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Fear not, fair neighbour, I'll protect you…
IN BRIEF MICHAEL NICHOLS/NATIONAL GEOGRAPHIC/GETTY
For new stories every day, visit www.NewScientist.com/news
Backward star ain’t from round here
Fear not, fair neighbour, I’ll protect you… FEMALE fiddler crabs mate with their neighbours in exchange for protection. The discovery of the sex-for-security trait helps to explain a surprising quirk, how it is that females defend their territory just as successfully as males despite their smaller claws. It is also the first known case of male and female neighbours teaming up to defend territory in any species, according to lead researcher Richard Milner of the Australian National University in Canberra. Fiddler crabs live in burrows and often fight to protect them from would-be squatters. Males have one giant
claw, sometimes as heavy of the rest of their body, which they use in fights. Females have two much smaller claws, yet are just as good at holding on to their territory. A willingness to offer sex to male neighbours seems to be behind this success, says Milner. He studied crabs on South Africa and Mozambique beaches and found males frequently defending the burrows of neighbouring females when rival males approached. Milner and colleagues also found 85 per cent of the mating they observed was between crabs with neighbouring burrows (Biology Letters, DOI: 10.1098/rsbl.2009.0767). Females of other species trade sex for material benefits. Red-winged blackbirds do so for the right to forage on a male’s territory, and Adelie penguins exchange sex for stones to build their nests.
Why fat angers the immune system OVERWEIGHT people get heart disease and diabetes – and more severe swine flu – because their fat triggers inflammation, an immune response meant to fight infection. Now the protein responsible for this sequence of events may have been found. Jerrold Olefsky and colleagues at the University of California at San Diego killed the bone marrow cells in mice that make immune
cells called macrophages. Then they injected the mice with macrophages lacking a surface protein called TLR4. When the team fed the mice high-fat diet, all grew obese, as did a group of normal mice. But unlike the normal mice, those with altered macrophages showed no signs of inflammation, such as changes in insulin production, high levels of immune chemicals,
and macrophages in their belly fat (Cell Metabolism, vol 10, p 419). Olefsky concludes that TLR4 mediates the immune system’s response to fat. He says that some fatty acids look like the bacterial invaders that TLR4 senses, prompting normal macrophages to mistake fatty acids for the enemy and turn on inflammation. His team is now testing drugs that block TLR4. One day these might help people dodge some of the health effects of being overweight.
HERE’S an apple that landed far from the tree. A dim star just 13 light years from Earth was born in a cluster 17,000 light years away. Kapteyn’s Star is the 25th nearest star system to our sun, but it is no local, says Elizabeth Wylie-de Boer of Mount Stromlo Observatory in Canberra. The cool star’s composition is tricky to study, but you can look at 16 other stars in the same “moving group”, all of which orbit the galaxy backwards and are very old. Of the stars, 14 had the same abundance of elements as Omega Centauri, the galaxy’s most luminous globular cluster. “It’s long been thought that Omega Centauri is the left-over nucleus of a dwarf galaxy that merged with the Milky Way,” says Wylie-de Boer, whose paper will appear in the Astronomical Journal. During the merger, some stars, including Kapteyn’s Star, were flung towards us.
Skin keeps tabs on your beating heart NOT everyone wears their heart on their sleeve, but tests on a braindamaged man suggest that we all sense our heartbeat with our skin. Awareness of our internal organs – the ability to feel your stomach growl and your heart beat – is known as “interoception” and has been linked to two regions of the brain. But Sahib Khalsa of the University of Iowa in Iowa City and colleagues found that a man with damage to these regions could feel his own heartbeat as clearly as healthy men. Only by numbing the skin on his chest could they remove the sensation. Khalsa says that nerves in the skin must play a role in heartbeat interoception, in addition to the brain (Nature Neuroscience, DOI: 10.1038/nn.2411). 7 November 2009 | NewScientist | 23
For new stories every day, visit www.NewScientist.com/news
Backward star ain’t from round here
Fear not, fair neighbour, I’ll protect you… FEMALE fiddler crabs mate with their neighbours in exchange for protection. The discovery of the sex-for-security trait helps to explain a surprising quirk, how it is that females defend their territory just as successfully as males despite their smaller claws. It is also the first known case of male and female neighbours teaming up to defend territory in any species, according to lead researcher Richard Milner of the Australian National University in Canberra. Fiddler crabs live in burrows and often fight to protect them from would-be squatters. Males have one giant
claw, sometimes as heavy of the rest of their body, which they use in fights. Females have two much smaller claws, yet are just as good at holding on to their territory. A willingness to offer sex to male neighbours seems to be behind this success, says Milner. He studied crabs on South Africa and Mozambique beaches and found males frequently defending the burrows of neighbouring females when rival males approached. Milner and colleagues also found 85 per cent of the mating they observed was between crabs with neighbouring burrows (Biology Letters, DOI: 10.1098/rsbl.2009.0767). Females of other species trade sex for material benefits. Red-winged blackbirds do so for the right to forage on a male’s territory, and Adelie penguins exchange sex for stones to build their nests.
Why fat angers the immune system OVERWEIGHT people get heart disease and diabetes – and more severe swine flu – because their fat triggers inflammation, an immune response meant to fight infection. Now the protein responsible for this sequence of events may have been found. Jerrold Olefsky and colleagues at the University of California at San Diego killed the bone marrow cells in mice that make immune
cells called macrophages. Then they injected the mice with macrophages lacking a surface protein called TLR4. When the team fed the mice high-fat diet, all grew obese, as did a group of normal mice. But unlike the normal mice, those with altered macrophages showed no signs of inflammation, such as changes in insulin production, high levels of immune chemicals,
and macrophages in their belly fat (Cell Metabolism, vol 10, p 419). Olefsky concludes that TLR4 mediates the immune system’s response to fat. He says that some fatty acids look like the bacterial invaders that TLR4 senses, prompting normal macrophages to mistake fatty acids for the enemy and turn on inflammation. His team is now testing drugs that block TLR4. One day these might help people dodge some of the health effects of being overweight.
HERE’S an apple that landed far from the tree. A dim star just 13 light years from Earth was born in a cluster 17,000 light years away. Kapteyn’s Star is the 25th nearest star system to our sun, but it is no local, says Elizabeth Wylie-de Boer of Mount Stromlo Observatory in Canberra. The cool star’s composition is tricky to study, but you can look at 16 other stars in the same “moving group”, all of which orbit the galaxy backwards and are very old. Of the stars, 14 had the same abundance of elements as Omega Centauri, the galaxy’s most luminous globular cluster. “It’s long been thought that Omega Centauri is the left-over nucleus of a dwarf galaxy that merged with the Milky Way,” says Wylie-de Boer, whose paper will appear in the Astronomical Journal. During the merger, some stars, including Kapteyn’s Star, were flung towards us.
Skin keeps tabs on your beating heart NOT everyone wears their heart on their sleeve, but tests on a braindamaged man suggest that we all sense our heartbeat with our skin. Awareness of our internal organs – the ability to feel your stomach growl and your heart beat – is known as “interoception” and has been linked to two regions of the brain. But Sahib Khalsa of the University of Iowa in Iowa City and colleagues found that a man with damage to these regions could feel his own heartbeat as clearly as healthy men. Only by numbing the skin on his chest could they remove the sensation. Khalsa says that nerves in the skin must play a role in heartbeat interoception, in addition to the brain (Nature Neuroscience, DOI: 10.1038/nn.2411). 7 November 2009 | NewScientist | 23