Modified milk could treat disease

By Michael Dickison

Michael Dickison reviews potential uses of GM highlighted by a global biotechnology conference in Rotorua.

Photo / Mark Mitchell
Photo / Mark Mitchell

New Zealand scientists have genetically engineered cows to produce milk that can treat a number of human diseases.

Cloning techniques have been adopted in the genetic modification of animals, a field looking to alter cows' milk to produce pharmaceuticals in an application known as "biopharming".

Crown Research Institute AgResearch says it has been the pioneer in transferring from mice to cows the concept of changing the composition of milk.

GM products have been at the forefront of the news after a biotech conference last week in Rotorua - even though much of the technology is banned from use here.

AgResearch has several "proof-of-concept" cows which could produce milk with human proteins that could treat human diseases. Recently, the research has extended to production of therapeutic antibodies in goatsmilk.

Touted by proponents as the next Green Revolution to help feed the world, and labelled "frankenfood" by critics, genetic modification has generated both interest and controversy.

The conference participants urged New Zealand to embrace the research.

AgResearch scientist Tony Conner said: "If we continue not to adopt this technology, you run a huge risk of being left behind ... in another decade, we could be dealing with yesterday's crops."

Among GM's more attention-grabbing experiments are glowing cats and bananas modified to administer vaccines. But globally, the most common application has been improvements to common crops such as corn and soy, usually to increase resistance to pests and herbicides.

GM's greatest hits

* Global applications

Insect-resistant crops
One of the most common GM applications is modifying crops to be toxic towards certain insects. The genes from soil-based bacteria that produce a toxin are inserted into the DNA of plants; the plants then produce the toxins themselves and become deadly to the larvae of pest insects. Huge tracts of corn, potato and cotton fields around the world have been grown with this genetic modification.

Herbicide tolerance
Crops can be designed through GM to ???survive particular herbicides. Soybeans have been grown in several countries with this modification, allowing herbicides to be used to kill weeds but not the crops.

Increased nutrition
Tomatoes have been modified to produce higher levels of an antioxidant, while canola has been engineered to yield low-cholesterol oil. A variety of rice makes vitamin A, cassava produces more proteins, and scientists in Japan have grown a coffee plant containing 50 to 70 per cent less caffeine.

* NZ research

Improved grass
Pastoral Genomics, a New Zealand GM research consortium, is developing a genetically modified grass to have at least 25 per cent more leaf mass, more protein for livestock and improved drought resistance, alongside other aims. The scientists have begun trials overseas.

Wasp-killing bacteria
The Ministry for the Environment says GM is being investigated as a potential tool for pest control, specifically "research to genetically modify bacteria from the gut of wasps to produce a toxin that could kill wasp species".

Drugs in cows' milk
AgResearch, a crown research institute, says it has produced "proof-of-concept cows" that produce milk with human proteins. The proteins in the milk can be tailored to be the equivalent of approved human therapeutic drugs, an application known as "biopharming".

* Odd examples

Glowing cats
Researchers in South Korea added the genetic instructions for a red fluorescent protein to the DNA of Turkish Angora cats. After a round of cloning, the cats' offspring glowed under an ultra-violet light. The research was for creating animals with human genetic disorders.

Banana vaccines
Bananas were genetically engineered to produce the chemicals in the Hepatitis B vaccine. Eating one of the bananas would be the GM equivalent of getting a jab. The researchers, from India, say the edible vaccine has economic and other advantages over injections.

Scorpion venom for cabbages
The up to 80 different toxins in the venom of scorpions were analysed by Chinese researchers and a particular chemical isolated. The DNA sequence that would produce the chemical was inserted into E. coli bacteria. These were then used to infect cabbage, which were fed to moth larvae to test toxicity.

How it works
One of many possible combinations of methods

Make a DNA sequence
The instructions that lead to the chemicals and make-up of an animal are recorded as a long string of just four DNA building blocks, often labelled by the letters A, C, G and T. Several companies now let you design a DNA sequence on a PC to have it strung together as a real molecule one block at a time, creating a set of potential modifications for an animal.

Inject DNA into animal cells
In a lab, the resulting set of instructions are inserted into cells taken from an animal. New DNA then combines with the animal's DNA. How (ie where) the two sets of DNA combine can be controlled, but the process itself has been descibed as "poorly understood".

Clone injected cells
The core nuclei of the modified cells are placed in egg cells, which can be induced to multiply.

Give birth to clones
The modified eggs are put in a surrogate mother and a genetically modified offspring is born.

- NZ Herald

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