Peers laud GE blowfly maker

A New Zealand scientist has been awarded a molecular biology medal for his research into genetically engineering Australian blowflies.

The work is aimed at the release of millions of sterile male blowflies, which will mate in the wild but produce no offspring and potentially eradicate the pest.

Max Scott, a senior lecturer in genetics at Massey University, was awarded the applied biosystems medal by the Society of Biochemistry and Molecular Biology for his research into chromosomes and gene structures.

Dr Scott and colleagues have been investigating how changing chromosome structures regulate genes.

He has used the basic knowledge to develop genetically engineered all-male populations of Australian sheep blowflies that would be ideal for sterile release programmes.

Blowflies mate only once, and repeated use of the sterile insect technique could, in theory, wipe out the species in New Zealand.

The release of sterilised males into the wild to mate with fertile females has worked with screw-worm in North America, tsetse fly in Zanzibar, Queensland fruitfly in Western Australia and Mediterranean fruitfly in Mexico.

The Massey blowfly project began after the Australian sheep blowfly, introduced into North Auckland in 1988, spread throughout the country.

Flystruck lambs shed weight, and losses of up to 1kg of wool and two-thirds of the value of the pelt total $9 an animal.

Flystrike also has serious long-term consequences as buyers in key overseas markets become less tolerant of insecticides used to control the maggots.

Overall, flystrike is estimated to cost $37 million annually in lost production and control measures.

Farmers facing increasing numbers of insecticide-resistant flies have been squeezed by buyers' demands for wool with low levels of insecticide residue.

The wool industry has helped pay for the GE-blowfly project since 1997 to obtain a biological method of control.

Working with Dr Allen Health's fly group at AgResearch's animal health laboratories at Wallaceville, near Wellington, Dr Scott has constructed a gene that under certain conditions is lethal to female flies.

He has also identified a method of carrying the gene into the blowfly chromosomes, and has developed a way of distinguishing the transgenic fly from the much more plentiful non-transgenic fly.

At one stage the researchers used enhanced green fluorescent protein from a jellyfish to mark transgenic blowfly larvae.

The researchers are now working on inserting the female-killing gene into blowflies.

Dr Scott's work is possible because one of the distinguishing features of fungi, plants and animals is that their genes are packaged in chains of chromosomes in the nucleus of the cell.

To house this entire DNA in the nucleus, organisms including the blowflies house it in a sophisticated, folded, compressed and closed structure, except for a small fraction exposed at whichever genes are switched on in that cell.

Dr Scott has exploited multi-protein complexes that regulate the portion of the DNA which is exposed, and has transferred some of them from vinegar flies to blowflies and effectively disabled the flies' male X chromosome.

- NZPA

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