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1.
Over the past 10 years, Ghusel VDC, Lalitpur District has moved from primarily subsistence agriculture into the wider cash economy aided by the Small Farmers' Development Program (SFDP), which provides credit to farmers mainly for the purchase of buffalo for milk production, and by the National Dairy Corporation, which supports local dairy cooperatives. Analysis reveals that buffalo-keeping and milk sales are increasing the well-being of many households, while at the same time creating new inequalities in gender roles and responsibilities, greater inequities between Brahmin and Tamang residents in Ghusel, and placing pressures on the ecosystem for increased supplies of fodder and fuelwood. Evidence suggests that there is critical, need for attention to the social, and particularly gender-based, implications of maintaining livestock for milk sales and to the ecological underpinnings of this livelihood system.  相似文献   

2.
Interaction of cis-dichloro(dipyridine)platinum(II) (cis-PPC) with calf thymus DNA, calf thymus histone, l-amino acids, poly-l-amino acids, nucleosides, and nucleotides has been evaluated by equilibrium dialysis technics. At least a 28 % decrease in the association of cis-PPC with DNA occurs when the platinum compound is pre-incubated with l-amino acids. The greatest decrease in association is seen upon pre-incubation of the platinum compound with the free amino acids. Glut, Asp, Lys, Arg, and CySH, before the addition of a sack containing a solution of DNA. The low level of association between DNA and the amino acids tends to rule out competition between cis-PPC and amino acids for DNA association sites. cis-PPC was repelled from sacks containing positively charged poly-l-Lys, poly-l-Arg, and calf thymus histone; however, in the presence of poly-l-Glut and poly-l-Asp, cis-PPC associated with these negatively charged polymers to a considerable degree. Enhanced chloride dissociation from cis-PPC was observed in the presence of all of the amino acids and the nucleotides GMP, CMP, UMP, and TMP, but not in the presence of AMP or the nucleosides rG and dG. In the presence of calf thymus histone, the association of cis-PPC with calf thymus DNA was reduced by more than 50% at histone/DNA ratios of 0.8–1.0.These data suggest that cis-PPC or cis-Pt(II) may associate with electron-rich areas of not only nucleic acids and proteins but also with body pools of free nucleotides and amino acids. The presence of positively charged histones shielding DNA strands in vivo suggests that the most probable point of platinum-DNA association would be at de-repressed areas of DNA which are undergoing RNA synthesis. The aquated form of the platinum complex may also associate with acidic proteins which appear to be involved in the positive control of RNA synthesis and, as a result, this interaction may be of pharmacological significance.  相似文献   

3.
The diets of over two-thirds of the world's population lack one or more essential mineral elements. This can be remedied through dietary diversification, mineral supplementation, food fortification, or increasing the concentrations and/or bioavailability of mineral elements in produce (biofortification). This article reviews aspects of soil science, plant physiology and genetics underpinning crop biofortification strategies, as well as agronomic and genetic approaches currently taken to biofortify food crops with the mineral elements most commonly lacking in human diets: iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), iodine (I) and selenium (Se). Two complementary approaches have been successfully adopted to increase the concentrations of bioavailable mineral elements in food crops. First, agronomic approaches optimizing the application of mineral fertilizers and/or improving the solubilization and mobilization of mineral elements in the soil have been implemented. Secondly, crops have been developed with: increased abilities to acquire mineral elements and accumulate them in edible tissues; increased concentrations of 'promoter' substances, such as ascorbate, β-carotene and cysteine-rich polypeptides which stimulate the absorption of essential mineral elements by the gut; and reduced concentrations of 'antinutrients', such as oxalate, polyphenolics or phytate, which interfere with their absorption. These approaches are addressing mineral malnutrition in humans globally.  相似文献   

4.
Electromagnetic fields (EMFs) played a role in the initiation of living systems, as well as subsequent evolution. The more recent literature on electrochemistry is documented, as well as magnetism. The large numbers of reports on interaction with living systems and the consequences are presented. An important aspect is involvement with cell signaling and resultant effects in which numerous signaling pathways participate. Much research has been devoted to the influence of man-made EMFs, e.g., from cell phones and electrical lines, on human health. The degree of seriousness is unresolved at present. The relationship of EMFs to reactive oxygen species (ROS) and oxidative stress (OS) is discussed. There is evidence that indicates a relationship involving EMFs, ROS, and OS with toxic effects. Various articles deal with the beneficial aspects of antioxidants (AOs) in countering the harmful influence from ROS-OS associated with EMFs. EMFs are useful in medicine, as indicated by healing bone fractures. Beneficial effects are recorded from electrical treatment of patients with Parkinson’s disease, depression, and cancer.  相似文献   

