Polyvinyl alcohol enhances detection of low abundance transcripts in early stage quail embryos in a nonradioactive whole mount in situ hybridization technique.

We have tested the ability of polyvinyl alcohol (PVA) to enhance the indoxyl-nitro blue tetrazolium alkaline phosphatase color reaction in whole mount in situ hybridizations of early stage quail embryos. Using detection of the myogenic factor qmyoD in hybridizations of 13-14 somite-pair quail embryos as a test system, 10% solutions of 13-23 kDa and 31-50 kDa PVA optimally enhanced the alkaline phosphatase color reaction. With the enhanced detection conditions, we have been able to measure qmyoD expression as early as the 3 somite-pair stage, whereas previously we were unable to detect qmyoD prior to the 10 somite-pair stage. PVA-enhanced detection of somitic qmyoD expression was specific as no corresponding signal was found in control hybridizations with a sense qmyoD probe.