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Genetically altered mosquitoes thwart dengue spreaders
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COLLAGEN growth has long been seen as the ultimate prize for makers of anti-ageing skin cream. Now there is a clue to how an ingredient in some anti-wrinkle treatments may stimulate this growth and restore skin’s elasticity. To find out how the compound Matrixyl works, Ian Hamley of the University of Reading, UK, examined the nanoscale arrangement of its long carbon chain and the peptide of five amino acids attached to one end. Similar compounds containing peptides made up of fewer amino acids tend to form cylindrical structures, with all the long chains pointing inwards and the peptides pointing outwards. In Matrixyl, however, such cylinders are outnumbered by flat “nanotapes”, in which the molecules are lined up in two layers with all the peptides on the upper and lower surfaces (Chemical Communications, DOI: 10.1039/c0cc03793a). The large, flat surface formed by nanotapes may facilitate the build-up of collagen, says Hamley. He hopes this work will help research into regenerative medicine for injuries to collagen-containing tissue such as skin and the eye. However, what happens when you actually apply it to skin is still unknown, says Christopher Griffiths at the University of Manchester, UK.
Missing: Milky Way’s smallest black holes BLACK holes a few times the mass of the sun aren’t just hard to spot: they may not exist. The finding offers a new twist in our idea of how black holes are born. Stars that are eight or more times the mass of the sun explode as supernovae at the end of their lives. If the core left behind weighs less than two or three suns, it will turn into a neutron star. If it weighs more, it will become a black hole. But there is a glaring lack of black holes observed at the lightest end of the spectrum, says Feryal Özel of the
University of Arizona in Tucson. Özel and colleagues studied 16 systems in the Milky Way that contain a black hole and a stellar partner, and found that none of these black holes had a mass between two and five times that of the sun. This can’t be explained by simple observational constraints, the team say. “These black holes really seem not to exist,” Özel says. The work will appear in The Astrophysical Journal. If the results are confirmed, they could give new insights into how stars collapse and
explode, says Chris Fryer of the Los Alamos National Laboratory in New Mexico. Larger stars are thought to explode with less energy than smaller ones, Fryer says. That means lower-mass stars that go on to form neutron stars would blast more of their outer layers away than higher-mass stars that become black holes. The extra material the higher-mass stars hold onto could then fall into the black holes, bulking them up. This could explain the dearth of the puniest black holes, he says. lucas jackson/reuters
The nano-secret of youthful skin
Mutant mosquitoes to tackle dengue GENETICALLY modified male Aedes aegypti mosquitoes could provide a potent new weapon against dengue fever, a disease which infects 50 million people annually and kills 25,000. In a six-month trial on the Caribbean island of Grand Cayman, 3.3 million of the mutant males were released into the wild. By the end of the trial the population of dengue-carrying A. aegypti females appeared to have plummeted. Oxitec, a company in Oxford, UK, bred males with an altered gene called tTA. This overcommits the gene transcription machinery of larvae and pupae, causing them to die prematurely. The number of females in the 16-hectare trial plot was estimated from the proportion of jam-jarsized pots placed there in which A. aegypti eggs were found. During the trial the proportion fell from 60 per cent to 10 per cent. In the past year, dengue has reappeared in the US for the first time in 65 years, and also in southern Europe. Oxitec has approval to conduct indoor trials in several dengue-affected countries, including Brazil, France, India, the US, Thailand, Singapore and Vietnam.
Hot rocks, peculiar plumbing… boom TWO types of magma and very odd plumbing – that’s wot dunnit. Iceland’s Eyjafjallajökull volcano took the world by surprise when it erupted in April and brought European airspace to standstill. Now a study of earthquake recordings and satellite data on deformations in the mountain has explained the eruption. Most active volcanoes have a single chamber that fills with magma, then pops. Instead, Eyjafjallajökull has a series of shallow horizontal chambers that lie parallel to each other, says Freysteinn Sigmundsson of the University of Iceland in
Reykjavik. As magma rises, it forms new horizontal sheets. Some began to form over 18 years ago, and in March the magma started to trickle out of an opening on the flank of Eyjafjallajökull (Nature, DOI: 10.1038/nature09558). And that might have been it, had the fresh magma in one sheet not bumped into a different type of magma, possibly lingering from the last eruption, 200 years ago. “The two had different compositions, temperatures and gas content and their meeting triggered the explosive eruption,” says Sigmundsson.
