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151.
152.
Impact of plant density and microbial composition on water quality from a free water surface constructed wetland 总被引:2,自引:0,他引:2
AIMS: To correlate microbial community composition and water quality changes within wetland cells containing varying plant densities and composition in a free water surface (FWS) constructed wetland. METHODS AND RESULTS: Water chemistry was monitored weekly for nitrate, orthophosphate, and suspended solids, at various sites throughout the wetland for 6 months. Treatment ponds with 50% plant cover had about a 96.3% nitrate removal. The average change between the influent and effluent was 50-60% nitrate removal and 40-50% orthophosphate removal. Community profile of total DNA, generated by using denaturing gradient gel electrophoresis (DGGE), was used to determine the major microbial composition associated with the wetland sediment, rhizosphere, and surface water. Bacterial cloned libraries were constructed, and 300 clones were analysed by amplified ribosomal DNA restriction analysis (ARDRA) and grouped into operational taxonomic units (OTUs). A total of 35, 31, and 36 different OTU were obtained from sediment, rhizosphere, and surface water, respectively. The bacterial members within the dominant group of our clone library belonged to unclassified taxa, while the second predominant group consisted of members of the phylum Proteobacteria. The dominant organisms within the class were in the gamma, beta, and delta classes. CONCLUSION: Microbial diversity as determined by Shannon-Weaver index (H) was higher in the wetland cells with 50% plant density than the 100%. This was in agreement with the most efficient wetland contaminant removal units. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides evidence that wetlands with 50% plant cover may promote the growth of diverse microbial communities that facilitate decomposition of chemical pollutants in surface water, and improve water quality. 相似文献
153.
Michał Gładysz Piotr Ruszkowski Jan Milecki 《Nucleosides, nucleotides & nucleic acids》2018,37(1):53-66
We describe synthesis of novel acyclic nucleoside analogues which are building blocks for CuAAC reaction and their activity against two types of human cancer cell lines (HeLa, KB). Three of chosen compounds show promising cytotoxic activity. Synthesis pathway starting from simple and easily accessible substrates employing DMT or TBDPS protective groups is described. Adenosine and thymidine analogues containing alkyne moiety and adenosine analogue containing azido group were synthesized. The obtained units showed ability of forming triazole motif under the CuAAC reaction conditions. 相似文献
154.
Surface modification of chitosan films. Effects of hydrophobicity on protein adsorption 总被引:2,自引:0,他引:2
The surface of chitosan films was modified using acid chloride and acid anhydrides. Chemical composition at the film surface was analyzed by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). ATR-FTIR data verified that the substitution took place at the amino groups of chitosan, thus forming amide linkages, and the modification proceeded to the depth at least 1 microm. Choices of molecules substituted at the amino groups of the glucosamine units did affect the hydrophobicity of the film surface, as indicated by air-water contact angle analysis. The surface became more hydrophobic than that of non-modified film when a stearoyl group (C(17)H(35)CO-) was attached to the films. The reaction of chitosan films with succinic anhydride or phthalic anhydride, however, produced more hydrophilic films. Selected modified films were subjected to protein adsorption study. The amount of protein adsorbed, determined by bicinchoninic acid (BCA) assay, related to the types of attached molecules. The improved surface hydrophobicity affected by the stearoyl groups promoted protein adsorption. In contrast, selective adsorption behavior was observed in the case of the chitosan films modified with anhydride derivatives. Lysozyme adsorption was enhanced by H-bonding and charge attraction with the hydrophilic surface. While the amount of albumin adsorbed was decreased possibly due to negative charges that gave rise to repulsion between the modified surface and albumin. This study has demonstrated that it is conceivable to fine-tune surface properties which influence its response to bio-macromolecules by heterogeneous chemical modification. 相似文献
155.
156.
The denitrification potential and density of denitrifying bacteria were determined in suboxidized sediments of Matupi Harbor
(Papua New Guinea). The sediments were characterized by low denitrification potentials, not exceeding 0.8 nM/(g h). The maximum
density of denitrifying bacteria was recorded in the upper sediment horizons and was 104 cells/g of wet ground. 相似文献
157.
《Bioorganic & medicinal chemistry》2016,24(12):2595-2602
Described herein are our limited structure–activity relationship (SAR) studies on a 5:7-fused heterocycle (1), containing the 4,6,8-triaminoimidazo[4,5-e][1,3]diazepine ring system, whose synthesis and potent broad-spectrum anticancer activity we reported a few years ago. Our SAR efforts in this study are mainly focused on judicial attachment of substituents at N-1 and N6-positions of the heterocyclic ring. Our results suggest that there is some subtle correlation between the substituents attached at the N-1 position and those attached at the N6-position of the heterocycle. It is likely that there is a common hydrophobic binding pocket on the target protein that is occupied by the substituents attached at the N-1 and N6-positions of the heterocyclic ligand. This pocket appears to be large enough to hold either a C-18 alkyl chain of N6 and no attachment at N-1, or a combined C-10 at N6 and a CH2Ph at N-1. Any alkyl chain shorter or longer than C-10 at N6 with a CH2Ph attached at N-1, would result in decrease of biological activity. 相似文献
158.
