Application of fluorescently labeled poly(dU) for gene expression profiling on cDNA microarrays

The membrane filter hybridization technique has been widely used for gene expression profiling. The preparation of sensitive and reliable probes is critical for quantitative analysis in this technique. We report a method in which fluorescently labeled poly(dU) is used to detect poly(A)-containing mRNA that hybridizes to specific gene targets. The probe can be used commonly for every sample, alleviating problems encountered in preparing cDNA probes by reverse transcription, particularly when many samples are to be analyzed. Moreover, the sensitivity is at least comparable to cDNA probes prepared by conventional protocols. and intensities of signals after hybridization are independent of mRNA sizes and solely dependent on copy numbers. This method was also shown to be applicable to DNA chip technology.