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71.
Seven new deoxyisoaustamide derivatives (1–7) together with known compounds (8–10) were isolated from the coral-derived fungus Penicillium dimorphosporum KMM 4689. Their structures were established using spectroscopic methods, X-ray diffraction analysis and by comparison with related known compounds. The absolute configurations of some alkaloids were determined based on CD and NOESY data as well as biogenetic considerations. The cytotoxic and neuroprotective activities of some of the isolated compounds were examined and structure-activity relationships were pointed out. New deoxyisoaustamides 4–6 at concentration of 1 µM revealed a statistical increase of PQ(paraquat)-treated Neuro-2a cell viability by 30–39%.  相似文献   
72.

Context

The effects of agricultural intensification on service-providing communities remain poorly studied in perennial cropping systems. However, such systems differ greatly from annual cropping systems in terms of spatio-temporal dynamics and levels of disturbance. Identifying how land use changes at different scales affect communities and ecosystem services in those habitats is of major importance.

Objectives

Our objectives were to examine the effects of local and landscape agricultural intensification on ground beetle community structure and weed seed predation services.

Methods

We examined the effects of local vegetation management and landscape context on ground beetle community structure and weed seed predation in 20 vineyards of southwestern France in 2013 and 2014. Vineyards were selected along a landscape complexity gradient and experienced different management of local vegetation.

Results

The activity-density of ground beetles decreased with increasing landscape complexity while species richness and evenness remained unchanged. Phytophagous and macropterous species dominated ground beetle communities. Seed predation was positively related to the activity-density of one species, Harpalus dimidiatus, and was not affected by local management or landscape context. We found that within-year temporal diversity in ground beetle assemblages increased with landscape complexity.

Conclusions

Our study shows that increasing the proportion of semi-natural habitats in vineyard landscapes enhances the temporal diversity of ground beetles. However, we also found that measures targeting specific species delivering biological control services are a reasonable strategy if we are to maximize natural pest control services such as weed seed regulation to support crop production and reduce agrochemical use.
  相似文献   
73.
Abstract

Soil dispersion induces soil erosion and colloidal leaching. Nutrients are lost at the same time and this causes water contamination. Phosphate is an essential element for living organisms. Because phosphate influences soil dispersion and it is an important limited resource, this influence must be evaluated well in order to diminish negative effects on soil structure. In this paper, we firstly evaluated the influence of phosphate sorption on soil dispersion by calculating repulsive potential energy between soil particles. Ferralsol, which is a typical soil in rainy tropical regions, was used as the material. The dispersion-flocculation phenomena were investigated with absorbance of soil suspension under different pH, phosphate adsorption and electrolyte concentration in an Na-NO3-PO4 system. The repulsive potential energy was calculated based on the diffuse double layer theory and the measured zeta potential. We indicated that the measured absorbance increased with the increase of the repulsive potential energy. The repulsive potential energy increased with increasing phosphate sorption up to about 5 to 20 mmol kg?1 at all pH, and it induced the soil dispersion, because phosphate sorption increased the negative charge of the soil. After its peak, it decreased with increasing phosphate sorption because the electrolyte concentration increased and the electrolyte screened the electric field near the soil surface. The repulsive potential energy also increased with increasing pH because of the increase of the negative charge of the soil. Even at low pH, after a certain amount of phosphate sorption, the soil dispersed due to the increase of repulsive potential energy, although the soil flocculated before phosphate application. Because the soil dispersion causes soil and phosphorus loss, the influence of soil pH and phosphate sorption on the soil dispersion should be considered for good soil management.  相似文献   
74.
Journal of Plant Diseases and Protection - Plum pox virus (PPV) is a plant virus (genus Potyvirus, family Potyviridae) infecting stone fruit trees. Since the first report from Bulgaria in 1917, PPV...  相似文献   
75.
Purpose

Sustainable management of riparian zone soils is required to ensure the health of natural ecosystems and maintenance of soil nitrogen (N) pools and soil N cycling. However, the effect of revegetation type and age on soil N pools remains poorly understood.

