title: Concepts and tools for gene editing.
abstract: Gene editing is a relatively recent concept in the molecular biology field. Traditional genetic modifications in animals relied on a classical toolbox that, aside from some technical improvements and additions, remained unchanged for many years. Classical methods involved direct delivery of DNA sequences into embryos or the use of embryonic stem cells for those few species (mice and rats) where it was possible to establish them. For livestock, the advent of somatic cell nuclear transfer platforms provided alternative, but technically challenging, approaches for the genetic alteration of loci at will. However, the entire landscape changed with the appearance of different classes of genome editors, from initial zinc finger nucleases, to transcription activator-like effector nucleases and, most recently, with the development of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas). Gene editing is currently achieved by CRISPR-Cas-mediated methods, and this technological advancement has boosted our capacity to generate almost any genetically altered animal that can be envisaged.
authors.affiliation: Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Josa
authors.affiliation: Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Davide
authors.initials: D
authors.lastname: Seruggia
authors.affiliation: Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Almudena
authors.initials: A
authors.lastname: Fernández
authors.affiliation: Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Lluis
authors.initials: L
authors.lastname: Montoliu