Cloned food

Imagine eating a delicious, tender stake and saving a little piece of the meat to produce another cow that will taste exactly the same. Or taking a dairy cow that produces large amounts of milk and producing a whole barn-full just like her.

These are the promises of biotechnologists working to clone the healthiest, fattest and fastest growing farm animals. They believe consumer acceptance of cloned foods will be higher than for genetically modified (GM) foods, because genes are not altered during cloning.

But cloning costs are so high that a single animal would cost $20,000 or more to produce, or around $100 per hamburger. Rather, biotech companies want to sell the sperm of clones, and farmers want to sell their milk.

But cloning is no substitute for good breeding. Clones are extremely difficult to make and have numerous health problems that could affect the quality of their meat or milk. Clones are not even identical, so there is no guarantee that meat will taste as delicious or animals will be as healthy.

Using the sperm from a healthy bull is much more likely to produce healthy herds than cloning that bull and then using the sperm of its clone. Cloning companies have yet to come up with a reason why cloning would be better than traditional breeding.

PA / The Guardian

Most cloned animals die before birth. Only one of every several hundred cloned eggs ever starts dividing and of these, only a small percentage result in pregnancies. Many of the animals that are born die soon after or suffer serious health problems. Some effects of cloning are not apparent in the days, weeks or even years after birth.

There is no one, specific thing that causes clones to go haywire. Rather, the cloning process itself seems to create random errors in the expression of individual genes. Those errors can produce any number of unpredictable problems, at any time in life. So even clones that appear healthy at birth may have underlying genetic abnormalities.

     • Dolly the sheep, the first animal cloned from an adult cell, was put down at six years old after developing lung cancer. Prior to her death, Dolly had suffered several other health problems - at only 3 years old she was aging faster than normal, she was overweight and developed premature arthritis at only 5 years. Sheep normally live for 10-16 years. It took 277 attempts to produce Dolly.

     • Australia's first cloned sheep, Matilda, died suddenly of unknown causes at only three years old.

     • A Jersey calf cloned at the University of Tennessee died after nine months of unknown causes.

     • AgResearch, which claims to be the most efficient animal cloning group in the world, only has a 6 percent survival rate of cloned animals surviving to three months. Almost a quarter of the calves and lambs cloned by AgResearch died within their first three months of life. The other clones did not survive pregnancy or were aborted because of deformities.

     • The University of Missouri published a study called "Phenotyping of Transgenic Cloned Pigs," which reported that 50 percent of cloned piglets died or were destroyed by researchers due to defects such as heart failure, lameness or anemia.

     • A Texas A&M study, entitled "A Highly Efficient Method for Porcine Cloning by Nuclear Transfer Using In Vitro - Matured Oocytes," documented a 94 percent failure rate. Out of the 511 cloned eggs transferred, only 28 pigs were born, one of which was dead and one "was born lacking an anus and tail."

     • The National Institute of Infectious Diseases in Tokyo reported that cloned mice initially appeared active and healthy, but the first clone died after only 311 days, and 83 percent were dead within 800 days, compared to only 23 percent of the normal animals.

     • Clones are often so oversized during pregnancy that they cannot be born naturally and their surrogate mother must undergo a cesarean. They also tend to become obese in old age.

     • Other problems seen in cloned animals include squashed faces, diabetes, enlarged tongues, intestinal blockages, weak immune systems, enlarged hearts or lungs that do not develop properly, pneumonia, liver failure, cancer and an inability to straighten their legs.

In addition, whole herds of cloned animals would be a "welfare disaster," according to Joyce D'Silva of Compassion in World Farming. "There would be a huge loss of genetic diversity with unforeseeable results in terms of animal illness."

Sexual reproduction shuffles genes from both parents to produce the best combinations and weed out inferior genes. It produces resistance to parasites by creating combinations of defense genes to which parasites are not adapted. There is even some evidence that mammals 'test-drive' embryos by stressing them, to remove substandard combinations.

But a lack of this genetic variety means certain diseases could wipe out entire herds of clones.

