Cloning and transgenics: progress and new approaches in domestic animals.

Abstract Cloning and transgenic modification of genomes of domesticated large animal species have significantly increased scientific discovery in both agricultural and biomedical research. The purpose of creating these modified animals includes biosynthesis of proteins in milk, human disease modelling, gene knockout models for potential utilization in xenotransplantation and improved animal performance. While several strategies, such as pronuclear injection and intracytoplasmic sperm injection are capable of producing transgenic animals, cloning with somatic cells allows an array of genetic modifications to be made and overcomes the lack of embryonic stem cells in these non-primate, non-rodent species. Numerous strategies for genetic modification of somatic cells are exploited in addition to methods enhancing donor cell nuclear reprogramming and remodelling to increase the efficiency of producing cloned, transgenic large animal models.