Diseases, genetic faults, food shortage, are some of the few problems that have plagued the human mind for centuries. But traditional plant and animal breeding to mutagenesis and the most recent genetic engineering, humans have found out many ways to combat these imperfections.
Genetic engineering involves genetic modification, i.e. it involves the use of recombinant DNA techniques and any organism that is generated using these techniques is considered to be a genetically modified organism. One of the most important applications of genetically engineering is a genetically engineered animal model, the most common being the mouse.
A genetically modified mouse is the one whose genome has been altered through genetic engineering techniques and are widely used for research. The two basic technical approaches to produce genetically modified mice are:
• A pronuclear injection into a single cell of the mouse embryo, where it will randomly integrate into the mouse genome. This method creates a transgenic mouse.
• Modification of embryonic stem cells with a DNA construct containing DNA sequences homologous to the target gene. Embryonic stem cells that recombine with the genomic DNA are selected for and they are then injected into the mice blastocysts. This method is used to manipulate a single gene, in most cases “knocking out” the target gene.
The most common type is the “Knock out” mice, where the activity of a single or multiple genes are removed. They have been used to study obesity, heart disease, diabetics, arthritis, substance abuse, anxiety, aging and Parkinson’s disease. Knock out mice devoid of pro- or anti-inflammatory mediators allows the examination of the effects of a specific cytokine and thereby help in the study of acute pancreatitis in humans. Transgenic mice generated to carry cloned oncogenes and knockout mice lacking the tumour suppressed genes have provided good models for human cancer. The disease symptoms and potential drugs or treatments can be tested against these mouse models.