Comparisons of Phlebiopsis gigantea transcript profiles when cultured different substrates
ABSTRACT: Collectively classified as white-rot fungi, certain basidiomycetes efficiently degrade the major structural polymers of wood cell walls. A small subset of these Agaricomycetes, exemplified by Phlebiopsis gigantea, is capable of colonizing freshly exposed conifer sapwood despite its high pitch content, which retards the establishment of other fungal species. The mechanism(s) by which P. gigantea tolerates and metabolizes resinous compounds have not been explored. Here, we report the annotated P. gigantea genome and compare profiles of its transcriptome and secretome when cultured on fresh-cut versus solvent-extracted loblolly pine. The P. gigantea genome contains a conventional repertoire of hydrolase genes involved in cellulose/hemicellulose degradation, whose patterns of expression were relatively unperturbed by the absence of extractives. The expression of genes typically ascribed to lignin degradation was also largely unaffected. In contrast, genes likely involved in the transformation and detoxification of pitch were highly induced in its presence. Their products included an ABC transporter, lipases, cytochrome P450s, glutathione S-transferase and aldehyde dehydrogenase. Other regulated genes of unknown function and several constitutively expressed genes are also likely involved in P. gigantea’s pitch metabolism. These results contribute to our fundamental understanding of conifer colonization and carbon cycling processes. Phlebiopsis gigantea was cultivated in media containing one of three carbon sources: freshly harvested loblolly pine (3 replicates), acetone extracted lobollly pine (3 replicates), or glucose (2 replicates). RNA was extracted and processed for Illumina sequencing as described below.
Project description:Certain wood decay basidiomycetes, collectively referred to as brown-rot fungi rapidly depolymerize cellulose while leaving behind the bulk of cell wall lignin as a modified residue. The mechanism(s) employed are unclear, but considerable evidence implicates the involvement of diffusible oxidants, particularly hydroxyl radical. Toward a better understanding of this process, we have examined the transcriptome and secretome of Wolfiporia cocos when cultivated on media containing glucose, purified crystalline cellulose, aspen (Populus grandidentata) or lodgepole pine (Pinus contorta) as sole carbon source. Compared to glucose, 39, 331 and 357 genes exhibited 4-fold increases in transcript levels in cellulose, aspen and lodgepole pine, respectively. Mass spectrometry identified peptides corresponding to 64 glycoside hydrolase (GH) proteins and, of these, 17 corresponded to transcripts upregulated on one or both woody substrates. Most of these genes were broadly categorized as hemicellulases or chitinases. Consistent with an important role for ·OH in cellulose depolymerization, high transcript levels and upregulation were observed for genes involved in iron homeostasis, iron reduction and extracellular peroxide generation. These patterns of regulation differ markedly from the closely related brown rot fungus, Postia placenta, and expand the number of enzymes potentially involved in the oxidative depolymerization of cellulose. Medium containing glucose, microcrystalline cellulose, ground aspen or ground lodgepole pine was inoculated with W. cocos. RNA was purified from cultures. Single read 100 bp Illumina runs were performed.
Project description:The biodegradation of lignocellulose requires the disruption of its lignin, which shields the metabolically assimilable polysaccharides in this recalcitrant natural composite. Although a variety of microorganisms can attack lignocellulose, white rot basidiomycetes are uniquely efficient at this process, cleaving the recalcitrant intermonomer linkages of lignin via extracellular oxidative mechanisms and mineralizing many of the resulting fragments to carbon dioxide via intracellular processes. Considerable progress has been made in understanding this process in the model white rot fungus Phanerochaete chrysosporium, which expresses important components of its ligninolytic system in response to nutrient limitation, as part of its secondary metabolism. Biochemical and genetic evidence point to an important role in P. chrysosporium for secreted lignin peroxidases (LiPs), manganese peroxidases (MnPs), and H2O2-producing oxidases, which are thought to work together to cleave lignin into low molecular weight fragments. However, many aspects of ligninolysis by P. chrysosporium remain poorly understood. Although a definitive picture of the entire ligninolytic system in P. chrysosporium is not yet attainable, transcriptome analyses of the fungus grown on wood can provide useful clues. With the advent of the initial genome assembly and annotations (v1.0 and v2.1), microarray-based transcriptome analysis allowed examination of transcript levels of P. chrysosporium genes when grown in ball-milled wood and in defined growth media. This approach provided useful insights but was limited to 10048 v2.1 targets and complicated by the unpredictable manner in which the fungus responds to unnatural carbon sources in submerged basal salts media. A complete, fully coordinated ligninolytic system is likely not expressed by P. chrysosporium on ball-milled wood, because a potential route for regulatory feedback has been eliminated: the cellulose and hemicellulose in this substrate is readily accessible to enzymes, and thus ligninolysis is not essential for growth. An alternative approach is to compare levels of gene expression just before and after the onset of secondary metabolism and extracellular substrate oxidation by P. chrysosporium as it utilizes solid wood as its carbon source. If this can be done, and decay of the substrate is also confirmed, then the genes undergoing marked changes in expression during the metabolic transition can be identified with greater confidence. Although not all such genes are expected to have roles in biodegradation, this strategy may identify interesting candidates for future investigation. Here we report RNAseq-based transcriptomes to characterize changes in gene expression that occur during the transition to ligninolytic metabolism. Phanerochaete chrysosporium was inoculated onto thin sections of wood. RNA was purified from colonized material after 40 and 96 hours. Single read 100 bp Illumina runs were performed.
