Project description:Background: Pyrazinamide (PZA) plays an essential part in the shortened 6-month tuberculosis (TB) treatment course due to its activity against slow-growing, semi-dormant organisms. We tested the paradigm that PZA preferentially targets slow growing cells of Mycobacterium tuberculosis that remain after the initial kill by isoniazid, by observing the response of either slow growing or fast growing bacilli to differing concentrations of PZA. Methods: M. tuberculosis H37Rv was grown in continuous culture at either a constant fast growth rate (Mean Generation Time [MGT] of 23.1 h) or slow growth rate (69.3 h MGT) at a controlled dissolved oxygen tension of 10% and a controlled acidity at pH 6.3 ± 0.1. The cultures were exposed to step-wise increases in the concentration of PZA (25 µg ml-1 to 250 µg ml-1) every 2 MGTs, and bacterial survival was measured. PZA-induced global gene expression was explored for each increase in PZA-concentration, using microarray.
Project description:Chemostats have been used for decades in studying cell growth under controlled environments. Whole transcriptome sequencing by RNA-seq is a relatively new method for gene expression analysis. We utilized both tools for expression analysis of Pseudomonas aeruginosa growing slowly in synthetic cystic fibrosis medium under growth-limiting nitrate and oxygen levels. We established steady-state cultures under two divergent growth rates and found that during slower growth at a doubling time of 9.8 h, 76 known quorum genes were up-expressed while just 11 were down-expressed. Quorum-controlled genes were also more expressed in response to oxygen limitation. 21% of up-expressed genes under slow, oxygen-limited growth are quorum controlled while just 6% are up-expressed under slow, nitrate-limited growth. We found that the autoinducer for regulator RhlR, C4-HSL, is ~3.4 times higher when cells are growing slowly under oxygen limitation while the concentration of the autoinducer for LasR remained unchanged. Experiments with deletion mutants show the importance of rhlR for expression of quorum-controlled genes under slow, oxygen-limited conditions. This is an intriguing observation since P. aeruginosa is likely growing in similar environments in the cystic fibrosis lung, and lasR mutations are known to arise during chronic infection.
2016-12-01 | GSE71880 | GEO
Project description:Luedemann Hypothesis: The Discovery of Novel Antimicrobials from Slow-Growing Microbes in Nutrient Limited Environments
Project description:Squamous cell carcinoma arising from mature teratoma (SCC-MT) is one of the rare ovarian malignancies. Therefore, the molecular background of SCC-MT remains largely unelucidated. In this study, we performed the spatial transcriptomics for SCC-MT.
Project description:Colorectal cancer (CRC) is characterized by extensive intra-tumor heterogeneity. The cancer stem cell (CSC) theory may explain the mechanisms underlying the non-genetic heterogeneity and their characteristics of prominent plasticity are emerging to be elucidated. By tracking the spheroid formation and growth capacity of CRC CSCs with a single-cell resolution using an organoid culture, we revealed CSCs consisted of subpopulations with a dual (fast and slow)-growing pattern. When isolated, the slow-growing CSCs remained slow-growing and converted into dual-growing CSCs under certain conditions. The slow-growing cells showed low levels of MAP kinase activity and were resistant to a MEK1/2 inhibitor as well as chemo-drugs. The MSI1 gene was down-regulated in the slow-growing CSCs and played a key role in the transition between slow- and dual-growing CSCs. Isolation of slow-growing CSCs will provide a platform to elucidate the role of the plasticity of CSCs in drug resistance and tumor recurrence. To disclose the molecular characteristics of the CSC subclones with the distinct growth features, we analyzed the differentially expressed genes between the subgroups.
2021-10-01 | GSE185012 | GEO
Project description:Bacterial communities in aquatic environments
| PRJNA877039 | ENA
Project description:Fungal communities in aquatic environments
Project description:Melanomas are genetically heterogeneous, displaying mitogen-activated protein kinase mutations and homozygous loss of tumor suppressor genes. Mouse models combining such mutations produce fast-growing, pigmented tumors. In contrast, rare, slow-growing, lowly-pigmented tumors arise in mice combining Braf activation with heterozygous loss of Pten or, as we show here, in albino mice bearing only a Braf mutation. Incidence kinetics suggest a stochastic event underlies tumorigenesis, but responsible de novo mutations or structural variants were not found. Single-cell transcriptomics of tumors identified a cell type resembling “neural crest-like” cells in human and mouse melanomas. These exist in normal mouse skin, expand upon Braf activation, and persist through serial transplantation; analyses of gene expression suggest they serve as precursors of malignant cells. This state may serve as an intermediate on a slow path to malignancy that, while not abundant in fast-growing, heavily-mutated tumors, may provide a diagnostically and therapeutically important source of cellular heterogeneity.