Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Comprehensive gene expression analysis of Bruce-4 embryonic stem cells by SAGE

ABSTRACT: Mouse embryonic stem cells lines derived from different mouse strains show considerable variation concerning their culture conditions, gene targeting efficiency and germ line transmission capacity. To gain insight into the basis for this phenomenon, we generated a SAGE library of the C57BL/6 derived ES cell line Bruce-4 and compared their gene expression to 129 strain-derived cells, which in general show the best performance in gene targeting experiments. Gene Ontology (GO) analyses for functional groups of genes demonstrated considerably higher expression of clusters indicating cellular differentiation as well as cell-cell and cell-matrix adhesion in R1 than in Bruce-4 cells. At the single gene level, almost 90% of the most strongly expressed transcripts in each library were significantly differential. Regarding transcripts that have been linked to stem cell state, seven of the 20 selected genes were expressed in both cell lines, eleven showed stronger expression in Bruce-4 ES cells and only one in R1 cells. These results suggest that expression of “stemness” genes cannot be used as a sole criterion for efficiency of ES cells in gene targeting experiments. Keywords: Embryonic stem cells, SAGE, gene expression profile We generated a SAGE library of the C57BL/6-derived ES cell line Bruce-4 and compared their gene expression to an already available SAGE library of 129-derived R1 ES cells generated by Anisimov et al (GSM72878).

ORGANISM(S): Mus musculus

SUBMITTER: Sandra Pennartz

PROVIDER: E-GEOD-9078 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The abundant and widespread coccolithophore Emiliania huxleyi plays an important role in mediating CO2 exchange between the ocean and the atmosphere through its impact on marine photosynthesis and calcification. Here, we use long serial analysis of gene expression (SAGE) to identify E. huxleyi genes responsive to nitrogen (N) or phosphorus (P) starvation. Long SAGE is an elegant approach for examining quantitative and comprehensive gene expression patterns without a priori knowledge of gene sequences via the detection of 21-bp nucleotide sequence tags. E. huxleyi appears to have a robust transcriptional-level response to macronutrient deficiency, with 42 tags uniquely present or up-regulated twofold or greater in the N-starved library and 128 tags uniquely present or up-regulated twofold or greater in the P-starved library. The expression patterns of several tags were validated with reverse transcriptase PCR. Roughly 48% of these differentially expressed tags could be mapped to publicly available genomic or expressed sequence tag (EST) sequence data. For example, in the P-starved library a number of the tags mapped to genes with a role in P scavenging, including a putative phosphate-repressible permease and a putative polyphosphate synthetase. In short, the long SAGE analyses have (i) identified many new differentially regulated gene sequences, (ii) assigned regulation data to EST sequences with no database homology and unknown function, and (iii) highlighted previously uncharacterized aspects of E. huxleyi N and P physiology. To this end, our long SAGE libraries provide a new public resource for gene discovery and transcriptional analysis in this biogeochemically important marine organism. Keywords: Emiliania, gene expression, nutrients, SAGE, phosphate, nitrogen Emiliania huxleyi CCMP 1516 was obtained from the Provasoli-Guillard Center for the Culture of Marine Phytoplankton, Bigelow Laboratories. Cultures were grown at 18°C on a 14 h:10 h light:dark cycle (140 µmol quanta m-2 s-1). Nitrogen and phosphate replete (Replete: 35 µM NO3- and 1.5 µM PO43-), low nitrogen (-N: 10 µM NO3-) and low phosphate (-P: 0 µM PO43-) cells were grown in f/50 medium without Si. Locally collected seawater was filtered (pore size, 0.2 µm) and autoclaved. Filter-sterilized inorganic nutrients, trace metals and vitamins (thiamin, biotin and B12) were added after autoclaving. The cells were grown in 8 L batch cultures. The growth of cultures was monitored daily by cell number counted on a hemacytometer, and by relative fluorescence using a Turner Designs AU Fluorometer. Replete cells were harvested in mid-log phase while –N and –P cells were harvested at the onset of stationary phase for SAGE analysis.

Project description:Perennial ryegrass (Lolium perenne L.) is a major grass species used for forage and turf throughout the world, and gains by conventional breeding have reached a plateau. Perennial ryegrass is an outcrossing, self-incompatible diploid (2n = 2x = 14) with a relatively large genome (4067 Mbp/diploid genome; Evans, G.M., Rees, H., Snell, C.L. and Sun, S. (1972). The relation between nuclear DNA amount and the duration of the mitotic cycle. Chrom. Today, 3, 24–31). Using tissues sourced from active pastures during the peak of the autumn, winter, spring and summer seasons, we analysed the ryegrass transcriptome employing a Serial Analysis of Gene Expression (SAGE™) protocol, with the dual goals of understanding the seasonal changes in perennial ryegrass gene expression and enhancing our ability to select genes for genetic manipulation. A total of 159 002 14-mer SAGE™ tags was sequenced and mapped to the perennial ryegrass DNA database, comprising methyl-filtered (GeneThresher®) and expressed sequence tag (EST) sequences. The analysis of 14 559 unique SAGE™ tags, which were present more than once in our SAGE™ library, revealed 964, 1331, 346 and 131 exclusive transcripts to autumn, winter, spring and summer, respectively. Intriguingly, our analysis of the SAGE™ tags revealed season-specific expression profiles for the small subunit of ribulose-1,5-bisphosphate carboxylase (Rubisco), LprbcS. The transcript level for LprbcS was highest in spring, and then decreased gradually between summer and winter. Five different copies of LprbcS were revealed in ryegrass, with one possibly producing splice variant transcripts. Two highly expressed LprbcS genes were reported, one of which was not active in autumn. Another LprbcS gene showed an inverse expression profile to the autumn inactive LprbcS in a manner to compensate the expression level. Keywords: paddock samples, pasture, perennial ryegrass, Serial Analysis of Gene Expression (SAGE™), season specific expression, monocot Ryegrass tissue Perennial ryegrass (Lolium perenne L.) cv. Bronsyn was used throughout this study. Field-grown samples, comprising mainly viable leaves and pseudostems, were collected at midday from livestock-active monocultural paddocks at Dexcel, Hamilton, New Zealand during the peak of each season, and frozen immediately in liquid nitrogen. Samples were transported in dry-ice and stored at ?80 oC until use. During spring and summer, care was taken not to include any floral stems in the tissue sample. Grass samples were collected from pregrazed (15–60 days post-grazing) and post-grazed (1 day post-grazing) ryegrass swards, which were visibly healthy and free of any pests. Construction of SAGE™ libraries RNA was extracted using TRIZOL® reagent (Invitrogen, Carlsbad,CA, USA). For each SAGE™ library, 100 ug of pre- and post-grazed sample-derived total RNA was employed, and the libraries were created using an I-SAGE™ or I-SAGE™Long Kit (Invitrogen) according to the manufacturer’s protocol. Pre- and post-grazed SAGE™ libraries were sequenced at the Australian Genome Research Facility (Brisbane, Australia), and the tags were extracted using SAGE2000 software and combined to produce the transcript profile for the season.

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Comprehensive gene expression analysis of Bruce-4 embryonic stem cells by SAGE

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