulic efficiency is related to greater leaf photosynthetic capacity, smaller hydraulic safety margin and lower woody density (P < 0.05, linear regressions), but not related to higher tree radial growth rate (P > 0.05). Rather, species with higher hydraulic conductivity and photosynthetic capacity were more sensitive to drought stress and tended to show weaker growth resistance to extreme drought events as quantified by tree-ring analyses, which is at least partially due to a trade-off between hydraulic efficiency and safety across species. This study thus demonstrates the importance of drought resilience rather than instantaneous water and carbon flux capacity in determining tree growth in water-limited environments.

Influence of dietary aconitine and nicotine on the gut microbiota of two lepidopteran herbivores.

The gut microbiota plays an important role in pheromone production, pesticide degradation, vitamin synthesis, and pathogen prevention in the host animal. Therefore, similar to gut morphology and digestive enzyme activity, the gut microbiota may also get altered under plant defensive compound-induced stress. To test this hypothesis, Dendrolimus superans larvae were fed either aconitine- or nicotine-treated fresh leaves of Larix gmelinii, and Lymantria dispar larvae were fed either aconitine- or nicotine-treated fresh leaves of Salix matsudana. Subsequently, the larvae were sampled 72hr after diet administration and DNA extracted from larval enteric canals were employed for gut microbial 16S ribosomal RNA gene sequencing (338 F and 806 R primers). The sequence analysis revealed that dietary nicotine and aconitine influenced the dominant bacteria in the larval gut and determined their abundance. Moreover, the effect of either aconitine or nicotine on D. superans and L. dispar larvae had a greater dependence on insect species than on secondary plant metabolites. These findings further our understanding of the interaction between herbivores and host plants and the coevolution of plants and insects.

Hydraulics play an important role in causing low growth rate and dieback of aging Pinus sylvestris var. mongolica trees in plantations of Northeast China.

The frequently observed forest decline in water-limited regions may be associated with impaired tree hydraulics, but the precise physiological mechanisms remain poorly understood. We compared hydraulic architecture of Mongolian pine (Pinus sylvestris var. mongolica) trees of different size classes from a plantation and a natural forest site to test whether greater hydraulic limitation with increasing size plays an important role in tree decline observed in the more water-limited plantation site. We found that trees from plantations overall showed significantly lower stem hydraulic efficiency. More importantly, plantation-grown trees showed significant declines in stem hydraulic conductivity and hydraulic safety margins as well as syndromes of stronger drought stress with increasing size, whereas no such trends were observed at the natural forest site. Most notably, the leaf to sapwood area ratio (LA/SA) showed a strong linear decline with increasing tree size at the plantation site. Although compensatory adjustments in LA/SA may mitigate the effect of increased water stress in larger trees, they may result in greater risk of carbon imbalance, eventually limiting tree growth at the plantation site. Our results provide a potential mechanistic explanation for the widespread decline of Mongolian pine trees in plantations of Northern China.

Antitumor effect and mechanisms of arsenic trioxide on subcutaneously implanted human gastric cancer in nude mice.

We sought to investigate the efficacy of arsenic trioxide (As(2)O(3)) against a human gastric cell line implanted in nude mice in vivo, as well as the mechanism involved. The solid tumor model was created in nude mice with the gastric cancer cell line SGC-7901. The animals were randomly divided into three groups. As(2)O(3) was injected into animals in two arsenic-treated groups (2.5 mg/kg and 5 mg/kg), and the same volume of saline solution was injected into the control group. The inhibitory effect was observed in every group. Apoptotic cells and apoptotic bodies were observed by transmission electron microscope; the fraction of apoptotic cells was detected by TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) under laser confocal technology. The expression of Fas and FasL was detected by immunohistochemical staining. In nude mice, after treatment with 5 mg/kg and 2.5 mg/kg As(2)O(3), approximately 50% and 30% tumor growth inhibition were observed, respectively (P < 0.05 for both treatment groups). Increase in apoptotic cells and apoptotic bodies appeared in As(2)O(3)-treated tumors compared with the control group. The fluorescence intensity levels of apoptotic cells in tumor were significantly higher in the arsenic-treated groups (P < 0.05 for both treatment groups). The fluorescence intensity level of apoptotic cells in the 5-mg/kg group was higher than that in the 2.5-mg/kg group (P < 0.05). The expression of Fas protein increased in dose- and time-dependent manner after the treatment with As(2)O(3), but that of FasL protein showed no significant difference between control and treated groups. As(2)O(3) did not induce hepatic and renal system injury in the nude mice. As(2)O(3) can inhibit the growth of human gastric cell implanted tumor. We ascribe this to upregulation of Fas, which can induce apoptosis of gastric cells.

[Effect of As(2)O(3) on expressions of COX-2 and matrix metalloproteinases in SGC7901 and K562 cells].

