Method for absolute quantification of microbial communities by using both microarrays and competitive PCR
Ontology highlight
ABSTRACT:
ORGANISM(S): Campylobacter rectus Prevotella intermedia Acinetobacter baumannii Streptococcus intermedius Neisseria meningitidis Streptococcus gordonii Streptococcus agalactiae Pseudomonas aeruginosa Streptococcus mutans Staphylococcus epidermidis Cereibacter sphaeroides Bacillus cereus Prevotella nigrescens Cutibacterium acnes Porphyromonas gingivalis Tannerella forsythia Treponema denticola Escherichia coli Fusobacterium nucleatum Lactobacillus gasseri Enterococcus faecalis Homo sapiens Capnocytophaga gingivalis Bacteria Helicobacter pylori Phocaeicola vulgatus Bifidobacterium adolescentis Aggregatibacter actinomycetemcomitans Schaalia odontolytica Staphylococcus aureus Deinococcus radiodurans Clostridium beijerinckii Fusobacterium nucleatum subsp. nucleatum
PROVIDER: GSE125085 | GEO | 2019/01/16
REPOSITORIES: GEO
Similar Datasets
Project description:Method for absolute quantification of microbial communities by using both microarrays and competitive PCR
| PRJNA515193 | ENA
Project description:High-throughput amplicon sequencing has become a well-established approach for microbial community profiling. Correlating shifts in the relative abundances of bacterial taxa with environmental gradients is the goal of many microbiome surveys. As the abundances generated by this technology are semi-quantitative by definition, the observed dynamics may not accurately reflect those of the actual taxon densities. We combined the sequencing approach (16S rRNA gene) with robust single-cell enumeration technologies (flow cytometry) to quantify the absolute taxon abundances. A detailed longitudinal analysis of the absolute abundances resulted in distinct abundance profiles that were less ambiguous and expressed in units that can be directly compared across studies. We further provide evidence that the enrichment of taxa (increase in relative abundance) does not necessarily relate to the outgrowth of taxa (increase in absolute abundance). Our results highlight that both relative and absolute abundances should be considered for a comprehensive biological interpretation of microbiome surveys.
| S-EPMC5270559 | biostudies-literature
Project description:MicroRNAs (miRNAs) have been shown to play an important role in many different cellular, developmental, and physiological processes. Accordingly, numerous methods have been established to identify and quantify miRNAs. The shortness of miRNA sequence results in a high dynamic range of melting temperatures and, moreover, impedes a proper selection of detection probes or optimized PCR primers. While miRNA microarrays allow for massive parallel and accurate relative measurement of all known miRNAs, they have so far been less useful as an assay for absolute quantification. Here, we present a microarray based approach for global and absolute quantification of miRNAs. The method relies on an equimolar pool of about 1000 synthetic miRNAs of known concentration which is used as an universal reference and labeled and hybridized in a dual colour approach on the same array as the sample of interest. Each single miRNA is quantified with respect to the universal reference outbalancing bias related to sequence, labeling, hybridization or signal detection method. We demonstrate the accuracy of the method by various spike in experiments. Further, we quantified miRNA copy numbers in liver samples and CD34(+)CD133(-) hematopoietic stem cells.
