Microarray analysis of high-glucose diet-induced changes in mRNA expression in jejunums of C57BL/6J mice reveals impairment in digestion, absorption

Dietary carbohydrate influences the colocalization pattern of Glucagon-like Peptide-1 with neurotensin in the chicken ileum

Glucagon-like peptide (GLP)-1 colocalizes with neurotensin (NT) in the same enteroendocrine cells (EECs) of the chicken ileum. The present study was designed to clarify the influence of dietary carbohydrate (CHO) on the colocalization pattern of GLP-1 with NT in the chicken distal ileum. Male White Leghorn chickens at 6 weeks of age (n = 15) were divided into three groups, a control and two experimental (low-CHO and CHO-free), with five chickens in each, and fed control or experimental diets for 7 d. Distal ileum was collected from each bird as a tissue sample and subjected to double immunofluorescence staining to detect GLP-1 and NT. Three types of EEC, GLP-1+/NT+, GLP-1+/NT- and GLP-1-/NT+, were demonstrated in the chicken ileum. GLP-1+/NT+ cells in the control group had a spindle-like shape with a long cytoplasmic process, but those in the experimental groups were round and lacked a cytoplasmic process. The ratio of GLP-1+/NT+ cells was significantly decreased in the two experimental groups compared with that in the control group. The ratio of GLP-1+/NT+ cells was significantly lower than those of GLP-1+/NT- and GLP-1-/NT+ cells in the two experimental groups. Most cells that were immunoreactive for GLP-1 and NT antisera lacked signals of proglucagon (PG) and NT precursor (NTP) mRNA in the experimental groups. The number of EECs expressing PG and NTP mRNA signals showed tendencies for decreases with a reduction of dietary CHO level. These findings suggest that dietary CHO could be a significant regulator of the pattern of colocalization pattern of GLP-1 with NT in the chicken ileum.

A Comprehensive Understanding of Dietary Effects on C. elegans Physiology

Diet has been shown to play an important role in human physiology. It is a predominant exogenous factor regulating the composition of gut microbiota, and dietary intervention holds promise for treatment of diseases such as obesity, type 2 diabetes, and malnutrition. Furthermore, it was reported that diet has significant effects on physiological processes of C. elegans, including reproduction, fat storage, and aging. To reveal novel signaling pathways responsive to different diets, C. elegans and its bacterial diet were used as an interspecies model system to mimic the interaction between host and gut microbiota. Most signaling pathways identified in C. elegans are highly conserved across different species, including humans. A better understanding of these pathways can, therefore, help to develop interventions for human diseases. In this article, we summarize recent achievements on molecular mechanisms underlying the response of C. elegans to different diets and discuss their relevance to human health.

Effect of dietary restriction and subsequent re-alimentation on the transcriptional profile of bovine jejunal epithelium

Compensatory growth (CG), an accelerated growth phenomenon which occurs following a period of dietary restriction is utilised worldwide in animal production systems as a management practise to lower feed costs. The objective of this study was to evaluate the contribution of jejunal epithelial to CG in cattle through transcriptional profiling following a period of dietary restriction as well as subsequent re-alimentation induced CG. Sixty Holstein Friesian bulls were separated into two groups; RES and ADLIB, with 30 animals in each. RES animals were offered a restricted diet for 125 days (Period 1) followed by ad libitum feeding for 55 days (Period 2). ADLIB animals had ad libitum access to feed across both periods 1 and 2. At the end of each period, 15 animals from each treatment group were slaughtered, jejunal epithelium collected and RNAseq analysis performed. Animals that were previously diet restricted underwent CG, gaining 1.8 times the rate of their non-restricted counterparts. Twenty-four genes were differentially expressed in RES compared to ADLIB animals at the end of Period 1, with only one gene, GSTA1, differentially expressed between the two groups at the end of Period 2. When analysed within treatment (RES, Period 2 v Period 1), 31 genes were differentially expressed between diet restricted and animals undergoing CG. Dietary restriction and subsequent re-alimentation were associated with altered expression of genes involved in digestion and metabolism as well as those involved in cellular division and growth. Compensatory growth was also associated with greater expression of genes involved in cellular protection and detoxification in jejunal epithelium. This study highlights some of the molecular mechanisms regulating the response to dietary restriction and subsequent re-alimentation induced CG in cattle; however the gene expression results suggest that most of the CG in jejunal epithelium had occurred by day 55 of re-alimentation.

Methods for quantifying gene expression in ecoimmunology: from qPCR to RNA-Seq

Historically, the use of cutting-edge molecular techniques to study immunological gene expression and related cellular pathways has been largely limited to model organisms. Few studies have been performed that quantify the molecular immunological responses of non-model species, especially in response to environmental factors, life-history events, or exposure to parasites. This dearth of information has largely occurred due to the lack of available non-model species-specific gene sequences and immunological reagents and also due to prohibitively expensive technology. However, with the rapid development of various sequencing and transcriptomic technologies, profiling the gene expression of non-model organisms has become possible. Technologies and concepts explored here include an overview of current technologies for quantifying gene expression, including: qPCR, multiplex branched DNA assays, microarrays, and profiling gene expression (RNA sequencing [RNA-Seq]) based on next-generation sequencing. Examples of the advancement of these technologies in non-model systems are discussed. Additionally, applications, limitations, and feasibility of the use of these methodologies in non-model systems to address questions in ecological immunology and disease-ecology are specifically addressed.

