Didymodon liae sp. nov. (Pottiaceae) from Tibet,China

Didymodon liae J. Kou, X.‐M. Shao & C. Feng sp. nov., is described and illustrated from Dagzê County in south central Tibet, China. The new species is most similar to Didymodon australasiae (Hook. & Grev.) R. H. Zander, but differs in plants growing loosely in a thin turf, stems without hyalodermis and sclerodermis, margins recurved from just above the base nearly to the apex, laminal cells strongly bulging, mammillose, covered with simple or forked papillae, and costa with a layer of ventral substereids. The new species is contrasted with other similar species of the genus. Information on its distribution and ecology is also provided.     

Accelerating haplotype-based genome-wide association study using perfect phylogeny and phase-known reference data

The genome-wide association study (GWAS) has become a routine approach for mapping disease risk loci with the advent of large-scale genotyping technologies. Multi-allelic haplotype markers can provide superior power compared with single-SNP markers in mapping disease loci. However, the application of haplotype-based analysis to GWAS is usually bottlenecked by prohibitive time cost for haplotype inference, also known as phasing. In this study, we developed an efficient approach to haplotype-based analysis in GWAS. By using a reference panel, our method accelerated the phasing process and reduced the potential bias generated by unrealistic assumptions in phasing process. The haplotype-based approach delivers great power and no type I error inflation for association studies. With only a medium-size reference panel, phasing error in our method is comparable to the genotyping error afforded by commercial genotyping solutions.     

1-(Arylsulfonyl)-2,3-dihydro-1H-quinolin-4-one derivatives as 5-HT(6) serotonin receptor ligands

Piperazinyl derivatives of 1-(arylsulfonyl)-2,3-dihydro-1H-quinolin-4-ones have been identified with high binding affinities for 5-HT₆ receptor. In particular, 2-methyl-5-(N-methyl-piperazin-1-yl)-1-(naphthalene-2-sulfonyl)-2,3-dihydro-1H-quinolin-4-one (8g) exhibits high binding affinity toward 5-HT₆ (IC₅₀ = 8 nM) receptor with good selectivity over other serotonin and dopamine receptors.     

Acylideneoxoindoles: a new class of reversible inhibitors of human transglutaminase 2

Inhibitors of human transglutaminase 2 (TG2) are anticipated to be useful in the therapy of a variety of diseases including celiac sprue as well as certain CNS disorders and cancers. A class of 3-acylidene-2-oxoindoles was identified as potent reversible inhibitors of human TG2. Structure-activity relationship analysis of a lead compound led to the generation of several potent, competitive inhibitors. Analogs with significant non-competitive character were also identified, suggesting that the compounds bind at one or more allosteric regulatory sites on this multidomain enzyme. The most active compounds had K_i values below 1.0 μM in two different kinetic assays for human TG2, and may therefore be suitable for investigations into the role of TG2 in physiology and disease in animals.     

Optimized ferrocene-functionalized ZnO nanorods for signal amplification in electrochemical immunoassay of Escherichia coli

A novel amplified electrochemical immunoassay based on ferrocene (Fc)-functionalized ZnO nanorods (NRs) was developed in the present work. The detection antibody ((d)Ab) and Fc were immobilized onto the surface of ZnO NRs, denoted as {(d)Ab-ZnO-Fc} bioconjugates. The amount of (d)Ab and Fc in the bioconjugates was investigated using the copper reduction/bicinchoninic acid reaction (BCA protein assay) and inductive coupled plasma-atomic emission spectroscopy (ICP-AES), respectively. Greatly amplified signal was achieved in the sandwich-type immunoassay when (d)Ab and Fc linked to ZnO NRs at a proper ratio. Using Escherichia coli (E. coli) as a model antigen, the designed immunoassay showed an excellent analytical performance, and exhibited a wide dynamic response range of E. coli concentration from 10(2) to 10(6)cfu/mL with a detection limit of 50 cfu/mL (S/N=3). By introducing a pre-enrichment step, the detection of 5 cfu/10 mL E. coli in hospital sewage water was realized. This proposed signal amplification strategy was promising and could be easily extended to monitor other biorecognition events.     

1H, 13C and 15N resonance assignments of rhodanese GlpE from Escherichia coli

Rhodanese catalyzes the sulfur-transfer reaction in which a sulfur atom is transferred from thiosulfate to cyanide by a double-displacement mechanism. During the reaction, a persulfide-intermediate form of rhodanese is generated by the reaction of a conserved active cysteine residue with thiosulfate. Escherichia coli GlpE is a prototype for the single-domain rhodanese superfamily. Though there are some studies on rhodaneses, the molecular mechanism of the catalytic activity of rhodaneses is still unclear. Herein, we report the resonance assignments of (1)H, (13)C and (15)N atoms of E. coli GlpE, which provides the basis for further structural, dynamic and functional studies of rhodaneses using NMR technique.     

