Abstract: Methods to measure a variety of DNA synthetic processes in live human cells by introducing and retrieving exogenous DNA probes are provided herein. Using fragments of bacterial plasmid or phage DNA, a wide array of DNA constructs may be assembled to mimic the intermediates of DNA transactions, including replication, translation synthesis, and end-joining. These DNA probes may be transfected into human cells and retrieved for mutational analysis using a modified Random Mutation Capture assay or NextGen DNA sequencing. These assays require only a small number of cells, such as might be available from biopsy material. Thus, the methods described herein may be applied to the early detection of cancer, predicting the responsiveness of individual cancers to chemotherapy, and measuring the DNA repair capacity of individuals to environmental DNA damaging agents. This approach may be automated and used for screening human populations for variations in DNA synthetic and repair activities.

Abstract: Novel thymidylate synthase (TS mutants) are disclosed differing from human wild type thymidylate synthase in single, double, or multiple mutations, which show intact enzyme activity and enhanced resistance to TS-inhibiting drugs like 5-fluorouracil or 5-fluoro-2-deoxyuridinemonophosphate. All these mutants can be used for the protection of normal human cell populations against the toxic manifestation of analogs that inhibited TS. Drugs for the local treatment or prevention of a mucositis in the oral cavity and the gastrointestinal tract caused by chemotherapy with TS-inhibitors are also provided.

Abstract: A method of obtaining an oligonucleotide capable of carrying out a predetermined biological function. A heterogeneous pool of oligonucleotides, x+y+z nucleotides in length, is first generated. Each oligonucleotide has a 5? randomized sequence, x nucleotides in length, a central preselected sequence, y nucleotides in length, and a 3? randomized sequence, z nucleotides in length. The resulting heterogeneous pool contains nucleic acid sequences representing a random sampling of the 4x+z possible sequences for oligonucleotides of the stated length. A random sampling of the heterogeneous pool of oligonucleotides is introduced Into a population of cells that do not exhibit the predetermined biological function. The population of engineered cells Is then screened for a subpopulation of cells exhibiting the predetermined biological function. From that subpopulation of cells Is Isolated an oligonucleotide containing the preselected sequence and capable of carrying out the predetermined biological function.

Abstract: A method of obtaining an oligonucleotide capable of carrying out a predetermined biological function. A heterogeneous pool of oligonucleotides, x+y+z nucleotides in length, is first generated. Each oligonucleotide has a 5? randomized sequence, x nucleotides in length, a central preselected sequence, y nucleotides in length, and a 3? randomized sequence, z nucleotides in length. The resulting heterogeneous pool contains nucleic acid sequences representing a random sampling of the 4x+z possible sequences for oligonucleotides of the stated length. A random sampling of the heterogeneous pool of oligonucleotides is introduced into a population of cells that do not exhibit the predetermined biological function. The population of engineered cells is then screened for a subpopulation of cells exhibiting the predetermined biological function. From that subpopulation of cells is isolated an oligonucleotide containing the preselected sequence and capable of carrying out the predetermined biological function.

Abstract: The present invention provides a method for identifying a thermostable polymerase having altered fidelity. The method consists of generating a random population of polymerase mutants by mutating at least one amino acid residue of a thermostable polymerase and screening the population for one or more active polymerase mutants by genetic selection. For example, the invention provides a method for identifying a thermostable polymerase having altered fidelity by mutating at least one amino acid residue in an active site O-helix of a thermostable polymerase. The invention also provides thermostable polymerases and nucleic acids encoding thermostable polymerases having altered fidelity, for example, high fidelity polymerases and low fidelity polymerases. The invention additionally provides a method for identifying one or more mutations in a gene by amplifying the gene with a high fidelity polymerase.

Abstract: The present invention is directed to the identification and use of ribonucleoside analogs to induce the mutation of an RNA virus, including BVDV, HIV and HCV, or a virus which otherwise replicates through an RNA intermediate. The increase in the mutation rate of the virus results in reduced viability of progeny generations of the virus, thereby inhibiting viral replication. In addition to these methods and related compositions, the invention provides methods and combinatorial chemistry libraries for screening ribonucleoside analogs for mutagenic potential.

Abstract: Novel thymidylate synthase (TS mutants) are disclosed differing from human wild type thymidylate synthase in single, double, or multiple mutations, which show enhanced resistant to TS-inhibiting drugs like 5-fluorouracil or 5-fluoro-2-deoxyuridinemonophosphate. All these mutants can be used for the protection of normal human cell populations against the toxic manifestation of analogs that inhibited TD.