Abstract: Nuclease-mediated methods for expanding repeats already present at a genomic locus are provided. Non-human animal genomes, non-human animal cells, and non-human animals comprising a heterologous hexanucleotide repeat expansion sequence inserted at an endogenous C9orf72 locus and methods of making such non-human animal cells and non-human animals through nuclease-mediated repeat expansion are also provided. Methods of using the non-human animal cells or non-human animals to identify therapeutic candidates that may be used to prevent, delay or treat one or more neurodegenerative disorders associated with repeat expansion at the C9orf72 locus are also provided.

Abstract: Nuclease-mediated methods for expanding repeats already present at a genomic locus are provided. Non-human animal genomes, non-human animal cells, and non-human animals comprising a heterologous hexanucleotide repeat expansion sequence inserted at an endogenous C9orf72 locus and methods of making such non-human animal cells and non-human animals through nuclease-mediated repeat expansion are also provided. Methods of using the non-human animal cells or non-human animals to identify therapeutic candidates that may be used to prevent, delay or treat one or more neurodegenerative disorders associated with repeat expansion at the C9orf72 locus are also provided.

Abstract: Methods and compositions are provided for generating F0 fertile XY female animals. The methods and compositions involve making XY pluripotent or totipotent animal cells, in vitro cell cultures, or embryos that are capable of producing a fertile female XY animal in an F0 generation. Such cells, embryos, and animals can be made by silencing a region of the Y chromosome. Optionally, the cells can also be cultured in feminizing medium such as a low-osmolality medium and/or can be modified to decrease the level and/or activity of an Sry protein. Methods and compositions are also provided for silencing a region of the Y chromosome in an XY pluripotent or totipotent animal cell, or in vitro cell cultures, embryos, or animals derived therefrom, by maintaining an XY pluripotent or totipotent animal cell in a feminizing medium.

Abstract: Methods and compositions are provided for generating targeted genetic modifications on the Y chromosome or a challenging target locus. Compositions include an in vitro culture comprising an XY pluripotent and/or totipotent animal cell (i.e., XY ES cells or XY iPS cells) having a modification that decreases the level and/or activity of an Sry protein; and, culturing these cells in a medium that promotes development of XY F0 fertile females. Such compositions find use in various methods for making a fertile female XY non-human mammal in an F0 generation.

Abstract: Methods and compositions are provided for generating F0 fertile XY female animals. The methods and compositions involve making XY pluripotent or totipotent animal cells, in vitro cell cultures, or embryos that are capable of producing a fertile female XY animal in an F0 generation. Such cells, embryos, and animals can be made by silencing a region of the Y chromosome. Optionally, the cells can also be cultured in feminizing medium such as a low-osmolality medium and/or can be modified to decrease the level and/or activity of an Sry protein. Methods and compositions are also provided for silencing a region of the Y chromosome in an XY pluripotent or totipotent animal cell, or in vitro cell cultures, embryos, or animals derived therefrom, by maintaining an XY pluripotent or totipotent animal cell in a feminizing medium.

Abstract: Methods and compositions are provided for generating targeted genetic modifications on the Y chromosome or a challenging target locus. Compositions include an in vitro culture comprising an XY pluripotent and/or totipotent animal cell (i.e., XY ES cells or XY iPS cells) having a modification that decreases the level and/or activity of an Sry protein; and, culturing these cells in a medium that promotes development of XY F0 fertile females. Such compositions find use in various methods for making a fertile female XY non-human mammal in an F0 generation.

Abstract: Nuclease-mediated methods for expanding repeats already present at a genomic locus are provided. Non-human animal genomes, non-human animal cells, and non-human animals comprising a heterologous hexanucleotide repeat expansion sequence inserted at an endogenous C9orf72 locus and methods of making such non-human animal cells and non-human animals through nuclease-mediated repeat expansion are also provided. Methods of using the non-human animal cells or non-human animals to identify therapeutic candidates that may be used to prevent, delay or treat one or more neurodegenerative disorders associated with repeat expansion at the C9orf72 locus are also provided.

Abstract: Methods and compositions are provided for generating or maintaining human iPS cells in culture. Methods include the use of a low osmolality medium to make human iPS cells, or use of a low osmolality medium to maintain human iPS cells. Methods for making targeted genetic modification to human iPS cells cultured in low osmolality medium are also included. Compositions include human iPS cells cultured and maintained using the low osmolality medium defined herein.

Abstract: Methods and compositions are provided for generating or maintaining human iPS cells in culture. Methods include the use of a low osmolality medium to make human iPS cells, or use of a low osmolality medium to maintain human iPS cells. Methods for making targeted genetic modification to human iPS cells cultured in low osmolality medium are also included. Compositions include human iPS cells cultured and maintained using the low osmolality medium defined herein.

Abstract: Methods and compositions are provided for modifying one or more target loci in a cell. Such methods comprise providing a cell comprising a first polynucleotide encoding a first selection marker operably linked to a first promoter active in the cell, wherein the first polynucleotide further comprises a first recognition site for a first nuclease agent. A first nuclease agent is introduced into a cell, wherein the first nuclease agent induces a nick or double-strand break at the first recognition site. Further introduced into the cell is a first targeting vector comprising a first insert polynucleotide flanked by a first and a second homology arm that correspond to a first and a second target site located in sufficient proximity to the first recognition site. At least one cell is then identified comprising in its genome the first insert polynucleotide integrated at the target locus.

