Dietary sterols/steroids and the generalist caterpillar Helicoverpa zea: physiology, biochemistry and midgut gene expression
ABSTRACT: Sterols are essential nutrients for insects because, in contrast to mammals, no insect (or arthropod for that matter) can synthesize sterols de novo. Cholesterol is the most common sterol in insects, but it is not found in plants in large quantities; plant-feeding insects typically generate their cholesterol by metabolizing phytosterols. However, different plants species can contain different types of phytosterols, and some phytosterols are not readily converted to cholesterol. In this study we examined, using artificial diets containing single sterols, how typical (cholesterol and stigmasterol) and atypical (cholestanol and cholestanone) sterols/steroids affect the performance of a generalist caterpillar (Helicoverpa zea), restricting this analysis to midgut tissue because this is where sterol/steroid absorption occurs, and the midgut is the putative site of dietary sterol/steroid metabolism. In general, H. zea performed best on the cholesterol and stigmasterol treatments; performance was reduced on cholestanol, and was very poor on cholestanone. We compared the transcript profiles of larval guts in response to differentially suitable sterols, using the optimal sterol, cholesterol, as a control, using a two-color reference design microarray experiment. Midgut gene expression patterns differed between the treatments; relative to cholesterol, differences were lowest on the stigmasterol treatment, intermediate on the cholestanol treatment, and greatest on the cholestanone treatment. Transcriptional profiling comparing Helicoverpa zea gut tissue from third instar larvae exposed to four different dietary sterols, namely Cholesterol (CON), Cholestanol (ChStanol), Cholestan-3-one (Ch3one) and Stigmasterol (Stigma). Two-color reference design. Biological replicates: 4 (5 individuals per replicate). 12 samples total.
Project description:Protease inhibitors (PIs) are among the most ubiquitous plant defences against herbivorous insects. These inhibitors arrest proteolytic digestion by binding to the proteases in the gut. However, many pest insects have coevolved mechanisms to counteract these effects. While the nature of these counter-defensive strategies has been well described for several insect pests, our understanding of how these responses are triggered and regulated remains limited. In this study we investigated the initiation of this adaptive response in the economically damaging migratory locust (Locusta migratoria), via microarray analysis of gut tissues following the dietary uptake of PIs. For this purpose, the total number of ESTs available for locusts was narrowed down to transcripts that were found expressed in gut and/or brain tissue. The remaining subset was used for the construction of an optimized microarray platform. Two condition experiment: locusts fed on control diet vs locusts fed on protease inhibitor-supplied diet (midgut samples), 3 biological repeats per condition. The overall experimental design consisted of an n+2 A-optimal design (n=6: 3 pooled midgut samples derived from control locusts - 3 pooled midgut samples derived from protease inhibitor-fed locusts)
Project description:The study evaluated effects of dietary cholesterol (1.5%) in Atlantic salmon fed a plant based diet for 77 days. Cholesterol supplementation did not affect growth or organ weights of Atlantic salmon, but promoted induction of cholesterol and plant sterol efflux in the intestine, whereas sterol uptake was suppressed. Microarray analyses in the liver indicated decreased cholesterol biosynthesis and enhanced conversion to bile acids. The marked effect of cholesterol on bile acid synthesis suggests that dietary cholesterol can be used to stimulate bile acid synthesis in fish. The study clearly demonstrated how Atlantic salmon adjusted metabolic functions in response to the dietary load of cholesterol, and has expanded our understanding of sterol metabolism and turnover that adds to the knowledge of these processes in fish. Atlantic salmon received feeds based on plant ingredients with (CH) and without (K) supplementation of cholesterol. Liver samples were collected after 77 days. Five individuals from each group were analyzed with microarrays, pooled liver sample of salmon fed with commerical fish meal based feed was used as a reference.
Project description:This is a cell culture based study to asses the impact of ZEA (Zearalenone) and E. coli co-contamination on IPEC cells, these is a normal epithelial cell line isolated from a new born piglet. ZEA is a mycotoxin with a negative impact in human health. The microarray is a custom Agilent Technology array slide with the AMAID: 05685.
