Here are four examples:
Xenotransplants have come a long way since Baby Fae, the first recipient of a heart transplant was performed back in 1984. At that time our ability to modify the genetic information of another species to make it compatible with humans didn’t exist. But today it does and as of February 10th, the heart transplant patient with his GM pig’s heart is now going through rehab.
GM engineering of plants and insects has been seen by a large number of people, mostly in the Global North (the rich western countries of the world) as human tinkering that is interfering with “God’s work.” Yet humans have been modifying plants and animals through selective breeding since the dawn of the Agricultural Revolution. The difference now is that science allows us to do this to a species’ DNA rather than trial and error experimentation involving multiple generations of cross-fertilization and observation.
Today we tolerate producing new breeds of dogs and cats and hybrid versions of wheat and corn, using a method that is 10,000-years old. But when scientific advancements give us the means to parse DNA and selectively remove a bad gene and replace it with a healthy one, or one that adds a specific advantageous attribute, many of us interpret it as almost obscene.
I know I have qualms, and you may have too, about sacrificing animals to save human lives when we are at the dawn of other medical breakthroughs that could make xenotransplants no longer a needed technology. If we can perfect the regrowing of human organs and other body parts using donated stem cells, and be able to do this safely and speedily, then like laboratory-grown meat which is becoming a reality, we will end the need for xenotransplants.
A final note about GM crops and ingredients in the foods we eat. Today when I shop in my local grocery store, products proudly display “no GMO” as if this statement means they are safer and more wholesome than other items on the shelves. But GMO for those living in the Global South can be the difference between a full belly and starvation. It can be the difference between being blind for life or being able to see. It can be the difference between dying from malaria or another vector-borne disease or thriving. And in one man’s life in the Global North, it is a beating heart.
]]>With Aedes aegypti, it is the female of the species that does the biting drawn to us first by visual cues and then as it nears by the exhalations of carbon dioxide (CO2) from our bodies, and by our skin heat and odour. But what if scientists could introduce a mutation that would impede the insect’s ability to see us from afar?
That’s what Yinpeng Zhan, from the Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, and Diego Alonso San Alberto, Claire Rusch, and Jeffrey Riffell from the Department of Biology, the University of Washington in Seattle have been working on using CRISPR-Cas9, the DNA editing tool.
Targeting two specific genes, Opsin1 (Op1), and Opsin2 (Op2), of the five responsible for light-sensor receptive proteins, known as rhodopsins, they were able to create genetically modified versions in an experimental group of mosquitoes. They did not tamper with the remaining three genes responsible for vision, or those responsible for olfactory or thermal sensing. The hoped-for result was the creation of a new version of the mosquito less capable of vision-guided flight to target humans. In other words, making us nearly invisible.
Aedes aegypti are daytime biters usually flying in search of prey around dawn and dusk. They use their sight during flight to find targets, and in particular, those that are dark clothed. This visual attraction from afar, when combined with olfactory and thermal cues picked up as the mosquito gets close, serves to navigate mosquitoes to their targets.
Wind tunnel testing of genetically modified females with mutated Op1 and Op2 rhodopsin-protein generators, against a control group of unmodified ones and under varying light conditions, produced results that showed the modified mosquitoes displayed no preference for dark or white targets. That, however, was not true for the unmodified control group that bee-lined to the dark ones.
The mutated mosquitoes’ olfactory and heat receptors remained unaffected, as did their remaining optical sensors. And testing also showed that the mutated mosquitoes could still see, but in flight were less visually perceptive.
Meanwhile, experiments with both mutated and unmutated groups showed equal responses to a combination of black targets in the presence of a 5% CO2 plume. But mutated mosquitoes had no preference for targets, either white or black, in the presence of CO2.
With both mutated and control-group mosquitoes, once they had landed on a target, had no trouble navigating while walking to a place to bite. The researchers concluded that elimination of the normal Op1 and Op2 genes and replacing them with mutations diminished light sensitivity during flight, solely, “below a threshold required for vision-guided target recognition.” Their research appeared in the July 30, 2021 edition of the journal, Current Biology, in a report entitled, “Elimination of vision-guided target attraction in Aedes aegypti using CRISPR.”
What are the implications for humanity? The Aedes aegypti mosquito infects 400 million humans globally and kills more than 700,000, a disproportionate number of them children, every year.
]]>The definition of GM is the alteration of the DNA of a plant or animal using bioengineering techniques where genetic information from one species is transferred to another unrelated or related species for the purpose of enhancing specific desirable traits.
GM staple crops like corn, soybean, and wheat have been developed to combat drought, and insect and weed infestations to improve yields. Companies like Bayer and Dow have taken out patents and created rules for the use of their GM seeds. The anti-Monsanto (now owned by Bayer) movement heads up those opposed to GM largely because of these chemical companies’ practices in enforcing patent protection.
