Geoengineering

In 1991, the Philippines' Mount Pinatubo volcano threw so much sulfur dioxide into the air that the sunlight was reduced by about 10%. As a result, global temperatures dropped by 0.5 degrees over the next 18 months.

A temperature reduction is what the Earth needs now, so a similar event may help us fight global warming, perhaps the most dangerous problem for humanity.

Geoengineering, the deliberate modification of the environment, has been considered the top of arrogance by many people and most environmentalists. We are very far from understanding how the climate system works. Who could say that we won't make things worse? We'd better be alert. Geoengineering should proceed with caution.

However, even if we try, it will take us decades to make the transition from a carbon-based economy to one powered by new energy technologies. In the meantime, it is possible that global warming may get to a point of no return. This is where geoengineering comes in: it's not a long-term solution but a way to keep the earth from overheating while we wait for efficient, green-energy technologies to come on line.

Can geoengineering really do the job? In fact, modern global warming is evidence of negative geoengineering, the result of all that carbon dioxide and other greenhouse gases we've been throwing into the atmosphere for a century or so. But it was the Pinatubo eruption that provided an example of geoengineering's potential. Scientists studying the eruption wondered if they could do the same thing deliberately.

They are, as many critics have pointed out, merely Band-Aids. But Band-Aids have their uses, except that the only real solution to global warming is to end our dependency on fossil fuels.

Adapted from an article by Bjorn Lomborg in Time Magazine. Picture by Getty Images.

NDM1 in Japan

A gene, NDM1, that makes microorganisms drug-resistant has been detected in Japan for the first time, in a man who had medical treatment in India. It is a serious case because scientists say the gene -which is frequent in India- alters bacteria, making them resistant to all antibiotics.

Drug-resistant bacteria are not new. Many bacteria are resistant to the world's first antibiotic, penicillin, as well as successive generations of drugs. Excessive use and improper use of antibiotics have made the problem worse.

NDM-1 could be a global health problem in a short time and international coordination is needed. Apart from India, the new gene has been detected in small numbers in Australia, Canada, the United States, the Netherlands, Sweden and the U.K. Investigators say that many Americans and Europeans travel to India and Pakistan for cosmetic surgery, and it is there where the generalizing process may begin.

Antimicrobial resistance -the ability of microorganisms to escape drugs' efficacy- is an increasing global health problem that could affect diseases such as respiratory infections and dysentery, according to the WHO (World Health Organization).

The WHO says NDM-1 requires monitoring and study. With effective measures, countries have successfully battled multi-drug resistant microorganisms in the past. It recommends that governments improve their efforts in four areas: surveillance, rational antibiotic use, legislation to stop sales of antibiotics without prescription, and infection prevention measures such as hand-washing in hospitals.

Red parrot feathers resist bacterial degradation

Many white bird species, such as gulls and geese, have black wing feathers. This is because black colour is the result of melanins that are incorporated into the feather while it is growing. Melanins make feathers stronger, especially in birds that fly long distances.

But among birds, parrots are unique: they sinthesize their bright reds, oranges and yellows, with pigments that are not found anywhere else. Unlike other birds, their colours are not derived from their diet. 

These unique feather pigments may serve more functions than just visual communication in parrots, according to Edward Burtt, a professor at an American university. He noticed that some microbes, -Bacillus licheniformis, Bacillus pumilus and other Bacillus species- were eating feathers, and he also found that green feathers were resistant to bacterial degradation. 
 
Dr Burtt's team first classified colourful feathers from thirteen parrot species into six general colour categories: blue, green, red, yellow, black and white. The team placed differently-coloured feathers into a bacterial medium containing Bacillus licheniformis, a bacteria that degrades feathers. They measured how much the bacteria broke down the feathers and compared this between feathers of different colours. The investigation resulted in clear conclusions: feather colour affected the bacterial degradation: white feathers degraded more rapidly than black, blue, green and red feathers. 
 
Biochemical analysis of yellow molecules found that they are formed by small carbon chains with few double-bonds, while red ones have longer carbon chains with more double-bonds. In short, red molecules are bigger than yellow ones and have stronger bonds, so they should be more difficult for bacteria to break down.
    
Adapted from an article in guardian.co.uk, based on Burtt, E., Schroeder, M., Smith, L., Sroka, L. and McGraw, K. (2010) Colourful parrot feathers resist bacterial degradation. Biology Letters DOI 10.1098/rsbl.2010.0716 

The Uncommon Life of Your Common Cold

Misinformation about the common cold is perhaps much more frequent than the cold itself.

