Project description:Recently, combining single-cell RNA sequencing (scRNA-seq) with upstream cell preservation procedures such as cryopreservation or methanol fixation has become more common. By separating cell handling and preparation, from downstream library generation, scRNA-seq workflows are more flexible and manageable. However, the inherent transcriptomics changes associated with cell preservation and how they may bias further downstream analysis remain unknown. Here, we present a side-by-side droplet-based scRNA-seq analysis, comparing the gold standard – fresh cells – to three different cell preservation workflows: dimethyl sulfoxide based cryopreservation, methanol fixation and CellCover reagent. Cryopreservation proved to be the most robust protocol, maximizing both cell integrity and low background ambient RNA. Importantly, gene expression profiles from fresh cells correlated most with those of cryopreserved cells. Such similarities were consistently observed across the tested cell lines (R ≥ 0.97), monocyte-derived macrophages (R = 0.97) and immune cells (R = 0.99). In contrast, both methanol fixation and CellCover preservation showed an increased ambient RNA background and an overall lower gene expression correlation to fresh cells. Thus, our results demonstrate the superiority of cryopreservation over other cell preservation methods. We expect our comparative study to provide single cell omics researchers invaluable support when integrating cell preservation into their scRNA-seq studies.
Project description:Recently, combining single-cell RNA sequencing (scRNA-seq) with upstream cell preservation procedures such as cryopreservation or methanol fixation has become more common. By separating cell handling and preparation, from downstream library generation, scRNA-seq workflows are more flexible and manageable. However, the inherent transcriptomics changes associated with cell preservation and how they may bias further downstream analysis remain unknown. Here, we present a side-by-side droplet-based scRNA-seq analysis, comparing the gold standard – fresh cells – to three different cell preservation workflows: dimethyl sulfoxide based cryopreservation, methanol fixation and CellCover reagent. Cryopreservation proved to be the most robust protocol, maximizing both cell integrity and low background ambient RNA. Importantly, gene expression profiles from fresh cells correlated most with those of cryopreserved cells. Such similarities were consistently observed across the tested cell lines (R ≥ 0.97), monocyte-derived macrophages (R = 0.97) and immune cells (R = 0.99). In contrast, both methanol fixation and CellCover preservation showed an increased ambient RNA background and an overall lower gene expression correlation to fresh cells. Thus, our results demonstrate the superiority of cryopreservation over other cell preservation methods. We expect our comparative study to provide single cell omics researchers invaluable support when integrating cell preservation into their scRNA-seq studies.
Project description:Longitudinal analysis of Salmonella typhimurium mRNA from superspeader mouse cecal content and stool compared to in vitro Salmonella typhimurium mRNA.
Project description:Cardioviruses are a genus of picornaviruses that cause severe illnesses in rodents, but little is known about the prevalence, diversity, or spectrum of disease of such agents among humans. We report the identification of a group of human cardioviruses that have been detected and cloned directly from patient specimens (Chiu and DeRisi, et al, PNAS, 2008). This series includes 9 arrays (both raw and normalized data) used to detect cardioviruses in human respiratory and stool specimens. The arrays employed here are capable of pan-viral detection (Wang and DeRisi, et al., PNAS, 2002). Keywords: viral detection, cardiovirus, TMEV, gastroenteritis The series includes 3 arrays from respiratory samples and 6 arrays from stool samples. Among the 3 arrays from respiratory sample, 1 array has a signature for an adenovirus, 1 array has a signature for human metapneumovirus, and 1 array has a signature for cardiovirus UC1 (see Chiu and DeRisi, et al., PNAS, in 2008). All 6 arrays from stool samples are cardiovirus-positive; some show evidence of dual infection with other gastroenteritis viruses (i.e. norovirus, rotavirus, etc.). Data in Sample records fed to E-Predict (Urisman, et al, Genome Biology, 2005) E-Predict normalization metrics Array Normalization: Sum E-Matrix Normalization: Quadratic Distance Metric: Pearson Uncentered
Project description:Understanding gene expression by bacteria during the actual course of human infection may provide important insights into microbial pathogenesis. In this study, we evaluated the transcriptional profile of Vibrio cholerae, the causative agent of cholera, in clinical specimens from cholera patients. We collected samples of human stool and vomitus that were positive by dark-field microscopy for abundant vibrios and used a microarray to compare gene expression in organisms recovered directly from the early and late stages of human infection. Our results reveal that V. cholerae gene expression within the human host environment differs from patterns defined in in vitro models of pathogenesis. tcpA, the major subunit of the essential V. cholerae colonization factor, was significantly more highly expressed in early compared with late infection; however, the genes encoding cholera toxin were not highly expressed in either phase of human infection. Furthermore, expression of the virulence regulators, toxRS and tcpPH, was uncoupled. Interestingly, the pattern of gene expression indicates that the human upper intestine may be a uniquely suitable environment for the transfer of genetic elements that are important in the evolution of pathogenic strains of V. cholerae. These findings provide a more detailed assessment of the transcriptome of V. cholerae in the human host than previous studies of organisms in stool alone and have implications for cholera control and the design of improved vaccines. The V. cholerae microarray consists of 3,890 full-length PCR products representing the annotated open reading frames from the initial release of the V. cholerae N16961 genome. Each labeling and hybridization was performed in duplicate. Genomic DNA was used as a universal internal control for the quality of the microarray and to allow for the comparison of results across multiple experiments. Data were normalized using locally-weighted regression (Lowess) to obtain the relative abundance of each transcript as an intensity ratio with respect to that of genomic DNA. High correlation coefficients were observed between technical replicates (Pearsonâs correlation coefficient (r) > 0.80) and between results of separate clinical specimens of vomitus (r > 0.77) and of stool (r > 0.80). Hence, the results from the two clinical vomitus specimens and the five clinical stool specimens were pooled. Fold changes for the relative expression of a given gene between the two clinical specimens were calculated by dividing the normalized median intensity ratios with respect to genomic DNA.