Materials and methods

This study compiled data from published articles to understand the effects of revegetation types and age on soil total N (TN) and soil inorganic N (NH4+-N, and NO3?-N) using a meta-analysis. We extracted 645 observations from 52 published scientific articles.

Results and discussion

The revegetation of riparian zones led to a significant increase of soil TN (mean effect size: 11.5%; 95% CI: 3.1% and 20.6%). Woodland increased soil TN significantly by 14.0%, which was associated with the presence of N fixing species and high litter inputs. Soil NH4+-N concentration significantly increased (mean effect size: 20.1%; 95% CI: 15.1% and 25.4%), whereas a significant decrease in soil NO3?-N (mean effect size: ? 21.5%; 95% CI: ? 15.0% and ? 27.5%) was observed. Of the revegetation types considered in this paper, NO3?-N concentration in soil followed the order: grassland < shrubland < woodland, suggesting that woodland might be more efficient in soil NO3?-N retention than grassland. The high plant N uptake and accelerated NO3?-N leaching in grassland could be related to the decreased soil NO3?-N in grassland compared with other revegetation types. Revegetation significantly decreased soil moisture by (mean effect size: ? 7.9%; 95% CI: ? 3.3% and ? 12.2%) compared with the control, which might be associated with the selection of exotic species as dominant vegetation in the riparian zone. Soil TN increased in revegetation ages between 10 and 40 years following revegetation and was related to increased soil organic carbon inputs within those ages following the establishment.

Conclusions

This study provides insight into influence of different vegetation types and age on soil N pools and soil moisture. This study also highlights the importance of revegetation in riparian zones to increase soil TN.

