Project description:We revealed a total of 398 gut genes differentially expressed (i.e., either up- or down-regulated genes with expression ratio ≥2.0) in S-strain larvae, while only 264 gut genes differentially expressed in R-strain larvae after fed transgenic corn leaves. Although the percentages of down-regulated genes among the total number of differentially expressed genes (199 genes or 50% in S-strain; 119 genes or 45% in R-strain) were similar between the R and S-strains, the expression ratios of down-regulated genes were much higher in S-strain than in R-strain. These results imply that R-strain larvae had an increased ability to deal with transgenic corn as compared with S-strain larvae. We also revealed that 17 and 9 significantly up- or down-regulated gut genes from S- and R-strain larvae, respectively, including serine proteases (trypsins and chymotrypsins) and aminopeptidases. Overall design: Trangenic corn induced gene expression was measured in O. nubilalis resistant and susceptible strains' gut at 6-hrs after transgenic corn feeding. Three independent experiments were performed using three insect gut samples ,and each sample was from five insects' gut pooled.
Project description:Male Sprague Dawley rats were treated orally for 5 days with reference hepatotoxicants, each at a single dose level, alpha-naphthylisothiocyanate 100mg/kg (vehicle 5ml/kg corn oil); carbon tetrachloride 1582mg/kg (vehicle 5ml/kg corn oil); methylenedianiline 100mg/kg (vehicle 35% ethanol); acetaminophen 1000mg/kg (vehicle 2ml/kg corn oil); diclofenac 10mg/kg (vehicle 10ml/kg water) Overall design: 3 rats were treated with each hepatotoxicant, 3 rats were treated with corresponding vehicle for each hepatotoxicant, total RNA was isolated form left lateral lobe of liver of all rats, samples run individually on Affymetrix GeneChip Rat Genome 230_2.0 Arrays
Project description:We wished to investigate if adaptation to host-plant diet is the basis of differentiation for two strains of Spodoptera frugiperda (Lepidoptera:Noctuidae). We performed reciprocal transplant experiments in laboratory conditions, feeding each strain (sf-C and sf-R) with artificial diet, corn plants or rice plants. RNA-Seq was performed on pooled 4th instar larvae from this experiment. We compared this transcriptional response with that of individual 4th instar larvae collected in corn and grass fields in Florida.
Project description:Paraburkholderia phymatum belongs to the β-subclass of proteobacteria. It has recently been shown to be able to nodulate and fix nitrogen in symbiosis with several mimosoid and papillionoid legumes. In contrast to symbiosis of legumes with α-proteobacteria, very little is known about the molecular determinants underlying the successful establishment of this mutualistic relationship with β-proteobacteria. In this study, we analyzed RNA-seq data of free-living P. phymatum growing under nitrogen replete and limited conditions, the latter partially mimicking the situation in nitrogen deprived soils. Among the genes up-regulated under nitrogen limitation, we found genes involved in exopolysaccharide production and motility, two traits relevant for plant root infection. Next, RNA-seq data of P. phymatum grown under free-living conditions and from symbiotic root nodules of Phaseolus vulgaris (common bean) were generated and compared. Among the genes highly up-regulated during symbiosis, we identified an operon encoding a potential cytochrome o ubiquinol oxidase (Bphy_3646-49). Bean root nodules induced by a cyoB mutant strain showed reduced nitrogenase and nitrogen fixation abilities suggesting an important role of the cytochrome for respiration inside the nodule. Analysis of mutant strains for RNA polymerase transcription factor rpoN (σ54) and its activator NifA indicated that – similar to the situation in α-rhizobia – P. phymatum RpoN and NifA are key regulators during symbiosis with P. vulgaris. Overall design: Unraveling the molecular basis of the nitrogen-fixing symbiosis between P. vulgaris and P. phymatum.