2009-10-27 | GSE15835 | GEO
Project description:Microarrays are useful tools for detecting and quantifying specific functional and phylogenetic genes in natural microbial communities. In order to track uncultivated microbial genotypes and their close relatives in an environmental context, we designed and implemented a “genome proxy” microarray that targets microbial genome fragments recovered directly from the environment. Fragments consisted of sequenced clones from large-insert genomic libraries from microbial communities in Monterey Bay, the Hawaii Ocean Time-series station ALOHA, and Antarctic coastal waters. In a prototype array, we designed probe sets to thirteen of the sequenced genome fragments and to genomic regions of the cultivated cyanobacterium Prochlorococcus MED4. Each probe set consisted of multiple 70-mers, each targeting an individual ORF, and distributed along each ~40-160kbp contiguous genomic region. The targeted organisms or clones, and close relatives, were hybridized to the array both as pure DNA mixtures and as additions of cells to a background of coastal seawater. This prototype array correctly identified the presence or absence of the target organisms and their relatives in laboratory mixes, with negligible cross-hybridization to organisms having ≤~75% genomic identity. In addition, the array correctly identified target cells added to a background of environmental DNA, with a limit of detection of ~0.1% of the community, corresponding to ~10^3 cells/ml in these samples. Signal correlated to cell concentration with an R2 of 1.0 across six orders of magnitude. In addition the array could track a related strain (at 86% genomic identity to that targeted) with a linearity of R2=0.9999 and a limit of detection of ~1% of the community. Closely related genotypes were distinguishable by differing hybridization patterns across each probe set. This array’s multiple-probe, “genome-proxy” approach and consequent ability to track both target genotypes and their close relatives is important for the array’s environmental application given the recent discoveries of considerable intra-population diversity within marine microbial communities. Keywords: target addition experiment, proof-of-concept for GPL6012
2007-10-31 | GSE9384 | GEO
Project description:MicroRNAs (miRNAs) have been shown to play an important role in many different cellular, developmental, and physiological processes. Accordingly, numerous methods have been established to identify and quantify miRNAs. The shortness of miRNA sequence results in a high dynamic range of melting temperatures and, moreover, impedes a proper selection of detection probes or optimized PCR primers. While miRNA microarrays allow for massive parallel and accurate relative measurement of all known miRNAs, they have so far been less useful as an assay for absolute quantification. Here, we present a microarray based approach for global and absolute quantification of miRNAs. The method relies on an equimolar pool of about 1000 synthetic miRNAs of known concentration which is used as an universal reference and labeled and hybridized in a dual colour approach on the same array as the sample of interest. Each single miRNA is quantified with respect to the universal reference outbalancing bias related to sequence, labeling, hybridization or signal detection method. We demonstrate the accuracy of the method by various spike in experiments. Further, we quantified miRNA copy numbers in liver samples and CD34(+)CD133(-) hematopoietic stem cells. Total liver RNA was mixed with 2.5 fmol of each of 18 RNA oligonucleotides reverse complement to miRControl 3 probes and subsequently fluorescently labelled by 3â ligation. Total RNA mix was hybridized in a dual colour approach to microarrays versus a second labelled synthetic miRNA pool (n = 6). The synthetic miRNA pool consisted of 2.5 fmol of each of 891 non redundant miRNAs sequences and miRControl 3 sequences. The array data was normalized by calculating the median of the miRControl 3 present in the liver and UR sample. The miRNA amount was calculated with respect to the corresponding miRNA in the UR.
2010-06-20 | E-GEOD-15835 | biostudies-arrayexpress
Project description:Microarrays are useful tools for detecting and quantifying specific functional and phylogenetic genes in natural microbial communities. In order to track uncultivated microbial genotypes and their close relatives in an environmental context, we designed and implemented a âgenome proxyâ microarray that targets microbial genome fragments recovered directly from the environment. Fragments consisted of sequenced clones from large-insert genomic libraries from microbial communities in Monterey Bay, the Hawaii Ocean Time-series station ALOHA, and Antarctic coastal waters. In a prototype array, we designed probe sets to thirteen of the sequenced genome fragments and to genomic regions of the cultivated cyanobacterium Prochlorococcus MED4. Each probe set consisted of multiple 70-mers, each targeting an individual ORF, and distributed along each ~40-160kbp contiguous genomic region. The targeted organisms or clones, and close relatives, were hybridized to the array both as pure DNA mixtures and as additions of cells to a background of coastal seawater. This prototype array correctly identified the presence or absence of the target organisms and their relatives in laboratory mixes, with negligible cross-hybridization to organisms having â¤~75% genomic identity. In addition, the array correctly identified target cells added to a background of environmental DNA, with a limit of detection of ~0.1% of the community, corresponding to ~10^3 cells/ml in these samples. Signal correlated to cell concentration with an R2 of 1.0 across six orders of magnitude. In addition the array could track a related strain (at 86% genomic identity to that targeted) with a linearity of R2=0.9999 and a limit of detection of ~1% of the community. Closely related genotypes were distinguishable by differing hybridization patterns across each probe set. This arrayâs multiple-probe, âgenome-proxyâ approach and consequent ability to track both target genotypes and their