20 November 2010 | NewScientist | 21
thomas reutter/plainpicture
COLLAGEN growth has long been seen as the ultimate prize for makers of anti-ageing skin cream. Now there is a clue to how an ingredient in some anti-wrinkle treatments may stimulate this growth and restore skin’s elasticity. To find out how the compound Matrixyl works, Ian Hamley of the University of Reading, UK, examined the nanoscale arrangement of its long carbon chain and the peptide of five amino acids attached to one end. Similar compounds containing peptides made up of fewer amino acids tend to form cylindrical structures, with all the long chains pointing inwards and the peptides pointing outwards. In Matrixyl, however, such cylinders are outnumbered by flat “nanotapes”, in which the molecules are lined up in two layers with all the peptides on the upper and lower surfaces (Chemical Communications, DOI: 10.1039/c0cc03793a). The large, flat surface formed by nanotapes may facilitate the build-up of collagen, says Hamley. He hopes this work will help research into regenerative medicine for injuries to collagen-containing tissue such as skin and the eye. However, what happens when you actually apply it to skin is still unknown, says Christopher Griffiths at the University of Manchester, UK.
Missing: Milky Way’s smallest black holes BLACK holes a few times the mass of the sun aren’t just hard to spot: they may not exist. The finding offers a new twist in our idea of how black holes are born. Stars that are eight or more times the mass of the sun explode as supernovae at the end of their lives. If the core left behind weighs less than two or three suns, it will turn into a neutron star. If it weighs more, it will become a black hole. But there is a glaring lack of black holes observed at the lightest end of the spectrum, says Feryal Özel of the
University of Arizona in Tucson. Özel and colleagues studied 16 systems in the Milky Way that contain a black hole and a stellar partner, and found that none of these black holes had a mass between two and five times that of the sun. This can’t be explained by simple observational constraints, the team say. “These black holes really seem not to exist,” Özel says. The work will appear in The Astrophysical Journal. If the results are confirmed, they could give new insights into how stars collapse and
explode, says Chris Fryer of the Los Alamos National Laboratory in New Mexico. Larger stars are thought to explode with less energy than smaller ones, Fryer says. That means lower-mass stars that go on to form neutron stars would blast more of their outer layers away than higher-mass stars that become black holes. The extra material the higher-mass stars hold onto could then fall into the black holes, bulking them up. This could explain the dearth of the puniest black holes, he says. lucas jackson/reuters
The nano-secret of youthful skin
Mutant mosquitoes to tackle dengue GENETICALLY modified male Aedes aegypti mosquitoes could provide a potent new weapon against dengue fever, a disease which infects 50 million people annually and kills 25,000. In a six-month trial on the Caribbean island of Grand Cayman, 3.3 million of the mutant males were released into the wild. By the end of the trial the population of dengue-carrying A. aegypti females appeared to have plummeted. Oxitec, a company in Oxford, UK, bred males with an altered gene called tTA. This overcommits the gene transcription machinery of larvae and pupae, causing them to die prematurely. The number of females in the 16-hectare trial plot was estimated from the proportion of jam-jarsized pots placed there in which A. aegypti eggs were found. During the trial the proportion fell from 60 per cent to 10 per cent. In the past year, dengue has reappeared in the US for the first time in 65 years, and also in southern Europe. Oxitec has approval to conduct indoor trials in several dengue-affected countries, including Brazil, France, India, the US, Thailand, Singapore and Vietnam.
Hot rocks, peculiar plumbing… boom TWO types of magma and very odd plumbing – that’s wot dunnit. Iceland’s Eyjafjallajökull volcano took the world by surprise when it erupted in April and brought European airspace to standstill. Now a study of earthquake recordings and satellite data on deformations in the mountain has explained the eruption. Most active volcanoes have a single chamber that fills with magma, then pops. Instead, Eyjafjallajökull has a series of shallow horizontal chambers that lie parallel to each other, says Freysteinn Sigmundsson of the University of Iceland in
Reykjavik. As magma rises, it forms new horizontal sheets. Some began to form over 18 years ago, and in March the magma started to trickle out of an opening on the flank of Eyjafjallajökull (Nature, DOI: 10.1038/nature09558). And that might have been it, had the fresh magma in one sheet not bumped into a different type of magma, possibly lingering from the last eruption, 200 years ago. “The two had different compositions, temperatures and gas content and their meeting triggered the explosive eruption,” says Sigmundsson.
20 November 2010 | NewScientist | 21