Project description:RpoN (σ54) is the key sigma factor for the regulation of transcription of nitrogen fixation genes in diazotrophic bacteria, which include alpha- and beta-rhizobia. Our previous studies showed that a rpoN mutant of the beta-rhizobial strain Paraburkholderia phymatum formed root nodules on Phaseolus vulgaris that were unable to reduce atmospheric nitrogen into ammonia. In an effort to further characterize the RpoN regulon of P. phymatum, transcriptomics was combined with a powerful metabolomics approach. The metabolome of P. vulgaris root nodules infected by the P. phymatum rpoN Fix- mutant revealed statistically significant metabolic changes compared to wild-type Fix+ nodules, including reduced amounts of chorismate and elevated levels of flavonoids. A transcriptome analysis on Fix+ and Fix- nodules – combined with a search for RpoN binding sequences in promoter regions of regulated genes – confirmed the expected control of σ54 on nitrogen fixation genes in nodules. The transcriptomic data also identified additional target genes, whose differential expression was able to explain the observed metabolite changes in a numerous cases. Moreover, the genes encoding the two-component regulatory system NtrBC were downregulated in root nodules induced by the rpoN mutant and contained a putative RpoN binding motif in their promoter region, suggesting direct regulation. The construction and characterization of an ntrB mutant strain revealed impaired nitrogen assimilation in free-living conditions, as well as a noticeable symbiotic phenotype by forming less but heavier nodules on P. vulgaris roots. Overall design: Unraveling the molecular basis of the nitrogen-fixing symbiosis between P. vulgaris and P. phymatum.
Project description:Insect pathogenic fungus Beauveria bassiana in one of the best studied insect biocontrol fungus, which infects insects by cuticle penetration. After breaking the cuticles, the fungus will propagate in insect hemocoel and kill insect hosts. It has also been found that the mycelia of B. bassiana can penetrate plant tissues to reach insect inside plant, e.g. corn borer (Ostrinia furnacalis), but do not cause damage to plants. The mechanism of fungal physiological plasticity is poorly understood. To accompany our genome sequencing work of B. bassiana strain ARSEF 2860, fungal transcriptional responses to different niches were studied using an Illumina RNA_seq technique. To examine fungal response to insect cuticle, conidia were inoculated on locust hind wings for 24 hours before used for RNA extraction. To evaluate fungal adaptation to insect hemocole, the fifth instar larvae of cotton bollworms were injected with spore suspension and fungal cells isolated by centrifugation in a step gradient buffer. To unveil the mechanism of interaction with plants, the fungus was grown in corn root exudates for 24 hours. After RNA sequencing, around three million tags were acquired for each sample and fungal transcriptional profiles were compared. Unveiling gene differential expression patterns when the insect biocontrol fungus Beauveria bassiana grown in insect hemocoel, corn root exudates and on insect cuticles.
Project description:The objective of this study was to evaluate the effect of the oomycete Aphanomyces euteiches (strain ATCC201684) on the legume model Medicago truncatula (F83005-5 line) transcritpome. Overall design: A total of 15 samples were analysed comprising 3 biological replicates for each of the 3 timepoints of the kinetic (1 day, 3 days, 9 days) on M truncatula roots, 3 biological replicates of a pool of A. euteiches mycelium grown 1, 3 or 9 days on CMA medium (8,5g/L Corn Meal Agar), and 3 biological replicates from zoospores samples.
Project description:The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is an important pest of corn (Zea mays) in the US. Annual crop rotation between corn and soybean (Glycine max) disrupts the corn-dependent WCR lifecycle and was widely adopted to manage WCR. However, this strategy selected for a rotation-resistant (RR) variant with reduced ovipositional fidelity to cornfields. Previous studies indicated that RR-WCR adults exhibit greater tolerance of soybean tissue diet, different gut physiology, and host-microbe interactions compared to wild-types (WT). To identify genetic mechanisms underlying these phenotypic changes, a de novo assembly of the WCR adult gut transcriptome was constructed and used for RNA-sequencing analyses on RNA libraries from different WCR phenotypes (RR and WT) fed with corn or soybean diets. Differential gene expression analyses and network-based methods were used to identify gene modules transcriptionally correlated with the RR phenotype. Gene ontology enrichment analyses on these modules were then conducted to understand their potential functions and biological importance. Differential gene expression analyses on RNA libraries from adult guts of different WCR phenotypes (rotation-resistant and wild-type) fed with corn or soybean diets
Project description:Microbiome regulation of lipid metabolism Germfree male C57BL/6J mice were purchased at 8 weeks of age from Charles River Laboratories (L'Arbresle, France). Mice were treated with 10^8 CFU/mL E. coli M8 strain (isolated from the feces of an ob/ob mouse) in drinking water for 14 days. At the end of the treatment, mice were subjected to an oral lipid tolerance test (OLTT) (with 6ml/kg of corn oil) after overnight fasting (14h). All mice were sacrificed 6 hours after the lipid tolerance test and ileum samples were collected for further analysis. Overall design: In order to identify key pathways involved in microbiome regulation of lipid metabolism we took advantage of gnotobiotic preclinical models and an E. coli strain isolated from an obesity mouse model (Ob/Ob).