Tag: Gene Editing

Genetically Modified Foods (GMOs) are they the technology we need to feed our Growing Population? Or are they a Frankenstein Monster waiting to strike? Two stories that Illustrate the Promise and the Peril.

You hear about Genetically Modified Organisms every now and then on the news. Usually referred to as GMOs they are generating a great deal of excitement among biochemists and the food industry while causing just as much fear in some parts of the general population.

In a sense we have been modifying living creatures for 10,000 years. Starting with wolves we selectively bred them to enhance the characteristics we desired until we got man’s best friend the dog. Using the same techniques human beings have selectively bred hundreds of species of plant and animal to give us pretty much all of the food we, and our selectively bred pets, eat!

Selective breeding is genetic modification from the outside however. It’s only over the last 30-40 years that biochemists have been able to go straight to a living creature’s DNA and directly modify it. And it’s only in the past five years that scientists have possessed the precise and efficient gene-modifying tool known as CRISPR. (See my Posts of 5Aug17, 1Sept18 and 1Dec18 to learn more about CRISPR and how this gene-editing tool works).

How CRISPR Works (Credit: Genetic Literacy Project)

Using CRISPR biochemists hope to modify the plants and animals we eat in order to make them to grow larger more quickly, while requiring less fertilizer or feed. This would of course make food both cheaper and more abundant and in a world where more than 10% of the population goes to bed hungry that has to be a good thing.

One study could be a real game changer in the effort to produce more nourishing food. Researchers at the University of Illinois have been able to genetically modify the biochemical factories of plants in order to dramatically increase the efficiency of photosynthesis itself.

Production of Glucose by Photosynthesis (Credit: 19.eap-ing.de)

You’ll recall that photosynthesis is the chemical process by which plants use sunlight to convert carbon dioxide and water into sugars. In fact photosynthesis is the basic chemical reaction by which all of the world’s food is produced! Photosynthesis is rather inefficient however; it is chemically unable to distinguish between a carbon dioxide and oxygen molecules. According to plant biologist Donald Ort, the study’s senior author, “This is essentially anti-photosynthesis, and the plant produces a toxic compound that it has to recycle and detoxify.”

The researchers modified the DNA of Tobacco plants to simplify and speed up that detoxifying process resulting in plants that grew larger much more quickly, see image below. Dr. Ort and his team choose tobacco plants as a test subject because tobacco grows quickly and possesses genes that are easy to manipulate. The results are certainly impressive with tobacco plants that are 40% larger than ordinary plants.

Increased Growth of Tobacco Plants Achieved by Gene Editing (Credit: Clair Benjamin)

Having demonstrated the advantages of their approach the biochemists are now applying their technique to more useful plants like potatoes and soybeans. If this enhanced photosynthesis can be applied to other vegetable crops the resulting increase in food production could go a long way to helping feed the hungry nations of the world.

Some scientists are using gene editing to be a little more creative. One group wants to develop a spicy, peppery tomato. Now it turns out that tomatoes and peppers are pretty closely related, having split apart only about 20 million years ago. This means that the genes to produce Capsaicin, the chemical that makes peppers spicy, are still there inside a tomato’s DNA but according to co-author Agustin Zsögön they “are just not active.” Dr. Zsögön hopes to reactivate those genes allowing the humble tomato the ability to be as hot as any chilli pepper.

Can Gene Editing Produce a Spicy Tomato (Credit: Healthy Eating)

So why would scientists be so keen on developing a spicy tomato. Well the chemical capsaicin does more than just make your food taste spicy. Research has shown that capsaicin compounds are high in antioxidants; help the body fight cancerous tumors while aiding in both weight and pain management.

Right now the challenge is in determining which genes within the tomato to either turn back on, or turn off in order to get tomatoes to start producing capsaicin. Still, in a few years you may not need that habanero pepper in order to put some heat in your recipe for enchilada sauce!

