Project description:The catalytic core of the RNA polymerase of most eubacteria is composed of two α subunits and β, β’ and ω subunits. In Escherichia coli, the ω subunit (encoded by the rpoZ gene) has been suggested to assist β’ during RNA polymerase core assembly. The function of the ω subunit is particularly interesting in cyanobacteria because the cyanobacterial β’ is split to N-terminal γ and C-terminal β’ subunits. The ∆rpoZ strain of the cyanobacterium Synechocystis sp. PCC 6803 grew well in standard conditions although the mutant cells showed low light-saturated photosynthetic activity, low Rubisco content and accumulated high quantities of protective carotenoids and α-tocopherol. The ∆rpoZ strain contained 15% less of the primary σ factor, SigA, than the control strain, and recruitment of SigA to the RNA polymerase core was inefficient in ∆rpoZ. Thus, a cyanobacterial RNA polymerase holoenzyme lacking the ω subunit contains less frequently the primary σ factor. A DNA microarray analysis revealed that this leads to specific down-regulation of highly expressed genes, like genes encoding subunits for Rubisco, ATP synthase, NADH-dehydrogenase and carbon concentrating mechanisms. On the contrary, many genes showing only low or moderate expression in the control strain were up-regulated in ∆rpoZ. A conserved -10 region was detected in promoters showing up or down-regulation in ∆rpoZ, but -35 regions of down-regulated genes completely differed from -35 regions of up-regulated genes.
Project description:The optimal ratio of omega-6 to omega-3 polyunsaturated fatty acids (PUFAs) is important for keeping homeostasis of biological processes and metabolism, yet the underlying biological mechanism is poorly understood. The objective of this study was to identify changes in the pig liver transcriptome induced by a diet enriched with omega-6 and omega-3 fatty acids, and to characterize the biological mechanisms related to PUFA metabolism. Polish Landrace pigs (n =12) were fed diet enriched with linoleic acid (LA, omega-6) and alpha-linolenic acid (ALA, omega-3 family) or standard diet as a control. The fatty acids profiling was assayed in order to verify how feeding influenced the fatty acids content in liver, and subsequently next-generation sequencing (NGS) was used to identify differentially expressed genes (DEG) between transcriptomes between dietary groups. The biological mechanisms and pathway interaction networks were identified by analysis in DAVID and Cytoscape tools. Fatty acids profile analysis indicated a higher contribution of PUFAs in liver for LA and ALA-enriched diet group, particularly for the omega-3 fatty acids family, but not omega-6. Next-generation sequencing identified 3,565 DEG, 1,484 of which were induced and 2,081 were suppressed by PUFA supplemenation. Low ratio of omega-6/-3 fatty acids resulted in modulation of fatty acids metabolism pathways and over-representation of genes involved in membrane composition, signal transduction and immune response pathways. In conclusion, a diet enriched with omega-6 and omega-3 fatty acids altered the transcriptomic profile of the pig liver and affected a set of genes involved in metabolic pathways important to animal health status. Hepatic mRNA profiles of Polish Landrace pig breed fed two different diets, were generated by deep sequencing, using Illumina MiSeq. Experimental diet was enriched with polyunsaturated fatty acids (omega-6 and omega-3), while standard diet remain as a cotrol. 2 pooled samples each containing RNA extracts from 6 individuals livers were analyzed.
Project description:The optimal ratio of omega-6 to omega-3 polyunsaturated fatty acids (PUFAs) is important for keeping homeostasis of biological processes and metabolism, yet the underlying biological mechanism is poorly understood. The objective of this study was to identify changes in the pig liver transcriptome induced by a diet enriched with omega-6 and omega-3 fatty acids, and to characterize the biological mechanisms related to PUFA metabolism. Polish Landrace pigs (n =12) were fed diet enriched with linoleic acid (LA, omega-6) and alpha-linolenic acid (ALA, omega-3 family) or standard diet as a control. The fatty acids profiling was assayed in order to verify how feeding influenced the fatty acids content in liver, and subsequently next-generation sequencing (NGS) was used to identify differentially expressed genes (DEG) between transcriptomes between dietary groups. The biological mechanisms and pathway interaction networks were identified by analysis in DAVID and Cytoscape tools. Fatty acids profile analysis indicated a higher contribution of PUFAs in liver for LA and ALA-enriched diet group, particularly for the omega-3 fatty acids family, but not omega-6. Next-generation sequencing identified 3,565 DEG, 1,484 of which were induced and 2,081 were suppressed by PUFA supplemenation. Low ratio of omega-6/-3 fatty acids resulted in modulation of fatty acids metabolism pathways and over-representation of genes involved in membrane composition, signal transduction and immune response pathways. In conclusion, a diet enriched with omega-6 and omega-3 fatty acids altered the transcriptomic profile of the pig liver and affected a set of genes involved in metabolic pathways important to animal health status.
Project description:This study explored how the omega-6 to omega-3 fatty acid ratio in low-fish oil aquafeeds influences Atlantic salmon's antiviral and antibacterial immune responses. Atlantic salmon were fed aquafeeds rich in soy oil (high in omega-6) or linseed oil (high in omega-3) for 12 weeks and then challenged with bacterial (formalin-killed Aeromonas salmonicida; Asal) or viral-like (polyriboinosinic polyribocytidylic acid; pIC) antigens. The mRNA levels of 46 immune-relevant genes in the head kidneys of the salmon were analyzed via quantitative real-time polymerase chain reaction (RT-qPCR).
