Up until now, I was under the impression that the DIG-labeled probes were the colored component used to stain the slides where pathogen DNA was present, but I was mistaken. The DIG probes are actually synthesized with antigens attached to the DNA backbone. Specifically, the antibodies are from sheep. We then apply sheep serum, which will bind to the antibodies in the backbone. If the pathogen DNA is present on our slides, the DNA will stick, and if it’s not, the DNA will wash off when soaked in a buffer. The antigens in the sheep serum will bind with the antibodies remaining on the slide. Finally, we apply a molecule that will show color when it binds to the antibodies. This makes a lot more sense than what I’d thought before, since it is similar to other antibody-antigen binding assays like ELISA.
I saw some black spots settling over the RLO phage slides after applying the antibody. I’m assuming since I hadn’t added the final incubator solution needed for visualization, it was just ink from the slide labels. If that was actually the color that attaches to the antibodies, then that’s good news for the RLO slides but bad news for our sea star slides, since I didn’t see any black spots.