Whether we use gene editing to greatly increase food production or just put a little more spice in our meals there are going to be people who are concerned about what other, unintentional chemicals we may be putting in what we eat. The workings of DNA, and the processes by which it controls the growth of cells are still largely unknown. The fear is that by modifying the genes of organisms to make them produce more food, we may also cause them to produce poisons or other deadly chemicals.

The scientists working on gene editing techniques are aware of this problem. As Dr. Ort says, “…any enhanced crops would undergo rigorous testing before they are ever consumed by humans.” Scientists like Dr. Ort may be determined to go slowly and test completely but what about large food corporations who are determined to both keep costs down and get their new products on the market before their competitors do. And not all the scientists are as trustworthy as Dr. Ort. Remember Chinese scientist He Jiankui who just two months ago revealed that he had used CRISPR on human embryos!

Dr. He defends his Research at the Genome Summit (Credit: BBC)

Like every advance in science gene editing can either benefit the world or harm it. It’s up to us, all of us to decide which it will be.

Gene Editing discovers a potential cure for Muscular Dystrophy, and a look back at the Jerry Lewis Telethon.

These next three days are celebrated as the Labour Day weekend here in the US and is also considered the unofficial end of summer. Back when I was growing up it was also the time of the Jerry Lewis telethon to benefit the fight against the disease Muscular Dystrophy (MD), a disorder that causes an almost total loss of strength and control of the muscles and is the leading genetic cause of death in children.

The Jerry Lewis Telethon began in 1966 and continued until 2010 (Credit: CBS)

Starting in 1966 and continuing until 2010 Jerry hosted the annual charity event which featured other celebrities and entertainment and which managed to raise $2.45 billion dollars for the study and treatment of MD. Despite the success of the telethon, and the large amount of money raised however MD has proven to be an intractable illness with little progress being made toward a treatment.

For those who aren’t familiar with MD it is a genetic disorder that prevents the production in the cells of the muscles of a shock absorbing protein called dystrophin. The lack of dystrophin causes the muscle cells to weaken and degenerate leading to a general failure of the bodies muscles. The first symptoms usually appear before a child is one year old.

Symptoms of MD (Credit: Pinterest)

Since MD is a genetic disorder it is not contagious but rather must be inherited from both parents, each of whom must carry a single recessive MD gene. Having a single MD gene does not cause the disease but by looking at the image below you can see how a man and woman, each of whom have one MD gene on their chromosome pair, can pass it on to their children.

Inheritance of a Recessive Genetic disorder such as MD (Credit: Human Illnesses)

Since a child gets one gene from each parent 25% get clean chromosomes from both parents, the child on the left. This child will not develop MD nor can it pass the mutated gene to its children. 50% of the offspring will get an MD gene from one parent but not the other; these are the two children in the middle. These children will not develop MD but carry the gene and can pass it on to their children just as they received it from their parents. Only the child on the right, the 25% who receive the MD gene from both parents, will actually develop the disease.

There has recently been some progress that offers a glimmer of hope in the fight against MD. The research was conducted on a family of dogs, King Charles Spaniels to be exact, who were found about ten years ago to also suffer from MD. The research used the new science of gene editing and in particular the gene cutting tool CRISPR that I discussed at some length in my post of 5Aug2018.

To put it simply CRISPR uses a virus, yes a virus to cut a section of DNA out of a chromosome with a cell and replace it with a different DNA section. The work was led by Eric Olsen at the University of Texas Southwestern Medical Center and consisted of using CRISPR to replace the mutated DNA in four one-month old male dogs.

CRISPR Working at the Molecular Level (Credit: Science)

Gene editing and CRISPR have been used before to treat other genetic disorders but MD was considered a long shot because the gene that manufactures dystrophin is the largest in the human genome and a large number of different mutations can lead to the disease. Still Dr. Olsen and his team injected the four dogs with millions of CRISPR viruses that were programmed to find and replace the mutated dystrophin gene.

The results were better than the researchers had expected. According to Dr. Olsen the dogs ‘…showed obvious signs of behavioral improvement…running, jumping…it was quite dramatic.”