  相似文献   
76.
The To Lich and Kim Nguu Rivers in Hanoi City are the main sources of irrigation water for suburban agricultural land and fish farm. Wastewater from the industrial plants located along these rivers has been discharged, and has degraded the water quality of the rivers. This study describes the chemical properties of water from the rivers, focusing on heavy metal pollution and the suitability of water quality for irrigation water. Water from the rivers was heavily polluted with organic matter and heavy metals such as Pb, Cu, Zn, Cr, Cd and Ni. Dissolved oxygen, chemical oxygen deman, and total suspended solids, and the concentrations of all heavy metals exceeded the Vietnamese standard for surface water quality in all investigated sites. The concentrations of some heavy metals such as Cu, Cd, Cr and Ni were above the internationally recommended WHO maximum level for irrigation water. A wide variation in the heavy metal concentration of water due to metal types is the result of wastewater discharged from different industrial sources.  相似文献   
77.
The study focused on kapok [Ceiba pentandra (L.) Gaertn.] fruit as a biomass for effective utilization. Kapok fruits were harvested just before full maturation at the campus of University of the Philippines Los Banos and in southern Vietnam. The kapok fibers are utilized locally as fiberfill in pillows, quilts, and some soft toys. Kapok fiber was isolated and analyzed microscopically, and the physicochemical properties were determined by spectroscopic methods. Some tests were done to determine the effective utilization of kapok fiber. Microscopic analysis of the higher structure of kapok fiber gave quite different results from cotton fiber, which has a significantly homogeneous hollow tube shape and is composed of cellulose (35 % dry fiber), xylan (22%), and lignin (21.5%). Kapok fiber is characterized by having a high level of acetyl groups (13.0%). Usually cell walls of plants contain about 1%–2% of acetyl groups attached to noncellulosic polysaccharides. Kapok fiber is significantly hydrophobic and does not get wet with water. Thus, the absorptivity of oil was tested. The fiber selectively absorbed significant amounts of oil (40 g/g of fiber) from an oil suspension in freshwater and seawater. It is suggested that this fiber could be used to recover oil spilled in seawater.  相似文献   
78.
Stable isotope analysis was used to determine the sources of dietary nitrogen (N) and carbon (C) for shrimp during the rearing phase in extensive rice‐shrimp ponds in My Xuyen and Gia Rai districts, Vietnam. Farm‐made feed was added as a food source in shrimp ponds in My Xuyen district, and based on stable isotope analyses, was generally a poor dietary source. The commercial formulated feed used in Gia Rai also appeared to contribute little directly to the nutritional needs of the shrimp. In contrast, the natural biota in all ponds appeared to contribute substantially. In particular, biota from beam trawls and benthic organic matter were the most likely sources of nutrition in My Xuyen ponds, while benthic organic matter was the main source in Gia Rai ponds. δ15N ratios in the natural biota in My Xuyen farms decreased over the growing season, suggesting increased N fixation in the case of the benthic organic matter reaching values as low as 1‰. This suggests N‐limitation in the ponds and that natural biota become increasingly dependent on N fixed by algae and/or other microorganisms. There is the potential to promote the growth of the plankton and hence, the other natural biota, by the judicious addition of fertilizer.  相似文献   
79.
Fucosylated chondroitin sulfates (FCSs) FCS-BA and FCS-HS, as well as fucan sulfates (FSs) FS-BA-AT and FS-HS-AT were isolated from the sea cucumbers Bohadschia argus and Holothuria (Theelothuria) spinifera, respectively. Purification of the polysaccharides was carried out by anion-exchange chromatography on DEAE-Sephacel column. Structural characterization of polysaccharides was performed in terms of monosaccharide and sulfate content, as well as using a series of non-destructive NMR spectroscopic methods. Both FCSs were shown to contain a chondroitin core [→3)-β-d-GalNAc-(1→4)-β-d-GlcA-(1→]n bearing sulfated fucosyl branches at O-3 of every GlcA residue in the chain. These fucosyl residues were different in pattern of sulfation: FCS-BA contained Fuc2S4S, Fuc3S4S and Fuc4S at a ratio of 1:8:2, while FCS-HS contained these residues at a ratio of 2:2:1. Polysaccharides differed also in content of GalNAc4S6S and GalNAc4S units, the ratios being 14:1 for FCS-BA and 4:1 for FCS-HS. Both FCSs demonstrated significant anticoagulant activity in clotting time assay and potentiated inhibition of thrombin, but not of factor Xa. FS-BA-AT was shown to be a regular linear polymer of 4-linked α-L-fucopyranose 3-sulfate, the structure being confirmed by NMR spectra of desulfated polysaccharide. In spite of considerable sulfate content, FS-BA-AT was practically devoid of anticoagulant activity. FS-HS-AT cannot be purified completely from contamination of some FCS. Its structure was tentatively represented as a mixture of chains identical with FS-BA-AT and other chains built up of randomly sulfated alternating 4- and 3-linked α-L-fucopyranose residues.  相似文献   
80.
The aim of this study was to investigate the ovarian follicular development, developmental competence of oocytes, and plasma anti‐Müllerian hormone (AMH) levels of Japanese wild boar crossbred (wild hybrid) gilts, whose litter size is inferior to that of European breeds. Ovary and plasma samples were collected from two different breeds of gilts (wild hybrid and Large White breeds). The ovaries from the wild hybrid gilts had a lower average numbers of secondary follicles and vesicular follicles in ovarian cross‐sections and of good quality oocytes collected from ovarian follicles as compared with those from Large White gilts (< 0.05). The development rate to the blastocyst stage of good quality oocytes after in vitro maturation, fertilization and culture was also lower (< 0.05) in wild hybrid gilts than in Large White gilts. Plasma AMH levels with >0.16 ng/ml were detected in 8.3% of the examined wild hybrid gilts and 33% of the Large White gilts. These results indicate that the low reproductive performance of wild hybrid breed may result in part from low numbers of vesicular follicles and good quality oocytes, and low developmental competence of oocytes. Moreover, plasma AMH levels may support low number of vesicular follicles in ovaries of wild hybrid gilts.  相似文献   
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