Simultaneous RNA–DNA FISH in mouse preimplantation embryos

Fluorescent in situ hybridization (FISH) is a powerful cytogenetic technique that allows the visualization and quantification of RNA and DNA molecules in different cellular contexts. In general, FISH applications help to advance research, cytogenetics, and diagnostics. DNA FISH can be applied, for example, for gene mapping and for detecting genetic aberrations. RNA FISH provides information about gene expression. However, in cases where RNA and DNA molecules need to be detected in the same sample, the result is often compromised by the fact that the tissue sample is damaged due to the multitude of processing steps that are required for each application. In addition, the sequential application of RNA and DNA FISH protocols on the same sample is very time consuming. Here we describe a brief protocol that enables the combined and simultaneous detection of Xist RNA and centromeric DNA of chromosome 6 in mouse preimplantation embryos. In addition, we describe how to generate indirect-labeled probes starting from BACs. This protocol may be applied to any combination of RNA and DNA detection.

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