The Safety of Genetically Modified Plants

09 November 2003
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Professor Roger Leigh joins the Naked Scientists to answer questions about how to make genetically modified (GM) plants, the uses of GM plants, the safety of GM plants and crops, and the environmental impact of genetically modified plants.

In this episode

Why Do Leaves Change Colour in Autumn ?

Tree use their leaves make food. The leaves contain chlorophyll, a green pigment which together with light from the Sun, carbon dioxide and water results in glucose. Leaves normally contain red, orange and yellow pigments but these are normally masked by the green chlorophyll. The colours are the result of anthocyanins giving pink, red and purple colours and carotenoids giving yellow and orange colours.The tree uses the leaf as a way of getting rid of waste products in Winter. In Autumn the trees stop producing sap, and photosynthesis can no longer take place so the green chlorophyll breaks down and disappears. The other colours are then apparent. By putting waste products in the leaves, as the leaves fall the tree conveniently gets rid of it's rubbish.

How To Avoid The Flu This Winter

How you feel can powerfully affect the strength of your immune system and how susceptible you are to infection. Scientists at the University of Wisconsin-Madison have found that negative emotions like depression, anger and fear can significantly weaken your immune response. Volunteers were asked to recall some of their best and worst experiences whilst the researchers monitored their brain activity and their physical signs of emotion. The volunteers were then given a flu jab and then a blood test to monitor the effectiveness of the vaccination 6 months later. The volunteers who showed the most intense negative emotions also produced the fewest antibodies, suggesting that they had lower immunity.

T'ai Chi Can Help Prevent Shingles

Shingles is caused by the same virus which causes chicken pox, the Herpes Zoster virus. Once you have had chicken pox, HZV lives in your nerve cells forever and can sometimes reactivate itself. It is usually kept at bay by the immune system by zoster virus specific immunity factor. If you are unwell or as you age, the HZV can flare-up causing chicken pox like spots along one nerve known as shingles. T'ai Chi seems to boost the level the zoster virus specific immunity factor by up to 50%. (this study looked at people doing T'ai Chi 3 times a week for 4 months.) It seems T'ai Chi reduces the levels of stress hormones, which boosts the immune system.

How Big Would Guy Fawkes' Bang Have Been ?

We light bonfires and set of fireworks on November the 5th to commemorate the fact that in 1605 Guido Fawkes, now known as Guy, failed to blow up the Houses of Parliament. But physicists from the Centre for Explosion Studies in Aberystwyth have shown that if he had actually succeeded, the results would have been devastating. Guy Fawkes packed about 2,500 kilos of gunpowder under Westminster, so the scientists could work out how big the bang would have been. They calculated that the blast would have destroyed Westminster Hall and Westminster Abbey as well as the streets surrounding them. Severe structural damage would have been seen up to a third of a mile away, as far as Whitehall. Fortunately for the government, Guy Fawkes was caught, otherwise the mother of all parliaments could have become the mother of all explosions!

Brain 'itch' Keeps Catchy Songs in Our Heads

Don't you just hate it when you get an annoying song stuck in your head and you can't stop humming it all day? Researchers in America think this happens because these repetitive, catchy songs give us a brain itch, which can only be cured by a cognitive scratch… otherwise known as listening to the offending tune over and over again. Prof James Kellaris from the University of Cincinnati has been studying these songs that he calls earworms, and has discovered that nearly everyone suffers from them at some time and that in general women are more susceptible to them than men, as are musicians. He's also shown that there is no guaranteed way of ever getting the song out of your head, especially if you try a replacement strategy by thinking of a different tune, because more likely than not if you'll replace one earworm for another! So, will this research lead to the pop industry releasing songs to deliberately plague us with hard-to-shift purpose-built earworms? (…some of you might say they already do that very well!) Well, maybe not. Prof Kellaris hasn't found a winning formula for an effective earworm since people react differently to different tunes. We do know that one of the key elements of an earworm is repetition, since a tune with a lot of variation isn't easily taken in.

New Bra To Help Smokers Quit

A Swiss underwear company has come up with a bra containing lavender and jasmine perfumed capsules, which makes cigarettes have an extremely unpleasant taste.

Uk Researchers Begin Anti-cocaine Vaccine Trial

A new vaccine to treat cocaine addiction is about to be put to the test in America by its UK designers Xenova Pharmaceuticals. Called TA-CD the vaccine works by encouraging an addict's immune system to produce antibodies to cocaine, in much the same way as it would against bacteria or viruses. These antibodies circulate in the bloodstream mopping up any cocaine taken into the body before it can get to the brain to produce the hit that the addict craves. The company also has a related product called TA-NIC which works in an identical way against nicotine and could potentially help smokers to kick the habit. So why don't people naturally develop antibodies like this, just by giving taking the drug ? The reason is that the nicotine and cocaine molecules are too small to be seen by the immune system. The breakthrough made by Xenova was to link nicotine and cocaine to a much bigger molecule which the immune system can see. As a result the antibodies produced can lock on to nicotine or cocaine on its own in the blood stream, and neutralise it. Both vaccines have passed safety trials. Now it just remains to be seen how effectively they work.

Hope For Dope ?

The results of the first large-scale trial to investigate the benefits of cannabis extracts in multiple sclerosis are out this week. Multiple sclerosis, or MS, is a crippling disease which attacks the nervous system, leading to muscle pain and spasms. Researchers at Plymouth University tested the effects of pills containing extracts from cannabis plants known as cannabinoids against a pill containing no drug. They found that the cannabis pills didn't help with the muscle spasms but were useful for controlling pain and improving walking, as well as making the patients feel their other symptoms were a lot better. However, it's hard to do a really accurate study as the side-effects of the drugs are fairly easy to spot and patients soon guess what they're taking. It is hoped that these trials will spark more interest in cannabinoids as medical therapy but that means more debate over legalising them even in a tablet form.


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