What labeling method is NOT used in hybridization?

The question asks about labeling methods that are not employed in hybridization techniques. The correct answer is crosslinking.

In hybridization processes, such as those used in molecular diagnostics and DNA analysis, various methods are used to label nucleic acid probes to detect complementary sequences in a target sample. End labeling, nick translation, and random priming are all established techniques that help generate labeled DNA or RNA probes.

End labeling involves adding a radioactive isotope or a fluorescent dye to the ends of a nucleic acid strand, making it suitable for hybridization studies. Nick translation is a technique where the DNA is enzymatically nicked, allowing the incorporation of labeled nucleotides that help enable the probe to be used for detecting specific sequences. Random priming is another approach that generates labeled probes by randomly priming a single-stranded template, resulting in probes that can hybridize to complementary sequences.

Crosslinking, on the other hand, does not fall under these labeling methods. It is a process commonly used to covalently link two or more molecules, such as DNA and proteins, but it is not inherently a labeling technique for hybridization purposes. Thus, it does not typically contribute to the creation of labeled probes used in hybridization.