Diverse Roles of the Salicylic Acid Receptors NPR1 and NPR3/NPR4 in Plant Immunity

The plant defense hormone salicylic acid (SA) is perceived by two classes of receptors, NPR1 and NPR3/NPR4. They function in two parallel pathways to regulate SA-induced defense gene expression. To better understand the roles of the SA receptors in plant defense, we systematically analyzed their contributions to different aspects of Arabidopsis (Arabidopsis thaliana) plant immunity using the SA-insensitive npr1-1 npr4-4D double mutant. We found that perception of SA by NPR1 and NPR4 is required for activation of N-hydroxypipecolic acid biosynthesis, which is essential for inducing systemic acquired resistance. In addition, both pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) are severely compromised in the npr1-1 npr4-4D double mutant. Interestingly, the PTI and ETI attenuation in npr1-1 npr4-4D is more dramatic compared with the SA-induction deficient2-1 (sid2-1) mutant, suggesting that the perception of residual levels of SA in sid2-1 also contributes to immunity. Furthermore, NPR1 and NPR4 are involved in positive feedback amplification of SA biosynthesis and regulation of SA homeostasis through modifications including 5-hydroxylation and glycosylation. Thus, the SA receptors NPR1 and NPR4 play broad roles in plant immunity.     

Mx1‐Cre mediated Rgs12 conditional knockout mice exhibit increased bone mass phenotype

Regulators of G‐protein Signaling (Rgs) proteins are the members of a multigene family of GTPase‐accelerating proteins (GAP) for the Galpha subunit of heterotrimeric G‐proteins. Rgs proteins play critical roles in the regulation of G protein couple receptor (GPCR) signaling in normal physiology and human diseases such as cancer, heart diseases, and inflammation. Rgs12 is the largest protein of the Rgs protein family. Some in vitro studies have demonstrated that Rgs12 plays a critical role in regulating cell differentiation and migration; however its function and mechanism in vivo is largely unknown. Here, we generated a floxed Rgs12 allele (Rgs12^flox/flox) in which the exon 2, containing both PDZ and PTB_PID domains of Rgs12, was flanked with two loxp sites. By using the inducible Mx1‐cre and Poly I:C system to specifically delete Rgs12 at postnatal 10 days in interferon‐responsive cells including monocyte and macrophage cells, we found that Rgs12 mutant mice had growth retardation with the phenotype of increased bone mass. We further found that deletion of Rgs12 reduced osteoclast numbers and had no significant effect on osteoblast formation. Thus, Rgs12^flox/flox conditional mice provide a valuable tool for in vivo analysis of Rgs12 function and mechanism through time‐ and cell‐specific deletion of Rgs12. genesis 51:201–209, 2013. © 2013 Wiley Periodicals, Inc.     

Permeation mechanism of a two-state potassium channel

A two-state hopping model was proposed to study the permeation of ion channel. The Nernst equation in equilibrium and the Michaelis-Menten relation in steady state were derived from the two-state kinetic model. The current-voltage relationship obtained in the symmetrical solutions case was linear when the applied potential was less than 100 mV, which met Ohm’s law. The conductance-concentration relationship exhibited the saturation property. Moreover, the characteristic time reaching the steady state of the KcsA channel was also discussed. Translated from Acta Biophysica Sinica, 2005, 21(4): 289–294 [译自: 生物物理学报]     

链霉菌G4溶菌酶的产生条件及特性

对链霉菌G4的产酶发酵条件和溶菌特性进行研究结果表明:蔗糖30 g/L、大豆蛋白胨12.5 g/L、牛肉膏2 g/L,对产酶最为有利;G4溶菌酶最适培养温度33 ℃,培养时间72 h,培养基初始pH 8.G4溶菌酶的最适作用温度和最适作用pH分别是55 ℃和6.5,多数金属离子会抑制G4溶菌酶的活性,其中Zn2+、Cu2+、Fe2+、 Pb2+几乎可以使其完全失活;对几种细菌、酵母菌的研究表明,G4溶菌酶对卵清溶菌酶不能作用的变形链球菌和金黄色葡萄球菌有很强的溶解活性.     

Scale-up and integration of alkaline hydrogen peroxide pretreatment, enzymatic hydrolysis, and ethanolic fermentation

Alkaline hydrogen peroxide (AHP) has several attractive features as a pretreatment in the lignocellulosic biomass‐to‐ethanol pipeline. Here, the feasibility of scaling‐up the AHP process and integrating it with enzymatic hydrolysis and fermentation was studied. Corn stover (1 kg) was subjected to AHP pretreatment, hydrolyzed enzymatically, and the resulting sugars fermented to ethanol. The AHP pretreatment was performed at 0.125 g H₂O₂/g biomass, 22°C, and atmospheric pressure for 48 h with periodic pH readjustment. The enzymatic hydrolysis was performed in the same reactor following pH neutralization of the biomass slurry and without washing. After 48 h, glucose and xylose yields were 75% and 71% of the theoretical maximum. Sterility was maintained during pretreatment and enzymatic hydrolysis without the use of antibiotics. During fermentation using a glucose‐ and xylose‐utilizing strain of Saccharomyces cerevisiae, all of the Glc and 67% of the Xyl were consumed in 120 h. The final ethanol titer was 13.7 g/L. Treatment of the enzymatic hydrolysate with activated carbon prior to fermentation had little effect on Glc fermentation but markedly improved utilization of Xyl, presumably due to the removal of soluble aromatic inhibitors. The results indicate that AHP is readily scalable and can be integrated with enzyme hydrolysis and fermentation. Compared to other leading pretreatments for lignocellulosic biomass, AHP has potential advantages with regard to capital costs, process simplicity, feedstock handling, and compatibility with enzymatic deconstruction and fermentation. Biotechnol. Bioeng. 2012; 109:922–931. © 2011 Wiley Periodicals, Inc.     

