What does cleavage enzyme recognize during signal amplification in FISH?

In the context of signal amplification in Fluorescence In Situ Hybridization (FISH), cleavage enzymes play a crucial role by specifically recognizing the structure of signal probes. These signal probes often contain specific sequences designed to hybridize with target nucleic acids, and they may also be equipped with structures that the cleavage enzyme can identify.

When the cleavage enzyme interacts with these structural features, it facilitates the release of signal amplification components, leading to an increased fluorescent signal that allows for better visualization of the target DNA or RNA in the sample. This process is essential for enhancing the sensitivity and specificity of FISH assays, which are critical in molecular diagnostics for detecting genetic anomalies.

In contrast, while single-stranded RNA probes and hybrid capture techniques are relevant in the broader context of nucleic acid detection, they do not directly pertain to the action of cleavage enzymes during the process of signal amplification in FISH. Similarly, the recognition of 5' end fragments does not apply as directly to the role of the cleavage enzyme in this specific amplification context. Therefore, recognizing the structure of the signal probes is central to the mechanism of amplification utilized in FISH.