In May, students in the Biology Department produced WHS’ first Genetically Modified Organism... More detailed science Experimental results Overview Photo gallery

Bacterial transformation was carried out using a gene from the bioluminescent jellyfish Aequorea victoria

Experimental Overview

Gene for green fluorescent protein (from the jellyfish) Gene for beta-lactamase (confers antibiotic resistance) The transformation was carried out using a pGLO plasmid which had been modified to contain two new genes..

If we could get pGLO into the bacteria, they would be antibiotic resistant and would emit green light under a UV lamp

Safety  Escherichia coli strain HB101 K-12 does not produce compounds or toxins that can make people sick.  Escherichia coli strain HB101 K-12 cannot survive outside the laboratory.

Basic Principles Students were working with tiny quantities (100 μl); They could hardly see any liquid at all! Quantities and timings were vital. The heat shock (50s at 42 o C) had to be timed precisely and transfer to ice needed to be immediate.

More detailed science... Or jump to: Experimental resultsPhoto gallery

More detailed science... If the pGLO plasmid is taken up, the genes for ampicillin resistance and GFP will be present.

Bla is the beta-lactamase gene. Inside bacterial cells it is transcribed into mRNA, then translated to produce the beta-lactamase enzyme. This enzyme inactivates ampicillin (an antibiotic). Why is bla important in this experiment?

araC is a gene required to promote the transcription of the arabinose operon (a series of genes that digest arabinose sugar). araC needs to bind with arabinose sugar in order to function as a promotor. If arabinose is absent, the gene is ‘silent’. What is the advantage of this to the bacterium?

Normally the operon has 3 genes coding for enzymes that break down arabinose sugar The gene is only expressed (transcribed) in the presence of arabinose araC needs to bind with arabinose before it allows pBAD to promote transcription. Arabinose is a food source for bacteria

In the pGLO plasmid, the arabinose operon (araA, araB and araD genes) have been replaced with the gene for GFP. If arabinose is present, it will promote transcription into mRNA, which will be translated into GFP.

RESULTS – MAY 2014

These E. coli bacteria have been modified with the pGLO plasmid. They are now resistant to the antibiotic ampicillin which was added to the growth medium. (Megan & Connie, Year 11)

These E. coli bacteria have also been modified with the pGLO plasmid and are resistant to the antibiotic ampicillin. These colonies have been grown on nutrient agar containing arabinose sugar, which switches on the gene expression for GFP (Green Fluorescent Protein). (James, Year 13)

Under UV light, the modified bacteria express GFP only when grown on nutrient agar containing arabinose sugar.

Our aseptic technique was not good enough to prevent contamination, but we did manage to transform two bacteria. (Tom & Jasper, Year 10)

Photo gallery

This practical work was made possible by the school’s More Able & Talented programme, and the superb support provided by the biology technicians. Thank you!