Identification of the primary factors that influence the ecological distribution of species groups is important to managers of lowland‐mountain forests in northern Iran. The aim of this study was to identify main ecological species groups, describe the site conditions associated with these species groups and the relationships between environmental factors and the distribution of ecological species groups using multi‐variate analysis (Detrended correspondence analysis (DCA) and Canonical correspondence analysis (CCA)). For this purpose, 50 relevés (400 m2 each) were sampled using the Braun‐Blanquet method. Vegetation was classified into three ecological species groups using a modified two‐way indicator species analysis (TWINSPAN). In each relevé, environmental factors (topographic and soil variables) were measured and analysed using one‐way ANOVA and Pearson r statistics. Further, species diversity indices were determined for the identified ecological species groups. Our results show that the environmental factors, e.g. elevation, slope, slope aspect, soil texture, pH and organic matter, were the most important factors explaining the distribution of the three ecological species groups in the study area. The diversity of the ecological species groups decreased with elevation. The results provide an ecological basis for forest management and for developing strategies for forest conservation in the study area. 相似文献
The anti-hypertensive drugs amlodipine, atenolol and lisinopril, in ordinary and PEGylated forms, with different combined-ratios, were studied by molecular dynamics simulations using GROMACS software. Twenty simulation systems were designed to evaluate the interactions of drug mixtures with a dimyristoylphosphatidylcholine (DMPC) lipid bilayer membrane, in the presence of water molecules. In the course of simulations, various properties of the systems were investigated, including drug location, diffusion and mass distribution in the membrane; drug orientation; the lipid chain disorder as a result of drug penetration into the DMPC membrane; the number of hydrogen bonds; and drug surface area. According to the results obtained, combined drugs penetrate deeper into the DMPC lipid bilayer membrane, and the lipid chains remain ordered. Also, the combined PEGylated drugs, at a combination ratio of 1:1:1, enhance drug penetration into the DMPC membrane, reduce drug agglomeration, orient the drug in a proper angle for easy penetration into the membrane, and decrease undesirable lipotoxicity due to distorted membrane self-assembly and thickness.
Bioprocess and Biosystems Engineering - A novel nickel oxide/carbon nanotube/polyaniline (NCP) nanocomposite has been prepared and used to modify the electrocatalytic properties of carbon cloth... 相似文献
The present investigation reports, the synthesis of manganese oxide (α-Mn2O3) nanobundles using thermal decomposition and its physicochemical characterization. The α-Mn2O3 nanobundles have been prepared using manganese oxalate dihydrate powders as precursor in the presence of oleylamine and triphenylphosphine as solvent and capping agent. Transmission electron microscopy (TEM) analysis demonstrated Mn2O3 nanobundles compose of nanospheres with diameter 30 nm. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. Manganese oxide nanocrystals have been prepared under different condition. The controlled experimental results showed that the use of oleylamine and triphenylphosphine as the solvent and capping agent in the chemical process played important role in the formation of the final products. 相似文献
The production of short-chain fatty acids, reductive enzymes, and hydrolytic enzymes by four gatifloxacin-selected, fluoroquinolone-resistant,
mutant strains of C. perfringens, with stable mutations either in DNA gyrase or in both DNA gyrase and topoisomerase IV, was compared with that produced by
the wild-type parent strains to investigate the effect of mutations associated with the selection of gatifloxacin resistance
on bacterial metabolic activities. The mutants differed from their respective wild-type parent strains in the enzymatic activities
of azoreductase, nitroreductase, and β-glucosidase and in the ratio of butyric acid to acetic acid production. Microarray
analysis of one wild type and the corresponding mutant revealed different levels of mRNA expression for the enzymes involved
in short-chain fatty acid (SCFA) synthesis and for β-glucosidase and oxidoreductases. In addition to mutations in the target
genes, selection of resistance to gatifloxacin resulted in strain-specific physiological changes in the resistant mutants
of C. perfringens that affected their metabolic activities. 相似文献
An isoenzyme analysis was performed on 109 individuals from 11 populations of Juniperus excelsa complex collected from Iran. A total of 61 allozymes from five enzyme systems were scored. The mean numbers of bands per presumed isoenzyme, ranged from 2.07 to 3.23. The value of Euclidean distance ranged from 1.920 to 4.411. The average value of Shannon diversity index (H′) estimated for each population ranged from 0.317 in the population sampled from ‘Fasa’ to 1.053 in the population of ‘Golestan’, and the average H′ value for each enzyme system ranged from 0.031 (SOD-3) to 1.670 (PPO-1). To reveal the relationships among these populations, a cluster analysis based on Euclidean distances was performed. The results of the analysis suggest recognizing three taxa in the complex in Iran: Juniperus polycarpos subsp. polycarpos, Juniperus polycarpos subsp. turcomanica, and one cryptic species not recorded from Iran until now. Moreover, the analysis presented, does not confirm the occurrence of J. excelsa in Iran. 相似文献
The protective properties of a prenylated coumarin, umbelliprenin (UMB), on the human lymphocytes DNA lesions were tested.
Lymphocytes were isolated from blood samples taken from healthy volunteers. DNA breaks and resistance to H2O2-induced damage were measured using a single-cell microgel electrophoresis technique under alkaline conditions (comet assay).
Human lymphocytes were incubated in UMB (10, 25, 50, 100, 200, and 400 μM) alone or a combination of different concentrations
of UMB (10, 25, 50, 100, 200, and 400 μM) and 25 μM H2O2. Untreated cells, ascorbic acid (AA; 25, 50, 100, 200, and 400 μM) and H2O2 (25 μM) were considered as negative control, positive control, and the standard antioxidant agent for our study, respectively.
Single cells were analyzed with “TriTek Cometscore version 1.5” software. The DNA damage was expressed as percent tail DNA.
UMB exhibited a concentration-dependent increase in protection activity against DNA damage induced by 25 μM H2O2 (from 67.28% to 39.17%). The antigenotoxic activity of AA, in the range 0–50 μM, was greater than that of UMB. However, no
significant difference (p > 0.05) in the protective activity was found between UMB and AA at concentrations of approximately higher than 50 μM. 相似文献
The production of hydrogen cyanide (HCN) and 2,4-diacetylphloroglucinol (DAPG) is a major factor in the control of soil-borne
diseases by Pseudomonas fluorescens CHA0. We investigated the impact of different biotic factors on the expression of HCN–in comparison to DAPG biosynthetic
genes in the rhizosphere. To this end, the influence of plant cultivar, pathogen infection, and coinoculation with other biocontrol
strains on the expression of hcnA-lacZ and phlA-lacZ fusion in strain CHA0 was monitored on the roots of bean. Interestingly, all the tested factors influenced the expression
of the two biocontrol traits in a similar way. For both genes, we observed a several-fold higher expression in the rhizosphere
of cv. Derakhshan compared with cvs. Goli and Naz, although bacterial rhizosphere colonization levels were similar on all
cultivars tested. Root infection by Rhizoctonia solani stimulated total phlA and hcnA gene expression in the bean rhizosphere. Coinoculation of strain CHA0 with DAPG-producing P. fluorescens biocontrol strains Pf-68 and Pf-100 did neither result in a substantial alteration of hcnA nor of phlA expression in CHA0 on bean roots. To our best knowledge, this is the first study investigating the impact of biotic factors
on HCN production by a bacterial biocontrol strain in the rhizosphere. 相似文献