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Smallest dark matter ‘bullet’ may be one among hundreds
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WHEN the cold of winter sets in, the goldenrod gall fly maggot takes a gung-ho approach: it freezes solid. Now it seems the maggot owes its survival to a newly described fat, which provides it with food by staying liquid at lower temperatures than other kinds of fat. The maggot (Eurosta solidaginis) spends its life in a lump called a gall on the stem of a goldenrod plant. In late autumn the plant dies, the gall turns hard and the maggot goes into suspended animation. In this state, it can endure temperatures as low as -60 °C, even if up to 60 per cent of
Brent Sinclair
the water in its body turns to ice. But the maggot still needs a source of energy to keep its systems ticking over. Most animals use fatty molecules, but the most efficient types solidify at the frigid temperatures the maggots endure. Katie Marshall at the University of Western Ontario in Canada and her colleagues have uncovered the secret. They looked at the maggots’ fat composition as they grew, and found they made a different type of fat to other freeze-tolerant insects. These acetylated triacylglycerols (acTAGs) stayed liquid in much chillier conditions than other fats. Production of acTAGs was boosted at the start of winter, and increased further if the maggots were frozen and thawed repeatedly (Journal of Experimental Biology, doi.org/sk9).
Itsy bitsy bacteria given enlarged genetic code THEY may look like any other microbe, but don’t be fooled. The bacteria growing in a Californian laboratory are the first organisms to have an expanded genetic code. Instead of four letters, their genetic alphabet has six, thanks to two artificial letters. “We have created the first organism that stores increased genetic information,” says Floyd Romesberg of the Scripps Research Institute in La Jolla. Life on Earth, from bacteria to humans, uses the same four “letters” or bases to build its DNA:
A, T, C and G. But there are many alternative molecules. Romesberg previously built two artificial letters, d5SICS and dNaM, that work well with the natural enzymes that build DNA. Now he has incorporated them into living E. coli bacteria. The cells naturally took them into their genome, making matching pairs that face each other on either side of the DNA double helix (Nature, DOI: 10.1038/nature13314). “It is astounding that it could work at all,” says Aaron Leconte of Claremont McKenna College
in California, who helped to design the new genetic letters. At first, the extra letters were slipped into the bacteria far from working genes, to avoid disrupting their function. But Romesberg is now putting the letters into those genes, to coax the cells into producing unnatural proteins. Nature only provides 20 amino acids, the building blocks of proteins. Romesberg’s work makes it possible to incorporate an additional 152 artificial ones. That could lead to new materials like nanowires, and better drugs. NASA/CXC/CfA/stsci/eso
Frozen maggot feeds on new fat
Dizzy exoplanet has 8-hour day IF YOU feel there is never enough time in a day, don’t move to Beta Pictoris b. The first measurement of an exoplanet’s rotation rate shows that a day on this fastpaced world lasts just 8 hours. Beta Pictoris b was discovered in 2008 in a picture taken by the Very Large Telescope in Chile. Ignas Snellen of Leiden University in the Netherlands and his colleagues used the same telescope to study the motion of gases in the planet’s dusty atmosphere. They were then able to calculate how fast Beta Pictoris b is spinning on its axis: about 25 kilometres a second. The planet is about 65 per cent bigger than Jupiter, which means it completes a full revolution – in other words, a day – roughly every 8 hours (Nature, doi.org/skz). Its fast spin matches the close relationship observed in our solar system between the mass of a planet and its rotation speed: in general, the heftier the world, the shorter the day. Snellen hopes to use the same technique to measure the length of days on other exoplanets, which could show whether the relationship between rotation and mass really does hold outside the solar system.
Smallest dark matter ‘bullet’ spotted THE smallest galactic smash-up to show evidence of dark matter has been found, and it hints at an army of similarly tiny twins. One of the most famous smoking guns for dark matter is the Bullet cluster, shown above. Here, a small galaxy cluster swept through a larger one about 100 million years ago. The galaxies passed far enough apart not to hit, but the hot gas (pink) in between them collided and pooled on the trailing ends of each cluster. Maps of mass distribution show there must be dark matter (blue) as well as visible matter, and that it travelled
faster than the gas, separating out to keep up with the galaxies. Similar examples have since been found but only in a handful of very massive clusters. Fabio Gastaldello at the National Institute for Astrophysics in Milan, Italy, and his team have now found a much smaller group that also shows separating dark matter (arxiv. org/abs/1404.5633). Small galaxy groups are about 1000 times more common than large clusters, so there should be many more Bullet-like groups. Finding them would help us refine models of dark matter interactions.
