Project description:Exposure to ambient particulate matter (PM) significantly increases cardiovascular morbidity and mortality in the general population. We hypothesized that some components of PM can affect the gene expression patterns in the hearts of rats exposed for 3 months to filtered air (FA), coarse (CP; 2.5 < dp < 10 μm), fine (FP; dp ≤ 2.5 μm) or ultrafine (UFP; dp ≤ 0.18 μm) components of PM. The median diameters of CP, FP, and UFP were 3 μm, 0.7 μm and 0.07 μm, respectively. Exposures (n = 8 per group) were performed using a particle concentrator system in Riverside, California, an area with high ambient levels of photochemically derived gaseous and particulate pollutants. At the end of the exposure, hearts were subjected to gene expression profiling by using Illumina RatRef-12 bead chips and levels of malonaldehyde (MDA), a biomarker of oxidative stress, were measured. Applying fold ratio >1.5 (for both up- and downregulated genes), we found three genes in the CP and nine genes in the UFP groups with significantly changed expression, compared with FA. No significant changes in gene expression patterns were observed in the FP group. In the UFP group, thioredoxin-interacting protein (Txnip), a negative regulator of an antioxidant enzyme thioredoxin, and cytochrome P450 (Cyp2e1), an enzyme involved in the metabolism of foreign substances, demonstrated significant up-regulation (fold ratios 1.79 and 1.57, respectively, with false discovery rate, FDR < 0.05). In the CP group, there was also a trend towards increased Txnip expression (fold ratio 1.43, FDR > 0.05) and significant increase in the Cyp2e1 expression (fold ratio 1.79, FDR < 0.05). Changes in the Txnip and Cyp2e1 expression showed statistically significant positive correlation to each other (p < 0.0009) and were confirmed by real-time PCR. In addition, Txnip and Cyp2e1 expression demonstrated statistically significant moderate correlation with the levels of MDA in the heart. Up-regulation of both Cyp2e1 and Txnip are observed in hearts of patients with certain cardiac diseases. Therefore, chronic exposure to CP and UFP directly affects expression of disease-relevant genes in the myocardium. Analysis was performed on 32 microarrays (eight microarrays in each group). After five chips with poor hybridization signals were removed, the final analysis included 27 microarrays (seven miocroarrays in the FA group, six microarrays in the CP group, six microarrays in the FP group and eight microarrays in the UFP group). The Bioconductor Lumi package was used to preprocess gene chip data with default settings (Du et al. 2007; Lin et al. 2008). Probes with all samples “Absent” (lower or around background levels) were removed from further analysis. After filtering the signals, 11,657 probes on the microarray (from a total of 22,226 probes) were kept for further analysis. To identify differentially expressed genes, we applied routines implemented in the Limma package (Linear model for microarray data) to fit linear models to normalized expression values. The variance used in the t-score calculation was corrected by an empirical Bayesian method (Smyth 2004). Genes with significantly changed expression (fold ratio >1.5 for both up- and downregulated genes) were selected. The gene list was further filtered by FDR (false discovery rate) of <0.05 and <0.25, which indicate that no more than 5% and 25% of all listed genes are false positives (an assumption that is not offered by a traditional p value-based analysis).

Project description:Native host plant insect resistance in the maize inbred line Mp708 was developed by traditional plant breeding. Resistant Mp708 thwarts feeding by fall armyworm (Spodoptera frugiperda [J.E. Smith]; Lepidoptera: Noctuidae), numerous other lepidopteran pests, and the coleopteran western corn rootworm. This broad resistance makes it an excellent model for studying native host plant resistance mechanisms. In response to caterpillar feeding, Mp708 rapidly mobilizes Mir1-CP, a unique cysteine protease that appears to translocate from roots to the maize midwhorl where it accumulates. This accumulation correlates with a significant reduction in caterpillar growth resulting from diminished food utilization. In addition, the peritrophic membrane (PM) that surrounds the food bolus in the mudgut (MG) is severely damaged in caterpillars fed on sweet corn callus transformed to express the gene encoding Mir1-CP or on midwhorl tissue from resistant Mp708 maize. Functions of the PM include assisting digestion and protecting the epithelium of the caterpillar MG from physical and chemical damage. Consequently, the reduced growth of caterpillars that feed on Mp708 is probably due to the action of Mir1-CP on PM physiology. In fact, previous in vitro studies indicated that Mir1-CP was capable of permeabilizing the PM. The present study used both targeted (qRT-PCR) and global (mRNA-seq) transcriptome analyses to explore the effect of eating Mir1-CP expressing Mp708 maize on abundance of transcripts in the MG of fall armyworm larvae in comparison to MGs from larvae fed on susceptible Tx601 maize that does not express Mir1-CP. Expression of genes encoding proteins involved in PM production is upregulated in MGs from fall armyworm fed on Mp708. Also, several digestive enzymes (endopeptidases, aminopeptidases, lipases, amylase) were more highly expressed in MGs from larvae fed on Mp708 than MGs from larvae fed on Tx601. Impaired growth of larvae fed on Mp708 probably results from metabolic costs associated with higher production of PM constituents and digestive enzymes in a compensatory attempt to maintain MG function.

