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PubMed2003

Mapping of porcine ESTs obtained from the anterior pituitary.

We report the physical mapping of porcine expressed sequence tags (ESTs) from anterior pituitary clones isolated by differential display PCR in a study using lines selected for reproduction. These ESTs were mapped using a somatic cell hybrid panel (SCHP) and a radiation hybrid panel (IMpRH) as follows (SCHP position, nearest marker on the RH map): SPARCL1 (8q23-q27, SSP1); ATF4 (5p11-p15, AC02); MEF2C [2(1/2q21)-(1/2q22), SW2134]; FTH1 (2p14-p17, SWR783); FRAP1 (6q22-q23, SW1355); PBP (14, SW2508); LOC92004 [13q23-(1/2q41), CP]; and PGRMC1 [Xq22, SW1943]. All RH assignments were at LOD score >6.0 except for PGRMC1 at LOD score 5.4. ESTs TCP1 [12p11-(2/3p13)], SF3B1 (15q23-q26) and Clock (8q11-q12) were assigned using only the SCHP. The map position of SPARCL1 coincides with a quantitative trait loci (QTL) for age at puberty found in the University of Nebraska selection lines. Physical mapping of ESTs reported in the present study contributes to characterization of the transcriptome of anterior pituitary of pigs, adds new information to the public database of the porcine genome expression map, and further develops the porcine-human comparative map.

Animals↗
PubMed2005

Pelophylaxins: novel antimicrobial peptide homologs from the skin secretion of the Fukien gold-striped pond frog, Pelophylax plancyi fukienensis: identification by "shotgun" cDNA cloning and sequence analysis.

Amphibian skin secretions are rich in antimicrobial peptides that act as important components of an innate immune system. Here, we describe a novel "shotgun" skin peptide precursor cloning technique that facilitates rapid access to these genetically encoded molecules and effects their subsequent identification and structural characterization from the secretory peptidome. Adopting this approach on a skin secretion-derived library from a hitherto unstudied Chinese species of frog, we identified a family of novel antimicrobial peptide homologs, named pelophylaxins, that belong to previously identified families (ranatuerins, brevinins and temporins) found predominantly in the skin secretions from frogs of the genus Rana. These data further substantiate the scientifically robust nature of applying parallel transcriptome and peptidome analyses on frog defensive skin secretions that can be obtained in a non-invasive, non-destructive manner. In addition, the present data illustrate that rapid structural characterization of frog skin secretion peptides can be achieved from an unstudied species without prior knowledge of primary structures of endogenous peptides.

Amino Acid Sequence↗
PubMed2004

LongSAGE analysis significantly improves genome annotation: identifications of novel genes and alternative transcripts in the mouse.

MOTIVATION: Owing to its increased tag length, LongSAGE tags are expected to be more reliable in direct assignment to genome sequences. Therefore, we evaluated the use of LongSAGE data in genome annotation by using our LongSAGE dataset of 202 015 tags (consisting of 41 718 unique tags), experimentally generated from mouse embryonic tail libraries. RESULTS: A fraction of LongSAGE tags could not be unambiguously assigned to its gene, due to the presence of widely conserved sequences downstream of particular CATG anchor sites. The presence of alternative forms of transcripts was confirmed in 45% of all detected genes. Surprisingly, a large fraction of LongSAGE tags with hits to the genome (66%) could not be assigned to any gene annotated in EnsEMBL. Among such cases, 2098 LongSAGE tags fell into a region containing a putative gene predicted by GenScan, providing experimental evidence for the presence of real genes, while 9112 genes were found out to be left out or wrongly annotated by the EnsEMBL pipeline. CONCLUSIONS: LongSAGE transcriptome data can significantly improve the genome annotation by identifying novel genes and alternative transcripts, even in the case of thus far best-characterized organisms like the mouse. CONTACT: imai@gsf.de.

Algorithms↗
PubMed2006

Capillary electrophoresis at the omics level: towards systems biology.