Project description:Maternal diet is associated with the development of metabolism-related and other non-communicable diseases in offspring. Underlying mechanisms, functional profiles, and molecular markers are only starting to be revealed. Here, we explored the physiological and molecular impact of maternal Western-style diet on the liver of male and female offspring. C57BL/6 dams were exposed to either a low fat/low cholesterol diet (LFD) or a Western-style high fat/high cholesterol diet (WSD) for six weeks before mating, as well as during gestation and lactation. Dams and offspring were sacrificed at postnatal day 14, and body, liver, and blood parameters were assessed. The impact of maternal WSD on the pups' liver gene expression was characterised by whole-transcriptome microarray analysis. Exclusively male offspring had significantly higher body weight upon maternal WSD. In offspring of both sexes of WSD dams, liver and blood parameters, as well as hepatic gene expression profiles were changed. In total, 686 and 604 genes were differentially expressed in liver (p≤0.01) of males and females, respectively. Only 10% of these significantly changed genes overlapped in both sexes. In males, in particular alterations of gene expression with respect to developmental functions and processes were observed, such as Wnt/beta-catenin signalling. In females, mainly genes important for lipid metabolism, including cholesterol synthesis, were changed. We conclude that maternal WSD affects physiological parameters and induces substantial changes in the molecular profile of the liver in two-week-old pups. Remarkably, the observed biological responses of the offspring reveal pronounced sex-specificity. C57BL/6 dams were exposed to either a low fat/low cholesterol diet (LFD) or a Western-style high fat/high cholesterol diet (WSD) as six weeks pre-treatment before mating, as well as during gestation and lactation. Offspring were sacrificed at postnatal week two, livers were removed and RNA samples were subjected to gene expression profiling.
Project description:Dietary supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs), specifically the fatty acids docosahexaenoic acid (DHA; 22:6 ω-3) and eicosapentaenoic acid (EPA; 20:5 ω-3), is known to have beneficial health effects including improvements in glucose and lipid homeostasis and modulation of inflammation. To evaluate the efficacy of two different sources of ω-3 PUFAs, we performed gene expression profiling in the liver of mice fed diets supplemented with either fish oil or krill oil. We found that ω-3 PUFA supplements derived from a phospholipid krill fraction (krill oil) downregulated the activity of pathways involved in hepatic glucose production as well as lipid and cholesterol synthesis. The data also suggested that krill oil-supplementation increases the activity of the mitochondrial respiratory chain. Surprisingly, an equimolar dose of EPA and DHA derived from fish oil modulated fewer pathways than a krill oil-supplemented diet and did not modulate key metabolic pathways regulated by krill oil, including glucose metabolism, lipid metabolism and the mitochondrial respiratory chain. Moreover, fish oil upregulated the cholesterol synthesis pathway, which was the opposite effect of krill supplementation. Neither diet elicited changes in plasma levels of lipids, glucose or insulin, probably because the mice used in this study were young and were fed a low fat diet. Further studies of krill oil supplementation using animal models of metabolic disorders and/or diets with a higher level of fat may be required to observe these effects. Twenty-one microarrays: three diets (CO, FO, KO) x seven mice per diet x one microarray per mouse
