Rapid copy number expansion and recent recruitment of domains in S-receptor kinase-like genes contribute to the origin of self-incompatibility

More than half of flowering plants have a sophisticated mechanism for self-pollen rejection, named self-incompatibility. In the Brassicaceae family, the recognition specificity of a self-incompatibility system is achieved by the interaction of the stigmatic S-receptor kinase and its ligand S-locus cysteine-rich protein, which are encoded by two tightly linked polymorphic genes. During the last two decades, many studies have explored their functions, although their origin and evolutionary history have still not been elucidated clearly. In the present study, an extensive survey in nine whole-genome sequenced plants, including one moss, one fern and seven flowering plants, was conducted to clarify these issues. The data obtained showed that S_locus_glycop domain-related genes, which are land plant specific, have an ancient origin that can be traced back to early land plants and also have a significantly expansion in flowering plants. In the four predominant domain architectures (Types I to IV) of these proteins, Type III genes had absolute predominance and appeared to be raw materials for diversification of the S_locus_glycop domain-related genes by frequent domain re-organizations. S-receptor kinase-like sequences (Type IV) might have originated from Type III genes by domain gains, and S-locus glycoprotein-like sequences (Type I) might have arisen by partial duplication of its linked S-receptor kinase genes. Although similar topologies were detected in S-receptor kinase and S-locus cysteine-rich protein trees, their physical linkage were found only in Brassicaceae, suggesting that the strong linkage disequilibrium and their co-evolution may be a key factor for the origin and maintenance of the S-receptor kinase-based self-incompatibility system in Brassicaceae.     

A high strength nanocomposite based on microcrystalline cellulose and polyurethane

A high-strength elastomeric nanocomposite has successfully been prepared by dispersing microcrystalline cellulose in a polyurethane matrix. The resulting nanocomposites show increased strain-to-failure in addition to increased stiffness and strength compared to the unfilled polyurethane. The optimal composite contained 5 wt % cellulose. The average true strength for this composition was 257 MPa, compared with 39 MPa for the neat polyurethane, and showed the highest strain-to-failure. The improvements of stiffness, strength, as well as strain-to-failure are believed to be due to good interaction, by both covalent and hydrogen bonds, between the polyurethane and the cellulose nanofibrils.     

Evaluation of ceftazidime contents in antibiotic discs by capillary electrophoresis

Good quality of antibiotic discs is a fundamental prerequisite to accurate antibiotic susceptibility tests. Capillary electrophoresis (CE) is a widely used method for quantitative analysis. Here, using ceftazidime as an example, we report an easy-to-perform strategy to determine ceftazidime content in discs. First, a serial of ceftazidime standard solutions was prepared to determine the detection linearity. Utilizing the background buffer containing 50 mmol/L Na2HPO4, 0.045 mmol/L beta-cyclodextrin and 3.15 mmol/L Tris (hydroxymethyl) aminomethane, ceftazidime of concentrations ranging from 1.875 to 60 microg/ml showed a linear response to detected peak areas. Subsequently, four kinds of ceftazidime discs were selected from different manufacturers. The discs were homogenized using 1 ml deionized water, and then detected by CE after filtration. The results showed that one kind of discs were of poor quality as further confirmed by disc diffusion tests using standard strains. This study proved the potential of CE as an easy choice to perform disc quality control under appropriate conditions.     

Synthesis of novel N-diazeniumdiolates based on hyperbranched polyethers

Novel N-diazeniumdiolate based on hyperbranched polyethers(HP-g-DACA/N(2)O(2)) were prepared through a two-step synthesized route. The alkyltrimethoxysilane containing secondary amine groups (DACA) was used to modify the hydroxyl end groups of hyperbranched polyethers (HP) to obtain the precursor hyperbranched diamine (HP-g-DACA). Then HP-g-DACA was reacted with NO at 80psi pressure to be converted into N-diazeniumdiolates. The structures were confirmed using (13)C NMR and IR spectra. UV-vis spectroscopy measurement indicated that the aqueous solution of obtained HP-g-DACA/N(2)O(2) had a characteristic absorption at 246nm. The final HP-g-DACA/N(2)O(2) product showed NO releasing within the prolonged periods of time, and the apparent half-life t(1/2) was more than 11min in phosphate buffer at 37 degrees C. The total amount of NO released from HP-g-DACA/N(2)O(2) could achieve to 0.43micromol/mg and was proportional to the modified degree of HP by DACA. In addition, the NO loading efficiency can be modulated by the modification degree of hyperbranched macromolecular end groups.     

