TitleN-ethylmaleimide (NEM) can significantly improve in situ hybridization results using S-35-labeled oligodeoxynucleotide or complementary RNA probes
Publication TypeJournal Article
Year of Publication1997
AuthorsZoeller, RT, Fletcher, DL, Butnariu, O, Lowry, CA, Moore, FL
JournalJournal of Histochemistry & Cytochemistry
Type of ArticleJournal Article

We predicted that a significant source of background labeling after in situ hybridization (ISH) using S-35-labeled probes is attributable to a chemical reaction between the phosphorothioate moiety of the probe [O3P=S] and disulfides in tissue. These covalent bonds would immobilize probe in the tissue, thereby increasing background labeling. On the basis of this view, we have explored the use of N-ethylmaleimide (NEM) to irreversibly alkylate the phosphorothioate moiety of the probe and/or to alkylate free sulfhydryls in tissue to block the formation of disulfides as a method of reducing background labeling. We report that NEM can significantly decrease background labeling of S-35-labeled oligodeoxynucleotide or cRNA probes but does not affect specific labeling. We conclude that the use of NEM in ISH protocols, as outlined here, may be an additional element researchers may consider to improve the signal-to-noise ratio.

URL<Go to ISI>://WOS:A1997XG94000012