Cross-platform microarray meta-analysis for the mouse jejunum selects novel reference genes with highly uniform levels of expression

Reference genes (RGs) with uniform expression are used for normalization of reverse transcription quantitative PCR (RT-qPCR) data. Their optimization for a specific biological context, e.g. a specific tissue, has been increasingly considered. In this article, we compare RGs identified by expression data meta-analysis restricted to the context tissue, the jejunum of Mus musculus domesticus, i) to traditional RGs, ii) to expressed interspersed repeated DNA elements, and iii) to RGs identified by meta-analysis of expression data from diverse tissues and conditions. To select the set of candidate RGs, we developed a novel protocol for the cross-platform meta-analysis of microarray data. The expression stability of twenty-four putative RGs was analysed by RT-qPCR in at least 14 jejunum samples of the mouse strains C57Bl/6N, CD1, and OF1. Across strains, the levels of expression of the novel RGs Plekha7, Zfx, and Ube2v1 as well as of Oaz1 varied less than two-fold irrespective of genotype, sex or their combination. The gene set consisting of Plekha7 and Oaz1 showed superior expression stability analysed with the tool RefFinder. The novel RGs are functionally diverse. This facilitates expression studies over a wide range of conditions. The highly uniform expression of the optimized RGs in the jejunum points towards their involvement in tightly regulated pathways in this tissue. We also applied our novel protocol of cross-microarray platform meta-analysis to the identification of RGs in the duodenum, the ileum and the entire small intestine. The selection of RGs with improved expression stability in a specific biological context can reduce the number of RGs for the normalization step of RT-qPCR expression analysis, thus reducing the number of samples and experimental costs.

Integration of metabolic and gene regulatory networks modulates the C. elegans dietary response

Expression profiles are tailored according to dietary input. However, the networks that control dietary responses remain largely uncharacterized. Here, we combine forward and reverse genetic screens to delineate a network of 184 genes that affect the C. elegans dietary response to Comamonas DA1877 bacteria. We find that perturbation of a mitochondrial network composed of enzymes involved in amino acid metabolism and the TCA cycle affects the dietary response. In humans, mutations in the corresponding genes cause inborn diseases of amino acid metabolism, most of which are treated by dietary intervention. We identify several transcription factors (TFs) that mediate the changes in gene expression upon metabolic network perturbations. Altogether, our findings unveil a transcriptional response system that is poised to sense dietary cues and metabolic imbalances, illustrating extensive communication between metabolic networks in the mitochondria and gene regulatory networks in the nucleus.

Effects of recombinant human intestinal trefoil factor on trinitrobenzene sulphonic acid induced colitis in rats

Intestinal trefoil factor (ITF) has been proved to be effective in treatment of ulcerative colitis. However, the mechanisms of it remain unclear. In this study, we observed the effects of combined treatment with 5-aminosalicylic acid (5-ASA) and recombinant human ITF (rhITF) on the expression of Myeloperoxidase (MPO), nuclear factor-κB (NF-κB) and epidermal growth factor (EGF) in trinitrobenzene sulphonic acid (TNBS) induced colitis in rats. Forty Sprague-Dawley (SD) male rats which were induced to distal colitis by the colonic administration of TNBS, were randomly divided into four groups and colonically treated with normal saline (A), 5-ASA (B), rhITF (C), respectively. The macroscopic and histological changes of the colon, activities of MPO, expressions of serum EGF and tissue NF-κB were detected. The results showed that manifestation, colonic damage score and MPO activities of the rats treated with 5-ASA or/and rhITFs were improved, serum EGF production was augmented and expression of tissue NF-κB was down-regulated. Single usage of 5-ASA or rhITF had no significant difference, but combined using of them had more significant and noticeable effects compared to any single treatment. It could be concluded that topical treatment with 5-ASA and rhITF had beneficial effects in treating TNBS-induced colitis of rats and combined treatment was better than single treatment. It was possibly related to suppression of neutrophil infiltration, down-regulation expression of NF-κB and up-regulation expression of EGF.

Oxidative stress induced by high-glucose diet in liver of C57BL/6J mice and its underlying mechanism

High glycemic index diet can induce multiple diseases. Many research indicated that oxidative stress played important role in many pathological conditions. However, the impact of gene expression and dietary habit on oxidation process are still less clear. We used high-glucose diet to feed C57BL/6J mice for 4 weeks, measured the redox status, physiological and biochemical changes related to diabetes and consequence of metabolic syndrome (nonalcoholic fatty liver, cardiovascular disease), and detected the expressions of 14,446 genes in liver of C57BL/6J mice with DNA microarray. The results showed high-glucose diet induced elevated fatty acid accumulation in liver, insulin resistance index and higher weight in C57BL/6J mice, which indicated high-glucose diet caused to the initiation and development of diabetes and consequence of metabolic syndrome. The results also showed high-glucose diet induced oxidative stress in liver of C57BL/6J mice, which might the cause of initiation and development of diabetes and consequence of metabolic syndrome. Microarray analysis found expressions of genes related to thiol redox, fatty acid oxidation in peroxisome and cytochrome P450 were significantly changed, indicating system in which non-enzyme antioxidant capacity was impaired and sources from which reactive oxygen species (ROS) generated, which revealed the molecular mechanism of oxidative stress induced by high-glucose diet. We validated our microarray findings by conducting real-time RT-PCR assays on selected genes.