Wednesday, April 3, 2013

Fun fact: Scientists are using DNA tools to speed production of genetically modified mice

A laboratory mouse in which a gene affecting hair growth 
has been knocked out (left), is shown next to a normal lab mouse
(Author: Maggie Bartlett, NHGRI)
The production of knock out mice is a labor intensive, expensive and time consuming process. However, these mice with altered genes or gene regions are invaluable to basic research into how diseases are triggered at the cell level. To traditionally produce a knock out mouse, scientists create stem cells that are genetically modified which are implanted into an embryo. The result is mice with both modified and unmodified cells that must be cross bred several times until the knockout characteristic is carried in all cells. In sum this process can take up to 2 years.

Now, a recent publication in PNAS reports the findings of a collaboration of German scientists that can produce a knockout mouse in under 5 months! They used transcription activator-like effector nuclease (TALEN) enzymes to directly modify genes in the fertilized mouse egg so that all cells in the mouse would carry the same genetic defect. Thus eliminating the breeding of numerous mice to eventually result in the desired knockout.

TALEN enzymes are dual functional; one part binds to a particular gene while another part cuts the DNA. Creation of variants in the binding function will allow scientists to make precise DNA cuts that can be used to modify specific genes.

Article: Direct production of mouse disease models by embryo microinjection of TALENs and oligodeoxynucleotides