Improved Production of Recombinant Myrosinase in Pichia pastoris

The effect of the deletion of a 57 bp native signal sequence, which transports the nascent protein through the endoplasmic reticulum membrane in plants, on improved AtTGG1 plant myrosinase production in Pichia pastoris was studied. Myrosinase was extracellularly produced in a 3-liter laboratory fermenter using α-mating factor as the secretion signal. After the deletion of the native signal sequence, both the specific productivity (164.8 U/L/h) and volumetric activity (27 U/mL) increased more than 40-fold compared to the expression of myrosinase containing its native signal sequence in combination with α-mating factor. The deletion of the native signal sequence resulted in slight changes in myrosinase properties: the optimum pH shifted from 6.5 to 7.0 and the maximal activating concentration of ascorbic acid increased from 1 mM to 1.5 mM. Kinetic parameters toward sinigrin were determined: 0.249 mM (K_m) and 435.7 U/mg (V_max). These results could be applied to the expression of other plant enzymes.     

The carbonization of granular polyaniline to produce nitrogen-containing carbon

Polyaniline (PANI) was prepared by the oxidative polymerization of aniline. The deprotonated product, a PANI base, was carbonized in an inert atmosphere at temperatures up to 800 °C for various times. The mass decreased to 40–50 wt.% at temperatures above 600 °C. The progress of molecular structure during carbonization was followed by infrared and Raman spectroscopies. The carbonization at 650 °C for 1 h is suggested for the optimum conversion of PANI to carbon. The product retained the original globular structure of PANI. The conductivity of the carbonized material was low for carbonizations below 600 °C, <10^?10 S cm^?1, and increased to 10^?4 S cm^?1 after treatment at 800 °C. The content of nitrogen, ～10 wt.%, was not affected appreciably by the carbonization.     

Conducting composites prepared by the reduction of silver ions with poly(p‐phenylenediamine)

Poly(p‐phenylenediamine) (PPDA) and also its ladder‐like analogue were prepared by oxidation of p‐phenylenediamine with ammonium peroxydisulfate in an aqueous solution of 0.4 mol L^?1 hydrochloric acid and converted to PPDA bases. These were used as reductants of silver nitrate to silver nanoparticles in 1 mol L^?1 methanesulfonic acid or in water at various mole ratios of silver nitrate to p‐phenylenediamine units from 0 to 1.8. The original conductivity of the PPDA, 10^?12 S cm^?1, increased to the order of 100 S cm^?1 for the PPDA–silver composites containing 27–40 wt% (i.e. 4.5–6.6 vol%) silver. Fourier transform infrared spectra indicated a practically unchanged molecular structure of PPDA in the composites. In contrast, Raman spectroscopy showed the existence of regions with unchanged molecular structure of PPDA as well as the presence of regions containing silver particles and oxidized PPDA moieties. © 2014 Society of Chemical Industry     

Atorvastatin Modulates Bile Acid Homeostasis in Mice with Diet-Induced Nonalcoholic Steatohepatitis

Bile acids (BA) play a significant role in the pathophysiology of nonalcoholic steatohepatitis (NASH). The present study evaluates the modulation of bile acid metabolomics by atorvastatin, a cholesterol-lowering agent commonly used to treat cardiovascular complications accompanying NASH. NASH was induced in mice by 24 weeks of consuming a high–saturated fat, high-fructose, and high-cholesterol diet (F), with atorvastatin administered orally (20 mg/kg/day) during the last three weeks. Biochemical and histological analyses confirmed the effectiveness of the F diet in inducing NASH. Untreated NASH animals had significantly reduced biliary secretion of BA and increased fecal excretion of BA via decreased apical sodium-dependent bile salt transporter (Asbt)-mediated reabsorption. Atorvastatin decreased liver steatosis and inflammation in NASH animals consistently with a reduction in crucial lipogenic enzyme stearoyl–coenzyme A (CoA) desaturase-1 and nuclear factor kappa light chain enhancer of activated B-cell pro-inflammatory signaling, respectively. In this group, atorvastatin also uniformly enhanced plasma concentration, biliary secretion and fecal excretion of the secondary BA, deoxycholic acid (DCA). However, in the chow diet–fed animals, atorvastatin decreased plasma concentrations of BA, and reduced BA biliary secretions. These changes stemmed primarily from the increased fecal excretion of BA resulting from the reduced Asbt-mediated BA reabsorption in the ileum and suppression of synthesis in the liver. In conclusion, our results reveal that atorvastatin significantly modulates BA metabolomics by altering their intestinal processing and liver synthesis in control and NASH mice.     

DNA delivery systems based on copolymers of poly (2-methyl-2-oxazoline) and polyethyleneimine: Effect of polyoxazoline moieties on the endo-lysosomal escape

Poly(2-methyl-2-oxazoline)-polyethylenimine (PMeOx-co-PEI) copolymers differing by degree of polymerization (DP = 50 and 200) and PEI content (from 37 to 99 mol%) were synthesized by living cationic ring-opening polymerization of 2-methyl-2-oxazoline, followed by partial hydrolysis. Upon mixing with DNA in a wide range of N/P ratios, they formed well-defined polyplex particles of small size (typically below 100 nm) and narrow size distribution. The polyplexes demonstrated good colloidal stability and very low in vitro cytotoxicity. The copolymers exhibited buffering capacity of over 50% relative to that of the reference PEI implying effective endo-lysosomal escape of the polyplexes. Increased cellular internalization of both PCR fragments and plasmid DNA, attributable to the strongly positive ζ potential and small size of the polyplexes, was observed. In spite of these favorable prerequisites, the transfection efficiency was low (below 20% relative to the control PEI) and was attributed to retarded swelling of the polyplex particles, endo-lysosomal rupture, and DNA release.     

Morphology of nymphs of common stored-product psocids (Psocoptera, Liposcelididae).

The last developmental instar of female nymphs of the 6 synanthropic Liposcelis species most frequently occurring in stored products worldwide are described. The morphological study deals with overall appearance, chaetotaxy and size measurements of nymphs. Morphological characters include the number and length of setae and their density on the pro- and mesothoracic sternites, vertex of head, lateral lobe of pronotum, abdominal tergites, and the number of ommatidia in the compound eyes. Morphological details are illustrated by SEM micrographs. A key for distinguishing the described instars of the six Liposcelis species is provided.