Now this is only a test on four dogs, much more research will have to be carried out before any testing is conducted on humans. Still this is one more case where gene editing, and CRISPR in particular are giving us tools to fight diseases against which we once had no hope.

Which brings us to the ethical question. Changing the genes of a one-month old infant, dog or human, is playing god if anything is. And the technology that can ‘repair’ a child with MD can also create a ‘designer baby’ if that’s what we want.

As I said in my post of a little over a year ago my opinion is that we should move forward with gene editing but slowly, maintaining ethical controls on the research. I also that it is very important that we have a full-scale public debate now about how we as a society will regulate and control gene editing.

I’ve now told you my opinion, what’s yours?

Gene Editing in Humans: The Promise and the Peril

A collaboration of researchers at Oregon’s Health and Science University and the Salk Institute have carried out the first successful attempt at modifying the DNA inside human embryos. The team, led by Shoukhrat Mitalipov removed a genetic ‘mistake’ that causes a heart defect in humans from 42 out of 58 fertilized egg cells.

Doctor Mitalipov and his team used a gene editing technique known as CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) to cut the DNA of the fertilized egg, remove the disease causing gene section and replace it with a healthy one. Chinese scientists had already attempted this technique several times but the CRISPR editing always resulted in a small number of editing ‘mistakes’ know as mosaicism and that when the fertilized cells began to divide to form an embryo not all of the cells received the edited correction. The picture below shows the CRISPR process being carried out on a fertilized human egg cell.

Gene Editing (Credit: Oregon Health and Science University)

In the paper Mitalipov and his team have published in the journal Nature their results indicate that they have succeeded in avoiding the errors in previous experiments. This is obviously of critical importance since any ‘off target’ results could easily cause more harm than good and the ethical controversy around gene editing is already a hot topic.

In order to avoid any such ethical concerns Mitalipov and his team only allowed the embryos in their study to develop for five days and there was never any intention of implanting the embryos into a womb. In fact any attempt to implant a gene edited human embryo into a womb is illegal in the US, Congress having forbidden the US Food and Drug administration from approving any such clinical trials.

When it comes to the technology of gene editing let’s face it, it’s only a matter of time before we can directly modify the DNA structure to suit our pleasure. If you think about it, we’ve been modifying the DNA of living creatures ever since we brought wolves into our caves and turned them into dogs but gene editing is a big leap forward and great harm could result from any carelessness.

Now anyone who has read some of my posts on this blogsite knows that I am pro-science and pro-technology. Also, the possible good that could be achieved by eliminating genetic disorders such as Hodgkin’s lymphoma, Huntington’s disease, the blood condition beta-thalassemia or Down’s syndrome or many others is just so great that we cannot simply refuse to try.

On the other hand, the possible harm that could occur to the children of gene editing experiments that resulted in ‘off target’ effects is simply horrible to consider. Any gene editing technique that we even consider employing on ourselves must be as perfect as is humanly possible before any clinical trials are attempted. In other words we have to do this slowly and carefully, making certain that the good will far outweigh any harm before proceeding.

I think most people can agree on such a policy. The possible rewards of gene editing are so great that we have to try, but slowly and carefully to avoid as many errors as we can. The real thorny ethical questions arise when we begin talking about using gene editing to ‘improve’ human beings, to create ‘designer babies’ rather than just to eliminate birth defects.

The problem is in finding any consensus on just what an ‘improvement’ might be, let alone on whose children will be ‘improved’. Now I’ve never been any good at telling people what is ethically right or wrong. However I will say this; each of us, wherever we live in this world, needs to consider this issue and make up our own mind!

Gene editing could very well become the most contentious issue of the 21st century and only an informed and thoughtful people can even hope to make the right choices. If you’d like to read more on the work at Oregon Health and Science University, the link below will take you to MIT’s Technology Review’s story.

https://www.technologyreview.com/s/608350/first-human-embryos-edited-in-us/