10 May 2014 | NewScientist | 17
WHEN the cold of winter sets in, the goldenrod gall fly maggot takes a gung-ho approach: it freezes solid. Now it seems the maggot owes its survival to a newly described fat, which provides it with food by staying liquid at lower temperatures than other kinds of fat. The maggot (Eurosta solidaginis) spends its life in a lump called a gall on the stem of a goldenrod plant. In late autumn the plant dies, the gall turns hard and the maggot goes into suspended animation. In this state, it can endure temperatures as low as -60 °C, even if up to 60 per cent of
Brent Sinclair
the water in its body turns to ice. But the maggot still needs a source of energy to keep its systems ticking over. Most animals use fatty molecules, but the most efficient types solidify at the frigid temperatures the maggots endure. Katie Marshall at the University of Western Ontario in Canada and her colleagues have uncovered the secret. They looked at the maggots’ fat composition as they grew, and found they made a different type of fat to other freeze-tolerant insects. These acetylated triacylglycerols (acTAGs) stayed liquid in much chillier conditions than other fats. Production of acTAGs was boosted at the start of winter, and increased further if the maggots were frozen and thawed repeatedly (Journal of Experimental Biology, doi.org/sk9).
Itsy bitsy bacteria given enlarged genetic code THEY may look like any other microbe, but don’t be fooled. The bacteria growing in a Californian laboratory are the first organisms to have an expanded genetic code. Instead of four letters, their genetic alphabet has six, thanks to two artificial letters. “We have created the first organism that stores increased genetic information,” says Floyd Romesberg of the Scripps Research Institute in La Jolla. Life on Earth, from bacteria to humans, uses the same four “letters” or bases to build its DNA:
A, T, C and G. But there are many alternative molecules. Romesberg previously built two artificial letters, d5SICS and dNaM, that work well with the natural enzymes that build DNA. Now he has incorporated them into living E. coli bacteria. The cells naturally took them into their genome, making matching pairs that face each other on either side of the DNA double helix (Nature, DOI: 10.1038/nature13314). “It is astounding that it could work at all,” says Aaron Leconte of Claremont McKenna College
in California, who helped to design the new genetic letters. At first, the extra letters were slipped into the bacteria far from working genes, to avoid disrupting their function. But Romesberg is now putting the letters into those genes, to coax the cells into producing unnatural proteins. Nature only provides 20 amino acids, the building blocks of proteins. Romesberg’s work makes it possible to incorporate an additional 152 artificial ones. That could lead to new materials like nanowires, and better drugs. NASA/CXC/CfA/stsci/eso
Frozen maggot feeds on new fat
Dizzy exoplanet has 8-hour day IF YOU feel there is never enough time in a day, don’t move to Beta Pictoris b. The first measurement of an exoplanet’s rotation rate shows that a day on this fastpaced world lasts just 8 hours. Beta Pictoris b was discovered in 2008 in a picture taken by the Very Large Telescope in Chile. Ignas Snellen of Leiden University in the Netherlands and his colleagues used the same telescope to study the motion of gases in the planet’s dusty atmosphere. They were then able to calculate how fast Beta Pictoris b is spinning on its axis: about 25 kilometres a second. The planet is about 65 per cent bigger than Jupiter, which means it completes a full revolution – in other words, a day – roughly every 8 hours (Nature, doi.org/skz). Its fast spin matches the close relationship observed in our solar system between the mass of a planet and its rotation speed: in general, the heftier the world, the shorter the day. Snellen hopes to use the same technique to measure the length of days on other exoplanets, which could show whether the relationship between rotation and mass really does hold outside the solar system.
Smallest dark matter ‘bullet’ spotted THE smallest galactic smash-up to show evidence of dark matter has been found, and it hints at an army of similarly tiny twins. One of the most famous smoking guns for dark matter is the Bullet cluster, shown above. Here, a small galaxy cluster swept through a larger one about 100 million years ago. The galaxies passed far enough apart not to hit, but the hot gas (pink) in between them collided and pooled on the trailing ends of each cluster. Maps of mass distribution show there must be dark matter (blue) as well as visible matter, and that it travelled
faster than the gas, separating out to keep up with the galaxies. Similar examples have since been found but only in a handful of very massive clusters. Fabio Gastaldello at the National Institute for Astrophysics in Milan, Italy, and his team have now found a much smaller group that also shows separating dark matter (arxiv. org/abs/1404.5633). Small galaxy groups are about 1000 times more common than large clusters, so there should be many more Bullet-like groups. Finding them would help us refine models of dark matter interactions.
10 May 2014 | NewScientist | 17