WHEN SCIENTISTS START MODIFYING DNA ,they are tempering with the basic building blocks of life -and no one knows what the outcome will be .
Environmental groups who are opposed to GM crops are already painting doomsday scenarios.Some claim that tampering with the genome would result in the complete breakdown of the DNA ,leaving plants unable to reproduce and driving crops that have sustained humankind throughout history into extinction.Other agencies warn that herbicide -resistant crops might transfer some of their resistance to weeds, producing new strains of super -weeds that will choke the countryside and prevent normal food crops growing .If either of these outcomes spread across the world ,global famine would be the result.
There are other dangers .Dutch scientists have shown that the DNA in GM crops fed to cows stays in their guts long enough to transfer some of their genetic code to the bacteria their .GM crops fed to livestock often use antibiotic -resistant genes as markers and these could be transfered to create antibiotic -resistant superbugs that could easily spread from animals to humans.
Similar super -bugs have already turned up in hospital ,but these are generated by Darwinian natural selection because of the frequent use of antibiotics there .Some 9 0 per cent of the staphylococcus aureus bacteria found in hospitals are resistant to penicillin. One super bug -known as methicillin -resistant staphylococcus aureus or MRSA-is resistant to almost all antibiotics ,including in some cases vancomycin ,the so -called 'antibiotic of last resort '. Staphylococcus aureus is present in the nose or on the skin of 3 0 per cent of people and is usually harmless .It only becomes dangerous when it infects those with a weakened immune system such as the elderly ,new born infants or patients recovering in hospital.Even so ,it kills around 5 ,000 people a year .The death toll will soar as the antibiotic -resistant strain spreads .As it is ,MRSA has escaped from hospitals and is now found in domestic dogs ,cats and rabbits.The UK's Health Protection Agency has warned pet owners not to let dogs lick their faces or allow pets to walk on surfaces where food is prepared.
If superbugs generated by natural selection can pose such a threat ,superbugs caused by genetic modifications are likely to be even more dangerous .This is because genetic modifications brought about through Darwinian selection occur slowly ,while the artificial cutting and splicing of genes is rapid ,allowing the human immune system little time to develop new defences .And it does not take huge modifications of a virus's DNA to great a global catastrophe.Take Ebola .It kills upto 9 0 %of those it infects and there is no known treatment.Currently it is contained in rural Africa because there is no carrier state ,and its incubation period is short -just 2 to 21 days -and death occurs within 8 to 30 days .If the incubation period was longer ,people would be likely to treavel further while infected ,and meet and infect more people before the symptoms showed ,there would be an unstoppable worldwide epidemic of the killer disease .
But there is more fun in store .Dr J.Craig Venter ,who helped sequence the human genome ,now plans to create GM microbes that will solve the world's energy crisis and global warming at a stroke.He wants to make bacteria that will eat up the excess carbon dioxide in the atmosphere and manufacture the organic chemicals currently synthesised from oil and gas .A second type will split water into its components ,hydrogen and oxygen ,which can then be recombined in a fuel cell to produce power.
He believes that this can be done by creating an artifitial chromosome comprising about 5 0 0 genes .It would then be inserted into a microbe whose original genome had been destroyed with radiation .The resulting bacteria could then be manufactured on a large scale in culture.The problem would be controlling them once they got outside the lab .They might eat all the carbaon dioxide in the atmosphere ,preventing photosynthesis ,causing mass famine and switching off the greenhouse effect .Or they might dissociate all the water ,leaving the planet parched ,and filling the atmosphere with an explosive mixture of hydrogen and oxygen that would go up at the slightest spark.