Project description:Transcriptional profiling of A. niger comparing different strains (WT, M-NM-^TXlnR, M-NM-^TaraR and M-NM-^TaraRM-NM-^TXlnR) treated with 25mM xylose + 25mM arabinose for 2 and 8h. The main objective was to identifiy genes related to primary metabolism and carbohydrate metabolism in general, for instance, cellulases and hemicellulases. The study will compare the differences between WT strain and the strains with the disrupted xylanolytic transcriptional activator gene, XlnR, the arabinolytic transcriptional activator gene, AraR, and the double mutant,after treatment with xylose+arabinose (XA treatment). The experiment was further validated by real-time PCR and enzymatic assays. Two-condition experiment : A. niger mutant strains on XA for 2 and 8 h at 30 oC in batch culture. Firstly, the strains were pre-grown in minimal medium with fructose as carbon source (control), and then transferred to xylose+arabinose (25 mM each) as carbon source.
Project description:Sirtuins are deacetylases implicated in stress responses and longevity in mammals. Although their differential impact on the two sexes has been noted, underlying causes for sex biases in aging and cancer are not known. Here, using Sirtuin 7 (SIRT7) as a model in mice, we probe mechanisms leading to sex differences. We find that Sirt7-/- females have decreased fitness during embryogenesis and throughout life. Intriguingly, SIRT7 preferentially localizes to the X-chromosome, suggesting a potential defect in X-inactivation — the arm of dosage compensation that equalizes X-chromosome expression between XX females and XY males. Indeed, SIRT7 ablation causes increased Xist RNA levels, H3K27me3 enrichment, and gene repression on the inactive X (Xi) chromosome. Surprisingly, however, loss of SIRT7 exerts greatest effects on the active X (Xa). In Sirt7-/- females, the Xa demonstrates 3D structural disorganization, increased chromatin mixing, and acute propensity to break and form chromosome fusions in an Xa-specific manner. Disproportional to autosomes and Xi, the Xa becomes super-acetylated on H3K36 and super-activated in gene expression, resulting in an imbalance in the 2nd arm of dosage compensation — known as “Xa-hyperactivation” — which evolved to balance X-linked gene expression against the genome. These data reveal a crosstalk between sirtuins and dosage compensation and identify a novel regulator of Xa-hyperactivation.
Project description:Transcriptional profiling of A. niger comparing different strains (WT, ΔXlnR, ΔaraR and ΔaraRΔXlnR) treated with 25mM xylose + 25mM arabinose for 2 and 8h. The main objective was to identifiy genes related to primary metabolism and carbohydrate metabolism in general, for instance, cellulases and hemicellulases. The study will compare the differences between WT strain and the strains with the disrupted xylanolytic transcriptional activator gene, XlnR, the arabinolytic transcriptional activator gene, AraR, and the double mutant,after treatment with xylose+arabinose (XA treatment). The experiment was further validated by real-time PCR and enzymatic assays.
Project description:In naïve human pluripotent stem cells (hPSCs) that represent the pre-implantation embryonic states, epigenetic regulators for cell identity remain poorly defined. One of the major remaining questions in naïve stem cell biology is how female cells mediate and regulate X chromosome inactivation (XCI). Recent studies incorporating single-cell RNA sequencing (scRNA-seq) have demonstrated that transcript-based technologies are insufficient to unequivocally resolve XCI regulation in a human system. Instead, 3D genomics shows immense promise for studying XCI by interrogating changes to the X chromosomes’ 3D states. Here, we sought to characterize the 3D state of the X chromosome in naïve and primed hPSCs. Using chromatin tracing, we analyzed the folding conformations of whole X chromosomes with megabase genomic resolution in multiple naïve and primed hPSC lines. Our data found that X chromosomes in female naive hPSCs exhibit a range of spatial folding conformations similar to the active X chromosome (Xa) and the inactive X chromosome (Xi) in somatic cells; these data suggest that naïve hPSCs have initiated XCI. As XCI process ultimately generates detectable differences in volume between the Xa and the Xi, we measured the radius of gyration of individual X chromosome copies across various hPSC cell lines and culture conditions. In naïve hPSCs, our results show that the X chromosomes with Xi-like conformations are not more compact than those with Xa-like conformation. This finding is directly counter to the Xi compaction typically observed in post-XCI female somatic cells. These contradictory 3D signatures of XCI suggest that female naïve hPSCs have initiated the XCI process, but are poised before XCI-driven silencing in a metastable state. As observed in H7 naïve hPSCs, this metastable state can be abolished through classically noted means, such as the loss of Xp chromatin, leading to the deleted p X chromosome (dXp). The Xp loss observed here seems to drive XIST expression and accumulation around the dXp chromosome. Overall, our findings provide insight into the previously undefined X chromosome status in naïve hPSCs in single chromosome resolution, and are critical in understanding the unique epigenetic regulation in early embryonic cells.
Project description:This genome-scale metabolic model (GEM) of Corynebacterium tuberculostearicum strain DSM 44922 (Taxon ID 38304) was initially built with CarveMe version 1.5.1 based on the genome assembly with NCBI accession GCF_013408445.1 and then underwent a series of careful semi-automatic and manual curation. It is the first model curated using the Python tool MCC for mass and charge curation.