The new array, the TaqMan Array Human microRNA Panel, uses the TaqMan assay chemistry seen by many as the gold-standard for quantitative gene expression to allow researchers the accuracy and reproducibility of real-time PCR to analyse the expression of 365 miRNAs. miRNAs are non-coding RNA molecules that are between 19 and 30 nucleotides in length, which are believed to regulate approximately 30 per cent of all human genes. "Although the discovery of microRNAs is a relatively recent event, there is still much to learn about their mechanism of action and research continues to reveal the significant role they play in a variety of fundamental cellular processes," said Peter Dansky, vice president of Applied Biosystems' molecular and cell biology consumables business. "With these new miRNA TaqMan arrays, researchers have fast, highly-sensitive tools with which to perform large-scale profiling of these important molecules and learn more about their biological role." So far there have been approximately 500 human miRNAs discovered and technologies such as IDT's miRCat are helping researchers discover more. Distinct miRNA expression patterns have recently been associated with various types of cancer as well as playing a role in regulating cell development, metabolism and viral infections. Indeed, recent research published in the journal Nature used ABI's non-arrayed assays to discover that three miRNAs, known as miR-34s, form an important part of the p53 tumour suppressor network. The miR-34s were expressed at levels of less than a few hundred copies per cell, making the sensitivity of the PCR technique essential to the success of the study. According to the company, the new miRNA TaqMan arrays require smaller amounts of starting RNA samples than other analysis methods providing a more efficient option for researchers working with very valuable samples. The technique also allows researchers to evaluate miRNA expression changes at levels too low for hybridisation microarray techniques to detect. The new arrays consist of hundreds of TaqMan miRNA assays that have been plated onto a microfluidic card to increase the efficiency of expression analysis without requiring liquid-handling robots or multichannel pipettes. Dr Peng Jin of Emory University, in the US, has been using the arrays in miRNA expression profiling experiments to better understand the role that miRNAs play in neurological disorders such as Rett syndrome and Fragile X syndrome. "Before we had access to the TaqMan arrays, we could only analyse about two samples a day. We can now analyse these same samples in about two hours," said Dr Jin. "The use of this technology has greatly increased the number of miRNAs we can screen per sample and the number of samples we can screen in a day."