Solution structure of homology region (HR) domain of type II secretion system

The type II secretion system of Gram-negative bacteria is important for bacterial pathogenesis and survival; it is composed of 12 mostly multimeric core proteins, which build a sophisticated secretion machine spanning both bacterial membranes. OutC is the core component of the inner membrane subcomplex thought to be involved in both recognition of substrate and interaction with the outer membrane secretin OutD. Here, we report the solution structure of the HR domain of OutC and explore its interaction with the secretin. The HR domain adopts a β-sandwich-like fold consisting of two β-sheets each composed of three anti-parallel β-strands. This structure is strikingly similar to the periplasmic region of PilP, an inner membrane lipoprotein from the type IV pilus system highlighting the common evolutionary origin of these two systems and showing that all the core components of the type II secretion system have a structural or sequence ortholog within the type IV pili system. The HR domain is shown to interact with the N0 domain of the secretin. The importance of this interaction is explored in the context of the functional secretion system.     

Combined anti-tumor effects of IFN-α and sorafenib on hepatocellular carcinoma in vitro and in vivo

Hepatocellular carcinoma (HCC) is among the most common and aggressive cancers worldwide, and novel therapeutic strategies are urgently required to improve clinical outcome. Interferon-alpha (IFN-α) and sorafenib are widely used as anti-tumor agents against various malignancies. In this study, we investigated the combined effects of IFN-α and sorafenib against HCC. We demonstrated that the combination therapy synergistically suppressed HCC cellular viability, arrested cell cycle propagation and induced apoptosis in HCC cells. Further research revealed that IFN-α and sorafenib collaboratively regulated the expression levels of cell cycle-related proteins Cyclin A and Cyclin B as well as the pro-survival Bcl-2 family proteins Mcl-1, Bcl-2 and Bcl-X(L). Moreover, sorafenib inhibited IFN-α induced oncogenic signaling of STAT3, AKT and ERK but not the activation of the tumor suppressor STAT1. Xenograft experiments also confirmed the combined effects of IFN-α and sorafenib on tumor growth inhibition and apoptosis induction in vivo. In conclusion, these results provide rationale for the clinical application of IFN-α and sorafenib combination therapy in HCC treatment.     

The proteomics of lipid droplets: structure, dynamics, and functions of the organelle conserved from bacteria to humans

Lipid droplets are cellular organelles that consists of a neutral lipid core covered by a monolayer of phospholipids and many proteins. They are thought to function in the storage, transport, and metabolism of lipids, in signaling, and as a specialized microenvironment for metabolism in most types of cells from prokaryotic to eukaryotic organisms. Lipid droplets have received a lot of attention in the last 10 years as they are linked to the progression of many metabolic diseases and hold great potential for the development of neutral lipid-derived products, such as biofuels, food supplements, hormones, and medicines. Proteomic analysis of lipid droplets has yielded a comprehensive catalog of lipid droplet proteins, shedding light on the function of this organelle and providing evidence that its function is conserved from bacteria to man. This review summarizes many of the proteomic studies on lipid droplets from a wide range of organisms, providing an evolutionary perspective on this organelle.     

In vitro selection of glyphosate-tolerant variants from long-term callus cultures of Zoysia matrella [L.] Merr

A complete protocol of in vitro selection and greenhouse screening for glyphosate-tolerant variants in manilagrass (Zoysia matrella [L.] Merr) was established in this study. Newly subcultured calli of more than 5?years?? old were transferred to selection medium containing 2?mM glyphosate. After two rounds of selection, 220 calli survived out of 840 and were transferred to regeneration medium without glyphosate. Regenerated plantlets were then transferred to regeneration medium containing 0.5?mM glyphosate to select tolerant plantlets. After 1-month growth, there were plantlets remained green and new shoots formed beside or on discolored explants. These surviving organisms were then transferred to fresh regeneration medium for further growth. Fully developed plantlets were transferred to a green house and then subjected to greenhouse screening by foliar spraying with 0.05?% glyphosate solution. Six glyphosate-tolerant plantlets, TP1-TP6, were obtained and proliferated for determination of sod-tolerance using morphological and physiological measurements. Fourteen days after foliar application with 0.1?% glyphosate, only TP5 showed enhanced sod-tolerance. The dark green color index value of TP5 was significantly higher than CK2, demonstrating that TP5 suffered less injury from glyphosate than CK2. Different physiological characters were also observed in CK1, CK2 and TP5. Significantly higher chlorophyll a content and catalase activity were observed in TP5 than in CK1. Fourteen days after treatment (DAT), the ion leakage, proline content and ascorbate peroxidase activity of CK2 and TP5 increased significantly, but the ion leakage of TP5 was significantly lower than that of CK2. The guaiacol peroxidase activity of TP5 increased significantly 14 DAT, and was significantly higher than that of CK1 and CK2. No change in shikimate content was observed in CK2 or TP5 14 DAT.     

