Recently, the worldwide spread of A/H5N1 avian influenza with high virulence has highlighted the potential threat of human influenza pandemic. Tamiflu and Relenza are currently the only two anti-influenza drugs targeting the neuraminidase (NA) enzyme of human influenza virus. Reports of the emergence of drug resistance further make the development of new potent anti-influenza inhibitors a priority. The X-ray crystallographic study of A/H5N1 avian influenza NA subtypes (Russell, R. J. Nature 2006, 443, 45-49) has demonstrated that there exist two genetically distinct groups, group-1 (N1, N4, N5 and N8) and group-2 (N2, N3, N6, N7 and N9), whose conformations are substantially different. The detailed comparison of their active sites has established, heretofore, the most accurate and solid molecular basis of structure and mechanism for the development of new anti-influenza drugs. In the present study, a three-dimensional structure of N1 subtype of human influenza type A virus (N1hA) has been generated by homology modeling using the X-ray crystallographic structure of N1 subtype of avian influenza virus (N1aA) as the template. Binding interaction analysis between the active site and its inhibitors has been performed by combining ab initio fragment molecular orbital (FMO) calculations and three-dimensional quantitative structure-activity relationship with comparative molecular field analysis (3D-QSAR CoMFA) modeling. Integrated with docking-based 3D-QSAR CoMFA modeling, molecular surface property (electrostatic and steric) mapping and FMO pair interaction analysis, a set of new receptor-ligand binding models and bioaffinity predictive models for rational design and virtual screening of more potent inhibitors of N1hA are established. In addition, the flexibility of the loop-150 of N1hA and N1aA has been examined by a series of molecular dynamics simulations.

Bioflocculants of Chlamydomonas reinhardtii were investigated under axenic conditions. C. reinhardtii was found to produce significant amounts of bioflocculants. Flocculating activity by C. reinhardtii began in the linear phase of growth and continued until the end of the stationary phase. The highest flocculating efficiency of the culture broth was 97.06%. The purified C. reinhardtii bioflocculant was composed of 42.1% (w/w) proteins, 48.3% carbohydrates, 8.7% lipids, and 0.01% nucleic acid. The optimum condition for bioflocculant production of C. reinhardtii was as follows: under temperature of 15°C to 25°C, pH 6-10 and illumination of 40-60 μmol photons m −2 s −1 . The bioflocculants produced by C. reinhardtii showed maximum activity in pH ranges from 2 to 10. The flocculating activity was significantly enhanced by the addition of CaCl 2 as a coflocculant at an optimal concentration of 4.5 mM.

Capability of three species of aquatic macrophytes to remediate pentachlorophenol (PCP)-contaminated sediments starting with initial concentration of 2,000 lg kg -1 dw (dry weight) was investigated. Negative effect of PCP on the plant growth, chlorophyll contents and root activities (p [ 0.05) of the three species of aquatic macrophytes during remediation was not observed. PCP removal was significantly enhanced in the phytoremediated sediments in comparison with the control sediments after 90 days treatment (p \ 0.05), and the removal rates of PCP in the sediments planted with P. communis Trin, T. orientalis and S. validus Vahl were 90.35 ± 0.03, 99.23 ± 0.02 and 99.33 ± 0.01%, respectively, while the rate was 29.87 ± 0.05% in the control sediments. Bioaccumulation by three macrophytes was confirmed; the maximum PCP contents in the roots of P. communis Trin, T. orientalis and S. validus Vahl were 419.50 ± 0.71, 1,833.33 ± 7.37 and 2,090.00 ± 2.65 lg kg -1 at the 30th day, respectively. In conclusion, P. communis Trin, T. orientalis and S. validus Vahl may act as promising tools for the PCP phytoremediation in aquatic environment, especially S. validus Vahl.

Phytoremediation is an economic and promising technique for removing toxic pollutants from the environment. Freshwater sediments are regarded as the ultimate sink of the widely used PBDE congener decabromodiphenyl ether (BDE-209) in the environment. In the study, the aquatic macrophyte Scirpus validus was selected to remove BDE-209 from three types of sediments (silt, clay, and sand) at an environmentally relevant concentration. After 18 months of phytoremediation experiment, S. validus significantly enhanced the dissipation rates of BDE-209 in all the sediments compared to the controls. Average removal rates of BDE-209 in the three treatments of silt, clay, and sandy sediments with S. validus were respectively 92.84, 84.04, and 72.22%, which were 148, 197, and 233% higher than that in the control sediments without S. validus. In the phytoremediation process, the macrophyte-rhizosphere microbe combined degradation was the main pathway of BDE-209 removal. Sixteen lower brominated PBDE congeners (di- to nona-) were detected in the sediments and plant tissues, confirming metabolic debromination of BDE-209 in S. validus. A relatively higher proportion of penta- and di-BDE congeners among the metabolites in plant tissues than that in the sediments indicated further debromination of PBDEs within plants. The populations and activities of microorganisms in the sediments were greatly promoted by S. validus. Bacterial community structure in BDE-209-contaminated rhizosphere sediments was different from that in the control rhizosphere sediment, as indicated by the dominant proportions of β-proteobacteria, δ-proteobacteria, α-proteobacteria, Acidobacteria, and Chloroflexi in the microbial flora. All these results suggested that S. validus was effective in phytoremediation of BDE-209 by the macrophyte-rhizosphere microbe combined degradation in aquatic sediments.