Abstract: Methods and compositions are provided for modifying one or more target loci in a cell. Such methods comprise providing a cell comprising a first polynucleotide encoding a first selection marker operably linked to a first promoter active in the cell, wherein the first polynucleotide further comprises a first recognition site for a first nuclease agent. A first nuclease agent is introduced into a cell, wherein the first nuclease agent induces a nick or double-strand break at the first recognition site. Further introduced into the cell is a first targeting vector comprising a first insert polynucleotide flanked by a first and a second homology arm that correspond to a first and a second target site located in sufficient proximity to the first recognition site. At least one cell is then identified comprising in its genome the first insert polynucleotide integrated at the target locus.

Abstract: Methods and compositions are provided for modifying one or more target loci in a cell. Such methods comprise providing a cell comprising a first polynucleotide encoding a first selection marker operably linked to a first promoter active in the cell, wherein the first polynucleotide further comprises a first recognition site for a first nuclease agent. A first nuclease agent is introduced into a cell, wherein the first nuclease agent induces a nick or double-strand break at the first recognition site. Further introduced into the cell is a first targeting vector comprising a first insert polynucleotide flanked by a first and a second homology arm that correspond to a first and a second target site located in sufficient proximity to the first recognition site. At least one cell is then identified comprising in its genome the first insert polynucleotide integrated at the target locus.

Abstract: Methods and compositions are provided for generating targeted genetic modifications on the Y chromosome or a challenging target locus. Compositions include an in vitro culture comprising an XY pluripotent and/or totipotent animal cell (i.e., XY ES cells or XY iPS cells) having a modification that decreases the level and/or activity of an Sry protein; and, culturing these cells in a medium that promotes development of XY F0 fertile females. Such compositions find use in various methods for making a fertile female XY non-human mammal in an F0 generation.

Abstract: Methods and compositions are provided for generating targeted genetic modifications on the Y chromosome or a challenging target locus. Compositions include an in vitro culture comprising an XY pluripotent and/or totipotent animal cell (i.e., XY ES cells or XY iPS cells) having a modification that decreases the level and/or activity of an Sry protein; and, culturing these cells in a medium that promotes development of XY F0 fertile females. Such compositions find use in various methods for making a fertile female XY non-human mammal in an F0 generation.

Abstract: Methods and compositions are provided for modifying one or more target loci in a cell. Such methods comprise providing a cell comprising a first polynucleotide encoding a first selection marker operably linked to a first promoter active in the cell, wherein the first polynucleotide further comprises a first recognition site for a first nuclease agent. A first nuclease agent is introduced into a cell, wherein the first nuclease agent induces a nick or double-strand break at the first recognition site. Further introduced into the cell is a first targeting vector comprising a first insert polynucleotide flanked by a first and a second homology arm that correspond to a first and a second target site located in sufficient proximity to the first recognition site. At least one cell is then identified comprising in its genome the first insert polynucleotide integrated at the target locus.

Abstract: Methods and compositions are provided for generating F0 fertile XY female animals. The methods and compositions involve making XY pluripotent or totipotent animal cells, in vitro cell cultures, or embryos that are capable of producing a fertile female XY animal in an F0 generation. Such cells, embryos, and animals can be made by silencing a region of the Y chromosome. Optionally, the cells can also be cultured in feminizing medium such as a low-osmolality medium and/or can be modified to decrease the level and/or activity of an Sry protein. Methods and compositions are also provided for silencing a region of the Y chromosome in an XY pluripotent or totipotent animal cell, or in vitro cell cultures, embryos, or animals derived therefrom, by maintaining an XY pluripotent or totipotent animal cell in a feminizing medium.

Abstract: Methods and compositions are provided for generating or maintaining human iPS cells in culture. Methods include the use of a low osmolality medium to make human iPS cells, or use of a low osmolality medium to maintain human iPS cells. Methods for making targeted genetic modification to human iPS cells cultured in low osmolality medium are also included. Compositions include human iPS cells cultured and maintained using the low osmolality medium defined herein.

Abstract: Compositions and methods are provided for modifying a genomic locus of interest in a eukaryotic cell, a mammalian cell, a human cell or a non-human mammalian cell using a large targeting vector (LTVEC) comprising various endogenous or exogenous nucleic acid sequences as described herein. Further methods combine the use of the LTVEC with a CRISPR/Cas system. Compositions and methods for generating a genetically modified non-human animal comprising one or more targeted genetic modifications in their germline are also provided.

Abstract: Methods and compositions are provided for generating targeted genetic modifications on the Y chromosome or a challenging target locus. Compositions include an in vitro culture comprising an XY pluripotent and/or totipotent animal cell (i.e., XY ES cells or XY iPS cells) having a modification that decreases the level and/or activity of an Sry protein; and, culturing these cells in a medium that promotes development of XY F0 fertile females. Such compositions find use in various methods for making a fertile female XY non-human mammal in an F0 generation.

Abstract: Methods and compositions are provided for modifying one or more target loci in a cell. Such methods comprise providing a cell comprising a first polynucleotide encoding a first selection marker operably linked to a first promoter active in the cell, wherein the first polynucleotide further comprises a first recognition site for a first nuclease agent. A first nuclease agent is introduced into a cell, wherein the first nuclease agent induces a nick or double-strand break at the first recognition site. Further introduced into the cell is a first targeting vector comprising a first insert polynucleotide flanked by a first and a second homology arm that correspond to a first and a second target site located in sufficient proximity to the first recognition site. At least one cell is then identified comprising in its genome the first insert polynucleotide integrated at the target locus.