LAB - Genetically Modified Organisms (GMOs)

Bio-Rad's GMO Investigator Kit

In this lab we are trying to find evidence of genes that have been inserted into a plant's genome. There are two ways of finding out:

1. Testing for the presence of proteins that the trans-genes produce
   
2. Amplifying a fragment of DNA that contains the trans-gene via PCR
   

Since we need a lot of fresh tissue and a kit to test for several of the proteins that the most common trans-genes code for, materials that we don't have, we are using the almighty PCR.

Most trans-genes have the 35S promoter from the cauliflower mosaic virus (CMV 35S), and the nopaline synthase (NOS) terminator from Agrobacterium tumefaciens. These sequences come from totally different organisms from that used to isolate the actual trans-gene, but they are recognized by the plant cell machinery (mainly its polymerase), so they can actually produce the product that the gene is intended for. Even if the gene is in the genome, it will NOT work if there are no promoters AND terminators that the plant can recognize. Since there is a number of genes that have been inserted in crops in the U.S., it's easier to go after the promoter and the terminator when using PCR. CMV 35S and NOS have been use in over 85% of the GMOs, so if we have primers to amplify them, we don't have to worry about which gene was inserted (as long as the question doesn't involve knowing the specific gene).

We extracted DNA from corn or soy that we presume have been genetically modified, and from a cerified non-GMO food control provided by Bio Rad, the manufacturers of the kit we use. The master mixes we used include primers for both CMV35S and NOS in the same mix, and in addition to those we are using a separate master mix with primers that will amplify a 455 bp region of the photosystem II (PSII) chloroplast gene, common to most plants. This will be a control to ensure we have successfully extracted DNA, so even non-GM plants should have the band present.

Speaking of PCR, watch the Bio Rad PCR animation NOW...!

Check the Bio-Rad web page for this lab!

The gel electrophoresis will be ran the following day.

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