Abstract: Methods and compositions for increasing or decreasing homologous recombination activity in a eukaryotic cell are provided. More particularly, various methods and compositions are provided which decrease the level of non-homologous recombination in a cell and thereby increase the frequency of targeted homologous recombination events. Various compositions including cells and kits that can be employed in the methods are also provided.

Abstract: The present invention provides compositions and methods for recombinational cloning. The compositions include vectors having multiple recombination sites and/or multiple topoisomerase recognition sites. The methods permit the simultaneous cloning of two or more different nucleic acid molecules. In some embodiments the molecules are fused together while in other embodiments the molecules are inserted into distinct sites in a vector. The invention also generally provides for linking or joining through recombination a number of molecules and/or compounds (e.g., chemical compounds, drugs, proteins or peptides, lipids, nucleic acids, carbohydrates, etc.) which may be the same or different.

Abstract: The invention provides methods and compositions related to the field of gene expression regulation. In particular, methods and compositions of the invention can be used to identify RNAi cleavage sites along a target RNA molecule. Methods and compositions of the invention may also be used to knockdown expression of nucleic acid molecules which encode reporters.

Abstract: A method of generating a double stranded (ds) recombinant nucleic acid molecule covalently linked in both strands by contacting two or more ds nucleotide sequences with a topoisomerase under conditions such that both termini of at least one end of a first ds nucleotide sequence are covalently linked by the topoisomerase to both termini of at least one end of a second ds nucleotide sequence is provided. Also provided is a method for generating a ds recombinant nucleic acid molecule covalently linked in one strand, by contacting two or more ds nucleotide sequences with a type IA topoisomerase under conditions such that one strand, but not both strands, of one or both ends of a first ds nucleotide sequence are covalently linked by the topoisomerase. Compositions for performing such methods, and compositions generated from such methods also are provided, as are kits containing components useful for conveniently practicing the methods.

Abstract: A method of generating a double stranded (ds) recombinant nucleic acid molecule covalently linked in both strands by contacting two or more ds nucleotide sequences with a topoisomerase under conditions such that both termini of at least one end of a first ds nucleotide sequence are covalently linked by the topoisomerase to both termini of at least one end of a second ds nucleotide sequence is provided. Also provided is a method for generating a ds recombinant nucleic acid molecule covalently linked in one strand, by contacting two or more ds nucleotide sequences with a type IA topoisomerase under conditions such that one strand, but not both strands, of one or both ends of a first ds nucleotide sequence are covalently linked by the topoisomerase. Compositions for performing such methods, and compositions generated from such methods also are provided, as are kits containing components useful for conveniently practicing the methods.

Abstract: The present invention provides compositions, methods, and kits for covalently linking nucleic acid molecules. The methods include a strand invasion step, and the compositions and kits are useful for performing such methods. For example, a method of covalently linking double stranded (ds) nucleic acid molecules can include contacting a first ds nucleic acid molecule, which has a topoisomerase linked to a 3? terminus of one end and has a single stranded 5? overhang at the same end, with a second ds nucleic acid molecule having a blunt end, such that the 5? overhang can hybridize to a complementary sequence of the blunt end of the second nucleic acid molecule, and the topoisomerase can covalently link the ds nucleic acid molecules. The methods are simpler and more efficient than previous methods for covalently linking nucleic acid sequences, and the compositions and kits facilitate practicing the methods, including methods of directionally linking two or more ds nucleic acid molecules.

Abstract: The present invention is in the fields of biotechnology and molecular biology. More particularly, the present invention relates to cloning or subcloning one or more nucleic acid molecules comprising one or more type IIs restriction enzyme recognition sites. The present invention also embodies cloning such nucleic acid molecules using recombinational cloning methods such as those employing recombination sites and recombination proteins. The present invention also relates to nucleic acid molecules (including RNA and iRNA), as well as proteins, expressed from host cells produced using the methods of the present invention.

Abstract: The invention provides methods of preparing nucleic acids, such as RNA molecules, of a defined size or range of sizes. The invention provides compositions, methods and kits for use in the production and preparation of small RNA molecules (including without limitation micro-RNA, siRNA, d-siRNA and e-siRNA) and other nucleic acids of various sizes.

Abstract: The present invention provides compositions and methods for recombinational cloning. The compositions include vectors having multiple recombination sites and/or multiple topoisomerase recognition sites. The methods permit the simultaneous cloning of two or more different nucleic acid molecules. In some embodiments the molecules are fused together while in other embodiments the molecules are inserted into distinct sites in a vector. The invention also generally provides for linking or joining through recombination a number of molecules and/or compounds (e.g., chemical compounds, drugs, proteins or peptides, lipids, nucleic acids, carbohydrates, etc.) which may be the same or different.

Abstract: The present invention provides compositions and methods for the construction of nucleic acids comprising all or portion of a viral genome. Nucleic acid molecules of the invention may be constructed to contain multiple recombination and/or topoisomerase recognition sites. The compositions include vectors having multiple recombination sites with unique specificity that contain all or a portion of a viral genome. The methods permit the insertion of a sequence of interest into a viral genome using recombinational and/or topoisomerase-mediated cloning. The present invention also provides methods of constructing recombinant virus, methods of expressing polypeptides, and methods of expressing fusion polypeptides.

Abstract: The present invention provides compositions and methods for recombinational cloning. The compositions include vectors having multiple recombination sites and/or multiple topoisomerase recognition sites. The methods permit the simultaneous cloning of two or more different nucleic acid molecules. In some embodiments the molecules are fused together while in other embodiments the molecules are inserted into distinct sites in a vector. The invention also generally provides for linking or joining through recombination a number of molecules and/or compounds (e.g., chemical compounds, drugs, proteins or peptides, lipids, nucleic acids, carbohydrates, etc.) which may be the same or different.