A Novel Strategy to Construct Yeast Saccharomyces cerevisiae Strains for Very High Gravity Fermentation

Very high gravity (VHG) fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition) and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2) with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes

Biocleavable Polycationic Micelles as Highly Efficient Gene Delivery Vectors

An amphiphilic disulfide-containing polyamidoamine was synthesized by Michael-type polyaddition reaction of piperazine to equimolar N, N′-bis(acryloyl)cystamine with 90% yield. The polycationic micelles (198 nm, 32.5 mV), prepared from the amphiphilic polyamidoamine by dialysis method, can condense foreign plasmid DNA to form nanosized polycationic micelles/DNA polyelectrolyte complexes with positive charges, which transfected 293T cells with high efficiency. Under optimized conditions, the transfection efficiencies of polycationic micelles/DNA complexes are comparable to, or even higher than that of commercially available branched PEI (Mw 25 kDa)

Prophage exotoxins enhance colonization fitness in epidemic scarlet fever-causing Streptococcus pyogenes

Abstract: The re-emergence of scarlet fever poses a new global public health threat. The capacity of North-East Asian serotype M12 (emm12) Streptococcus pyogenes (group A Streptococcus, GAS) to cause scarlet fever has been linked epidemiologically to the presence of novel prophages, including prophage ΦHKU.vir encoding the secreted superantigens SSA and SpeC and the DNase Spd1. Here, we report the molecular characterization of ΦHKU.vir-encoded exotoxins. We demonstrate that streptolysin O (SLO)-induced glutathione efflux from host cellular stores is a previously unappreciated GAS virulence mechanism that promotes SSA release and activity, representing the first description of a thiol-activated bacterial superantigen. Spd1 is required for resistance to neutrophil killing. Investigating single, double and triple isogenic knockout mutants of the ΦHKU.vir-encoded exotoxins, we find that SpeC and Spd1 act synergistically to facilitate nasopharyngeal colonization in a mouse model. These results offer insight into the pathogenesis of scarlet fever-causing GAS mediated by prophage ΦHKU.vir exotoxins

Epigenetic modulators as therapeutic targets in prostate cancer

Prostate cancer is one of the most common non-cutaneous malignancies among men worldwide. Epigenetic aberrations, including changes in DNA methylation patterns and/or histone modifications, are key drivers of prostate carcinogenesis. These epigenetic defects might be due to deregulated function and/or expression of the epigenetic machinery, affecting the expression of several important genes. Remarkably, epigenetic modifications are reversible and numerous compounds that target the epigenetic enzymes and regulatory proteins were reported to be effective in cancer growth control. In fact, some of these drugs are already being tested in clinical trials. This review discusses the most important epigenetic alterations in prostate cancer, highlighting the role of epigenetic modulating compounds in pre-clinical and clinical trials as potential therapeutic agents for prostate cancer management.info:eu-repo/semantics/publishedVersio

Efficient gene delivery system mediated by cis-aconitate-modified chitosan-g-stearic acid micelles

Jing-Jing Yao, Yong-Zhong Du, Hong Yuan, Jian You, Fu-Qiang HuCollege of Pharmaceutical Sciences, Zhejiang University, Hangzhou, People’s Republic of ChinaAbstract: Cis-aconitate-modified chitosan-g-stearic acid (CA-CSO-SA) micelles were ­synthesized in this study to improve the gene transfection efficiency of chitosan-g-stearic acid (CSO-SA). The CA-CSO-SA micelles had a similar size, critical micelle concentration, and ­morphology, but their zeta potential and cytotoxicity were reduced compared with CSO-SA micelles. After modification with cis-aconitate, the CA-CSO-SA micelles could also compact plasmid DNA (pDNA) to form nanocomplexes. However, the DNA binding ability of CA-CSO-SA was slightly reduced compared with that of CSO-SA. The transfection efficiency mediated by CA-CSO-SA/pDNA against HEK-293 cells reached up to 37%, and was much higher than that of CSO-SA/pDNA (16%). Although the cis-aconitate modification reduced cellular uptake kinetics in the initial stages, the total amount of cellular uptake tended to be the same after 24 hours of incubation. An endocytosis inhibition experiment showed that the internalization mechanism of CA-CSO-SA/pDNA in HEK-293 cells was mainly via clathrin-mediated endocytosis, as well as caveolae-mediated endocytosis and macropinocytosis. Observation of intracellular trafficking indicated that the CSO-SA/pDNA complexes were trapped in endolysosomes, but CA-CSO-SA/pDNA was more widely distributed in the cytosol. This study suggests that modification with cis-aconitate improves the transfection efficiency of CSO-SA/pDNA.Keywords: chitosan-g-stearic acid, cis-aconitate, micelles, transfection efficiency, intracellular traffickin

Specific targeting of A54 homing peptide-functionalized dextran-g-poly(lactic-co-glycolic acid) micelles to tumor cells

Jun-Qing Situ,1 Yi-Qing Ye,2 Xiu-Liang Zhu,3 Ri-Sheng Yu,3 Jian You,1 Hong Yuan,1 Fu-Qiang Hu,1 Yong-Zhong Du11College of Pharmaceutical Sciences, 2Women’s Hospital, 3Department of Radiology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of ChinaAbstract: The delivery of chemotherapeutics into tumor cells is a fundamental knot for tumor-target therapy to improve the curative effect and avoid side effects. Here, A54 peptide-functionalized poly(lactic-co-glycolic acid)-grafted dextran (A54-Dex-PLGA) was synthesized. The synthesized A54-Dex-PLGA self-assembled to form micelles with a low critical micelle concentration of 16.79 µg·mL-1 and diameter of about 50 nm. With doxorubicin (DOX) base as a model antitumor drug, the drug-encapsulation efficiency of DOX-loaded A54-Dex-PLGA micelles (A54-Dex-PLGA/DOX) reached up to 75%. In vitro DOX release from the A54-Dex-PLGA/DOX was prolonged to 72 hours. The A54-Dex-PLGA micelles presented excellent internalization ability into hepatoma cells (BEL-7402 cell line and HepG2 cell line) in vitro, and the cellular uptake of the micelles by the BEL-7402 cell line was specific, which was demonstrated by the blocking experiment. In vitro antitumor activity studies confirmed that A54-Dex-PLGA/DOX micelles suppressed tumor-cell (BEL-7402 cell) growth more effectively than Dex-PLGA micelles. Furthermore, in vivo biodistribution testing demonstrated that the A54-Dex-PLGA micelles had a higher distribution ability to BEL-7402 tumors than that to HepG2 tumors.Keywords: homing peptide, polymeric micelles, doxorubicin, tumor-cell targetin

Enhanced Proton Conduction in Polymer Electrolyte Membranes as Synthesized by Polymerization of Protic Ionic Liquid-Based Microemulsions

Proton-conducting membranes were prepared by polymerization of microemulsions consisting of surfactant-stabilized protic ionic liquid (PIL) nanodomains dispersed in a polymerizable oil, a mixture of styrene and acrylonitrile. The obtained PIL-based polymer composite membranes are transparent and flexible even though the resulting vinyl polymers are immiscible with PIL cores. This type of composite membranes have quite a good thermal stability, chemical stability, tunability, and good mechanical properties. Under nonhumidifying conditions, PIL-based membranes show a conductivity up to the order of 1 x 10(-1) S/cm at 160 degrees C, due to the well-connected PIL nanochannels preserved in the membrane. This type of polymer conducting membranes have potential application in high-temperature polymer electrolyte membrane fuel cells