The invention provides methods for reprogramming somatic cells to generate multipotent or pluripotent cells. Such methods are useful for a variety of purposes, including treating or preventing a medical condition in an individual. The invention further provides methods for identifying an agent that reprograms somatic cells to a less differentiated state.

The present invention provides modified oocytes having a nuclear genome derived from a first oocyte and cytoplasm derived from a second oocyte from a different subject, and methods for making and using such modified oocytes. The methods and compositions of the present invention can be useful in a variety of settings including, but not limited to, in in vitro fertilization (IVF) procedures.

Compositions and methods are provided for making rat pluripotent and totipotent cells, including rat embryonic stem (ES) cells. Compositions and methods for improving efficiency or frequency of germline transmission of genetic modifications in rats are provided. Such methods and compositions comprise an in vitro culture comprising a feeder cell layer and a population of rat ES cells or a rat ES cell line, wherein the in vitro culture conditions maintain pluripotency of the ES cell and comprises a media having mouse leukemia inhibitory factor (LIF) or an active variant or fragment thereof. Various methods of establishing such rat ES cell lines are further provided. Methods of selecting genetically modified rat ES cells are also provided, along with various methods to generate a transgenic rat from the genetically modified rat ES cells provided herein. Various kits and articles of manufacture are further provided.

Provided are a method for preparing a mammalian ovum or embryo in which zona pellucida has been thinned or eliminated, and a method for fertilization using the mammalian ovum prepared by the aforementioned method. The resulting mammalian ovum or embryo is capable of realizing an improved fertilization rate and development rate when used for in vitro fertilization, transplantation of a fertilized ovum, or for preparation of an embryo in the early stages of development used in the production of a genetically modified animal.

The disclosure relates to a method of reprogramming one or more somatic cells, e.g., partially differentiated or fully/terminally differentiated somatic cells, to a less differentiated state, e.g., a pluripotent or multipotent state. In further embodiments the invention also relates to reprogrammed somatic cells produced by methods of the invention, to uses of said cells, and to methods for identifying agents useful for reprogramming somatic cells.

An amyotrophic lateral sclerosis (ALS)-simulating model and a method for constructing the ALS-simulating model based on a caspase-4 (CASP4) gene are provideds. The method includes: (1) constructing a targeting fragment for knock-in of the CASP4 gene; (2) injecting gRNA, Cas9 mRNA, and the targeting fragment into a mouse zygote, culturing, and passaging to produce a hCASP4flox mouse with the CASP4 gene stably inherited; and (3) crossing the hCASP4flox mouse with a Cre driver mouse to produce a double-positive heterozygous mouse, which is a mouse model in which the CASP4 gene is specifically expressed in a nervous system. An ALS-simulating animal model is constructed based on a humanized CASP4 gene. The method can effectively avoid the mouse death caused by this apoptotic factor, and leads to an ALS-simulating mouse model in which TDP-43 fragments accumulate in the cytoplasm and TDP-43 is deleted in the nucleus.