Project description:Inflammatory Bowel Disease (IBD) is a term describing a collection of conditions characterised by chronic inflammatory disorder of the gastrointestinal tract involving an inappropriate immune response to commensal microorganisms in a genetically susceptible host. Four kiwifruit extracts, aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (A. deliciosa), have previously demonstrated anti-inflammatory activity using in vitro models of IBD. This study examined whether these kiwifruit extracts had immune modulating effects in vivo against inflammatory processes known to be increased in patients with IBD. KFEs were used as a dietary intervention in Il10-/- mice (an in vivo model of IBD) and the C57BL/6J background strain in a 3 x 2 factorial design. While all Il10-/- mice developed significant colonic inflammation compared to the C57BL/6J mice, this was not affected by the inclusion of KFE in the diet. Whole genome gene and protein expression level profiling indicated that KFEs influenced immune signalling pathways and metabolic processes within the colonic tissue; however, the effects were subtle. In particular, adaptive immune pathways were reduced by three out of four kiwifruit extracts, with greater reduction seen in the C57BL/6J mice. This suggests that while immune-modulating activity was present in vivo, KFEs did not reduce inflammatory processes relevant to IBD. Experimental design. Two experiments were conducted, one using extracts from gold kiwifruit and one using extracts from green kiwifruit. Within each experiment, both Il10-/- and C57 mice were randomly divided into three diet treatment groups, to ive the following 12 treatments: 1) Gold Kiwifruit Experiment, C57BL/6J mice, Control diet (AIN-76A), 2) Gold Kiwifruit Experiment, C57BL/6J mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 3) Gold Kiwifruit Experiment, C57BL/6J mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) 4) Gold Kiwifruit Experiment, Il10-/- mice, Control diet (AIN-76A), 5) Gold Kiwifruit Experiment, Il10-/- mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 6) Gold Kiwifruit Experiment, Il10-/- mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) 7) Green Kiwifruit Experiment, C57BL/6J mice, Control diet (AIN-76A), 8) Green Kiwifruit Experiment, C57BL/6J mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 9) Green Kiwifruit Experiment, C57BL/6J mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) 10) Green Kiwifruit Experiment, Il10-/- mice, Control diet (AIN-76A), 11) Green Kiwifruit Experiment, Il10-/- mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 12) Green Kiwifruit Experiment, Il10-/- mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) Six biological replicates were analysed from each treatment group, except for groups 3 and 7 where five replicates were analysed due to array quality issues with the sixth replicate. Each replicate contained mRNA from one mouse. A reference design was used, where each slide was hybridised with mRNA from one sample (green channel) and mRNA from a common reference pool (red channel).

Project description:Background: Anaerobic Saccharomyces cerevisiae cultures require glycerol formation to re-oxidize NADH formed in biosynthetic processes. Introduction of the Calvin-cycle enzymes phosphoribulokinase (PRK) and ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCO) has been shown to couple re-oxidation of biosynthetic NADH to ethanol production and improve ethanol yield on sugar in fast-growing batch cultures. Since growth rates in industrial ethanol-production processes are not constant, performance of engineered strains was studied in slow-growing cultures. Results: In slow-growing anaerobic chemostat cultures (D = 0.05 h-1), an engineered PRK-RuBisCO strain produced 80-fold more acetaldehyde and 30-fold more acetate than a reference strain. This observation suggested an imbalance between in vivo activities of PRK-RuBisCO and formation of NADH in biosynthesis. Lowering the copy number of the RuBisCO-encoding cbbm expression cassette from 15 to 2 reduced acetaldehyde and acetate yields by 67% and 29%, respectively. Additional C-terminal fusion of a 19 amino-acid tag to PRK reduced its protein level by 13-fold while acetaldehyde and acetate production decreased by 94% and 61%, respectively, relative to the 15x cbbm strain. These modifications did not affect glycerol production at 0.05 h-1 but caused a 4.6 fold higher glycerol production per amount of biomass in fast-growing (0.29 h-1) anaerobic batch cultures than observed for the 15x cbbm strain. In another strategy, the promoter of ANB1, whose transcript level positively correlated with growth rate, was used to control PRK synthesis in a 2x cbbm strain. At 0.05 h-1, this strategy reduced acetaldehyde and acetate production by 79% and 40%, respectively, relative to the 15x cbbm strain, without affecting glycerol yield. The maximum growth rate of the resulting strain equalled that of the reference strain, while its glycerol yield was 72% lower. Conclusions: Acetaldehyde and acetate formation by slow-growing cultures of engineered S. cerevisiae strains carrying a PRK-RuBisCO bypass of yeast glycolysis was attributed to an in vivo overcapacity of PRK and RuBisCO. Reducing the capacity of PRK and/or RuBisCO was shown to mitigate this undesirable byproduct formation. Use of a growth-rate-dependent promoter for PRK expression highlighted the potential of modulating gene expression in engineered strains to respond to growth-rate dynamics in industrial batch processes.

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Saccharomyces cerevisiae

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