[miRNA-191-5p represses cell growth by targeting CDK6 in gastric cancer].

Objective: To investigate the effects of miR-191-5p on cell migration, clone formation and proliferation of gastric cancer (GC) cells. Methods: The level of miR-191-5p expression was detected by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in 60 paired GC tissues and their adjacent normal tissues. miR-191-5p overexpression was achieved by transfection of construct pcDNA-miR-191-5p into GC cells. The migration, clone formation and proliferation of GC cells were detected by the scratch wound assay, clone formation assay and cell counting kit-8 (CCK-8), respectively. Low expression of miR-191-5p was achieved with miRNA-191-5p inhibitor. The binding sites of cyclin-dependent kinase 6 (CDK6) and miR-191-5p were analyzed using TargetScan software, and the interaction of CDK6 and miR-191-5p was verified using dual-fluorescence reporter gene expression. Western blot (WB) was used to detect the effect of miR-191-5p on the expression of p21 and CDK6 proteins. Results: miR-191-5p decreased in 53 cases (88%) of GC tissues compared to their controls. Furthermore, overexpression of miR-191-5p effectively inhibited the migration, clone formation and proliferation of GC cells (P<0.05). Dual-fluorescence reporter confirmed that miR-191-5p bound to 3'UTR of CDK6. WB showed that pcDNA-miR-191-5p inhibited the CDK6 expression but promoted the p21. Conclusion: Down-regulation of miR-191-5p has a correlation with the progression of GC. Overexpression of miR-191-5p can decrease the expression of CDK6 and inhibit the growth of GC cells.

Characterization of reconstituted Fo from wild-type Escherichia coli and identification of two other fluxes co-purifying with Fo.

We purified the ATPase Fo sector from a nonoverexpressing strain of Escherichia coli, reconstituted it into lipid vesicles made of either asolectin or two different mixtures of purified lipids, and measured proton flux through the reconstituted proton channel. We measured single-channel conductances and found that Fo activity depends on both lipids and reconstitution methods. In asolectin vesicles, Fo has a single-channel conductance of about 0.2 fS. Additionally, the relatively impure Fo prepared from cells carrying single-copy ATPase genes allowed us to observe two other fluxes, a nonselective cation leak (C(L)) and a slow H+ flux (Hs). Unlike the Fo flux, these fluxes could not be blocked by the Fo inhibitor DCCD. The C, reduces the total apparent trapped volume inside vesicles and therefore must equilibrate both H+ and K+ in the vesicles that contain it. When reconstituted into bilayers, these Fo preparations displayed a 120 pS cation channel with characteristics consistent with C(L) flux. The Hs conducts only H+ but at a slower rate than the Fo. We were therefore able to: 1) quantitate the single-channel conductance of the Fo, 2) demonstrate that our Fo purification method co-purified other membrane proteins that have ion-conduction properties, and 3) show that certain lipids are necessary for functional reconstitution of Fo.

Repeated solid-phase fermentation and extraction for enzyme production.

Solid-phase fermentation has been found to have a much higher productivity than the popular liquid submerged fermentation in producing cellulase enzymes. The highest reported productivity in the literature for cellulases by Trichoderma cultures in submerged fermentation is 158 filter paper units (FPU)/(h.L) of fermenting liquid. From preliminary experiments of solid-phase fermentation in 1000-mL flasks, a productivity of 234 FPU of cellulases/(h.L) of solid-bed volume was obtained. When two novel techniques--pressure pulsation and repeated extraction--were applied, a productivity of 806 FPU/(h.L) was achieved. The same techniques also greatly enhanced the productivity of other enzymes by fungal cultures in solid-phase fermentation.

Coproduction of ethanol and glycerol.

Ethanol and glycerol are both metabolic products of yeasts. There are occasions when coproduction of both is considered desirable in industrial operations. In this article, we describe the potential of integrating the two processes. A LORRE Y8 yeast culture isolated from molasses is capable of efficient glycerol production from glucose, and a yeast Culture 1400 is an excellent producer of ethanol. By controlling the process conditions, the ratio of ethanol and glycerol production can be varied.

Ethanol production from renewable resources.

Vast amounts of renewable biomass are available for conversion to liquid fuel, ethanol. In order to convert biomass to ethanol, the efficient utilization of both cellulose-derived and hemicellulose-derived carbohydrates is essential. Six-carbon sugars are readily utilized for this purpose. Pentoses, on the other hand, are more difficult to convert. Several metabolic factors limit the efficient utilization of pentoses (xylose and arabinose). Recent developments in the improvement of microbial cultures provide the versatility of conversion of both hexoses and pentoses to ethanol more efficiently. In addition, novel bioprocess technologies offer a promising prospective for the efficient conversion of biomass and recovery of ethanol.

Production of multifunctional organic acids from renewable resources.

Recently, the microbial production of multifunctional organic acid has received interest due to their increased use in the food industry and their potential as raw materials for the manufacture of biodegradable polymers. Certain species of microorganisms produce significant quantities of organic acids in high yields under specific cultivation conditions from biomass-derived carbohydrates. The accumulation of some acids, such as fumaric, malic and succinic acid, are believed to involve CO2-fixation which gives high yields of products. The application of special fermentation techniques and the methods for downstream processing of products are described. Techniques such as simultaneous fermentation and product recovery and downstream processing are likely to occupy an important role in the reduction of production costs. Finally, some aspects of process design and current industrial production processes are discussed.

The effect of cell density on the production of xylitol from D-xylose by yeast.

The rate of xylitol production from D-xylose increased with increasing yeast cell density. The optimal temperature for xylitol production is 36 degrees C, and the optimal pH range is from 4.0 to 6.0. At high initial yeast cell concentration of 26 mg/mL, 210 g/L of xylitol was produced from 260 g/L of D-xylose after 96 h of incubation with an indicated yield of 81% of the theoretical value.