Project description:Native host plant insect resistance in the maize inbred line Mp708 was developed by traditional plant breeding. Resistant Mp708 thwarts feeding by fall armyworm (Spodoptera frugiperda [J.E. Smith]; Lepidoptera: Noctuidae), numerous other lepidopteran pests, and the coleopteran western corn rootworm. This broad resistance makes it an excellent model for studying native host plant resistance mechanisms. In response to caterpillar feeding, Mp708 rapidly mobilizes Mir1-CP, a unique cysteine protease that appears to translocate from roots to the maize midwhorl where it accumulates. This accumulation correlates with a significant reduction in caterpillar growth resulting from diminished food utilization. In addition, the peritrophic membrane (PM) that surrounds the food bolus in the mudgut (MG) is severely damaged in caterpillars fed on sweet corn callus transformed to express the gene encoding Mir1-CP or on midwhorl tissue from resistant Mp708 maize. Functions of the PM include assisting digestion and protecting the epithelium of the caterpillar MG from physical and chemical damage. Consequently, the reduced growth of caterpillars that feed on Mp708 is probably due to the action of Mir1-CP on PM physiology. In fact, previous in vitro studies indicated that Mir1-CP was capable of permeabilizing the PM. The present study used both targeted (qRT-PCR) and global (mRNA-seq) transcriptome analyses to explore the effect of eating Mir1-CP expressing Mp708 maize on abundance of transcripts in the MG of fall armyworm larvae in comparison to MGs from larvae fed on susceptible Tx601 maize that does not express Mir1-CP. Expression of genes encoding proteins involved in PM production is upregulated in MGs from fall armyworm fed on Mp708. Also, several digestive enzymes (endopeptidases, aminopeptidases, lipases, amylase) were more highly expressed in MGs from larvae fed on Mp708 than MGs from larvae fed on Tx601. Impaired growth of larvae fed on Mp708 probably results from metabolic costs associated with higher production of PM constituents and digestive enzymes in a compensatory attempt to maintain MG function. Beginning as neonates, fall armyworm larvae used in the mRNA-seq experiment were reared on yellow-green midwhorl foliage from resistant Mp708 maize or susceptible Tx601 maize. Old foliage and frass were removed every other day and replaced with fresh foliage. Larvae were reared in an environmental chamber at 27M-BM-0C, 14:10 (light:dark) photoperiod, and 70% relative humidity. Midguts were dissected from larvae 2 d after molting to the last instar with masses between 300 and 400 mg. Dissections were done with cold anesthetized larvae submerged in Bombyx saline. After removing Malpighian tubules, foregut anterior to the stomodial valve, hindgut and food bolus, the MG was transferred from the body cavity, rinsed well with cold saline, and preserved in RNAlaterM-BM-.. Equal amounts (3 M-BM-5g) of total RNA from an individual MG were randomly pooled into three replicates per treatment (i.e., Mp708 or Tx601) such that each treatment replicate derived from 12-13 MGs. Each pool of total RNA was separately enriched for poly(A+) RNA and submitted to the Penn State Genomics Core Facility (University Park, PA) where barcoded cDNA libraries were prepared and equimolar quantities of each library sequenced on the SOLiD 3 Plus System. Sequence reads were filtered to accept reads whose median score threshold was M-bM-^IM-%12, contained M-bM-^IM-%25 bases and contained one or more bases with a quality score M-bM-^IM-%14. The 138911 Sanger ESTs in SPODOBASE (http://bioweb.ensam.inra.fr/spodobase) were assembled into a reference transcriptome using SeqMan Pro version 8.0.2. Filtered reads from each library representing a replicate within a maize inbred treatment were mapped separately to the reference transcriptome using the Bowtie-like algorithm in NextGENeM-BM-. with the requirement that 85% of 12 or more nucleotides comprising a read must match the reference. A read was allowed to map only once (i.e., no ambiguous mapping). The number of mapped reads per contig (i.e., gene model) in each treatment replicate-library were summed by NextGENeM-BM-. as read counts per gene and subsequently used in differential expression analyses.

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Chronic exposure to ambient particulate matter alters cardiac gene expression patterns and markers of oxidative stress in rats

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