Abstract: This invention describes methods for the generation of nucleic acid probes that improve the sensitivity of hybridization assays. The sensitivity increase results from structural modifications of nucleic acids that promote network formation during hybridization with the result that a single target molecule becomes attached to a complex of many probe molecules. The structural modification involves fragmentation of the probe nucleic acid followed by joining the fragments together such that their order and orientation and number is altered from the original probe molecule. The result is the generation of permuted probe libraries. Probes made according to this invention can be used in many kinds of hybridization assays including Southern blots. Northern blots. Dot blots. Nucleic acid Array hybridization, ‘in situ’ hybridization with fluorescent or other labels (FISH) and various kinds of sandwich hybridization assays.

Abstract: This invention describes methods for the generation of nucleic acid probes that improve the sensitivity of hybridization assays. The sensitivity increase results from structural modifications of nucleic acids that promote network formation during hybridization with the result that a single target molecule becomes attached to a complex of many probe molecules. The structural modification involves fragmentation of the probe nucleic acid followed by joining the fragments together such that their order and orientation and number is altered from the original probe molecule. The result is the generation of permuted probe libraries. Various fragmentation and joining methods are described. Labeling can be done by standard methods before during or after formation of permuted probe libraries. Individual members of permuted probe libraries can be isolated and amplified and perpetuated.

Abstract: This invention describes methods for generating nucleic acid probes that improve the sensitivity of hybridization assays. The sensitivity increase results from structural modifications of nucleic acids that promote network formation during hybridization with the result that a single target molecule becomes attached to a complex of many probe molecules. The structural modification involves fragmentation of the probe nucleic acid followed by joining the fragments together such that their order and orientation and number is altered from the original probe molecule. The result is the generation of permuted probe libraries. Individual members of permuted probe libraries can be isolated, amplified and perpetuated. Libraries can be prepared with additional sequences not present in the target and the fraction of the library made up by such sequences controlled.

Abstract: Certain small RNA molecules can serve as templates for exponential replication by Q-beta replicase. A single molecule can give rise to easily detectable replication products. This permits their detection at the single molecule level. In this patent application tripartite chimeric molecules composed of an RNA segment bounded on each side by a DNA segment are described. Although these chimeras are not templates for exponential amplification by Q-beta replicase they can give rise to such templates by enzymatic reactions which depend on the activity of reverse transcriptase. They can therefore be used as the basis for ultra-sensitive assays for reverse transcriptase. Modifications of the templates and the assays permit application of these chimeras and Q-beta replicase to ultra-sensitive nucleic acid hybridization assays and to assays for non-nucleic acid targets.

Abstract: This invention describes methods for the generation of nucleic acid probes that improve the sensitivity of hybridization assays. The sensitivity increase results from structural modifications of nucleic acids that promote network formation during hybridization with the result that a single target molecule becomes attached to a complex of many probe molecules. The structural modification involves fragmentation of the probe nucleic acid followed by joining the fragments together such that their order and orientation and number is altered from the original probe molecule. The result is the generation of permuted probe libraries. Various fragmentation and joining methods are described. Labeling can be done by standard methods before during or after formation of permuted probe libraries. Individual members of permuted probe libraries can be isolated and amplified and perpetuated.