close relatives is important for the arrayâs environmental application given the recent discoveries of considerable intra-population diversity within marine microbial communities. Keywords: target addition experiment, proof-of-concept for GPL6012 ***Overall Array design*** The prototype microarray targeted thirteen BAC or fosmid genome fragments (20-160kb) from both bacteria and archaea, recovered from a variety of marine habitats, as well as the cyanobacterium Prochlorococcus MED4. These clones were originally sequenced because of the presence of taxonomic marker or specific functional genes. This array consisted of sets of 70-bp oligonucleotides targeting each genome or genome fragment (Fig. 1), dispersed along the target sequences with no more than one probe per gene, and excluding rRNA genes as targets. The probes were selected solely based on theoretical thermodynamic properties and GC content (~40%); that is, probe selection did not focus on specific genes or regions, but simply produced the âoptimalâ probes for each genome proxy based on the probesâ predicted hybridization properties. rRNA genes were excluded, because this probe design approach, which avoids sequence alignments and considerations of RNA secondary structure, would be unlikely to result in useful rRNA probes. Furthermore, rRNA probes of traditional design could not be included on the array because their appropriate hybridization conditions would be very different from those of this arrayâs probes. ***Microarray probe design*** Microarray 70-mer probes were designed using the program ArrayOligoSelector (Zhu et al., 2003) with the following settings: target %GC = 40%, 1 probe/gene, with the ORFs for each genome fragment as both the input and the database file. The output candidate 70mers were then sorted based on their %GC and those closest to 40% were chosen. In the case of more than the target number of probes having 40%GC, the subset with the lowest free energy of hybridization were selected as probes. Generally, 20 probes were selected per organism. Prochlorococcus MED4 was represented by 60 probes total, 20 each for three different 80kb âgenome-proxyâ regions: 0-80kb, 1.29-1.37Mbp, and 1.58 to 1.66Mbp. Using the same method, a set (n=20) of positive control probes were designed to the genome of the halophillic archaeon Halobacterium salinarum NRC-1. Negative control probes (n=28) were designed to a set of 49 random 1000-base sequences (Stothard, 2000). ***Microarray construction and hybridization*** Oligonucleotides were synthesized (Illumina, San Diego, California), suspended in 3XSSC to a concentration of 40pmol/μl, and spotted on homemade poly-L-lysine-coated glass slides using a QArray 2 microarraying robot (Genetix, Hampshire, England). Six replicates of each probe were spotted. ***Microarray data analysis*** Hybridized arrays were scanned using an Axon Instruments 4000B scanner (Foster City, CA) and the data was normalized and filtered using perl scripts written for the purpose, by the following steps. (1) Signal intensities for each spot were calculated by subtracting the local background (mean F532 â median B532, as calculated by GenePix Pro 5.1 software, Axon Instruments). (2) The median value across replicates was calculated for each probe. (3) For each probe set, the number of probes greater than twice the mean negative control signal was calculated, before further processing. (4) Filter I: Arrays with less than half their positive control probes exceeding twice the mean negative control signal were considered poor quality, low dynamic range, arrays and were excluded from further analysis. (5) Each probe signal was corrected for non-specific binding by subtracting the mean negative control spot signal. (6) The data was then normalized for array-to-array variations in brightness by dividing each probe signal by the mean positive control signal. This positive control signal was the mean signal across the Halobacterium salinarum probes in each hybridization, with identical amounts of H. salinarum DNA having been added to each reaction prior to amplification and labeling. (7) Filter II: In order for a genotype to be considered âpresentâ, at least 45% of its probes had to exceed twice the mean negative control signal. (8) Finally, each genotype signal was calculated as either the MEAN or TUKEY BIWEIGHT across its probe set. ***Experimental Design*** The array was hybridized to laboratory mixtures of cloned environmental genomic DNA targeted by the array, in varying ratios. The use of multiple probes to target many genes from each organism helped to normalize probe-to-probe heterogeneity, by averaging across all probes in a set (as described below). The evenness of probe response across each genotypeâs set was also used to evaluate the relatedness of hybridizing DNA. To more precisely define the arrayâs phylogenetic range and specificity, it was tested against DNA from Prochlorococcus MED4 and related strains, spanning the known range of Prochlorococcus phylogenetic diversity. To test the effects of hybridization stringency on the specificity and signal of the MED4 probes, Prochlorococcus strains were hybridized at a range of conditions. To test whether the specificity results for Prochlorococcus were comparable for other targeted clades, two genome fragments recovered from closely related phylotypes within the SAR86 clade of the gamma-proteobacteria were represented on the array, and were tested for specificity. To understand the equivalence of probe sets targeting different regions of the same organismâs genome, we targeted three 80kb âgenome proxyâ regions of the Prochlorococcus MED4 genome. One of the regions fell in a genomic âislandâ where inter-strain variability is concentrated (âISL5â in Coleman et al., 2006). To test the array in a complex environmental context, we collected coastal seawater (lacking detectable Prochlorococcus cells by flow cytometry) and added Prochlorococcus cells from strains MED4, MIT9515, MIT9312 and MIT9313 over a range of concentrations from ~101 â 106 cells/ml (Fig. 3). The seawater was then filtered and the DNA extracted, amplified, labeled, and hybridized to the array.
