Effect of viral infection on host cell metabolism: a review / 生物工程学报

As specialized intracellular parasite, viruses have no ability to metabolize independently, so they completely depend on the metabolic mechanism of host cells. Viruses use the energy and precursors provided by the metabolic network of the host cells to drive their replication, assembly and release. Namely, viruses hijack the host cells metabolism to achieve their own replication and proliferation. In addition, viruses can also affect host cell metabolism by the expression of auxiliary metabolic genes (AMGs), affecting carbon, nitrogen, phosphorus, and sulfur cycles, and participate in microbial-driven biogeochemical cycling. This review summarizes the effect of viral infection on the host's core metabolic pathway from four aspects: cellular glucose metabolism, glutamine metabolism, fatty acid metabolism, and viral AMGs on host metabolism. It may facilitate in-depth understanding of virus-host interactions, and provide a theoretical basis for the treatment of viral diseases through metabolic intervention.

Xiaokeping-induced autophagy protects pancreatic ß-cells against apoptosis under high glucose stress.

Xiaokeping (XKP), a prescribed Traditional Chinese Medicine (TCM), has been used to treat patients with type Ⅱ diabetes mellitus for many years; however, the molecular mechanism of its effects is unknown. As the only insulin producer, the pancreatic ß cell plays an important role in diabetes. Whether XKP influences the viability of pancreatic ß cells remains to be substantiated. In the present study, autophagy/apoptosis analyses were used to evaluate the therapeutic effect of XKP on pancreatic ß-cells induced by high glucose levels and to investigate a potential causal molecular mechanism of XKP effect on the cells. The pancreatic ß-cell lines MIN-6 were divided into four groups: control, high glucose (33.3 mmol/L), high glucose with XKP, high glucose with XKP and 3-Methyladenine (3-MA). Immunofluorescence assay was employed to determine autophagosome formation and flow cytometry was used to determine apoptotic rates of the ß cells by the detecting expression of autophagy- and apoptosis-related proteins. High glucose increased the apoptotic rate of ß-cells from 5.37% to 23.24%; however addition of XKP mitigated the rate at 10.92%. Data indicate that autophagy of ß-cells was induced by XKP via the mammalian target of rapamycin (mTOR) pathway. Where the autophagy inhibitor 3-MA was added, the apoptotic rate was 23.94%, similar to the high glucose group rate. The results suggest a potential cytoprotective effect of XKP from high glucose toxicity by its induction of autophagy which may be linked to mTOR-mediated autophagy.

Metagenomic analysis of the diversity of microbes in the Napahai plateau wetland and their carbon and nitrogen metabolisms / 生物工程学报

Due to the special geographical location and the complex ecosystem types, plateau wetlands play important ecological roles in water supply, greenhouse gas regulation and biodiversity preservation. Napahai plateau wetland is a special wetland type with low latitude and high altitude, and its microbial diversity was rarely studied. The diversity of microbial communities in the Napahai plateau wetland was analyzed using metagenomics method. Among the microbes detected, 184 phyla, 3 262 genera and 24 260 species belong to the bacterial domain, 13 phyla and 32 genera belong to the archaeal domain, and 13 phyla and 47 genera belong to the fungal domain. Significant differences in species diversity between soil and water were observed. Acidobacteria, Proteobacteria and Actinobacteria were dominant phyla in soil, while Proteobacteria and Bacteroides were dominant phyla in water. Since the carbon and nitrogen metabolism genes were abundant, the pathways of carbon fixation and nitrogen metabolism were analyzed. Calvin cycle, reductive tricarboxylic acid cycle and 3-hydroxypropionic acid cycle were the main carbon fixation pathways, while Proteobacteria, Chloroflexi, and Crenarchaeota were the main carbon-fixing bacteria group. As for the nitrogen cycle, nitrogen fixation and dissimilatory nitrate reduction were dominant in water, while nitrification and denitrification were dominant in soil. Proteobacteria, Nitrospirae, Verrucomicrobia, Actinobacteria, Thaumarchaeota and Euryarchaeota contributed to the nitrogen cycle. The study on microbial diversity of Napahai plateau wetlands provides new knowledge for the comprehensive management and protection of wetland environment in China.

The analysis of promoters and the effective expression of exogenous proteins in a cold-adapted bacterium / 生物工程学报

Based on the constructed promoter probe vectors that could replicate both in E. coli and in a cold-adapted bacterium, several candidate promoters were isolated and their activities were evaluated by RT-PCR. The transcription initiation sites and core sequence of promoters were determined by primer extension analysis. A low-temperature expression vector was constructed by using the strongest promoter and a thermolabile alpha-amylase gene was successfully overproduced under control of this promoter at low temperature (7 degrees C), while the secreted alpha-amylase amounted up to 35% of the total extracellular proteins. The expression system is expected to be useful for the production of thermolabile exogenous proteins at low temperatures.

Cloning and characterization of the chloramphenicol resistant gene of Serratia marcescens strain KMR-3 / 生物工程学报

Chloramphenicol-resistant gene was cloned and analyzed by constructing genomic DNA library of Serratia marcescens KMR-3. It showed that cloned chloramphenicol-resistant gene encoded a protein product of 397 amino acids. The protein belonged to PRK10473 protein, and it showed 92% similarity to drug resistance transporter, Bcr/CflA subfamily of Serratia proteamaculans 568. Regulation elements including promoter, terminator, Shine-Dalgarno (SD) sequence and transcription start site also were identified.

Solid wastes treatment process and biohydrogen / 生物工程学报

As a clean energy source and industrial material, hydrogen is very valuable. Electrolysis of water and chemical methods are well-known for producing hydrogen, however, all of these methods need additional energy supply. Besides highly energy cost, the chemical methods will lead to serious environment pollution. Compared with traditional methods, biological production of hydrogen has showed significant advantages. Bio-hydrogen can be produced by anaerobic and photosynthetic microorganisms during treatment of organic waste. It provides a low cost method for producing hydrogen gas, and a way of utilizing waste at the same time. This paper summarized the procedures of treatment of solid waste and the production of bio-hydrogen.