5.
To investigate the regulation of Drosophila melanogaster behavior by biogenic amines, we have exploited the broad requirement of the vesicular monoamine transporter (VMAT) for the vesicular storage and exocytotic release of all monoamine neurotransmitters. We used the Drosophila VMAT (dVMAT) null mutant to globally ablate exocytotic amine release and then restored DVMAT activity in either individual or multiple aminergic systems, using transgenic rescue techniques. We find that larval survival, larval locomotion, and female fertility rely predominantly on octopaminergic circuits with little apparent input from the vesicular release of serotonin or dopamine. In contrast, male courtship and fertility can be rescued by expressing DVMAT in octopaminergic or dopaminergic neurons, suggesting potentially redundant circuits. Rescue of major aspects of adult locomotion and startle behavior required octopamine, but a complementary role was observed for serotonin. Interestingly, adult circadian behavior could not be rescued by expression of DVMAT in a single subtype of aminergic neurons, but required at least two systems, suggesting the possibility of unexpected cooperative interactions. Further experiments using this model will help determine how multiple aminergic systems may contribute to the regulation of other behaviors. Our data also highlight potential differences between behaviors regulated by standard exocytotic release and those regulated by other mechanisms.  相似文献   

6.
Three new chiral ligands bearing an O,O′,N donor set (OmethoxyOhydroxyNpyridine) were synthesised and coordinated to FeIII, FeII, NiII, CuII and ZnII to yield complexes with the general formula [M(OON)Clx]y. While the pyridine N and the hydroxy O atoms coordinate strongly to all applied metal ions, the methoxy donor seems not to be involved in coordination, although some evidence for a weak interaction between OMe and the ZnII were found in NMR spectra. In the bidentate O′,N coordination mode the new ligands exhibit several coordination geometries as analysed in the solid compounds by XRD, EXAFS and EPR and in solution by UV-Vis absorption, cyclic voltammetry, EXAFS, EPR or NMR spectroscopy.  相似文献   

7.
Preparations, XPS and electronic spectroscopy, and magnetism of seven new one-dimensional cyano-bridged coordination polymers, chiral [Cu(RR-chxn)2][Pd(CN)4] · 2H2O (1), [Cu(trans-chxn)2][M(CN)4] · 2H2O (2, 4, and 6 for M = Pd, Ni, and Pt), and [Cu(cis-chxn)2][M(CN)4] · 2H2O (3, 5, and 7 for M = Pd, Ni, and Pt) (RR-chxn = cyclohexane-(1R,2R)-diamine, trans-chxn = racemic trans-cyclohexane-(1,2)-diamine, and cis-chxn = racemic cis-cyclohexane-(1,2)-diamine) have been reported in view of tuning of their electronic properties by stereochemistry of chxn ligands and metal-substitution. Comparison of Cu 2p1/2 and 2p3/2 peaks of XPS and broad d-d bands around 18 000 cm−1 of electronic spectra are described systematically for 1-7. Variable-temperature magnetic measurement shows that complexes 1-7 indicate weak antiferromagnetic interactions via cyano-bridges. Because of semi-coordination coupled with pseudo Jahn-Teller elongation and electrostatic interaction for 1, the axial Cu-N coordination bond distances of 2.330(7) and 3.092(8) Å are considerably longer than those of equatorial ones in the range from 2.016(6) to 2.030(6) Å. The former bond distances of 1 are intermediate values among the related Ni (2.324(6) and 3.120(8) Å) and Pt (2.34(1) and 3.09(1) Å) complexes.  相似文献   

8.
This study consisted of sampling benthic algae at 32 sites in the Gangqu River, an important upstream tributary of the Yangtze River. Our aims were to characterize the benthic algae communities and relationships with environmental variables. Among the 162 taxa observed, Achnanthes linearis and Achnanthes lanceolata var. elliptica were the dominant species (17.10% and 14.30% of the total relative abundance, respectively). Major gradients and principal patterns of variation within the environmental variables were detected by principal component analysis (PCA). Then non-metric multidimensional scaling (NMS) divided all the sites into three groups, which were validated by multi-response permutation procedures (MRPP). Canonical correspondence analysis (CCA) indicated that three environmental variables (TN, TDS, and TP) significantly affected the distribution of benthic algae. Weighted averaging regression and cross-calibration produced strong models for predicting TN and TDS concentration, which enabled selection of algae taxa as potentially sensitive indicators of certain TN and TDS levels: for TN, Achnanthes lanceolata, Achnanthes lanceolata var. elliptica, and Cymbella ventricosa var. semicircularis; for TDS, Cocconeis placentula, Cymbella alpina var. minuta, and Fragilaria virescens. The present study represents an early step in establishing baseline conditions. Further monitoring is suggested to gain a better understanding of this region.  相似文献   

