May 20 2004
Scientists at the University of Bristol have taken the first steps towards producing a sustainable and pure source of the healthy fats found in oily fish.
Eating such fish is encouraged as part of a healthy diet as their oils are rich in very long chain polyunsaturated fatty acids (VLCPUFAs). However, views on the health-promoting nature of VLCPUFAs have to be balanced against the marine pollution that can cause fish, and the oils extracted from them, to be contaminated with heavy metals and dioxins, and the fact that fish stocks are in global decline.
In work published in Nature Biotechnology in June, University of Bristol scientists and collaborators describe the first steps towards producing VLCPUFAs in the form of oilseed crop plants.
By adding three genes to the genome of Arabidopsis thaliana (the roadside weed known as thale cress) the researcher produced plants with a substantial content of the valuable VLCPUFAs arachidonic acid (AA) and eicosapentaenoic acid (EPA), both of which are sold as dietary supplements.
Fundamental to this success was the identification of a gene, from a planktonic micro-alga, that is responsible for lengthening 18-carbon fatty-acid chains, of the sort that are abundant in plant oils, to 20 carbons. The other two genes, from a protist and a fungus, code for enzymes that introduce extra double bonds at specific sites in the 20-carbon chains (that is, make them more desaturated).
Dr Baoxiu Qi isolated the key gene in Dr Colin Lazarus's laboratory in the School of Biological Sciences, where the transgenic plants were also constructed, and Dr Tom Fraser characterised the novel fatty acid content of the plants in Professor Keith Stobart's laboratory.
Before exploitation of these results can become a reality it will be necessary to replicate the work in an oilseed crop plant, such as linseed or soy, and overcome the problem of incorporating the VLCPUFAs in the seed oils. However, getting a higher plant to produce substantial quantities of AA and EPA is a significant first step – not least because it indicates that genetic modification and sustainability are not mutually exclusive terms. http://www.bris.ac.uk