Receptor binding characteristics of the endocrine disruptor bisphenol A for the human nuclear estrogen-related receptor gamma. Chief and corroborative hydrogen bonds of the bisphenol A phenol-hydroxyl group with Arg316 and Glu275 residues

Bisphenol A, 2,2-bis(4-hydroxyphenyl)propane, is an estrogenic endocrine disruptor that influences various physiological functions at very low doses, even though bisphenol A itself is ineffectual as a ligand for the estrogen receptor. We recently demonstrated that bisphenol A binds strongly to human estrogen-related receptor gamma, one of 48 human nuclear receptors. Bisphenol A functions as an inverse antagonist of estrogen-related receptor gamma to sustain the high basal constitutive activity of the latter and to reverse the deactivating inverse agonist activity of 4-hydroxytamoxifen. However, the intrinsic binding mode of bisphenol A remains to be clarified. In the present study, we report the binding potentials between the phenol-hydroxyl group of bisphenol A and estrogen-related receptor gamma residues Glu275 and Arg316 in the ligand-binding domain. By inducing mutations in other amino acids, we evaluated the change in receptor binding capability of bisphenol A. Wild-type estrogen-related receptor gamma-ligand-binding domain showed a strong binding ability (K(D) = 5.70 nm) for tritium-labeled [(3)H]bisphenol A. Simultaneous mutation to Ala at positions 275 and 316 resulted in an absolute inability to capture bisphenol A. However, individual substitutions revealed different degrees in activity reduction, indicating the chief importance of phenol-hydroxyl<-->Arg316 hydrogen bonding and the corroborative role of phenol-hydroxyl<-->Glu275 hydrogen bonding. The data obtained with other characteristic mutations suggested that these hydrogen bonds are conducive to the recruitment of phenol compounds by estrogen-related receptor gamma. These results clearly indicate that estrogen-related receptor gamma forms an appropriate structure presumably to adopt an unidentified endogenous ligand.     

5-[(2-Methyl-1,3-thiazol-4-yl)ethynyl]-2,3'-bipyridine: a highly potent, orally active metabotropic glutamate subtype 5 (mGlu5) receptor antagonist with anxiolytic activity

Structure-activity relationship studies leading to the discovery of a new, orally active mGlu5 receptor antagonist are described. The title compound, 5-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-2,3'-bipyridine, is highly potent in vitro, has good in vivo receptor occupancy, and is efficacious in the rat fear-potentiated startle model of anxiety following oral dosing.     

Triterpenoid Saponin W3 from Anemone flaccida Suppresses Osteoclast Differentiation through Inhibiting Activation of MAPKs and NF-κB Pathways

Excessive bone resorption by osteoclasts within inflamed joints is the most specific hallmark of rheumatoid arthritis. A. flaccida has long been used for the treatment of arthritis in folk medicine of China; however, the active ingredients responsible for the anti-arthritis effects of A. flaccida are still elusive. In this study, W3, a saponin isolated from the extract of A. flaccida was identified as the major active ingredient by using an osteoclast formation model induced by receptor activator of nuclear factor kappa-B ligand (RANKL). W3 dose-dependently suppressed the actin ring formation and lacunar resorption. Mechanistic investigation revealed that W3 inhibited the RANKL-induced TRAF6 expression, decreased phosphorylation of mitogen-activated protein kinases (MAPKs) and IκB-α, and suppressed NF-κB p65 DNA binding activity. Furthermore, W3 almost abrogated the expression of c-Fos and nuclear factor of activated T cells (NFATc1). Therefore, our results suggest that W3 is a potential agent for treating lytic bone diseases although further evaluation in vivo and in clinical trials is needed.