A novel anti-lymphoma protein RE26 from <Emphasis Type="Italic">Rozites emodensis</Emphasis> (Berk.) Moser

A novel antitumor protein, designated RE26, with anti-lymphoma activity was purified from a Tris–HCl buffer extract of Rozites emodensis (Berk.) Moser by three successive steps of ion exchange chromatography. SDS-PAGE and gel filtration chromatography revealed that RE26 is a monomeric protein of 26 kDa, and isoelectrofocusing assay indicated its isoelectric point of 4.3–4.4. RE26 has high stability over a wide pH range (pH 3–11) but is sensitive to temperature and only stable under 40 °C. Partial amino acid sequences of two RE26 peptide fragments were determined by Edman degradation as GLEEEETLLLLFFPP and GTEQE. The half-maximal inhibitory concentration (IC₅₀) of RE26 against tested lymphoma cell lines was around 4 μg/ml. In vitro experiments showed that RE26 could specifically bind to lymphoma cells; activate the caspases, including caspases 3, 8, and 9 in host cells; and induce apoptosis. Experiments in nude mice indicated local RE26 injection adjacent to tumor site could inhibit lymphoma formation.     

腹侧黄斑小鼠的部分特征及其突变基因的染色体定位

腹侧黄斑小鼠(VYSlac)是在B6小鼠繁殖生产过程中被发现、分离的突变系小鼠,呈单基因显性遗传,其头颈及躯干的腹侧为黄色。VYSlac腹部表皮多巴(+)黑色素细胞及毛囊内黑色素较其背景品系B6少;腹部毛发颜色浅黄、多数无黑色素沉积,但结构正常。通过微卫星标记与48只F2小鼠(VYSlacD2F1回交D2)的连锁分析发现,突变基因与D2Mit229间的LOD值为5.79,确定连锁。随后,在突变基因附近反复多次筛选新的微卫星或SNP标记,通过对196例F2小鼠的多次连锁分析,将突变基因所在区域缩小到rs13476833(距着丝粒149804749bp)与rs27310903(距着丝粒155060764bp)间约5256015bp的范围内。     

Analysis of alkane-dependent methanogenic community derived from production water of a high-temperature petroleum reservoir

Microbial assemblage in an n-alkanes-dependent thermophilic methanogenic enrichment cultures derived from production waters of a high-temperature petroleum reservoir was investigated in this study. Substantially higher amounts of methane were generated from the enrichment cultures incubated at 55 °C for 528 days with a mixture of long-chain n-alkanes (C₁₅–C₂₀). Stoichiometric estimation showed that alkanes-dependent methanogenesis accounted for about 19.8% of the total amount of methane expected. Hydrogen was occasionally detected together with methane in the gas phase of the cultures. Chemical analysis of the liquid cultures resulted only in low concentrations of acetate and formate. Phylogenetic analysis of the enrichment revealed the presence of several bacterial taxa related to Firmicutes, Thermodesulfobiaceae, Thermotogaceae, Nitrospiraceae, Dictyoglomaceae, Candidate division OP8 and others without close cultured representatives, and Archaea predominantly related to uncultured members in the order Archaeoglobales and CO₂-reducing methanogens. Screening of genomic DNA retrieved from the alkanes-amended enrichment cultures also suggested the presence of new alkylsuccinate synthase alpha-subunit (assA) homologues. These findings suggest the presence of poorly characterized (putative) anaerobic n-alkanes degraders in the thermophilic methanogenic enrichment cultures. Our results indicate that methanogenesis of alkanes under thermophilic condition is likely to proceed via syntrophic acetate and/or formate oxidation linked with hydrogenotrophic methanogenesis.