Emerging systems biology aims at integrating the enormous amount of existing omics data in order to better understand their functional relationships at a whole systems level. These huge datasets can be obtained through advances in high-throughput, sensitive, precise, and accurate analytical instrumentation and technological innovation. Separation sciences play an important role in revealing biological processes at various omic levels. From the perspective of systems biology, CE is a strong candidate for high-throughput, sensitive data generation which is capable of tackling the challenges in acquiring qualitative and quantitative knowledge through a system-level study. This review focuses on the applicability of CE to systems-based analytical data at the genomic, transcriptomic, proteomic, and metabolomic levels.

Animals↗
PubMed2006

Myc target transcriptomes.

The c-Myc oncogenic transcription factor plays a central role in many human cancers through the regulation of gene expression. Although the molecular mechanisms by which c-Myc and its obligate partner, Max, regulate gene expression are becoming better defined, genes or transcriptomes that c-Myc regulate are just emerging from a variety of different experimental approaches. Studies of individual c-Myc target genes and their functional implications are now complemented by large surveys of c-Myc target genes through the use of subtraction cloning, DNA microarray analysis, serial analysis of gene expression (SAGE), chromatin immunoprecipitation, and genome marking methods. To fully appreciate the differences between physiological c-Myc function in normal cells and deregulated c-Myc function in tumors, the challenge now is to determine how the authenticated transcriptomes effect the various phenotypes induced by c-Myc and to define how c-Myc transcriptomes are altered by the Mad family of proteins.

Animals↗
PubMed2005

Novel frenatins from the skin of the Australasian giant white-lipped tree frog, Litoria infrafrenata: cloning of precursor cDNAs and identification in defensive skin secretion.

The Australasian anuran amphibian genus Litoria, contains many phenotypically-diverse species as a result of radial evolution of an ancestral species into different biotopes much in the manner of the indigenous marsupial mammals. In common with members of the Central/South American genus Phyllomedusa, their specialized skin granular glands are factories for the production of a plethora of biologically-active peptides. Here we report a more detailed study of those present in the defensive skin secretion of the Australasian giant white-lipped tree frog, Litoria infrafrenata, and, for the first time, we have identified three novel frenatins by deduction of primary structures from cDNAs that were cloned from a library constructed from lyophilized skin secretion using a recently-developed technique. All open-reading frames consisted of a putative signal peptide and an acidic pro-region followed by a single copy of a frenatin peptide. Processed peptides corresponding in molecular mass to the deduced molecular masses of frenatins (named 1.1, 3, 3.1 and 4.1) were identified in the same secretion sample using HPLC and mass spectroscopy. The application of this technique thus permits parallel peptidomic and transcriptomic analyzes on the same lyophilized skin secretion sample circumventing sacrifice of specimens from endangered herpetofauna.

Amphibian Proteins↗
PubMed2006

Global transcriptional and physiological responses of Saccharomyces cerevisiae to ammonium, L-alanine, or L-glutamine limitation.

The yeast Saccharomyces cerevisiae encounters a range of nitrogen sources at various concentrations in its environment. The impact of these two parameters on transcription and metabolism was studied by growing S. cerevisiae in chemostat cultures with l-glutamine, l-alanine, or l-ammonium in limitation and by growing cells in an excess of ammonium. Cells grown in l-alanine-limited cultures had higher biomass yield per nitrogen mole (19%) than those from ammonium-limited cultures. Whole-genome transcript profiles were analyzed with a genome-scale metabolic model that suggested increased anabolic activity in l-alanine-limited cells. The changes in these cells were found to be focused around pyruvate, acetyl coenzyme A, glyoxylate, and alpha-ketoglutarate via increased levels of ALT1, DAL7, PYC1, GDH2, and ADH5 and decreased levels of GDH3, CIT2, and ACS1 transcripts. The transcript profiles were then clustered. Approximately 1,400 transcripts showed altered levels when amino acid-grown cells were compared to those from ammonium. Another 400 genes had low transcript levels when ammonium was in excess. Overrepresentation of the GATAAG element in their promoters suggests that nitrogen catabolite repression (NCR) may be responsible for this regulation. Ninety-one genes had transcript levels on both l-glutamine and ammonium that were decreased compared to those on l-alanine, independent of the concentration. The GATAAG element in these genes suggests two groups of NCR-responsive genes, those that respond to high levels of nitrogen and those that respond to levels below 30 muM. In conclusion, our results reveal that the nitrogen source has substantial influence on the transcriptome of yeasts and that transcriptional changes may be correlated to physiology via a metabolic model.