Project description:Background: Interindividual differences in liver functions such as protein synthesis, lipid and carbohydrate metabolism and drug metabolism are influenced by epigenetic factors. The role of the epigenetic machinery in such processes has, however, been barely investigated. 5-hydroxymethylcytosine (5hmC) is a recently re-discovered epigenetic DNA modification that plays an important role in the control of gene expression. Results: In this study, we investigate 5hmC occurrence and genomic distribution in 8 fetal and 7 adult human liver samples in relation to ontogeny and function. LC-MS analysis shows that in the adult liver samples 5hmc comprises up to 1% of the total cytosine content, whereas in all fetal livers it is below 0.125%. Immunohistostaining of liver sections with a polyclonal anti-5hmC antibody shows that 5hmC is detected in most of the hepatocytes. Genome-wide mapping of the distribution of 5hmC in human liver samples by next-generation sequencing shows significant differences between fetal and adult livers. In adult livers, 5hmC occupancy is overrepresented in genes involved in active catabolic and metabolic processes, whereas 5hmC elements which are found in genes exclusively in fetal livers and disappear in the adult state, are more specific to pathways for differentiation and development. Conclusions: Our findings suggest that 5-hydroxymethylcytosine plays an important role in the development and function of the human liver and might be an important determinant for development of liver diseases as well as of the interindividual differences in drug metabolism and toxicity. 8 fetal and 7 adult human liver samples
Project description:RNA-directed DNA methylation (RdDM) is a transcriptional silencing mechanism mediated by small and long noncoding RNAs produced by the plant-specific RNA polymerases Pol IV and Pol V, respectively. Through a chemical genetics screen with a luciferase-based DNA methylation reporter, LUCL, we found that camptothecin, a compound with anti-cancer properties that targets DNA topoisomerase 1α (TOP1α) was able to de-repress LUCL by reducing its DNA methylation and H3K9 dimethylation (H3K9me2) levels. Further studies with Arabidopsis top1α mutants showed that TOP1α promotes RdDM by facilitating the production of Pol V-dependent long non-coding RNAs, AGONAUTE4 recruitment and H3K9me2 deposition at transposable elements (TEs). ten bisufite libraries were sequenced
Project description:We identified an enrichment in IFN-gamma dependent genes in the prefrontal cortex of group housed mice compared to single housed mice. Mice were house either grouped or single for 6 days. Mice were euthanized and brains were removed. The prefrontal cortex was disected and prepared for RNA-seq analysis.
Project description:We used single-cell whole genome sequencing (scWGS) to assess aneuploidy in isolated neurons from the frontal cortex individuals with mild AD (Braak stage III) and individuals with advanced AD (Braak stage VI). This experiment is related to E-MTAB-4185, which contains control samples.
Project description:We used single-cell whole genome sequencing (scWGS) to assess aneuploidy in isolated neurons from the frontal cortex of control individuals. This experiment is related to E-MTAB-4184, which contains Alzheimer's disease samples.
Project description:We found that the non-essential amino acid L-proline (L-Pro) acts as a signaling molecule that promotes the conversion of embryonic stem cells (ESCs) into mesenchymal-like, spindle-shaped, highly motile, invasive pluripotent stem cells.This embryonic stem cell-to-mesenchymal-like transition (esMT) is accompanied by a genome-wide remodeling of the H3K9me3 and H3K36me3 histone marks. Examination of 2 different histone modifications in untreated ESCs and L-Pro treated ESCs