02 Markers for Genetic Engineering
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Original genetic engineering techniques used antibiotic resistance genes as markers, but there were risks of pathogenic bacteria acquiring these resistance genes. Fluorescent markers are now commonly used instead. Fluorescent markers allow transformed cells to be easily identified under ultraviolet light, without risks of spreading antibiotic resistance. The document discusses how fluorescent markers, along with the desired genes, are incorporated into plant cell nuclei using microprojectiles, resulting in quicker transformation and a higher proportion of transformed plants compared to antibiotic resistance markers.
02 Markers for Genetic Engineering
- 1. Markers for genetic engineering ALBIO9700/2006JK
- 2. Why fluorescent markers (easily stained substance) are now used instead of antibiotic resistance markers • Antibiotic resistance markers – Original selected plasmid has antibiotic resistance genes to two different antibiotics (A and B) – Restriction enzyme is selected so that it cuts in the middle of one of these antibiotic resistance genes – Bacteria that have taken up the plasmid all have a successfully working copy of antibiotic resistance gene A. – Many plasmids also have a working copy of antibiotic resistance gene B, showing that the plasmids have failed to form recombinant DNA. – Bacteria that have taken up recombinant plasmids containing the cDNA insulin gene do not contain a working copy of the antibiotic resistance gene B. ALBIO9700/2006JK
- 4. • Potential problem: plasmids commonly transferred between bacteria of the same species and also of different species meaning that pathogenic strains could receive plasmid with antibiotic resistance gene • Risk is a hypothetical one • Alternative method: – Incorporate a markergene for a protein that fluoresces green under ultra-violet light, along with desired genes (genes added using a micro-projectile to shoot them into plant cell nuclei) – quicker, higher proportion of transformed plants – Incorporate alongside the desired gene another marker gene that produces harmless product that is easily stained and is not normally produced by the cells ALBIO9700/2006JK