This study was aimed to investigate on effect of As(2)O(3) on expressions of COX-2, MMP-2 and MMP-9 in SGC7901 and K562 cells. SGC7901 and K562 cells were cultured in RPMI 1640 medium and were inoculated in culture medium with different concentrations of As(2)O(3) and at different times. Expressions of COX-2, MMP-2 and MMP-9 in SGC7901 and K562 cells were measured by using Western blot, while the levels of COX-2 mRNA and MMP-2 mRNA were measured with fluorescence quantitative RT-PCR. The results showed that the expression of COX-2, MMP-2 and MMP-9 decreased in dose- and time-dependent manners after treating with As(2)O(3). The levels of COX-2 mRNA and MMP-2 mRNA reduced in groups treated with As(2)O(3). In conclusion, As(2)O(3) inhibits expressions of COX-2, MMP-2 and MMP-9 in K562 and SGC7901 cells, suggesting that As(2)O(3) inhibits tumor development through its effect on angiogenesis involved in solid and hematologic malignancies.

[Effect of arsenic trioxide on vascular endothelial growth factor-C and its receptor (VEGFR-3) in nude mice with gastric cancer].

This study was aimed to investigate the effect of arsenic trioxide (As2O3) on expression of vascular endothelial growth factor-C (VEGF-C) and its receptor VEGFR-3 in gastric cancer in order to clarify the role of As2O3 in lymphangiogenesis and metastasis of tumor. The gastric cancer model was established in nude mice by using gastric cancer cell line SGC-7901. As2O3 was injected to the two treatment groups (2.5 mg/kg and 5 mg/kg) and the same volume of saline solution was injected to the control group. Expression of VEGF-C and VEGFR-3 were detected by immunohistochemistry and were analyzed with QWin550cW image Acquiring & Analysis System. The results showed that the expression of VEGF-C and VEGFR-3 in cancer cells significantly reduced in the arsenic -treated groups. The expression of VEGF-C and VEGFR-3 in 5 mg/kg group was significantly less than that in 2.5 mg/kg group. The gray ratio analysis confirmed that there were significant difference between control group and two treated group, as well as between 2.5 mg/kg-treated group and 5 mg/kg-treated group. It is concluded that As2O3 can inhibit expression of VEGF-C and VEGFR-3 of human gastric cancer xenografts in nude mice, which suggests that As2O3 may inhibit the lymphangiogenesis by suppressing the expression of VEGF-C and VEGFR-3.

Effect of arsenic trioxide on vascular endothelial cell proliferation and expression of vascular endothelial growth factor receptors Flt-1 and KDR in gastric cancer in nude mice.

AIM: To investigate the effect of arsenic trioxide (As2O3) on expression of vascular endothelial growth factor receptor-1 (VEGFR-1, Flt-1) and VEGFR-2 (KDR) in human gastric tumor cells and proliferation of vascular endothelial cells. METHODS: The solid tumor model was formed in nude mice with the gastric cancer cell line SGC-7901. The animals were treated with As2O3. Microvessel density (MVD) and expression of Flt-1 and KDR were detected by immunofluorescence laser confocal microscopy. SGC-7901 cells were treated respectively by exogenous recombinant human VEGF165 or VEGF165 + As2O3. Cell viability was measured by MTT assay. Cell viability of ECV304 cells was measured by MTT assay, and cell cycle and apoptosis were analyzed using flow cytometry. RESULTS: The tumor growth inhibition was 30.33% and 50.85%, respectively, in mice treated with As2O3 2.5 and 5 mg/kg. MVD was significantly lower in arsenic-treated mice than in the control group. The fluorescence intensity levels of Flt-1 and KDR were significantly less in the arsenic-treated mice than in the control group. VEGF165 may accelerate growth of SGC7901 cells, but As2O3 may disturb the stimulating effect of VEGF165. ECV304 cell growth was suppressed by 76.51%, 71.09% and 61.49% after 48 h treatment with As2O3 at 0.5, 2.5 and 5 micromol/L, respectively. Early apoptosis in the As2O3-treated mice was 2.88-5.1 times higher than that in the controls, and late apoptosis was 1.17-1.67 times higher than that in the controls. CONCLUSION: Our results showed that As2O3 delays tumor growth, inhibits MVD, down-regulates Flt-1 and KDR expression, and disturbs the stimulating effect of VEGF165 on the growth of SGC7901 cells. These results suggest that As2O3 might delay growth of gastric tumors through inhibiting the paracrine and autocrine pathways of VEGF/VEGFRs.

Inhibitory effect of arsenic trioxide on angiogenesis and expression of vascular endothelial growth factor in gastric cancer.