Alanine↗
PubMed2006

In silico assessment of gene function involved in cysteine biosynthesis in Arabidopsis: expression analysis of multiple isoforms of serine acetyltransferase.

In plants, the inorganic sulfur is first fixed into cysteine by the cysteine biosynthetic pathway. This biosynthetic pathway of cysteine involves several enzymatic reactions. In Arabidopsis thaliana, multiple isoforms seem to participate in each enzymatic step for cysteine biosynthesis. To obtain more insights on the specific role of each isoform involved in the cysteine biosynthesis, in silico analysis of these isoforms using Arabidopsis expressed sequence tags (EST) database was carried out. This EST database analysis revealed distinct population distribution of ESTs among multiple isoforms, suggesting that each isoform has its particular expression pattern, presumably associated with its specific role in cysteine biosynthesis. As another in silico analysis, co-expression analysis of genes involved in sulfur metabolism in Arabidopsis was performed using a public transcriptome database of DNA microarrays. This co-expression analysis also suggested specific function and co-regulation of some isoform genes for cysteine biosynthesis by consideration on the clustering of co-expressed genes. From the results of sensitivity to feedback regulation, subcellular localization and expression of mRNA analyses, each serine acetyltransferase (SATase) isoform seems to have its specific role for cysteine biosynthesis. Similar expression patterns were observed between the experimental results of expression data for SATase isoforms and the in silico results of "digital northern" analysis using EST database.

Arabidopsis↗
PubMed2006

Transcriptional organization and regulation of magnetosome operons in Magnetospirillum gryphiswaldense.

Genes involved in magnetite biomineralization are clustered within the genomic magnetosome island of Magnetospirillum gryphiswaldense. Their transcriptional organization and regulation were studied by several approaches. Cotranscription of genes within the mamAB, mamDC, and mms clusters was demonstrated by reverse transcription-PCR (RT-PCR) of intergenic regions, indicating the presence of long polycistronic transcripts extending over more than 16 kb. The transcription start points of the mamAB, mamDC, and mms operons were mapped at 22 bp, 52 bp, and 58 bp upstream of the first genes of the operons, respectively. Identified -10 and -35 boxes of the P(mamAB), P(mamDC), and P(mms) promoters showed high similarity to the canonical sigma(70) recognition sequence. The transcription of magnetosome genes was further studied in response to iron and oxygen. Transcripts of magnetosome genes were detected by RT-PCR both in magnetic cells grown microaerobically under iron-sufficient conditions and in nonmagnetic cells grown either aerobically or with iron limitation. The presence of transcripts was found to be independent of the growth phase. Further results from partial RNA microarrays targeting the putative magnetosome transcriptome of M. gryphiswaldense and real-time RT-PCR experiments indicated differences in expression levels depending on growth conditions. The expression of the mam and mms genes was down-regulated in nonmagnetic cells under iron limitation and, to a lesser extent, during aerobic growth compared to that in magnetite-forming cells grown microaerobically under iron-sufficient conditions.

Base Sequence↗
PubMed2004

The mRNA surveillance protein hSMG-1 functions in genotoxic stress response pathways in mammalian cells.

Members of the PI 3-kinase-related kinase (PIKK) family function in mitogenic and stress-induced signaling pathways in eukaryotic cells. Here, we characterize the newest PIKK family member, hSMG-1, as a genotoxic stress-activated protein kinase that displays some functional overlap with the related kinase, ATM, in human cells. Both ATM and hSMG-1 phosphorylate Ser/Thr-Gln-containing target sequences in the checkpoint protein p53 and the nonsense-mediated mRNA decay (NMD) protein hUpf1. Expression of hSMG-1 is required for optimal p53 activation after cellular exposure to genotoxic stress, and depletion of hSMG-1 leads to spontaneous DNA damage and increased sensitivity to ionizing radiation (IR). Moreover, IR exposure triggers hUpf1 phosphorylation at Ser/Thr-Gln motifs, and both ATM and hSMG-1 contribute to these phosphorylation events. Finally, NMD is suppressed in hSMG-1- but not ATM-deficient cells. These results indicate that hSMG-1 plays important roles in the maintenance of both genome and transcriptome integrity in human cells.

