Spectroscopic investigation of the structure of protoxin protein isolated from Bacillus thuringiensis contacted with minerals

Effects of minerals on the conformational changes of protoxin isolated from Bacillus thuringiensis were investigated by circular dichroism and fluorescence spectroscopy. Contact of the protoxin with attapulgite, montmorillonite and kaolinite for 3 h resulted in no significant changes in the spectra of circular dichroism and a slight decrease in the fluorescence intensity. There were significant changes in spectra of circular dichroism of protoxin after desorption in comparison to the native protoxin. The fluorescence intensity of protoxins desorbed from minerals retained 77.5, 63.7 and 60.4% of intensity of native protoxin, respectively. The influential extent of desorption on the secondary structure was higher than that of contact.     

A marine bacterium accumulates polyhydroxyalkanoate consisting of mainly 3-hydroxydodecanoate and 3-hydroxydecanoate

A deep-sea psychrotrophic bacterium Pseudoaltermonas sp. SM9913, isolated from abyssalbenthic sediments in Bohai Sea, was found to be able to synthesize polyhydroxyalkanoate (PHA) polymer consisting of mainly 3-hydroxydecanoate and 3-hydroxydodecanoate. PHA accumulation in Pseudoaltermonas sp. SM9913 was confirmed by transmission electron microscope, Nile red dye and gas chromatography/mass spectral. The PHA content was determined as high as 2–3% of cell dry weight when the strain was grown in a sea water-based liquid medium. The relationship between PHA and exopolysaccharide accumulation in this strain was discussed.     

Discovery and synthesis of 6,7,8,9-tetrahydro-5H-pyrimido-[4,5-d]azepines as novel TRPV1 antagonists

Utilization of a tetrahydro-pyrimdoazepine core as a bioisosteric replacement for a piperazine-urea resulted in the discovery a novel series of potent antagonists of TRPV1. The tetrahydro-pyrimdoazepines have been identified as having good in vitro and in vivo potency and acceptable physical properties.     

An efficient system to detect protein ubiquitination by agroinfiltration in Nicotiana benthamiana

The ubiquitination proteasome pathway has been demonstrated to regulate all plant developmental and signaling processes. E3 ligase/substrate‐specific interactions and ubiquitination play important roles in this pathway. However, due to technical limitations only a few instances of E3 ligase–substrate binding and protein ubiquitination in plants have been directly evidenced. An efficient in vivo and in vitro ubiquitination assay was developed for analysis of protein ubiquitination reactions by agroinfiltration expression of both substrates and E3 ligases in Nicotiana benthamiana. Using a detailed analysis of the well‐known E3 ligase COP1 and its substrate HY5, we demonstrated that this assay allows for fast and reliable detection of the specific interaction between the substrate and the E3 ligase, as well as the effects of MG132 and substrate ubiquitination and degradation. We were able to differentiate between the original and ubiquitinated forms of the substrate in vivo with antibodies to ubiquitin or to the target protein. We also demonstrated that the substrate and E3 ligase proteins expressed by agroinfiltration can be applied to analyze ubiquitination in in vivo or in vitro reactions. In addition, we optimized the conditions for different types of substrate and E3 ligase expression by supplementation with the gene‐silencing suppressor p19 and by time‐courses of sample collection. Finally, by testing different protein extraction buffers, we found that different types of buffer should be used for different ubiquitination analyses. This method should be adaptable to other protein modification studies.     

Piperazine sulfonamide BACE1 inhibitors: Design,synthesis, and in vivo characterization

With collaboration between chemistry, X-ray crystallography, and molecular modeling, we designed and synthesized a series of novel piperazine sulfonamide BACE1 inhibitors. Iterative exploration of the non-prime side and S2′ sub-pocket of the enzyme culminated in identification of an analog that potently lowers peripheral Aβ₄₀ in transgenic mice with a single subcutaneous dose.     

Synthesis and molecular docking studies of novel 2-chloro-pyridine derivatives containing flavone moieties as potential antitumor agents

A series of novel 2-chloro-pyridine derivatives containing flavone, chrome or dihydropyrazole moieties as potential telomerase inhibitors were synthesized. The bioassay tests showed that compounds 6e and 6f exhibited some effect against gastric cancer cell SGC-7901 with IC₅₀ values of 22.28 ± 6.26 and 18.45 ± 2.79 μg/mL, respectively. All title compounds were assayed for telomerase inhibition by a modified TRAP assay, the results showed that compound 6e can strongly inhibit telomerase with IC₅₀ value of 0.8 ± 0.07 μM. Docking simulation was performed to position compound 6e into the active site of telomerase (3DU6) to determine the probable binding model.     

利用大肠杆菌工程菌廉价高效生产聚羟基丁酸酯

利用大肠杆菌生产聚羟基脂肪酸酯是近来国际上生物可降解塑料的研究热点,本研究通过对适宜于聚羟基脂肪酸酯生产的大肠杆菌菌株的选择和碳源利用试验,初步确立了大肠杆菌代谢工程改造生产聚羟基脂肪酸酯的基础。并在此基础上,通过对大肠杆菌磷酸烯醇式丙酮酸葡萄糖转移酶系统的改造和工程菌环境诱导系统的应用,解决了大肠杆菌工程菌无法同时利用多种碳源合成聚羟基脂肪酸酯的难题。发酵试验证明,工程化改造的大肠杆菌利用廉价底物在5L发酵罐中分批培养32h后,菌体终浓度能够达到8.24g/L,聚羟基脂肪酸酯占细胞干重的84.6%。     

Spatial genetic structure and dispersal of giant pandas on a mountain-range scale

Understanding the spatial genetic structure of populations can provide insight into the ecological or evolutionary processes of the species, and enable wise conservation decisions. We examined the spatial genetic structure of a giant panda (Ailuropoda melanoleuca) population in a heterogeneous mountainous landscape using noninvasive genetic sampling and 12 microsatellite loci. Nonrandom genetic structure was detected through spatial autocorrelation analysis, demonstrating a significantly positive autocorrelation over closer distances. Additional spatial analyses showed significantly positive genetic correlation among spatially-proximate males, and no correlation among females and among male–female pairs. These findings suggest a female-biased dispersal pattern and cryptic family grouping among giant pandas on a large mountain-range scale. The spatial extent of genetic structure occurred within 12.5 km, measured by a least-cost path distance model integrating information of habitat quality and habitat preferences of this species. Using the bearing analysis of PASSAGE, we found that directional genetic autocorrelations were in agreement with habitat structure, and habitat heterogeneity may affect the direction of giant panda dispersal. The characterization of spatial genetic structure can provide potentially valuable information for the conservation and management of giant pandas and their habitat.