Comparison of ethylene carbonate and formamide as components of the hybridization mixture in FISH

The protocols for in situ hybridization (ISH) techniques can vary considerably; however, they usually include denaturation and hybridization steps. Denaturing compounds are used to reduce denaturation and hybridization temperature, which keeps the proper morphology of the preparation. Formamide is the most commonly used reagent in in situ hybridization to lower the melting temperature. The substitution of toxic formamide for a non-toxic ethylene carbonate at 20 % and 50 % concentration in the hybridization mixture helped obtain a high quality in situ hybridization result with two sequences characteristic for rye, JNK, and Bilby. The results after hybridization, with a duration of 90 min and 16 h, were identical when formamide or ethylene carbonate were used in the mixture. In addition, the toxic formamide was eliminated from the post-hybridization steps and specific hybridization signals for both probes were still obtained.