2,733 research outputs found

    Biologically relevant effects of mRNA amplification on gene expression profiles

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    BACKGROUND: Gene expression microarray technology permits the analysis of global gene expression profiles. The amount of sample needed limits the use of small excision biopsies and/or needle biopsies from human or animal tissues. Linear amplification techniques have been developed to increase the amount of sample derived cDNA. These amplified samples can be hybridised on microarrays. However, little information is available whether microarrays based on amplified and unamplified material yield comparable results. In the present study we compared microarray data obtained from amplified mRNA derived from biopsies of rat cardiac left ventricle and non-amplified mRNA derived from the same organ. Biopsies were linearly amplified to acquire enough material for a microarray experiment. Both amplified and unamplified samples were hybridized to the Rat Expression Set 230 Array of Affymetrix. RESULTS: Analysis of the microarray data showed that unamplified material of two different left ventricles had 99.6% identical gene expression. Gene expression patterns of two biopsies obtained from the same parental organ were 96.3% identical. Similarly, gene expression pattern of two biopsies from dissimilar organs were 92.8% identical to each other. Twenty-one percent of reporters called present in parental left ventricular tissue disappeared after amplification in the biopsies. Those reporters were predominantly seen in the low intensity range. Sequence analysis showed that reporters that disappeared after amplification had a GC-content of 53.7+/-4.0%, while reporters called present in biopsy- and whole LV-samples had an average GC content of 47.8+/-5.5% (P <0.001). Those reporters were also predicted to form significantly more (0.76+/-0.07 versus 0.38+/-0.1) and longer (9.4+/-0.3 versus 8.4+/-0.4) hairpins as compared to representative control reporters present before and after amplification. CONCLUSION: This study establishes that the gene expression profile obtained after amplification of mRNA of left ventricular biopsies is representative for the whole left ventricle of the rat heart. However, specific gene transcripts present in parental tissues were undetectable in the minute left ventricular biopsies. Transcripts that were lost due to the amplification process were not randomly distributed, but had higher GC-content and hairpins in the sequence and were mainly found in the lower intensity range which includes many transcription factors from specific signalling pathways

    Oligonucleotide-assisted cleavage and ligation: a novel directional DNA cloning technology to capture cDNAs. Application in the construction of a human immune antibody phage-display library

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    The use of oligonucleotide-assisted cleavage and ligation (ONCL), a novel approach to the capture of gene repertoires, in the construction of a phage-display immune antibody library is described. ONCL begins with rapid amplification of cDNA ends to amplify all members equally. A single, specific cut near 5′ and/or 3′ end of each gene fragment (in single stranded form) is facilitated by hybridization with an appropriate oligonucleotide adapter. Directional cloning of targeted DNA is accomplished by ligation of a partially duplex DNA molecule (containing suitable restriction sites) and amplification with primers in constant regions. To demonstrate utility and reliability of ONCL, a human antibody repertoire was cloned from IgG mRNA extracted from human B-lymphocytes engrafted in Trimera mice. These mice were transplanted with peripheral blood lymphocytes from Candida albicans infected individuals and subsequently immunized with C.albicans glyceraldehyde-3-phosphate dehydrogenase (GAPDH). DNA sequencing showed that ONCL resulted in efficient capture of gene repertoires. Indeed, full representation of all V(H) families/segments was observed showing that ONCL did not introduce cloning biases for or against any V(H) family. We validated the efficiency of ONCL by creating a functional Fab phage-display library with a size of 3.3 × 10(10) and by selecting five unique Fabs against GAPDH antigen

    Continuous glucose monitoring metrics and pregnancy outcomes in insulin-treated diabetes : A post-hoc analysis of the GlucoMOMS trial

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    Funding Information: BWM is supported by a NHMRC investigatorgrant (GNT1176437) and BWM reports consultancy, travel support and research funding from Merck. All other authors declare no conflict of interest. The GlucoMOMS trial was funded by ZonMw, the Dutch Organisation for Health Research and Development, project number 80‐82310‐97‐11157. Continuous Glucose Monitors were purchased at a discount price at Medtronic®, Heerlen, The Netherlands. Neither ZonMw nor Medtronic had a role in study design, data collection, data analysis, data interpretation, or writing of the reports of either the original study or the current post hoc analysis. 10 Publisher Copyright: © 2023 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.Peer reviewedPublisher PD

    Conserved and divergent functions of Drosophila atonal , amphibian, and mammalian Ath5 genes

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    Insect and vertebrate eyes differ in their formation, cellular composition, neural connectivity, and visual function. Despite this diversity, Drosophila atonal and its vertebrate Ortholog in the eye, Ath5 , each regulate determination of the first retinal neuron class—R8 photo-receptors and retinal ganglion cells (RGCs)—in their respective organisms. We have performed a cross-species functional comparison of these genes. In ato 1 mutant Drosophila , ectopic Xenopus Ath5 ( Xath5 ) rescues photoreceptor cell development comparably with atonal . In contrast, mouse Ath5 ( Math5 ) induces formation of very few ommatidia, and most of these lack R8 cells. In the developing frog eye, ectopic atonal , like Xath5 , promotes the differentiation RGCs. Despite strong conservation of atonal , Xath5 , and Math5 structure and shared function, other factors must contribute to the species specificity of retinal neuron determination. These observations suggest that the atonal family may occupy a position in a gene hierarchy where differences in gene regulation or function can be correlated with evolutionary diversity of eye development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72909/1/j.1525-142X.2003.03058.x.pd
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