Alternative nucleophilic residues in intein catalysis of protein splicing

Protein-splicing inteins are widespread in nature and have found many applications in protein research and engineering. The mechanism of protein splicing typically requires a nucleophilic amino acid residue at both position 1 (first residue of intein) and position +1 (first residue after intein), however it was not clear whether or how the three different nucleophilic residues (Cys, Ser, and Thr) would work differently at these two positions. To use intein in a target protein of interest, one needs to choose an intein insertion site to have a nucleophilic residue at position +1, therefore it is desirable to know what nucleophilic residue(s) are preferred by different inteins. In this study we began with a statistical analysis of known inteins, which showed an unequal distribution of the three nucleophilic residues at positions 1 and +1, and then subjected six different mini-inteins to site-directed mutagenesis to systematically test the functionality of the three nucleophilic residues at the two positions. At position 1, most natural inteins had Cys and none had Thr. When the Cys at position 1 of the six inteins was mutated to Ser and Thr, the splicing activity was abolished in all except one case. At position +1, Cys and Ser were nearly equally abundant in natural inteins, and they were found to be functionally interchangeable in the six inteins of this study. When the two positions were studied as 1/+1 combination, the Cys/Ser combination was abundant in natural inteins, whereas the Ser/Cys combination was conspicuously absent. Similarly, all of the six inteins of this study spliced with the Cys/Ser combination, whereas none spliced with the Ser/Cys combination. These findings have interesting implications on the mechanism of splicing and the selection of intein insertion sites, and they also produced two rare mini-inteins that could splice with Thr at position +1.     

Augmenter of liver regeneration (ALR) gene therapy attenuates CCl₄-induced liver injury and fibrosis in rats

Liver fibrosis represents a process of healing and scarring in response to chronic liver injury. Augmenter of liver regeneration (ALR) has been shown to protect hepatocytes from various toxins. The aim of this study was to investigate the effects of ALR gene therapy on liver injury and fibrosis induced by CCl(4) in rats and further explore the underlying mechanisms. Human ALR expression plasmid was delivered via the tail vein. ALR gene therapy might protect the liver from CCl(4)-induced injury and fibrogenesis by attenuating the mitochondrial dysfunction, suppressing oxidative stress, and inhibiting activation of HSCs. This report demonstrated that ALR gene therapy protected against the ATP loss, increased the activity of ATPase, decreased intrahepatic reactive oxygen species level, and down-regulated transforming growth factor-β1, platelet-derived growth factor-BB, and α-smooth muscle actin expression. Following gene transfer liver function tests were significantly improved. In brief, ALR gene therapy might be an effective therapeutic reagent for liver fibrosis with potential clinical applications.     

Quercetin inhibits IL-1β-induced inflammation, hyaluronan production and adipogenesis in orbital fibroblasts from Graves' orbitopathy

Management of Graves' orbitopathy (GO) is challenging, as no reliable, specific, and safe medical therapeutic agents have yet been developed. We investigated the effect of quercetin in primary cultured orbital fibroblasts from GO, targeting pathways of inflammation, aberrant accumulation of extracellular matrix macromolecules, and adipose tissue expansion. Quercetin significantly attenuated intercellular adhesion molecule-1 (ICAM-1), interleukin (IL) -6, IL-8, and cyclooxygenase (COX) -2 mRNA expression, and inhibited IL-1β-induced increases in ICAM-1, IL-6, and IL-8 mRNA. Increased hyaluronan production induced by IL-1β or tumor necrosis factor-α was suppressed by quercetin in a dose- and time-dependent manner. Treatment with noncytotoxic doses of quercetin inhibited accumulation of intracytoplasmic lipid droplets and resulted in a dose-dependent decrease in expression of peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein (C/EBP) α, and C/EBPβ proteins. In conclusion, inhibition of inflammation, hyaluronan production, and adipogenesis by the natural plant product quercetin in vitro provides the basis for further study of its potential use in the treatment of GO.     

In vitro screening system for hepatotoxicity: Comparison of bone‐marrow‐derived mesenchymal stem cells and Placenta‐derived stem cells

Stem cells have unique properties such as self‐renewal, plasticity to generate various cell types, and availability of cells of human origin. The characteristics are attentive in the toxicity screening against chemical toxicants. Placenta‐derived stem cells (PDSCs) have been spotlighted as a new cell source in stem cell research recently because they are characterized by their capacity to differentiate into multilineages. However, the use of PDSCs as an in vitro screening model for potential drug candidates has not yet been studied. Here, we analyzed the potentials for bone‐marrow‐derived mesenchymal stem (BM‐MSCs), which is a representative adult stem cells and PDSCs as an in vitro hepatotoxicity screening system, using well‐known hepatotoxicants. BM‐MSCs and PDSCs were analyzed to the potential for hepatogenic differentiation and were cultured with different concentrations of hepatotoxicants for time courses. The viability and ATP‐binding cassette (ABC) transporters were measured by the MTT assay and RT‐PCR, respectively. The sensitivities of PDSCs to hepatotoxicants are more sensitive than those of BM‐MSCs. The viability (IC₅₀) to in PDSCs was less than that of BM‐MSCs after 48 and 72 h (P < 0.05) of CCl₄ exposure. The toxicities of CCl₄ were decreased by fourfold in hepatogenic differentiation inducing PDSCs compared to the undifferentiated cells. The alteration of ABCGs was observed in PDSCs during differentiation. These findings suggest that the naïve PDSCs expressing ABCGs can be used as a source for in vitro screening system as well as the expression patterns of ABCG1 and ABCG2 might be involved in the sensitivity of PDSCs to hepatotoxicants. J. Cell. Biochem. 112: 49–58, 2011. © 2010 Wiley‐Liss, Inc.