Project description:There is a gap in our understanding of the protective effect of the essential ω-3 long-chain polyunsaturated fatty acid (LCPUFA) docosahexaenoic acid (DHA) on proliferative retinopathies. In retinopathy of prematurity (ROP), DHA supplementation alone may not reduce the risk for severe disease. We found that in mouse neonates with hyperglycemia-associated retinopathy (HAR) with impaired retinal vessel growth modeling Phase I ROP versus controls, there was a strong metabolic shift in almost all types of retinal neuronal cells identified with single-cell transcriptomics. Loss of adiponectin (Apn-/-), modeling low APN seen in premature infants, caused a ω-3 and ω-6 LCPUFA imbalance in HAR mouse retinas. Dietary intake of ω-3 vs ω-6 LCPUFA promoted retinal vessel growth, associated with increased APN levels and increased retinal APN receptor AdipoR1 gene expression. Interestingly, we found that ω-6 vs. ω-3 LCPUFA was essential in maintaining retinal metabolism and neuronal development. Our findings suggest that both ω-3 and ω-6 LCPUFA are essential in protecting against retinal neurovascular dysfunction in Phase I ROP model. Maintaining adequate ω-6 LCPUFA levels is required while supplementing ω-3 LCPUFA to prevent retinopathy.
Project description:Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFA) have important signalling roles in the hypothalamus, a region of the brain that regulates whole-body energy homeostasis. While evidence suggests that high PUFA intake can impact hypothalamic activity, the underlying molecular mechanisms regulated by essential dietary PUFA (i.e., linoleic acid and alpha-linolenic acid) remain poorly described in this brain region. To differentiate the roles of essential dietary PUFA on hypothalamic function, we fed male rats high-fat diets (35% kcal/d) containing either safflower (linoleic acid) or flaxseed (alpha-linolenic acid) oil for 2 months. Control rats were fed a low-fat (16% kcal/d) diet containing soybean oil. Hypothalmic gene expression was investigated by microrray.
Project description:Staphylococcus aureus is a major human pathogen that causes infection in a wide variety of sites within the human body. Its ability to adapt to the human host, and to produce a successful infection, requires precise orchestration of gene expression. While DNA-dependent RNA polymerase (RNAP) is generally well characterized, the role of several small accessory subunits within the complex has yet to be fully explored. This is particularly true for the omega (ω or RpoZ) subunit, which has been extensively studied in Gram-negative bacteria, but largely neglected in Gram-positive counterparts. In Escherichia coli, it has been shown that ppGpp binding, and thus control of the stringent response, is facilitated by ω. Interestingly, key residues that facilitate ppGpp binding by ω are not conserved in S. aureus, and consequently, survival under starvation conditions is unaffected by rpoZ deletion. Further to this, ω-lacking strains of S. aureus display structural changes in the RNAP complex, which result from increased degradation and misfolding of the β’ subunit, alterations in δ and σ-factor abundance, and a general dissociation of RNAP in the absence of ω. Through RNAseq analysis we detected a variety of transcriptional changes in rpoZ-deficient strains, presumably as a response to the negative effects of ω-depletion on the transcription machinery. These transcriptional changes translated to an impaired ability of ΔrpoZ mutant strains to resist stress, and to fully form a biofilm. Collectively, our data underlines, for the first time, the importance of ω for RNAP stability, function and cellular physiology in S. aureus.
Project description:Soybean oil consumption is increasing worldwide and parallels the obesity epidemic in the U.S. Rich in unsaturated fats, especially linoleic acid, soybean oil is assumed to be healthy, and yet it induces obesity, diabetes, insulin resistance and fatty liver in mice. The genetically modified soybean oil Plenish came on the U.S. market in 2014: it is low in linoleic acid and similar to olive oil in fatty acid composition. Here we show that Plenish induces less obesity than conventional soybean oil: metabolomics, proteomics and a transgenic mouse model implicate oxylipin metabolites of omega-6 and omega-3 fatty acids (linoleic and α-linolenic acid, respectively), which are generated by target genes of nuclear receptor HNF4α. While Plenish induces less insulin resistance than conventional soybean oil, it results in hepatomegaly and liver dysfunction as does olive oil. Altering the fatty acid profile of soybeans could help reduce obesity but may also cause liver complications.
Project description:The rpoZ gene encodes the small ω subunit of RNA polymerase (RNAP). A ∆rpoZ strain of the cyanobacterium Synechocystis sp. PCC 6803 grew well in standard conditions (constant illumination at 40 µmol photons m-2s-1; 32 °C; ambient CO2) but was heat sensitive and died at 40 °C. In the control strain , 71 genes were at least two-fold up-regulated and 91 genes down-regulated after a 24-h treatment at 40 °C, while in ∆rpoZ 394 genes responded to heat. Only 62 of these heat-responsive genes were similarly regulated in both strains, and 80 % of heat-responsive genes were unique for ΔrpoZ. The RNAP core and the primary σ factor SigA were down-regulated in control strain at 40 °C, but not in ΔrpoZ. In accordance with reduced RNAP content, the total RNA content of mild-heat-stress-treated cells was lower in control strain than in ΔrpoZ. Light-saturated photosynthetic activity decreased more in ΔrpoZ than in control strain upon mild heat stress. The amounts of Photosystem II and Rubisco decreased at 40 °C in both strains while PSI and the phycobilisome antenna protein allophycocyanin remained at the same level as in standard conditions. The phycobilisome rod proteins, phycocyanins, diminished during the heat treatment in ΔrpoZ but not in control strain, and the nblA1 and nblA2 genes (encode NblA proteins required for phycobilisome degradation) were up-regulated only in ΔrpoZ. Our results show that the ω subunit of RNAP is essential in heat stress because it is required for heat acclimation of diverse cellular processes.