title: Effects of target length on the hybridization efficiency and specificity of rRNA-based oligonucleotide microarrays.
abstract: The effect of target size on microarray hybridization efficiencies and specificity was investigated using a set of 166 oligonucleotide probes targeting the 16S rRNA gene of Escherichia coli. The targets included unfragmented native rRNA, fragmented rRNA ( approximately 20 to 100 bp), PCR amplicons (93 to 1,480 bp), and three synthetic single-stranded DNA oligonucleotides (45 to 56 bp). Fluorescence intensities of probes hybridized with targets were categorized into classes I (81 to 100% relative to the control probe), II (61 to 80%), III (41 to 60%), IV (21 to 40%), V (6 to 20%), and VI (0 to 5%). Good hybridization efficiency was defined for those probes conferring intensities in classes I to IV; those in classes V and VI were regarded as weak and false-negative signals, respectively. Using unfragmented native rRNA, 13.9% of the probes had fluorescence intensities in classes I to IV, whereas the majority (57.8%) exhibited false-negative signals. Similar trends were observed for the 1,480-bp PCR amplicon (6.6% of the probes were in classes I to IV). In contrast, after hybridization of fragmented rRNA, the percentage of probes in classes I to IV rose to 83.1%. Likewise, when DNA target sizes were reduced from 1,480 bp to 45 bp, this percentage increased approximately 14-fold. Overall, microarray hybridization efficiencies and specificity were improved with fragmented rRNA (20 to 100 bp), short PCR amplicons (<150 bp), and synthetic targets (45 to 56 bp). Such an understanding is important to the application of DNA microarray technology in microbial community studies.
authors.affiliation: Division of Environmental Science and Engineering, National University of Singapore, Block E2, no. 04-07, 1 Engineering Drive 2, Singapore 117576. eseliuwt@nus.edu.sg
authors.forename: Wen-Tso
authors.initials: WT
authors.lastname: Liu
authors.forename: Huiling
authors.initials: H
authors.lastname: Guo
authors.forename: Jer-Horng
authors.initials: JH
authors.lastname: Wu
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D009693:Nucleic Acid Hybridization / Q000379:methods*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial; D015345:Oligonucleotide Probes; D012336:RNA, Ribosomal, 16S