GM Crops, Noses and Coffee

19 October 2003
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Blood test for cancer and how DNA repairs itself, coffee and your sperm, coffee prevents colon cancer, underwear that can save your life, bathroom lost to meteorite and special guests Dr. Ruth Welters discussing the recent GM crop field trial results, and Dr. Peter Brennan "what is a smell, and how does your nose work ?"

In this episode

Blood Test For Cancer & How DNA Is Repaired

Scientists in Israel recently announced that they had come up with a blood test that could predict a person's risk of developing lung cancer, particularly if that person is a smoker. Cancers develop when our DNA is mutated, or damaged, by harmful substances in the environment like smoke or ultraviolet rays from the sun. Because there are so many things that can damage DNA during our lives, our cells have evolved ways to sniff out areas of damaged DNA and repair them before they can cause problems. The Israeli team have found that in people who develop lung cancer, the levels of one key DNA repair-enzyme, called OGG1, are much lower than in people who remain cancer free. So a person who smokes and has low levels of the repair enzyme stands a much higher chance of developing lung cancer than a smoker with normal levels (5-10x the chance), or a non smoker. But how do your cells know what to repair, and spot the damaged DNA so quickly ? Indeed there are 3 billion DNA letters in the human genetic blueprint and it's taken us over 10 years to work them all out, yet our cells can do this almost faultlessly day after day. Well, scientist Jacqueline Barton and her team from the California Institute of technology in the US think that our DNA repair systems use electricity to test long sections of our DNA so that they don't have to laboriously check all of it. The researchers have found that normal DNA conducts electricity, but damaged DNA doesn't. They suggest that working together in pairs at each end of a section of DNA, the repair enzymes send an electrical current along the DNA. If the current arrives normally that piece of DNA must be normal and the repair systems look elsewhere. But if the electrical signal doesn't arrive correctly there must be a region of damage somewhere within the section of DNA being tested and the repair enzymes then work their way towards each other checking each part of the DNA sequence as they go until they discover the damaged area, which is snipped out and replaced. The importance of this work is that the more we understand about how DNA repair systems work, the better equipped we are to help people with cancers, and inherited conditions that pre-dispose them to cancers.

Sperm And Coffee

The last week has seen a handful of discoveries about sperm. Coffee speeds up sperm, cannabis makes them speed up and burn out quickly, and overweight men suffer from sperm DNA fragmentation. Researchers from Brazil found that men who drink coffee have higher sperm motility compared to non coffee drinkers, which means that in the future caffeine could be used as the basis of an infertility treatment for men. Cannabis contains an active compound called tertahydrocannabinol or THC, which can acts on receptors found in human sperm. Previous studies have shown that THC can stop sperm from binding to eggs and This new study from researchers in America, looked at sperm from 22 cannabis smoking men, revealed that they became prematurely hyperactive, which could lead to reduced fertilising capacity as the sperm can burn out too early before reaching the egg. Cannabis smoking could also reduce female fertility by raising levels of THC in their reproductive tract, which could then impact sperm. A third study showed that overweight men have reduced fertility due to DNA fragmentation in their sperm. A team from Atlanta Georgia, were the first to compare men's body mass index or BMI (which is weight in kgs, divided by the height in metres, then divided by the height again) with the integrity of a protein called chromatin, which is crucial for the structure of DNA. And they found that as BMI goes up so does the rate of DNA fragmentation. Other factors that are thought to increase sperm DNA fragmentation are being over 50 years old, smoking and being exposed to air pollution.

Coffee Can Prevent Colon Cancer

Good news this week for coffee drinkers because German researchers have tracked down a chemical in coffee that may help to prevent colon cancer- the second leading cause of death in the USA. Coffee has been known for some time to be rich in antioxidants - chemicals that mop up molecules in our cells that can damage DNA. It's this damaged DNA that can cause cells to become cancerous. The anticancer chemical is a compound called methylpyridinium, and appears to be unique to coffee. It's created during the roasting process and is present in decaffeinated coffee as well as the normal type, and also in instant coffee. The researchers treated human intestine cells, grown in culture in the lab, with coffee extracts and found an increase in the levels of so-called 'phase two' enzymes, which have anticancer properties. When they fed either coffee extracts or pure methylpyridinium to rats, the rats had a massive increase in their phase two enzymes- up to forty percent. Thomas Hofman, one of the team that did the research, says that it's impossible to know exactly how much coffee might be protective in humans and whether there are any side effects until proper clinical trials are done, but he thinks that getting in a few strong brews every day may well have a beneficial effect. And for those who don't like coffee, perhaps a methylpyridinium pill might be the solution in the future.

Underwear To Die For (but it Could Save your Life)

Soon sufferers of heart conditions could be wearing super-smart electronic underwear that will call an ambulance when they need one. German researchers have developed bras and underpants with sensors in them that monitor the wearer's heart beat and a microprocessor that analyses signals and looks for signs of dangerous heart rhythms, such as very fast or slow beats. If trouble is detected, the smart pants will automatically dial up for medical assistance, either via a blue-toothed enabled mobile phone or by connecting directly to a telephone network. Unlike previous electrocardiograms that are used in hospitals to monitor heart beats, the new underwear doesn't have sensors that are stuck on the skin, and instead uses a new type of dry electrode that has to remain in contact with the skin, which is why the sensors are being incorporated into tight fitting underwear. And luckily the control unit is removable so the underwear can be machine washed and ironed.

Meteoric Bathroom

American Roy Fausset returned to his New Orleans home on 23rd september to find that a meteorite had demolished his recently-renovated bathroom. It seems to be the season for near-earth objects at the moment with an asteroid the size of a small house passing within 80,000 km of the Earth on 27th September.

Gm Crop Field Trial Results Announced

After a three years of farm-scale trials looking at the environmental impact of GM crops the results are finally out this week. These were the biggest trials carried out anywhere in the world, showing just how concerned the government are that they get enough information to make a decision about whether Britain should adopt the new technology. The trials were looking at three different crops, sugar beet, maize and oilseed rape- all of which had been genetically modified to be resistant to particular herbicides (chemicals that kill weeds). The idea behind the crops is that farmers will be able to treat fields less frequently with weedkillers, as the treatments will be more effective and only target the weeds without damaging the crops. This would save time and money, as well as reducing the amount of chemicals farmers are using in total. But the fields trials suggest that at least two out of the three GM crops, beet and oilseed rape, had a harmful impact on the environment in and around the fields where they were grown. This included a decrease in the number of bees and butterflies, as well as a reduction in the number of wild plant seeds available to feed animals like birds. But they did find more soil insects present in the fields sown with the GM beet and oilseed rape, which may be because herbicides were used less often. There was good news for fans of GM technology as well- GM maize was found to be better for wild plants, animals and insects than normal maize. It's important to point out that these effects on the local wildlife are nothing to do with the actual genetic modification of the plants, but more to do with the levels and types of weedkillers used by the farmers, as well as how often they treated their fields. The results are now going to the government committee responsible for regulating the new technology to see whether any of the crops will be approved for commercial use in the UK. The committee are still waiting for the results from one further trial of oilseed rape. A decision from this current crop of results is expected around December or early January, and if it's a yes then we could see some GM crops being grown in the UK within the next couple of years.

Other Links

Radio show featuring Peter Brennan discussing the science of smell (2005)


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