AIM: To investigate the inhibitory effect of As(2)O(3) on angiogenesis of tumor and expression of vascular endothelial growth factor (VEGF) in tumor cells in vivo and in vitro. METHODS: The solid tumor model was formed in nude mice with the gastric cancer cell line SGC-7901. The animals were randomly divided into three groups. As(2)O(3) was injected into the arsenic-treated groups (2.5 mg/kg and 5 mg/kg) and the same volume of saline solution was injected into the control group. Microvessel density (MVD) and expression of VEGF were detected with immunofluorescence laser confocal technology. Further expression of VEGF protein and VEGF mRNA was measured with Western bloting and fluorescence quantitative RT- PCR in SGC-7901 cells treated with As(2)O(3). RESULTS: In nude mice, after treatment with 5 mg/kg and 2.5 mg/kg As(2)O(3) respectively, about 50% and 30% tumor growth inhibition were observed correspondingly (P<0.05, P<0.05). Decrease in MVD appeared in As(2)O(3)-treated tumors compared with control group (P<0.001, P<0.001). MVD in tumors was significantly lower in 5 mg/kg group than in 2.5 mg/kg group (P<0.01). The fluorescence intensity levels of VEGF in tumor cells were significantly lowered in the arsenic-treated groups (P<0.01, P<0.01). The fluorescence intensity level of VEGF in 5 mg/kg group was lower than that in 2.5 mg/kg group (P<0.01). In vitro, the expression of VEGF protein decreased in dose- and time-dependent manner after the treatment with As(2)O(3), but in VEGF mRNA no significant difference was found between the control group and the treated groups. CONCLUSION: As(2)O(3) can inhibit solid tumor growth by inhibiting the formation of new blood vessels. One of the mechanisms is that As(2)O(3) can inhibit VEGF protein expression.

Dinuclear (d(3)-d(3)) Diolate Complexes of Molybdenum and Tungsten. 3.(1) Bridging and Chelating Isomers of M(2)(NMe(2))(2)(O approximately approximately CHMe approximately approximately O)(2), Where O approximately approximately CHMe approximately approximately O Is the Dianion of 2,2'-Ethylidenebis(4,6-di-tert-butylphenol). Kinetic versus Thermodynamic Considerations.

Hydrocarbon solutions of Mo(2)(NMe(2))(6) and 2,2'-ethylidenebis(4,6-di-tert-butylphenol), HO approximately approximately CHMe approximately approximately OH (2 equiv), react to give a mixture of two isomers, A and B, of formula Mo(2)(NMe(2))(2)(O approximately approximately CHMe approximately approximately O)(2). Both A and B are shown to contain the bridging &mgr;-O approximately approximately CHMe approximately approximately O ligands. They are diastereomers differing with respect to the positioning of the CHMe moiety as a result of ring closure with elimination of HNMe(2). Compounds A and B are thermally persistent at 100 degrees C in the solid state and in toluene, but compound A isomerizes in the presence of pyridine to the thermodynamically favored chelate isomer Mo(2)(NMe(2))(2)(eta(2)-O approximately approximately CHMe approximately approximately O)(2), C. Compound C is related to the previously characterized isomer Mo(2)(NMe(2))(2)(eta(2)-O approximately approximately CH(2) approximately approximately O)(2), where the methylene proton that is distal to the Mo-Mo triple bond is replaced by a Me group. Compound B cannot rearrange to this isomer without Mo-O bond dissociation. W(2)(NMe(2))(6) and HO approximately approximately CHMe approximately approximately OH (2 equiv) react to give W(2)(NMe(2))(2)(eta(2)-O approximately approximately CHMe approximately approximately O)(2), D, which is an analogue of C. The three molybdenum isomers A-C and tungsten complex D have been structurally characterized by single crystal X-ray studies. The results of this work are discussed in terms of the earlier work involving the related 2,2'-methylenebis(6-tert-butyl-4-methylphenoxides) and reveal that the initial ring closure reaction determines the stereochemistry of the subsequent substitution by the biphenoxide at the dinuclear center. Crystal data: for A.PhMe at -168 degrees C, a = 16.585(5) Å, b = 19.480(6) Å, c = 10.960(3) Å, alpha = 98.39(2) degrees, beta = 103.19(1) degrees, gamma = 91.44(2) degrees, space group P&onemacr;; for B.2PhH at -168 degrees C, a = 15.167(3) Å, b = 18.210(3) Å, c = 13.964(3) Å, alpha = 92.81(1) degrees, beta = 100.40(1) degrees, gamma = 71.16(1) degrees, space group P&onemacr;; for C.1.5Et(2)O at -168 degrees C, a = 16.483(3) Å, b = 16.817(3) Å, c = 14.305(2) Å, alpha = 106.13(1) degrees, beta = 108.80(1) degrees, gamma = 71.70(1) degrees, space group P&onemacr;; and for D at -168 degrees C, a = 14.638(2) Å, b = 21.188(4) Å, c = 10.273(2) Å, alpha = 94.80(1) degrees, beta = 95.05(1) degrees, gamma = 100.85(1) degrees, space group P&onemacr;.