Methods and Technologies Behind Genetic Engineering

Understanding the Fear

Genetic engineering often carries a certain fear, an image of something unknowable and potentially dangerous. It's essential to understand exactly what's happening. This article explores the methods of genetic engineering.

Three Methods

Genetic engineering aims to introduce specific DNA (like producing a substance that repels pests) into a crop's cells. But how is the DNA introduced? There are mainly three methods:

1. Using Microorganisms (Agrobacterium method) The most common method involves using a microorganism called Agrobacterium. In the wild, Agrobacterium can infect plants and insert its DNA into the plant DNA, forcing the plant to produce nutrients for the microbe. Scientists modify the Agrobacterium to carry the desired DNA and then infect the crops, thus introducing the DNA.

Photo: Creative Commons 0

1. Shooting DNA (Particle gun method) This method involves coating metallic particles with DNA and then shooting them into cells at high speeds. The image shows the particle gun machine.

Photo: Creative Commons 0

1. Wounding and Soaking in DNA (Whisker method) "Whiskers" refer to spiky crystals. In this method, plant tissues, whiskers, and a solution containing DNA are mixed vigorously. The DNA solution then enters the cells that the whiskers have wounded.

Marker Genes

Even when using these methods, the chances of successfully introducing the desired DNA are very low. That's where marker genes come in. Marker genes are DNA pieces that make it easier to identify whether the desired DNA has been inserted. For instance, a gene that makes a cell resistant to antibiotics can be used as a marker gene. After attempting DNA insertion, cells are exposed to antibiotics.

Cells that didn't take up the desired DNA or couldn't express its traits will likely also lack the marker gene, causing them to die in the presence of antibiotics. Thus, cells that survive the antibiotics likely also possess the desired DNA. Other marker genes include genes that produce fluorescence or confer resistance to herbicides.

References

• "Misunderstandings about Genetically Modified Crops" by Masami Kojima, Energy Forum Co., Ltd.