Hybridization probe

Gene probes are poly - or oligonucleotides (usually single-stranded DNA, RNA rare ) having a complementary base sequence for this gene and able to attach to the appropriate DNA sequence of an ( immobilized ) DNA. The stability of the deposition depends on the compliance of the DNA sequences and the length of the probes or the number of hybridized base. Through intensive washing all can not be separated perfectly homologous sequences again, just to get signals at exact matches.

They are connected for the purpose of detecting or detecting with marker molecules. For direct detection of radioactive isotopes ( 32P, 35S ) or fluorescent dyes for the indirect detection via intermediary molecules as biotin streptavidin or antibodies to digoxigenin. At the " mediator molecules " dyes or enzymes are coupled to each other by either detection method (fluorescence ). Enzymes commonly used for this purpose are the alkaline phosphatase or peroxidase.

Gene probes detected either directly by detecting the radioactivity ( autoradiography or scintillation ), or the corresponding dyes (fluorescence microscopy, photometry ) or indirectly by enzyme substrate reaction in which either chemiluminescence, dye envelope or Farbstoffpräzipitation is generated. The detection of the marker molecules (directly or indirectly ) shall be evidence of the specific gene probe and thus the analyzed DNA or RNA with which the probe has hybridized.