Amino Acid Motifs↗
PubMed2005

Nocturnal changes in leaf growth of Populus deltoides are controlled by cytoplasmic growth.

Growing leaves do not expand at a constant rate but exhibit pronounced diel growth rhythms. However, the mechanisms giving rise to distinct diel growth dynamics in different species are still largely unknown. As a first step towards identifying genes controlling rate and timing of leaf growth, we analysed the transcriptomes of rapidly expanding and fully expanded leaves of Populus deltoides Bartr. ex. Marsh at points of high and low expansion at night. Tissues with well defined temporal growth rates were harvested using an online growth-monitoring system based on a digital image sequence processing method developed for quantitative mapping of dicot leaf growth. Unlike plants studied previously, leaf growth in P. deltoides was characterised by lack of a base-tip gradient across the lamina, and by maximal and minimal growth at dusk and dawn, respectively. Microarray analysis revealed that the nocturnal decline in growth coincided with a concerted down-regulation of ribosomal protein genes, indicating deceleration of cytoplasmic growth. In a subsequent time-course experiment, Northern blotting and real-time RT-PCR confirmed that the ribosomal protein gene RPL12 and a cell-cycle gene H2B were down-regulated after midnight following a decrease in cellular carbohydrate concentrations. Thus, we propose that the spatio-temporal growth pattern in leaves of P. deltoides primarily arises from cytoplasmic growth whose activity increases from afternoon to midnight and thereafter decreases in this species.

Carbohydrate Metabolism↗
PubMed2026

Characterizing the Discordance between AT-Rich Interacting Domain 1A Protein and Genotype in Endometrioid-Type Endometrial Tumors.

ARID1A is one of the most frequently mutated genes in endometrial cancer, with approximately 40% of patients harboring an ARID1A mutation. However, relatively little is known about how AT-rich interacting domain 1A (ARID1A) protein loss shapes endometrial cancer pathogenesis. Mounting evidence from other malignancies suggests that ARID1A protein can be regulated post-translationally, independent of genotype. However, most studies in endometrial cancer evaluate genotype alone, overlooking the potential for alternative mechanisms of ARID1A loss. To address this gap, ARID1A protein expression and genotype were examined in endometrioid tumors, and associated transcriptional changes were characterized. Evaluation of ARID1A protein in 71 human endometrioid tumors demonstrates that protein loss can occur regardless of ARID1A genotype. Retention or deficiency of ARID1A protein was not significantly related to variant allele frequency or location of mutation in human tumors with mutant ARID1A. A human endometrial cancer cell model suggests that ARID1A protein loss can occur through proteasomal degradation. Furthermore, ARID1A protein expression was found to be a predictor of worse overall survival in The Cancer Genome Atlas cohort of ARID1A wild-type endometrioid tumors. Spatial transcriptomics of 16 human endometrioid tumors revealed that both genotype and protein expression of ARID1A play a role in shaping unique transcriptional signatures in endometrial cancer and can be used to predict patient prognosis. Suggesting evaluation of ARID1A should not be done solely by sequencing techniques.

Humans↗
PubMed2026

Molecular biomarker profiling in noninfectious uveitis: a chronological review of discovery.

PURPOSE OR REVIEW: Noninfectious uveitis (NIU) encompasses a heterogeneous group of immune-mediated intraocular inflammatory diseases whose complexity has driven systematic molecular biomarker discovery. This review presents NIU molecular biomarkers organized by biological category; autoantigens, human leukocyte antigens (HLA) and genetic markers, cellular immune subsets, cytokines, chemokines, and multiomics platforms including proteomics, microbiome metagenomics, metabolomics, and single-cell transcriptomics with each category presented in strict chronological order of landmark discovery. RECENT FINDINGS: We present a review organized along two nested timelines. Categories are presented in the order they historically emerged in the field, and within each category, landmark discoveries appear in chronological sequence. This allows the reader to trace how each biomarker category evolved: from foundational autoantigen identification in experimental uveitis models, through the genomic revolution of HLA association studies, into cellular immunophenotyping, cytokine profiling of aqueous humor, chemokine mapping of intraocular trafficking, and finally the emerging omics platforms that may potentially anchor precision medicine in NIU. Each biomarker is paired in line with its linked targeted therapeutic. SUMMARY: Biomarker research has transformed the understanding of NIU from a clinically defined syndrome into a group of molecularly distinct immune disorders. Advances spanning autoantigens, genetics, immune-cell profiling, cytokines, chemokines, and multiomics have revealed novel pathogenic mechanisms and therapeutic targets. Integration of these biomarkers with targeted therapies may accelerate the transition toward precision medicine in uveitis care.