Effects of siRNA Targeting c‐Myc and VEGF on Human Colorectal Cancer Volo Cells

c‐Myc and vascular endothelial growth factor (VEGF) genes are frequently deregulated and overexpressed in this malignancy, and strategies designed to inhibit c‐Myc and VEGF expression in cancer cells may have considerable therapeutic value. In the present study, we design and use short interfering RNA (siRNA) to inhibit c‐Myc and VEGF expression in colorectal cancer Volo cells and validate their effects on cell proliferation, cell cycle, apoptosis, and cell metastasis. Upon transient transfection with plasmid‐encoding siRNA, it was found that expression of c‐Myc and VEGF was significantly downregulated in siRNA‐transfected cells and the downregulation of c‐Myc and VEGF inhibited cell growth and induced apoptosis and metastasis of Volo cells. c‐Myc and VEGF downregulation also increased cell population in the G0–G1 phase. In conclusion, the specific siRNA efficiently silenced the expression of c‐Myc and VEGF, further suppressed the cell proliferation, triggered cell apoptosis, and inhibited cell invasiveness of colorectal cancer Volo cells. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:499‐505, 2012;Viewthis article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21455     

Purification and Characterisation of Keratinase from a Thermotolerant Feather-degrading Bacterium

Summary Isolation and identification of a thermotolerant feather-degrading bacterial strain from Thai soil as well as purification and properties of its keratinase were investigated. The thermotolerant bacterium was identified as Bacillus licheniformis. The keratinase was purified to homogeneity by three-step chromatography. The purified enzyme exhibited a high specific activity (218 U mg⁻¹) with 86-fold purification and 25% yield. The enzyme was monomeric and had a molecular mass of 35 kDa. The optimum pH and temperature for the enzyme were 8.5 and 60 °C, respectively. The enzyme activity was significantly inhibited by PMSF and partly inhibited by EDTA and iodoacetamide, but was stimulated by metal ions. It hydrolysed soluble proteins with a relative activity of 4–100% and insoluble proteins, including keratins, with a relative activity of 3–35%. Therefore, the enzyme could improve the nutritional value of meat- and poultry-processing wastes containing keratins, collagen and gelatin.     

Down-regulation of GPR137 expression inhibits proliferation of colon cancer cells

G protein-coupled receptors （GPRs） are highly related to oncogenesis and cancer metastasis. G protein-coupled re- ceptor 137 （GPR137） was initially reported as a novel orphan GPR about 10 years ago. Some orphan GPRs have been implicated in human cancers. The aim of this study is to investigate the role of GPR137 in human colon cancer. Expression levels of GRP137 were analyzed in different colon cancer cell lines by quantitative polymerase chain re- action and western blot analysis. Lentivirus-mediated short hairpin RNA was specifically designed to knock down GPR137 expression in colon cancer cells. Cell viability was measured by methylthiazoletetrazolium and colony forma- tion assays. In addition, cell cycle characteristic was investi- gated by flow cytometry. GRP137 expression was observed in aH seven colon cancer cell lines at different levels. The mRNA and protein levels of GPR137 were down-regulated in both HCTll6 and RKO cells after lentivirus infection. Lentivirus-mediated silencing of GPR137 reduced the proliferation rate and colonies numbers. Knockdown of GPR137 in both cell lines led to cell cycle arrest in the G0/G1 phase. These results indicated that GPR137 plays an important role in colon cancer cell proliferation. A better understanding of GPR137＇s effects on signal transduction pathways in colon cancer cells may provide insights into the novel gene therapy of colon cancer.     

变溶菌素(Mutanolysin)研究历史和发展前景

变溶菌素(Ｍｕｔａｎｏｌｙｓｉｎ)是由球孢链霉菌(Ｓｔｒｅｐｔｏｍｙｃｅｓｇｌｏｂｉｓｐｏｒｕｓ)的培养液制备的由多种不同溶菌酶组成的粗酶液。这种溶菌酶群在防治龋齿、从细菌细胞壁制取免疫活性物质等方面及一些科研领域有着良好的应用前景,其研究越来越受到广泛?..     

N‐glycosylation proteomic characterization and cross‐species comparison of milk fat globule membrane proteins from mammals

Glycosylation of proteins has been implicated in various biological functions and has received much attention; however, glycoprotein components and inter‐species complexity have not yet been elucidated fully in milk proteins. N‐linked glycosylation sites and glycoproteins in milk fat globule membrane (MFGM) fractions were investigated by combining N‐glycosylated peptides enrichment and high‐accuracy Q Exactive identification, to map the N‐glycoproteome profiles in Holstein and Jersey cows, buffaloes, yaks, goats, camels, horses, and humans. A total of 399 N‐glycoproteins with 677 glycosylation sites were identified in the MFGM fractions of the studied mammals. Most glycosylation sites in humans were classified as known and those in the other studied mammals as unknown, according to Swiss‐Prot annotations. Functionally, most of the identified glycoproteins were associated with the ‘response to stimulus’ GO category. N‐glycosylated protein components of MFGM fractions from Holstein and Jersey cows, buffaloes, yaks, and goats were more similar to each other compared with those of camels, horses and human. The findings increased the number of known N‐glycosylation sites in the milk from dairy animal species, revealed the complexity of the MFGM glycoproteome, and provided useful information to further explore the mechanism of MFGM glycoproteins biosynthesis among the studied mammals.