Madushi Wanaguru Cécile Crosnier Steven Johnson Julian C. Rayner Gavin J. Wright 《The Journal of biological chemistry》2013,288(45):32106-32117
PfEBA175 has an important role in the invasion of human erythrocytes by Plasmodium falciparum and is therefore considered a high priority blood-stage malaria vaccine candidate. PfEBA175 mediates adhesion to erythrocytes through binding of the Duffy-binding-like (DBL) domains in its extracellular domain to Neu5Acα2–3Gal displayed on the O-linked glycans of glycophorin-A (GYPA). Because of the difficulties in expressing active full-length (FL) P. falciparum proteins in a recombinant form, previous analyses of the PfEBA175-GYPA interaction have largely focused on the DBL domains alone, and therefore they have not been performed in the context of the native protein sequence. Here, we express the entire ectodomain of PfEBA175 (PfEBA175 FL) in soluble form, allowing us to compare the biochemical and immunological properties with a fragment containing only the tandem DBL domains (“region II,” PfEBA175 RII). Recombinant PfEBA175 FL bound human erythrocytes in a trypsin and neuraminidase-sensitive manner and recognized Neu5Acα2–3Gal-containing glycans, confirming its biochemical activity. A quantitative binding analysis showed that PfEBA175 FL interacted with native GYPA with a KD ∼0.26 μm and is capable of self-association. By comparison, the RII fragment alone bound GYPA with a lower affinity demonstrating that regions outside of the DBL domains are important for interactions with GYPA; antibodies directed to these other regions also contributed to the inhibition of parasite invasion. These data demonstrate the importance of PfEBA175 regions other than the DBL domains in the interaction with GYPA and merit their inclusion in an EBA175-based vaccine. 相似文献
159.
Saritha Tantravedi Saibal Chakraborty Niti H. Shah James C. Fishbein Ramachandra S. Hosmane 《Bioorganic & medicinal chemistry》2013,21(17):4893-4903
Guanase is an important enzyme of the purine salvage pathway of nucleic acid metabolism and its inhibition has beneficial implications in viral, bacterial, and cancer therapy. The work described herein is based on a hypothesis that azepinomycin, a heterocyclic natural product and a purported transition state analog inhibitor of guanase, does not represent the true transition state of the enzyme-catalyzed reaction as closely as does iso-azepinomycin, wherein the 6-hydroxy group of azepinomycin has been translocated to the 5-position. Based on this hypothesis, and assuming that iso-azepinomycin would bind to guanase at the same active site as azepinomycin, several analogs of iso-azepinomycin were designed and successfully synthesized in order to gain a preliminary understanding of the hydrophobic and hydrophilic sites surrounding the guanase binding site of the ligand. Specifically, the analogs were designed to explore the hydrophobic pockets, if any, in the vicinity of N1, N3, and N4 nitrogen atoms as well as O5 oxygen atom of iso-azepinomycin. Biochemical inhibition studies of these analogs were performed using a mammalian guanase. Our results indicate that (1) increasing the hydrophobicity near O5 results in a negative effect, (2) translocating the hydrophobicity from N3 to N1 also results in decreased inhibition, (3) increasing the hydrophobicity near N3 or N4 produces significant enhancement of inhibition, (4) increasing the hydrophobicity at either N3 or N4 with a simultaneous increase in hydrophobicity at O5 considerably diminishes any gain in inhibition made by solely enhancing hydrophobicity at N3 or N4, and (5) finally, increasing the hydrophilic character near N3 has also a deleterious effect on inhibition. The most potent compound in the series has a Ki value of 8.0 ± 1.5 μM against rabbit liver guanase. 相似文献
160.
Berry S 《Journal of molecular evolution》2002,54(5):595-613
All organisms rely on chemiosmotic membrane systems for energy transduction; the great variety of participating proteins
and pathways can be reduced to a few universal principles of operation. This chemical basis of bioenergetics is reviewed with
respect to the origin and early evolution of life. For several of the cofactors which play important roles in bioenergetic
reactions, plausible prebiotic sources have been proposed, and it seems likely that these cofactors were present before elaborate
protein structures. In particular, the hydrophobic quinones require only a membrane-enclosed compartment to yield a minimum
chemiosmotic system, since they can couple electron transport and proton translocation in a simple way. It is argued that
the central features of modern bioenergetics, such as the coupling of redox reactions and ion translocation at the cytoplasmic
membrane, probably are ancient features which arose early during the process of biogenesis. The notion of a thermophile root
of the universal phylogenetic tree has been discussed controversially, nevertheless, thermophiles are interesting model organisms
for reconstructing the origin of chemiosmotic systems, since they are often acidophiles and anaerobic respirers exploiting
iron–sulfur chemistry. This perspective can help to explain the prominent role of iron–sulfur proteins in extant biochemistry
as well as the origin of both respiration and proton extrusion within the context of a possible origin of life in the vicinity
of hot vents.
Received: 6 June 2001 / Accepted: 16 October 2001 相似文献