cytokines↗
PubMed2007

Transcriptome analysis reveals season-specific rbcS gene expression profiles in diploid perennial ryegrass (Lolium perenne L.).

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.

Alternative Splicing↗
PubMed2025

Post-genome-wide association study dissects genetic vulnerability and risk gene expression of Sjögren's disease for cardiovascular disease.

OBJECTIVES: This study aims to clarify the genetic associations between Sjögren's Disease (SD) and cardiovascular disease (CVD) outcomes, and to conduct an in-depth exploration of specific pleiotropic susceptibility genes. METHODS: We performed two-sample and multivariable Mendelian randomization (MR) analysis to investigate the association between SD and the risk of ischemic heart disease (IHD) and stroke. Linkage disequilibrium score regression (LDSC) and Bayesian co-localization analyses were employed to assess the genetic associations between traits. Cross-phenotype analyses were employed to identify shared variants and genes, followed by a Transcriptome-Wide Association Study (TWAS) and Multi-marker Analysis of Genomic Annotation (MAGMA) based on Multi-Trait Analysis of GWAS (MTAG) results. To validate the pleiotropic genes, we further analyzed tissue-specific differentially expressed genes (DEGs) related to SD using RNA sequencing data. RESULTS: The two-sample and multivariable MR analyses revealed that SD confers a genetic vulnerability to IHD and stroke. LDSC and co-localization analyses indicated a strong genetic linkage between SD and CVDs. Cross-phenotype analyses identified 38 and 37 pleiotropic single nucleotide polymorphisms (SNPs) for SD-Stroke and SD-IHD, respectively, primarily located within the MHC class region on 6p21.32:33 loci. Additionally, TWAS and MAGMA analyses identified pleiotropic genes located outside the MHC regions-seven associated with stroke (UHRF1BP1, SNRPC, BLK, FAM167A, ARHGAP27, C8orf12, and PLEKHM1) and two associated with IHD (UHRF1BP1 and SNRPC). Proxy variants within these genes in SD suggested an increased causal risk for stroke or IHD. Co-localization analysis further reinforced that SD and stroke share significant SNPs within the loci of FAM167A, BLK, C8orf12, SNRPC, and UHRF1BP1. DEG analysis revealed a significant up-regulation of the identified genes in SD-specific tissues. CONCLUSIONS: SD appears genetically predisposed to an increased risk of CVDs. Moreover, this research not only identified pleiotropic genes shared between SD and CVDs, but also, for the first time, detected key gene expressions that elevate CVD risk in SD patients-findings that may offer promising therapeutic targets for patient management.

Humans↗
PubMed2004

Serial analysis of gene expression (SAGE): application in cancer research.

Serial analysis of gene expression (SAGE) is a powerful tool that allows digital analysis of overall gene expression patterns. SAGE provides quantitative and comprehensive expression profiling in a given cell population. Because SAGE does not require a preexisting clone, it can be used to identify and quantitate new as well as known genes. It works by isolating short fragments of genetic information from the genes expressed in the cell being studied. These short sequences, called SAGE tags, are linked together for efficient sequencing. SAGE is particularly well suited for organisms whose genome is not completely sequenced, because it does not require a hybridization probe for each transcript and allows new genes to be discovered. New modifications of SAGE now permit the analysis of gene expression in cell sub-populations or micro-anatomic structures, providing access to unexplored transcriptomes of normal and disease biology. Data derived using the SAGE technology have been used to identify tumor markers for a variety of cancers, including gastrointestinal cancer, lung and thyroid cancer, breast and ovarian cancer, neuroblastoma and glioblastoma, prostate cancer, and renal cell carcinoma. In this review we present an outline of the method and updated information on the applications of SAGE technology to various cancers.

