Protocol Online logo
Top : Forum Archives: : siRNA, microRNA and RNAi

Gene Knockout - (Oct/09/2008 )

How much time does it take to develop gene knock out mice.


A gene knockout is a genetic technique in which an organism is engineered to carry genes that have been made inoperative (have been "knocked out" of the organism). This is done for research purposes. Also known as knockout organisms or simply knockouts, they are used in learning about a gene that has been sequenced, but which has an unknown or incompletely known function. Researchers draw inferences from the difference between the knockout organism and normal individuals.
Our mission is to provide high quality end to end solutions to the BPO segment in a manner that will improve the operational efficiency while reducing the cost of the services to the client.


Knockout is a difficult procedure, involving homologous recombination to make an embryonic stem cell carrying the knockout allele, hopefully as a homozygote. The modified stem cell is inserted into a group of blastocysts and put into a foster mother, where it develops and a chimeric pup is born, with some cells carrying the knockout allele. Some of these chimeric mice will carry the knockout allele in germline cells; you breed the chimeric mice and screen offspring for the knockout. Next you breed together animals that carry the knocked-out gene to establish a true-breeding line. This might take a half-year to a year or more. Here is a historical review of knockout technology:

I work for Gene Tools and the Vivo-Morpholinos described below are our product.

Knockdowns and knockouts are different approaches to gene inactivation. Knockdowns are an alternative that is more convenient. You put in an antisense oligo or double-stranded RNA targeting the gene you want to knock down. In adult animals, you need a systemic delivery system. One example of systemic antisense are Vivo-Morpholinos ( These are transient knockdowns, they will not last for the life of the organism but may last long enough to be experimentally useful -- and they are much easier. The Vivo-Morpholino is a Morpholino antisense oligo (a synthetic, non-natural steric blocking form of antisense) covalently linked to a delivery moiety, which is an eight-tipped dendrimer carrying a guanidinium group at each tip. The guanidinium groups interact with the phospholipids of endosomes, making the endosomal membrane leaky; this allows Vivo-Morpholino that have been endocytosed to escape the endosome into the cytosol/nuclear compartment of cells.

Li YF, Morcos PA. Design and Synthesis of Dendritic Molecular Transporter that Achieves Efficient in Vivo Delivery of Morpholino Antisense Oligo. Bioconjug Chem. 2008 Jul;19(7):1464-70. Epub 2008 Jun 20.

-Jon Moulton-