Project description:Cholesterol is one of the key molecules in mammals and the most striking examples of its deficiency are the inborn errors of cholesterol biosynthesis that manifest in severe whole body phenotypes. Liver, the principal site of cholesterol homeostasis, has rarely been investigated in these defects. We thus focused on the hepatocyte-specific deletion of lanosterol 14α-demethylase (CYP51) catalyzing the rate-limiting step in the post-squalene part of cholesterol synthesis. Liver-specific Cyp51 KO (LKO or K) and littermate control (LWT or W) mice (129/Pas (10%) × C57BL/6J (90%)) of both sexes (F and M) were investigated in the context of different nutritional availability of fat and cholesterol (standard laboratory diet without cholesterol (LFnC or L), high-fat diet without cholesterol (HFnC or H) and high-fat diet with cholesterol (HFC or C) due to the known sexual dimorphism in hepatic gene expression, where lipid metabolic pathways are among the most biased. 3 condition experimental design: 3 diets (LFnC or L, HFnC or H, HFC or C), 2 genotypes (LWT or W, LKO or K), 2 sexes (F, M), 3 biological replicates per condition, 36 mice altogether
Project description:All but a few eukaryotes die without oxygen and respond dynamically to changes in the level of oxygen available to them. One ancient oxygen-requiring biochemical pathway in eukaryotes is the pathway for the biosynthesis of sterols, leading to cholesterol in animals and ergosterol in fungi. Mutations in this pathway are a frequent cause of azole drug resistance in pathogenic fungi. The regulatory mechanism for the sterol pathway is also widely conserved between animals and fungi and is centred on a transcription activator, SREBP, that forms part of a sterol-sensing complex. However, in one group of yeasts – the Saccharomycotina, which includes the major pathogen Candida albicans – control of the sterol pathway has been taken over by an unrelated regulatory protein, Upc2. We show here by analysis of the yeast Yarrowia lipolytica that the evolutionary switch from SREBP to Upc2 was a two-step process in which Upc2 appeared in an ancestor of Saccharomycotina, and SREBP subsequently degenerated and lost its sterol-regulatory function while retaining an ancient role in filamentation. RNA was isolated from Y. lipolytica wildtype (JMY2900) in normoxia (21% oxygen, 4 biological replicates), wildtype (JMY2900) in hypoxia (1% oxygen, 5 biological replicates), upc2 deletion (SMY2) in hypoxia (1% oxygen, 3 biological replicates), and from sre1 (SMY5, SMY8) deletion in hypoxia (1% oxygen, 2 biological replicates). Gene expression was determined using strand-specific RNA-seq.
Project description:Ergosterol is a prominent component of the yeast plasma membrane and essential for yeast cell viability. It is synthesized in the endoplasmic reticulum and transported to the plasma membrane by non-vesicular mechanisms requiring carrier proteins. Oxysterol binding protein homologues and yeast StARkin proteins have been proposed to function as sterol carriers. Although many of these proteins are capable of transporting sterols between synthetic lipid vesicles in vitro, they are not essential for ergosterol transport in cells, indicating that they may be functionally redundant with each other or with additional - as yet unidentified - sterol carriers. To address this point we hypothesized that sterol transport proteins are also sterol binding proteins (SBPs), and used an in vitro chemo-proteomic strategy to identify all cytosolic SBPs. We generated a cytosol fraction enriched in SBPs and captured the proteins with a photoreactive clickable cholesterol analog. Quantitative proteomics of the captured proteins identified 342 putative SBPs. Analysis of these identified proteins based on their annotated function, reported drug phenotypes, interactions with proteins regulating lipid metabolism, gene ontology, and presence of mammalian orthologs revealed a subset of 62 characterized and nine uncharacterized candidates. Five of the uncharacterized proteins play a role in maintaining plasma membrane integrity as their absence affects the ability of cells to grow in the presence of nystatin or myriocin. We anticipate that the dataset reported here will be a comprehensive resource for functional analysis of sterol binding/transport proteins and provide insights into novel aspects of non-vesicular sterol trafficking.