Do you catch cold from the cold? Cold doesn't cause colds, viruses do. Colds are more common in the fall and winter because the cooler, wetter weather drives people inside, and viruses can more easily jump from one person to the next.

Are some people genetically more inclined to colds? Scientists are really interested in this idea that if you infect people with the virus, everybody will get infected, but only 75% of people will actually come down with the cold.

What is the biggest mistake about colds? Probably that susceptibility to colds requires a weak immune system. If you want to diminish your cold symptoms, boosting elements of your immune system may be the last thing you want to do.

Will there ever be a cure for the common cold? Some promising drugs are being investigated. But it's a really tough nut to crack.

What about the power of empathy? Empathy can actually cut short a cold by a full day. That's better than any drug on the market, and there aren't any side effects!
Adapted from an article by Alexandra Silver. Picture by Corbis.

Animal and plant genes create new species

The genes of plants and animals act as engines for speciation, that is, they are “programmed” to cause the development of new species, according to investigations on two very different groups of organisms.

When two diverging populations of organisms do not interbreed — a phenomenon of hybrid sterility or incompatibility — the number of genes that prevent them from producing new organisms starts to grow very fast. This process promotes the evolution of new species.

In the first of the studies, Daniel Matute and his colleagues at the University of Chicago counted the number of genes in species incompatibility between fruitflies that belong to three species: Drosophila melanogaster, Drosophila simulans and Drosophila santomea. These three species can interbreed, but the new organisms are sterile.

The team created two hybrid populations — one by crossing D. melanogaster with D. simulans and the other by crossing D. melanogaster with D. santomea — and counted the number of incompatibilities in the hybrid chromosomes.

They found 65 incompatibilities in the hybrids between D. melanogaster and D. santomea, while there were just ten in the hybrids between D. melanogaster and D. simulans. Taking into account the relative number of genetic changes between species, this suggests that the number of incompatibilities does not increase in a linear way, but is accelerating.

Similar results were found out when studying the plant genus “solanum”, which includes potatoes and tomatoes. A lot of genes contributing to sterility were growing faster than the linear rate, while genes that had nothing to do with sterility were not.
Adapted from an article by Joseph Milton in Nature. Picture by Stockphoto.

Precursor to H.I.V. Was in Monkeys for Millenniums

In a discovery that throws new light on the history of AIDS, scientists have found evidence that the ancestor to the virus that causes the disease has been in monkeys for at least 32,000 years.

That means humans have presumably been exposed many times to SIV, the simian immunodeficiency virus, because people have been hunting monkeys for millenniums.

So what happened in Africa in the early 20th century that turned an unimportant monkey disease into one of history’s great killers, 25 million human lives so far?

Confirming that the virus is very old also helps explain why it infects almost all African monkeys but does not sicken them. A disease kills off vulnerable victims, but the host adapts to it.

The new study, published on Thursday in Science magazine, was relatively simple. Scientists tested 79 monkeys from Bioko, a volcanic island 19 miles off the West African coast. Bioko used to be the end of a peninsula what is now Cameroon, but it was cut off when sea levels went up 10,000 years ago.

Since then, six monkey species have developed in isolation on the island, and scientists found that four of them were infected with SIV. The disease must have existed before Bioko was cut off.

AIDS is obviously very new to us. If it had been in humans before the 20th century, it would have arrived in America in some of the 12 million Africans carried as slaves.
Adapted from an article by Donald G. McNeil in The New York Times. Picture by Tim Laman.

Skin cells converted to heart muscle cells

By simply switching on three critical genes, scientists turned mouse skin cells into heart muscle cells. So far, this has been only possible with embryonic cells.

If the technique works in humans, it could provide new heart muscle for the millions of people who suffer from heart failure each year. It is also a new example of a process called 'transdifferentiation', in which adult cells take on an entirely different identity.

Once it is damaged, heart muscle cannot repair itself. Further damage makes the heart weaker, eventually causing it to fail. In the United States, 5 million patients have heart failure, but only 2,000 heart transplants are performed each year.

A team of scientists searched for genes that are expressed at high levels in heart muscle cells, and then narrowed the list down to three that were sufficient to convert another type of heart cell, structural cells called cardiac fibroblasts, into heart muscle cells. Activating those three genes was sufficient to convert the cardiac fibroblasts or similar cells in skin to heart muscle cells. When implanted into mouse hearts, the cells made from cardiac fibroblasts contracted normally.

The results raise the possibility that a similar approach could be used to convert cardiac fibroblasts already in the heart to muscle cells, without the need for cell transplants. The team is now investigating whether the same three genes are enough to switch cell identity in humans. 

Adapted from an article by Heidi Ledford in Nature. IStockphoto