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February 3, 2012 8:57 pm
Opponents of genetic crop modification sometimes point out that similar results can be achieved by applying modern technology to conventional plant breeding techniques. But that is not true of bananas – a crop important not only for the ripe yellow “dessert bananas” of the commercial fruit trade but also for the green “cooking bananas” and plantains that are a calorie-rich staple across much of tropical Africa.
The main varieties of dessert and cooking banana are sterile – and propagated vegetatively – which makes them very hard to improve through conventional breeding. So they are a tempting target for GM.
Howard Atkinson, a plant science professor at Leeds University, is working with the International Institute of Tropical Agriculture to make GM bananas that resist nematode worms – tiny pests that eat their roots and cause huge crop losses in sub-Saharan Africa.
“Bananas are sexually isolated from other varieties,” says Atkinson. “So even if natural resistance genes are found in other banana types they cannot be improved readily by crossing.”
His project, which is funded jointly by the UK Biotechnology and Biological Sciences Research Council and the Department for International Development, has transferred two anti-nematode genes into African cooking bananas and plantains. The genes were developed individually at Leeds to protect potatoes and their effectiveness in tandem will be tested for the first time later this year, in a field trial in Uganda.
The first gene is designed to disrupt the “chemosensory” organs that nematodes use to detect the presence of tasty roots in the nearby soil. The second blocks an enzyme that nematodes need to digest plant proteins but which is not required by other animals.
Measuring differences in blood pressure between someone’s left and right arm should be part of routine care: it could be a sign of vascular disease, according to a study in the Lancet.
Both genes and their products are harmless to humans, says Atkinson, but as a precaution they are designed only to be active in the banana roots.
Part of the project involved developing a new system, based on a digital camera, to measure the impact on the plants’ canopy growth of nematode infestation of the roots. A fish-eye lens on the ground automatically records the leaf cover – far less laborious than previous methods of measuring plants, which can grow up to 3m high, by hand.
If the Uganda test goes well, says Atkinson, “we are looking to trial the banana plants in countries across Africa and also to move our GM technology into other neglected African crops [such as yams] that suffer severe nematode damage.”
It would work for dessert bananas grown for export to temperate, industrialised countries – but public acceptance of GM food there might be more of an obstacle than it is for cooking bananas produced for local consumption in Africa.
How elephants keep their cool
How does an elephant keep cool in the tropics, with its gigantic body and relatively small surface area from which to dissipate heat?
Zoologists know that African elephants use their huge ears, which make up 20 per cent of their total body surface, to cool down. But Asian elephants have smaller ears – about 8 per cent of body area – which do not radiate heat so well.
Now, a study with thermal imaging cameras at Busch Gardens zoo in Tampa, Florida, shows that Asian elephants lose most of their excess heat from the surface of their trunks rather than their ears. Both species have evolved a similar thermoregulatory strategy, which tolerates a build-up of body heat during the day, followed by cooling down at night. While the human body temperature typically fluctuates by 1C over 24 hours, elephants’ core temperature varies by 5C.
The study followed five female Asian elephants over 10 nights with infra-red imaging cameras, which allowed the researchers to estimate changes in temperature of different body parts. Their trunks remained hotter than their ears and other areas, suggesting that they were acting as heat-emitting “radiators”.
The researchers were particularly pleased when the elephants urinated: urine temperature provides an excellent measure of body heat.
Presenting their findings in the journal Zoo Biology, the researchers say zoos should allow elephants to remain outside overnight in hot weather.
“Elephants appear to use the night sky as a sink for radiating heat from their bodies, and the effect of such radiation would be reduced should they be... [in] a closed enclosure,” they write.
Dirt sticks – and so does soap
Chemists at Bristol University have made the world’s first magnetic soap. Because the soap and the dirt it dissolves can be removed with a magnet, the technology could be used for cleaning up oil spills and other forms of pollution.
The magnetic soap is a typical surfactant (soap or detergent), consisting of long molecules with different ends: one is attracted to oily substances and the other to water. But in magnetic soap the water-loving or hydrophilic end is an iron compound rather than a simple chloride or bromide ion. Individual iron molecules are not magnetic. To behave as magnets, they need to clump together.
The Institut Laue-Langevin (ILL) in France used an intense neutron source to probe the structure of materials, confirming that the soap is magnetic because its iron compounds cluster into nanoparticles about 5 nanometres across. A report of the research, published in the journal Angewandte Chemie, shows droplets containing the new soap being attracted to solid magnets.
“As most magnets are metals, from a purely scientific point of view these ionic liquid surfactants are highly unusual, making them a particularly interesting discovery,” says Julian Eastoe, chemistry professor at Bristol. “Though these exact liquids aren’t yet ready to appear in any household product, future work can reproduce the same phenomenon in more commercially viable liquids.” Applications could include water treatment.
The workout cure for horrible bosses
If you have an abusive boss, then try to persuade him or her to take more exercise. A study by James Burton and colleagues at Northern Illinois University shows that stressed supervisors, struggling with time pressures, vent their frustrations on their employees less when they get regular, moderate exercise.
The study included 98 employees and their 98 line managers. All the employees were taking part-time MBA courses at US universities.
Employees rated their perceptions of how abusive their current manager was: for example, “my supervisor tells me my thoughts or feelings are stupid” or “my supervisor puts me down in front of others”.
Managers answered questions about how often they exercised and about their workplace stress: for example, “working my current job leaves me little time for other activities”, or “I have too much work and too little time to do it in”.
The research, published online in the Journal of Business and Psychology, shows, as expected, that when managers were stressed their subordinates felt more victimised.
But analysis also showed that when managers experienced stress but engaged in exercise, employees reported lower levels of abusive supervision. Even moderate exercise, such as yoga or running twice a week, made a difference.
The authors conclude: “Wellness programs, often inclusive of exercise components, have been advocated to control workplace stress for years. This study adds support to their specific relevancy in smoothing supervisor-subordinate relationships.”
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