2010-05-25 | E-GEOD-9384 | biostudies-arrayexpress
Project description:Resource competition and metabolic cross-feeding are among the main drivers of microbial community assembly. Yet the degree to which these two conflicting forces are reflected in the composition of natural communities has not been systematically investigated. Here, we use genome-scale metabolic modelling to assess the potential for resource competition and metabolic cooperation in large co-occurring groups (up to 40 members) across thousands of habitats. Our analysis reveals two distinct community types, which are clustered at opposite ends of a spectrum in a trade-off between competition and cooperation. At one end are highly cooperative communities, characterized by smaller genomes and multiple auxotrophies. At the other end are highly competitive communities, which feature larger genomes and overlapping nutritional requirements, and harbour more genes related to antimicrobial activity. The latter are mainly present in soils, whereas the former are found in both free-living and host-associated habitats. Community-scale flux simulations show that, whereas competitive communities can better resist species invasion but not nutrient shift, cooperative communities are susceptible to species invasion but resilient to nutrient change. We also show, by analysing an additional data set, that colonization by probiotic species is positively associated with the presence of cooperative species in the recipient microbiome. Together, our results highlight the bifurcation between competitive and cooperative metabolism in the assembly of natural communities and its implications for community modulation.
| S-EPMC7610595 | biostudies-literature
Project description:A DNA microarray to monitor the expression of bacterial metabolic genes within mixed microbial communities was designed and tested. Total RNA was extracted from pure and mixed cultures containing the 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterium Ralstonia eutropha JMP134, and the inducing agent 2,4-D. Induction of the 2,4-D catabolic genes present in this organism was readily detected 4, 7, and 24 h after the addition of 2,4-D. This strain was diluted into a constructed mixed microbial community derived from a laboratory scale sequencing batch reactor. Induction of two of five 2,4-D catabolic genes (tfdA and tfdC) from populations of JMP134 as low as 10(5) cells/ml was clearly detected against a background of 10(8) cells/ml. Induction of two others (tfdB and tfdE) was detected from populations of 10(6) cells/ml in the same background; however, the last gene, tfdF, showed no significant induction due to high variability. In another experiment, the induction of resin acid degradative genes was statistically detectable in sludge-fed pulp mill effluent exposed to dehydroabietic acid in batch experiments. We conclude that microarrays will be useful tools for the detection of bacterial gene expression in wastewaters and other complex systems.
| S-EPMC143597 | biostudies-literature
Project description:MicroRNAs (miRNAs) have been shown to play an important role in many different cellular, developmental, and physiological processes. Accordingly, numerous methods have been established to identify and quantify miRNAs. The shortness of miRNA sequence results in a high dynamic range of melting temperatures and, moreover, impedes a proper selection of detection probes or optimized PCR primers. While miRNA microarrays allow for massive parallel and accurate relative measurement of all known miRNAs, they have so far been less useful as an assay for absolute quantification. Here, we present a microarray based approach for global and absolute quantification of miRNAs. The method relies on an equimolar pool of about 1000 synthetic miRNAs of known concentration which is used as an universal reference and labeled and hybridized in a dual colour approach on the same array as the sample of interest. Each single miRNA is quantified with respect to the universal reference outbalancing bias related to sequence, labeling, hybridization or signal detection method. We demonstrate the accuracy of the method by various spike in experiments. Further, we quantified miRNA copy numbers in liver samples and CD34(+)CD133(-) hematopoietic stem cells.
2009-10-27 | GSE15831 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2014-12-21 | GSE64376 | GEO