Dr. Ryuzo Yanagimachi, University of Hawaii

Cloning made easy

Genes contain the instructions for building a plant or animal. During development, each cell switches different genes on or off - a heart cell switches on the genes needed to make a heart, a skin cell switches on the genes for making skin and so on. Once a cell has switched on its 'heart genes,' it cannot change its mind and become a skin or liver cell, but the complete set of genes remains present in every cell.

In cloning, a developed cell can be re-programmed to switch off its genes and become an egg again. A skin cell from the udder of an adult sheep was used to create Dolly.

Clones are created by a technique called nuclear transfer, which requires a cell from the animal to be cloned and a host egg cell from another animal. The genes from the host egg are sucked out and the two cells are fused together using an electric current. The egg believes it has been fertilized and starts to divide. It is implanted into a surrogate mother seven days later, and each cell switches on the genes it needs for development.

No one knows how the egg re-programs the adult cell's genes, but this is at least one of the reasons that deaths and deformities are so common. During sexual reproduction, sperm and eggs take months and years, respectively, to develop and program their genes. But during cloning the egg has only minutes or hours to re-program before it starts to divide. If re-programming is not perfect, problems are likely to occur during development or later life.

Research at the Massachusetts Institute of Technology found that cloned mice had errors in about 50 percent of re-programmed genes. It is likely that all cloned mammals will show around the same level of mistakes.

Copycats

Surprisingly, cloned animals are not identical. Some clones are larger than their 'parent,' while others have different markings or colorings.

Take for example Cc - or Carbon copy - the world's first cloned house cat. Cc was cloned by scientists at Genetic Savings and Clone in College Station, Texas. The DNA used to make Cc came from a calico cat called Rainbow, whose fur has orange and black patches (left in photo). However, Cc is a black and white tiger tabby (right).

The scientists who created Cc believe that the differences in coat color may be because the two cats are female. Whereas males have one X and one Y chromosome, females have two X chromosomes and so have a 'choice' of which chromosome to use. The genes for hair color are located on the X chromosome.

Six going on twelve

Although Dolly was six when she died, her genes originally came from a six-year-old sheep, making her genetically 12 years old - a more normal lifespan for a sheep.

All female and most male chromosomes are X-shaped, and each of the four ends has a 'cap' called a telomere to protect it from fraying. Each time a cell divides the telomeres become a little shorter, until they eventually crumble away and the cell dies.

When Dolly was only 3 years old, her telomeres were shorter than for a normal sheep of her age, suggesting that she was genetically older than her years.

The udder genes

Clones do not have identical genes. During nuclear transfer, the host egg has its nuclear chromosomes removed and replaced. Nuclear chromosomes contain most of an animal's genes, but not all. Genes are also present in mitochondria - the 'batteries' of the cell.

Experiments on Dolly found that 99.5% of her 37 mitochondrial genes came from the host egg, not the udder cell. And because mitochondria play a vital role in cells throughout the body, this difference might lead to significant physical differences between two clones.




Is it safe to eat?

Very little research has been done to assess the health or safety of consuming cloned food products. The National Academy of Sciences has ruled that food from cloned animals poses no significant health risks, but the academy also concluded that GM foods are safe, despite a wealth of evidence suggesting otherwise.

The academy said, "There is a very low probability food allergies will occur, but if they do occur it could potentially be of high risk to some people."

Researchers also said feces from cloned animals could contain a larger amount of harmful bacteria, such as salmonella or E. coli O157:H7, indirectly causing a greater food safety risk. But there was not enough information available to either disprove or support this.

Studies funded by the cloning company Infigen Inc. reported that clones and normal cattle produce milk that is "virtually identical" in protein, milk solids, fat and minerals, with some differences in the levels of a number of nutrients.

But given the level of genetic defects, diseases and physical abnormalities in clones, it is likely that their meat and milk would be substandard and could affect human health. Even small imbalances in hormones, proteins and fat levels could alter the quality and safety of cloned products.

There are currently no laws or regulations governing the sale of cloned food products. The US Food and Drug Administration (FDA) and Health Canada are in the process of creating guidelines that could allow cloned foods onto the market as soon as 2004. Like GM foods, it is very unlikely that cloned foods will be labeled as such. The only way for consumers to be sure that their food is not cloned will be to choose organic.