An Improved Staining Method for Low Signal LacZ Reporter Detection in Mouse Embryos

In many fields of biology, especially in the field of developmental biology, LacZ reporter staining is an approach used to monitor gene expression patterns. In the LacZ reporter system, the LacZ gene is inserted in the endogenous location of the target gene via gene knock-in or by constructing a transgenic cassette in which LacZ is placed downstream of the promoter of the target gene being examined. Currently, the most common LacZ staining methods used are X-gal/FeCN staining and S-gal/TNBT staining. A serious limitation of both of these methods is that they are not effective when the LacZ gene is expressed at a low level. In an attempt to remedy this problem, we have established a new staining protocol which combines both methods. When compared to them, the method described here is better for visualizing lowly expressed genes and it has low background with high sensitivity.