Two new flavonoids from Derris laxiflora Benth

Two new compounds, derriscoumaronochromone (1) and cis-3,4′-dihydroxy- 5,7-dimethoxyflavan (2), as well as trans-4'-O-methylcatechin (3) were isolated from Derris laxiflora, The structures of these compounds were determined by analysis of their spectroscopic data.     

Genetic assessment of captive Chinese water deer populations in Zhoushan Archipelago,China

Chinese water deer is a rare and vulnerable animal in China because of the poaching for medical use and the habitat loss. In this study, the genetic diversity and population genetic structure of 40 Chinese water deer from three populations in Zhoushan Archipelago were investigated with ten highly polymorphic microsatellite loci, including 4 screened from the nuclear DNA in the study, and 6 selected from the literature. According to the results, these captive populations had a higher genetic diversity than other rare cervid species, such as forest musk deer. No signs of inbreeding were detected. Low genetic differentiation among these populations was found. The probable reasons included the isolation by distance, the exchange among islands, or the supplement of the wild Chinese water deer. We proposed the deer raisers to strengthen the exchanges from different islands or mainland, and if possible, some deer would be returned to the wild to expand the wild population.     

Cumulative consumption of the lake macrophyte Elodea by abundant generalist invertebrate herbivores

Previous investigations have shown that macrophyte biomass can be substantially reduced by invertebrate herbivores but have not provided evidence for the links between the magnitude of the observed damage and the densities of herbivores. The results of this study support the hypothesis that the abundant occurrence of the epiphytic generalist herbivores may result in their cumulative consumption which, in turn, can be regarded as the mechanism responsible for often observed relatively high level of herbivory on freshwater macrophytes. The percentage of Elodea sp. biomass consumed by invertebrates was estimated for six European lakes, based on analysis of gut contents, daily rations and the density of epiphytic herbivores. Although the daily ration of these invertebrates when feeding upon Elodea averaged only 14.6% of their dry mass, their biomass was relatively high (from 0.163 to 1.161 g DW per 100 g DW plant). The estimated percentage of Elodea biomass consumed during one summer month by epiphytic invertebrates ranged from 0.5 to 5.9%. These values, after extrapolating to the whole growing season would mean that the biomass of Elodea lost to herbivory was between about 2 and 23%, an estimate which are within the range of consumption reported by other authors.     

A single-nucleotide mutation within the TBX3 enhancer increased body size in Chinese horses

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A Novel Optimization of Water-Soluble Compound Polysaccharides from Chinese Herbal Medicines by Quantitative Theory and Study on Its Characterization and Antioxidant Activities

The present study optimized the extraction characterization and antioxidant activities of water-soluble compound polysaccharides (CPs) from hawthorn, lotus leaf, Fagopyrum tataricum, semen cassiae, Lycium barbarum, and Poria cocos Chinese herbal medicines that have mass ratios of 4 : 2 : 2 : 1.5 : 1 : 1. The CPs yield equation was predicted using quantitative theory, to which a maximum CPs yield of 7.18±0.24 % under the following optimal extraction conditions: a water-to-raw material ratio of 30 mL/g, an extraction temperature of 65 °C, an extraction time of 45 min, and extraction mode ultrasonic-assistant extraction. CPs were consisted of Ara, Gal, Glc, Xyl, Man, GalA and GlcA in a molar ratio of 3.1 : 2.6 : 50.6 : 1.7 : 20.4 : 17.2 : 4.2. The HPGPC profiles and FT-IR spectra implied that CPs were heterogeneous acidic polysaccharides and possessed the β-d -pyranose configuration. Congo red test, CD spectrum and SEM revealed that CPs with three helix conformation showed a flocculent, granulous or sheet-like appearance. Furthermore, the relationships between antioxidant activity and concentration of CPs displayed significant positive correlation, and the scavenging abilities for DPPH, hydroxyl radical, ABTS, superoxide-anion radical and reducing power of CPs were 93.56±2.51 %, 84.03±1.69 %, 83.29±1.93 %, 37.49±1.93 % and 0.467±0.006 at a concentration of 4.0 mg/mL. Therefore, CPs could be applied as a potential natural antioxidant in pharmaceutical or functional food fields.     

Estimates of protozoan- and viral-mediated mortality of bacterioplankton in Lake Bourget (France)

1. We performed three, 1‐week in situ experiments in March‐April (expt 1), May (expt 2) and August (expt 3) 2003 in order to assess protozoan and virus‐induced mortality of heterotrophic bacteria in a French lake. Viral and bacterial abundances were obtained using flow cytometry (FCM) while protozoa were counted using epifluorescence microscopy (EFM). 2. A dilution approach, applied to pretreated grazer‐free samples, allowed us to estimate that viral lysis could be responsible for 60% (expt 1), 35% (expt 2) and 52% (expt 3) of daily heterotrophic bacterial mortality. Flagellate (both mixotrophic and heterotrophic) grazing in untreated samples, was responsible for 56% (expt 1), 63% (expt 2) and 18% (expt 3) of daily heterotrophic bacteria removal. 3. These results therefore suggest that both viral lysis and flagellate grazing had a strong impact on bacterial mortality, and this impact varied seasonally. 4. From parallel transmission electron microscopy (TEM) analysis, we found that the burst size (i.e. the number of viruses potentially released per lysed cell) ranged from nine to 25 (expt 1), 10 to 35 (expt 2) and eight to 25 (expt 3). The percentage of infected heterotrophic bacteria was 5.7% (expt 1), 3.4% (expt 2) and 5.7% (expt 3) so that the calculated percentage of bacterial mortality induced by viruses was 6.3% (expt 1), 3.7% (expt 2) and 6.3% (expt 3). 5. It is clear that the dilution‐FCM and TEM methods yielded different estimates of viral impact, although both methods revealed an increased impact of viruses during summer.     

A novel potent metal-binding NDM-1 inhibitor was identified by fragment virtual,SPR and NMR screening

NDM-1 can hydrolyze nearly all available β-lactam antibiotics, including carbapenems. NDM-1 producing bacterial strains are worldwide threats. It is still very challenging to find a potent NDM-1 inhibitor for clinical use. In our study, we used a metal-binding pharmacophore (MBP) enriched virtual fragment library to screen NDM-1 hits. SPR screening helped to verify the MBP virtual hits and identified a new NDM-1 binder and weak inhibitor A1. A solution NMR study of ¹⁵N-labeled NDM-1 showed that A1 disturbed all three residues coordinating the second zinc ion (Zn2) in the active pocket of NDM-1. The perturbation only happened in the presence of zinc ion, indicating that A1 bound to Zn2. Based on the scaffold of A1, we designed and synthesized a series of NDM-1 inhibitors. Several compounds showed synergistic antibacterial activity with meropenem against NDM-1 producing K. pneumoniae.