Project description:Freshwater ecosystems can be largely affected by neighboring agriculture fields where potential fertilizer nitrate run-off may leach into surrounding water bodies. To counteract this eutrophic driver, farmers often utilize denitrifying woodchip bioreactors (WBRs) in which a consortium of microorganisms convert the nitrate into nitrogen-gases in anoxia, fueled by the degradation of lignocellulose. Polysaccharide-degrading strategies have been well-described for various aerobic and anaerobic systems, including the use of carbohydrate-active enzymes, utilization of lytic polysaccharide monooxygenases (LPMOs) and other redox enzymes, as well as the use of cellulosomes and polysaccharide utilization loci. However, for denitrifying microorganisms, the lignocellulose-degrading strategies remain largely unknown. Here, we have applied a combination of enrichment techniques, gas measurements, multi-omics approaches, and amplicon sequencing of fungal ITS and procaryotic 16S rRNA genes to highlight microbial drivers for lignocellulose transformation in woodchip bioreactors with the aim to provide an in-depth characterization of the indigenous microorganisms and their active enzymes. Our findings highlight a microbial community enriched for lignocellulose-degrading denitrifiers with key players from Giesbergeria, Cellulomonas, Azonexus, and UBA5070, including polysaccharide utilization loci from Bacteroidetes. A wide substrate specificity is observed among the many expressed carbohydrate active enzymes (CAZymes), evidencing a swift degradation of lignocellulose, including even enzymes with auxiliary activities whose functionality is still puzzling under strict anaerobic conditions.
Project description:Physiologically based pharmacokinetic (PBPK) models were developed using MATLAB Simulink(®) to predict diurnal variations of endogenous melatonin with light as well as pharmacokinetics of exogenous melatonin via different routes of administration. The model was structured using whole body, including pineal and saliva compartments, and parameterized based on the literature values for endogenous melatonin. It was then optimized by including various intensities of light and various dosage and formulation of melatonin. The model predictions generally have a good fit with available experimental data as evaluated by mean squared errors and ratios between model-predicted and observed values considering large variations in melatonin secretion and pharmacokinetics as reported in the literature. It also demonstrates the capability and usefulness in simulating plasma and salivary concentrations of melatonin under different light conditions and the interaction of endogenous melatonin with the pharmacokinetics of exogenous melatonin. Given the mechanistic approach and programming flexibility of MATLAB Simulink(®), the PBPK model could provide predictions of endogenous melatonin rhythms and pharmacokinetic changes in response to environmental (light) and experimental (dosage and route of administration) conditions. Furthermore, the model may be used to optimize the combined treatment using light exposure and exogenous melatonin for maximal phase advances or delays
Model is encoded by Ruby and submitted to BioModels by Ahmad Zyoud.
2020-03-20 | MODEL2003190006 | BioModels
Project description:Study on Sulfur Autotrophic Denitrifying Microorganisms
Project description:The conserved core domain of the TATA binding protein (TBP) interacts with multiple partners forming the complexes required for transcription by RNA Polymerases I, II and III. We use genetically modified mouse embryonic fibroblasts to show that many TBP core domain mutants complement loss of endogenous TBP, but this often results in a slow growth phenotype. Two TBP mutations, R188E and K243E, disrupt the TBP-BTAF1 interaction and B-TFIID complex formation. Transcriptome and ChIP-seq analyses show that loss of B-TFIID does not affect global genomic distribution of TBP, but positively or negatively affects TBP and/or RNA Polymerase II (Pol II) recruitment to a selected set of promoters. We identify a set of promoters where wild-type TBP assembles a partial inactive preinitiation complex lacking Pol II and TAF1. Our results suggest that an exchange of the B-TFIID complex in wild-type cells for TFIID in R188E and K243E mutant cells at these primed promoters recruits Pol II to activate their expression. We also observe that both Wt and mutant TBP can occupy promoters without concurrent Pol II recruitment and active transcription. Our data reveal a novel regulatory mechanism involving the formation of a partial preinitiation complex that primes the promoter for productive preinitiation complex formation in mammalian cells. Using homologous recombination, we generated ES cells and mice harbouring a null allele in the Tbp gene by insertion of a hygromycin resistance cassette in exon III and a floxed allele, in which exon III is surrounded by LoxP sites. From these mice, we generated an embryonic fibroblast Tbplox/- cell line in which TBP expression can be inactivated by expression of the Cre recombinase leading to cell death. We adopted a two-step strategy to generate Tbp-/- cell lines expressing human (h)TBP. Cells were first infected with pBABE retrovirus vectors expressing Wt hTBP or a series of mutants in the TBP core region, all of which carry a Flag-HA tag on their N-terminus. Cells expressing endogenous mTBP and exogenous hTBP were then infected with a second retrovirus expressing the 4 hydroxy-tamoxifen (OHT) inducible Cre-ERT2. Subsequently, multiple clonal populations from the OHT treated cells were isolated and genotyped by PCR to identify the Tbp-/-clones. At least two independent clones where expression of the endogenous mTBP was lost and replaced by the exogenous hTBP were isolated.