9.
10.
Extracellular vesicles are known as actual intermediaries of intercellular communications, such as biological signals and cargo transfer between different cells. A variety of cells release the exosomes as nanovesicular bodies. Exosomes contain different compounds such as several types of nucleic acids and proteins. In this study, we focused on exosomes in colorectal cancer as good tools that can be involved in various cancer-related processes. Furthermore, we summarize the advantages and disadvantages of exosome extraction methods and review related studies on the role of exosomes in colorectal cancer. Finally, we focus on reports available on relations between mesenchymal stem cell–derived exosomes and colorectal cancer. Several cancer-related processes such as cancer progression, metastasis, and drug resistance of colorectal cancer are related to the cargoes of exosomes. A variety of molecules, especially proteins, microRNAs, and long noncoding RNAs, play important roles in these processes. The microenvironment features, such as hypoxia, also have very important effects on the properties of the origin cell–derived exosomes. On the other hand, exosomes derived from colorectal cancer cells also interfere with cancer chemoresistance. Furthermore, today it is known that exosomes and their contents can likely be very effective in noninvasive colorectal cancer diagnosis and therapy. Thus, exosomes, and especially their cargoes, play different key roles in various aspects of basic and clinical research related to both progression and therapy of colorectal cancer.  相似文献   

11.
The vegetative nucleus (VN) of Nicotiana tabacum L. has been qualitatively and quantitatively studied in fresh, hydrated, and activated pollen. Techniques included the use of optical sectioning by confocal scanning laser microscopy to obtain volume and surface area measurements, and stereoscopic pairs; and freeze-etch electron microscopy to estimate the frequency of nuclear pores per m2 in the vegetative nucleus. Several morphological changes were observed to occur in pollen grain nuclei during the early processes of tube growth. In freshly dehisced pollen grain, the vegetative and generative nuclei were side by side, but following hydration and activation of the grain, the elongated generative nucleus became partially surrounded by the vegetative nucleus. It was found that during hydration, the surface area of the vegetative nucleus increased and there was a decrease in the frequency of nuclear pores. The calculated total number of pores remained similar. After activation and pollen-tube growth, the vegetative nucleus retained the same surface area as in the hydrated state but the frequency of nuclear pores decreased; therefore, the calculated total number of pores was significantly lowered. When considered alongside complementary biochemical data, these morphological results indicate that RNA production in the vegetative nucleus decreases following germination.Abbreviations VN vegetative nucleus (nuclei) - GN generativenucleus - GC generative cell - CSLM confocal scanning laser microscope We acknowledge research support by the Biotechnology Action Programm of the Commission of European Communities, and CNR for the fellowship awarded to Dr. Wagner. We would also like to thank Mrs. C. Faleri for the expert technical help.  相似文献   

12.
13.
Contamination within sediments of Sydney Harbour (once a major industrial port) were evaluated using a multiple lines-of-evidence (LOE) ecological risk assessment (ERA) approach prior to divestiture of the harbor. The multiple LOE approach included: (1) measurement of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals, metalloids, petroleum hydrocarbons(PHCs), and total organic carbon (TOC) concentrations in surface sediments from multiple Sydney Harbour locations; (2) identification and application of sediment quality guidelines (SQGs) from various jurisdictions; (3) comparisons of harbor sediment chemistry against background/reference sediment chemistry; (4) determining number and frequency of exceedances over SQGs; (5) calculating mean probable effect level-quotients (PEL-Qs); (6) PAH forensic source evaluation; (7) review of previous sediment chemistry and biota tissue data; and (8) characterizing benthic habitat at harbor stations. The ERA determined that current sediments exhibited mostly low probability of adverse effects. Furthermore, contaminated sediments exhibiting a high probability of adverse effects were localized to only a few stations within the harbor. Ongoing natural recovery of harbor sediments is likely responsible for attenuating contaminants that historically were higher than those measured in this study and were previously distributed over much wider areas of the harbor. Results suggest that legacy industrial activities and current urban sewage effluents are the major sources of contamination in Sydney Harbour sediments.  相似文献   

14.
15.
王小蕾  张润杰 《生态科学》2009,28(5):471-476
对瓜实蝇Bactrocera (Tetradacus) minax (Enderlein)、桔小实蝇Bactrocera (Bactrocera) dorsalis (Hendel)和桔大实蝇Bactrocera (Zeugodacus) cucurbitae (Coquillett)的形态学、生物学、生态学等方面进行了比较和分析,包括三种实蝇在国内外的分布情况,对寄主选择的差异,各种虫态的形态特征,发育历期和生活史,并对它们的危害状况和防治方法分别作了介绍,可为3种实蝇的鉴定和防治提供参考.  相似文献   