Biomedical Research↗
PubMed2026

Single-cell transcriptomics reveals distinct microglial state remodeling associated with the (R)-nicotine/diosmetin combination and galantamine in LPS-challenged BV2 cells.

BACKGROUND: Microglial neuroinflammation contributes to the progression of neurodegenerative diseases, yet it remains challenging to attenuate inflammatory responses while preserving cellular function. The effects of (R)-nicotine, diosmetin, their combined administration, and galantamine on heterogeneous BV2 transcriptional states have not been compared at single-cell resolution. METHODS: LPS-stimulated BV2 microglial-like cells were treated with (R)-nicotine, diosmetin, their combination (DR), or galantamine. Single-cell RNA sequencing was performed with three biological replicates per group and integrated with RNA velocity and SCENIC regulon inference to characterize treatment-associated state redistribution, inferred local transcriptional directionality and regulon-activity patterns. Functional validation included CCK-8 metabolic activity assays, multiplex cytokine ELISA, BDNF/GDNF quantification, qPCR, and high-content immunofluorescence analysis of iNOS and Arg1 at single-cell resolution. RESULTS: LPS decreased the relative abundance of the Itgae+/Plk4+ cluster while increasing the Nmur1+/Limk2+ cluster and inflammatory effector programs. DR treatment suppressed pro-inflammatory cytokine release without significantly reducing CCK-8-assessed metabolic activity, increased the Itgae+/Plk4+ cluster proportion, and increased BDNF/GDNF relative to LPS. RNA velocity and SCENIC analyses suggested that DR and galantamine showed distinct transcriptional and regulatory patterns: DR attenuated Batf-associated inflammatory regulons and was associated with increased Atf3-linked stress-response activity, whereas galantamine preferentially engaged DNA repair and genome-maintenance programs. CONCLUSION: These findings indicate that the DR condition was associated with remodeling of LPS-challenged BV2 microglial-like states, attenuation of inflammatory programs, and increased neurotrophic outputs relative to LPS, without significantly reducing CCK-8-assessed metabolic activity. This study provides a single-cell characterization of distinct treatment-associated responses to (R)-nicotine, diosmetin, their combined administration, and galantamine.

Microglia↗
PubMed2005

An analysis of the use of genomic DNA as a universal reference in two channel DNA microarrays.

BACKGROUND: DNA microarray is an invaluable tool for gene expression explorations. In the two-dye microarray, fluorescence intensities of two samples, each labeled with a different dye, are compared after hybridization. To compare a large number of samples, the 'reference design' is widely used, in which all RNA samples are hybridized to a common reference. Genomic DNA is an attractive candidate for use as a universal reference, especially for bacterial systems with a low percentage of non-coding sequences. However, genomic DNA, comprising of both the sense and anti-sense strands, is unlike the single stranded cDNA usually used in microarray hybridizations. The presence of the antisense strand in the 'reference' leads to reactions between complementary labeled strands in solution and may cause the assay result to deviate from true values. RESULTS: We have developed a mathematical model to predict the validity of using genomic DNA as a reference in the microarray assay. The model predicts that the assay can accurately estimate relative concentrations for a wide range of initial cDNA concentrations. Experimental results of DNA microarray assay using genomic DNA as a reference correlated well to those obtained by a direct hybridization between two cDNA samples. The model predicts that the initial concentrations of labeled genomic DNA strands and immobilized strands, and the hybridization time do not significantly affect the assay performance. At low values of the rate constant for hybridization between immobilized and mobile strands, the assay performance varies with the hybridization time and initial cDNA concentrations. For the case where a microarray with immobilized single strands is used, results from hybridizations using genomic DNA as a reference will correspond to true ratios under all conditions. CONCLUSION: Simulation using the mathematical model, and the experimental study presented here show the potential utility of microarray assays using genomic DNA as a reference. We conclude that the use of genomic DNA as reference DNA should greatly facilitate comparative transcriptome analysis.

DNA↗