But there are other GM examples far different than the Monsanto experience. For example, a genetic modification to rice developed in 2000, at the Swiss Federal Institute of Technology, in Zurich, added a beta carotene gene to the plant. The end product is called Golden Rice. The biofortification meant growers could switch to Golden Rice away from traditional rice varieties found in Bangladesh, China, India, and other South Asian countries to address a health problem endemic to the region. There is a Vitamin A deficiency in the diet of many South Asians who rely almost exclusively on three meals of rice per day for nutrition. Traditional rice lacks beta carotene which when ingested turns into Vitamin A necessary for normal cell development and vision. Vitamin A deficiency in South Asia is linked to a million premature deaths and 500,000 cases of blindness in children annually. By creating rice containing beta carotene these two catastrophes would be averted. Better yet the developers of the rice made the seed freely available to farmers who were then encouraged to save Golden Rice seeds for replanting every year. Golden Rice was created without a profit motive. So wouldn’t you think that resistance to it would be negligible? Not so. In the two decades since its invention, Golden Rice has been attacked by environmentalists, organic food activists, government regulators, and NGOs like Greenpeace. Why? Because Golden Rice is a GM product. As a result, child mortality numbers and child blindness from Vitamin A deficiency remain endemic in South Asia.
The World Health Organization (WHO) comments extensively on GM foods. A whole section of its website is devoted to the subject. It discusses safety, environmental risk, the public debate, and regulatory issues governing planting, sale and international distribution of GM foods. It also looks at biochemical and biopharmaceutical companies that are in the business of creating GM crops and foods for profit, and the challenges faced by farmers to own the GM seeds produced by them when they plant. It notes that current GM foods available today have passed all safety assessments regarding risk to human health. But the assurances from the WHO site fall on many deaf ears.
So what happens when GM biotechnology is deployed to deal with the scourge of insect-borne diseases? The same levels of resistance, unfortunately. And we are talking about mosquitoes being the targeted species, not harmless butterflies or honey bees.
Better late than never the WHO is weighing in on GM mosquitoes at last. Mosquitoes, states the latest report, are described as “the deadliest animal on earth.” They transmit malaria, dengue, West Nile virus, chikungunya, yellow fever and Zika and cause 700 million infections annually. Areas, where mosquito-borne infectious diseases spread, are home to billions. In dengue areas, for example, 2.5 billion people reside. And dengue is the fastest-growing mosquito-borne disease with a 3,000% rise in incidents over the last 50 years.
Where malaria incidences are in decline because of the deployment of an army of mosquito control mechanisms the world is in better shape. But based on my family’s experience of a few years aog when we vacationed in Cuba, our defences remain reactive and primitive. Where we stayed in Varadero, airplanes carrying insecticides spread aerosol insecticides over the landscape several times in just one week. We were advised to stay by the pool in the morning and not go down to the beach until the aerosol vapours cleared.
For many countries tending with mosquito-borne infectious diseases, insecticides remain the primary tools of combat. The problem in continuing to use them is biological resistance. The more you spray, the mosquitoes that survive pass on that ability to their progeny. The result today, is that in more than 75% of countries fighting malaria transmission by this type of program using four different classes of insecticides, we are seeing decreasing effectiveness when deployed.
The idea behind modifying mosquitoes genetically was conceived of several decades ago. The first GM mosquitoes were unleashed only in laboratories. But only recently have GM mosquito trials been tested in limited pilot projects. After more than a decade of fighting to get regulatory approval and public acceptance, Oxitec, a British biotechnology company, has received permission to release its GM mosquito in a U.S. trial. Prior to the May 2021 release, the company has demonstrated success in Brazil, Panama, the Cayman Islands, and Malaysia with no ill effects.
The U.S. trial in the Florida Keys is aimed at the wild population of Aedes aegypti, the mosquito species known to spread Zika, dengue, chikungunya and yellow fever. ALl the Oxitec GM mosquitoes are male and when released are competing for the favours of the wild female population. The mating of the two produces larval offspring of both sexes.But the GM modification contains a gene that allows only the non-biting males to pass turn into adults while killing all females while they are still larvae. The males then carry the modified gene with them and mate with other wild females. The end result should see a decline in the Aedes aegypti mosquito population.
An analogy that may make sense to those who condemn GM anything may be of some help. Think of the current COVID-19 pandemic. We tried to combat the disease with defensive measures after people were originally infected. We put on masks, isolated, and washed our hands. But over 3 million documented deaths happened just in 2020 alone. It was as if we were applying insecticides to the disease after it was already out and circulating in the human population. At the same time, our GM equivalent strategy was the development of vaccines which in time will cause the virus population to shrink.
The WHO, in issuing its latest GM guidance states that as a novel control, GM mosquitoes may be added to the current arsenal of tools to fight insect-borne diseases. Still a maybe. But maybe may soon be replaced by absolutely once testing moves beyond current pilot programs like the one launched in Florida last month. After it and a few more, we should have enough data to validate this GM strategy and other gene drive technologies like CRISPR/Cas9 and come up with criteria and rules for their safe use.
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