16.
<正>鞘尾蝠科(Emballonuridae)墓蝠属(Taphozous)在全世界共有14种(Wilson and Mittermeier, 2019),分布在赤道与南北回归线之间的热带和亚热带地区(Kitchener et al., 1993)。该属在我国仅分布2种,即黑髯墓蝠(Taphozous melanopogon)和大墓蝠(Taphozous theobaldi),前者主要分布于广东、广西、云南、贵州、海南、澳门和香港(蒋志刚等,2015),为广布种;后者文献记录甚少,标本稀缺,  相似文献   

17.
A new series of heterocyclic molecules bearing sulfonamide linkage has been synthesized and screened for antibacterial activity. During antibacterial screening using broath dilution method, molecules were found to be highly active (MIC value 50–3.1?µg/mL) against different human pathogens, namely B. cerus, S. aureus, E. coli and P. aeruginosa, and most effective against E. coli. A great synergistic effect was observed during determination of FIC where molecules were used in combination with reference drugs chloramphenicol and sulfamethoxazole. The MIC value of the combination – varying concentration of test compounds and ½ MIC of reference drugs or varying concentration of reference drugs and ½ MIC of test compounds, was reduced up to 1/4 or 1/32 of the original value, indicating thereby the combination was 4–32 times more potent than the test molecule. The molecules also showed low degree of cytotoxicity against PBM, CEM and VERO cell lines. The results positively indicated towards the development of lead antibacterials using the combination approach.  相似文献   

18.
Synthesis, crystal structures, and spectroscopic and magnetic properties of new one-dimensional cyano-bridged bimetallic complexes, [CuII(N-Eten)2][MII(CN)4] (N-Eten = N-ethylethylenediamine; MII = NiII (1) and PtII (2)), have been reported. Both complexes consist of one-dimensional alternate chains of CuII and MII moieties. The Pt-C bond distances of 1.997(3) and 2.001(3) Å for 2 are considerably longer than the Ni-C bond lengths of 1.866(3) and 1.872(3) Å for 1. Because of pseudo Jahn-Teller distortion, the axial Cu-N bond distances of 2.554(2) and 2.550(3) Å for 1 and 2 are longer than those of equatorial ones of 2.008(2) and 2.056(2) Å for 1 and 2.010(2) and 2.054(2) Å for 2. In contrast to MII-C bond distances, the Cu-N ones of 1 are similar to those of 2 regardless of element-substitution. These complexes indicate weak antiferromagnetic interactions with Weiss constants = − 4.68 and −3.95 K for 1 and 2, respectively. The emission spectrum of 2 (λex = 360 nm) exhibits a broad band with peaks at 22 800 and 24 000 cm−1 at 298 K. The Cu 2p1/2 and 2p3/2 peaks of XPS spectra are compared systematically to various copper(II) complexes showing different bridging features or distorted coordination geometries as models for excited structures induced by external physical conditions. The spectroscopic properties are discussed from the viewpoint of magneto-optical properties.  相似文献   

19.
Unsubstituted aromatic, heterocyclic and perfluoroalkylic sulfonamides possessing the general formula RSO 2 NH 2 act as powerful inhibitors of the zinc enzyme carbonic anhydrase (CA). Unsaturated primary/substituted sulfonamides have never been investigated for their interaction with the enzyme. Here it is shown that such compounds, and more precisely allyl-sulfonamide and trans -styrene sulfonamide possessing the above general formula (with R=CH 2 =CH-CH 2 - and C 6 H 5 -CH=CH-, respectively) behave as nanomolar inhibitors of the physiologically relevant isozymes CA I and CA II. Some other derivatives of these two leads (incorporating Si(IV), Ge(IV) and B(III) moieties among others) were also synthesized and investigated for their interaction with CA, but showed decreased affinity for both isozymes. The structure-activity relationship for this class of CA inhibitors is discussed. Furthermore, it was observed that allylsulfonyl chloride is a strong CA inactivator, probably by reacting with amino acid residues critical for the catalytic cycle.  相似文献   

20.
The aim of sustainable heavy-metal management in agroecosystems is to ensure that the soil continues to fulfill its functions: in agricultural production, in environmental processes such as the cycling of elements, and as a habitat of numerous organisms. To understand and manage heavy-metal flows effectively, a consistent approach to modeling the flows is needed within the particular agro-system under study. General aspects of heavy-metal balance studies in agro-ecosystems were described in part I of this study. In this article (part II), several European studies of heavy-metal balances at varying spatial scales and in a variety of agro-ecosystems are reviewed. Sectoral studies at the national and international levels provide information for economic analyses and generic regulations; however, policies implemented at these levels often ignore farm characteristics and individual management options. Field-scale and farm-gate balances give farmers specific feedback on effective options for better heavy-metal management. Heavy-metal balances could be incorporated in an environmental management system of certified farms. In this way, farm certification may well serve as a basis from which to develop policy to address environmental issues in agriculture.  相似文献   

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