How can hybrids be detected after nucleic acid hybridization?

Hybrids can be detected after nucleic acid hybridization in several ways by radioisotopes, chemiluminescent, enzymes, or fluorescent labels attached to the probe. 

• When using a radiolabeled DNA probe, the DNA is first heated to 95°C, separating it into single strands. Then, the radiolabeled probe is introduced, and the temperature is lowered to 65°C, allowing the probe to bind to complementary sequences in the DNA, forming double-stranded molecules. The radioactive probe attached to the target sequences can be detected, indicating the presence of the desired DNA sequence. 
• Enzymes like horseradish peroxidase (HRP) or alkaline phosphatase (AP) can be conjugated to the DNA probe. Substrates specific to these enzymes are added, and upon enzyme-substrate interaction, a detectable color or luminescent signal is generated. 
• Fluorescent dyes or fluorophores can be conjugated to the DNA probe, allowing visualization under a fluorescence microscope or detection using a fluorescence reader. Fluorescence in situ hybridization (FISH) utilizes fluorescent reporters for DNA hybrid detection. 
• Chemiluminescent molecules such as luminol or acridinium esters can be attached to the DNA probe. Upon hybridization with the target DNA, a chemical reaction occurs, emitting light that can be detected using a luminometer.