Project description:Iron is an essential nutritional element; its deficiency in the body causes nutritional problems and a decrease in iron storage that can lead to anemia. The liver not only stores iron but is an important metabolic target as well. Dietary iron deficiency is associated with changes in the metabolism of nutrients such as lipids. However, to the best of our knowledge, a global analysis detailing the consequences of iron deficiency in the body has not yet been reported. We performed a comprehensive transcriptome analysis using DNA microarray technology to reveal the effects of iron deficiency on hepatic gene expression. Four-week-old rats were fed an iron-deficient diet or a control diet for 16 days. On day 17, the rats were sacrificed under anesthesia, and their livers were dissected for DNA microarray analysis. We identified 600 up-regulated and 500 down-regulated probe sets to characterize the iron-deficient diet group. The up-regulated probe sets contained genes for enzymes that are involved in cholesterol, amino acid, and glucose metabolisms, as well as in apoptosis. The down-regulated probe sets included genes for enzymes associated with lipid metabolism. Additionally, the 16-day iron-deficient diet induced anemia. Our gene expression analysis revealed that, as a result, cholesterol biosynthesis, gluconeogenesis, and apoptosis due to endoplasmic reticulum stress were accelerated, while fatty acid biosynthesis was suppressed by dietary iron deficiency. Our analysis also showed that cholesterol metabolism, including bile acid biosynthesis, was accelerated in the initial stages of cholesterol accumulation. Experiment Overall Design: Male 3-week-old Sprague Dawley rats were purchased from Charles River Japan (Kanagawa, Japan) and housed in a room conditioned at 24 ± 1°C and 40 ± 5% humidity with a 12-h light-dark cycle (lights on at 08:00). The rats were given a control diet and water for 24 h ad libitum. Diets for rats were obtained from Research Diets, Inc. (New Brunswick, NJ, USA). The composition of the control diet was based on the AIN93G diet , except that cellulose was replaced by Avicel, since cellulose is an ingredient of variable iron content. The iron-deficient diet was prepared by removal of iron (ferric citrate) from the control diet. At day 8, rats were divided into two groups comprising animals of similar body weights. One group (n = 6) was fed the control diet and the other group (n = 7) was fed the iron-deficient diet (iron-deficient diet group). After iron-deficient diet feeding was started, blood hemoglobin levels were measured every two days. Blood samples for hemoglobin measurements were collected from the tail vein, and hemoglobin levels were measured by using the Wako Hemoglobin B test (Wako Pure Chemical Industries, Osaka, Japan). On day 12 of the iron-deficient diet treatment, diets were removed at 17:00, and feeding was conducted between 09:00 and 17:00 for another 4 days. This protocol was intended to synchronize the rats’ feeding behavior. On day 17 of the iron-deficient diet treatment, rats were fed for 1.5 h prior to sacrifice under anesthesia. Livers were then excised and subsequently immersed in RNAlater (Applied Biosystems Japan, Tokyo, Japan). Blood hemoglobin level of rats fed an iron-deficient diet decreased significantly over the course of the feeding. On day 17, the hemoglobin level in the iron-deficient diet group was 42% of that of the control diet group (P < 0.01).
Project description:Fungal infections are a serious health problem in clinics especially in the immune-compromised patient. Disease ranges from widespread superficial infections like vulvovaginal infections to life-threatening systemic candidiasis. Especially for systemic mycoses only a limited arsenal of antifungals is available. The most commonly used classes of antifungal compounds used include azoles, polyenes and echinocandines. Due to emerging resistance to standard therapy and significant side effects and high costs for several antifungals.,there is a medical need for new antifungals in the clinic and general practice. In order to expand the arsenal of compounds with antifungal activities we previously screened a compound library, using a new type of activity-selectivity (AS) assay analysing both the antifungal activity and the compatibility with human cells at the same time. One compound, ((S)-2-(1-aminoisobutyl)-1-(3-chlorobenzyl) benzimidazole (EMC120B12)), showed high antifungal activity against several species of pathogenic yeasts including C. glabrata and C. krusei, species which are highly refractory to antifungals, especially to the commonly used azoles. Here we could show by transcriptional profiling and sterol analysis that the target of this new antifungal compound is the ergosterol pathway. The effects of EMC120B12 on sterol biosynthesis mimic those of fluconazole, strongly indicating that EMC120B12 also targets ERG11 like the azols. But not only the marker sterol 14 methylergosta 8,24(28) dien 3β,6α diol accumulated in C. krusei under EMC120B12 treatment, but also hitherto unknown related sterols. The novel sterols have a 3β,6α diol structure. Furthermore, this is the first time that a benzimidazole structure has been shown to result in a block of the sterol pathway by accumulating marker sterols connected to ERG11 inactivation. In total, three biological replicates were performed. All experiments were performed as dye swaps. Thus, in total 18 arrays have been hybridzed. Hybridization experiments included an untreated reference sample and a sample of cells treated with either ((1S)-1-[1-(3-chlorobenzyl)-1H-benzimidazol-2-yl]-2-methylpropyl-amine) (EMC120B12), Fluconazole or Nocodazole. The array included one technical replicate of each probe.