Project description:We report the application of single-molecule-based sequencing technology for REST and its cofactors genome wide binding sites in E14 cells.We then combine these binding sirtes with REST regulating gene profiling, to understand REST binding and regulation in E14 cells. Examination of REST and 5 cofactors(RCOR1, RCOR2,RCOR3,SIN3A,SIN3B) in E14 cells, REST and SIN3A endogenous antibody were used for ChIP experiment. The stable E14 cells expressing low level exogenous RCOR1, RCOR2, RCOR3,and SIN3B with V5 tag were used for ChIP experiment with V5 antibody to obtain individual ChIP DNA.
Project description:In C. elegans worms, epigenetic information transmits transgenerationally. Still, it is unknown whether the effects transfer to the next generation inside or outside of the nucleus. Here we use the tractability of gene-specific double-stranded RNA-induced silencing to demonstrate that RNAi can be inherited independently of any nuclear factors via mothers that are genetically engineered to transmit only their ooplasm but not the oocytes’ nuclei to the next generation. We characterize the mechanisms and, utilizing RNA sequencing, chimeric worms and sequence polymorphism between different isolates, identify endogenous small RNAs which, similarly to exogenous siRNAs, are inherited in a nucleus-independent manner. From an historical perspective, these results might be regarded as partial vindication of discredited cytoplasmic inheritance theories from the 19th century, such as Darwin’s “pangenesis” theory.
Project description:Argonaute-associated siRNAs and Piwi-associated piRNAs have overlapping roles in silencing mobile genetic elements in animals. In C. elegans, mutator-class (mut) genes mediate siRNA-guided repression of transposons as well as exogenous RNA-directed gene silencing (RNAi), but their roles in endogenous RNA silencing pathways are not well understood. To characterize the endogenous small RNAs dependent on mutator-class genes, small RNA populations from a null allele of mut-16, as well as a regulatory mut-16(mg461) allele that disables only somatic RNAi, were subjected to deep sequencing.
Project description:The conversion of cell fates is controlled by hierarchical gene regulatory networks (GRNs) that induce remarkable alterations of cellular and transcriptome states. The identification of key regulators within these networks from myriad of candidate genes, however, poses a major research challenge. Here we present Convert-seq, combining single-cell RNA sequencing (scRNA-seq) and pooled (mutiplexed) ectopic gene expression with a new strategy to discriminate sequencing reads derived from exogenous and endogenous transcripts. We demonstrate Convert-seq by associating hundreds of single cells at multiple time-points during direct conversion of human fibroblasts to induced neurons (iN) with exogenous and endogenous transcriptional signatures. Convert-seq simultaneously identified GRNs that modulate the emergence of parallel developmental trajectories during iN conversion and predicted combinatorial interactions of exogenous transcription factors controlling iN subtype specification. Validation of iN subtypes generated by novel combinations of exogenous transcription factors establish Convert-seq as a broadly applicable workflow to rapidly identify key transcription factors and GRNs orchestrating the direct conversion of virtually any cell type.