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Voyager space probes show outsiders' view of Milky Way
IN BRIEF
Ron Austing/FLPA
ABANDON the rat race at your peril. Naked mole rat colonies contain just one sexually active male – and the lack of competition has left its sperm shrivelled and sluggish. Liana Maree of the University of the Western Cape in Bellville, South Africa, and colleagues took sperm from captive naked mole rats and subjected them to a battery of tests. Only 7 per cent of the sperm actually moved, and they swam at around 35 micrometres per second – possibly the slowest sperm of any mammal (BMC Evolutionary Biology, in press). “The reason they swim so slowly is there is no sperm competition,” says Maree. Naked mole rats live in colonies dominated by the queen, who chooses one male at a time to mate with. She suppresses the reproductive instincts of every other male in the colony. The chosen male has exclusive mating rights, so he can afford to produce listless sperm. “The naked mole rat is actually a very good model for what happens in humans,” Maree says. Previous studies have found faster sperm in more promiscuous species. Humans are relatively monogamous, so sperm competition is fairly low and abnormalities are common. About 60 per cent of human sperm are motile, compared with 95 per cent in more promiscuous species.
18 | NewScientist | 10 December 2011
Blue eyes? You can run but you can’t hide from IrisPlex POLICE with no leads can now predict the eye colour of their suspect from DNA recovered at the crime scene. It’s the first time such a tool has been available. Manfred Kayser at Erasmus University Medical Centre in the Netherlands and colleagues have developed IrisPlex, which can predict with 94 per cent accuracy whether a person has blue or brown eyes from a sample of DNA. The Dutch Ministry of Security and Justice is expected to approve the kit in the coming weeks, while the UK could use it immediately.
It is the first validated tool to help police home in on a possible suspect by predicting a visible trait, says Kayser. This could be useful in cases where police have DNA from a crime scene, but can’t find a match on a DNA database. It is not accurate enough to secure convictions in court, however. IrisPlex examines six singleletter variations in DNA, known as single nucleotide polymorphisms (SNPs), which have been strongly linked to eye colour, and categorises them as blue, brown or “undefined” – an intermediate
colour such as green, grey, or a mix of colours. Tests of the kit, carried out on populations from seven different European countries, confirm that it can predict blue or brown eye colour with a high degree of accuracy (Forensic Science International: Genetics, DOI: 10.1016/j.fsigen.2011.07.009). The identification of three new SNPs may soon enable IrisPlex to predict the shade as well as colour. A different kit that combines both eye and hair colour is also being tested. JPl archive/nasa
The worst sperm – no competition
For new stories every day, visit newscientist.com/news
My love nest is bigger than his… IF YOU thought estate agents knew how to sell a house, take a look at male Emei music frogs. They attract a mate by singing the praises of the burrows they have dug. Other than humans, they are the only animal known to advertise their homes in their calls. Males of the species Babina daunchina are famous for their musical call, which sounds like an ascending scale. They live on the fringes of ponds in central China, where males dig nests. Yezhong Tang of the Chinese Academy of Sciences in Chengdu and his team found that males calling from inside a nest used lower and longer calls than usual. When the researchers recorded typical calls and “nest calls”, and played both back to females, they found that over 70 per cent of females moved towards the nest calls (Biology Letters, DOI: 10.1098/rsbl.2011.1091). Carl Gerhardt of the University of Missouri in Columbia says that in most species males don’t advertise resources like nests in their calls, perhaps because doing so would attract the attention of other males with the strength to take the nest from them.
Voyagers see outsider’s view of galaxy TALK about distance bringing perspective. The twin Voyager probes are so far from the sun that they can see a kind of light from the Milky Way that we on Earth cannot. The Voyagers, which were launched in 1977 and are about 100 times as far from the sun as Earth is, have detected a kind of light called Lyman-alpha emission from our galaxy for the first time. The light is useful because it is a trace of star formation. We are blind to it when it originates in our own galaxy: it is emitted in the ultraviolet range of the spectrum and so
becomes lost in the glare of the sun’s emissions. It can be seen coming from other galaxies, however, because it enters the detectable visible range after being stretched out by the expansion of space on its journey across the universe. Now Rosine Lallement of the Paris Observatory in France and her colleagues have confirmed that the Voyagers have seen through the solar haze into star-forming regions in the Milky Way (Science, DOI: 10.1126/science.1197340). This could help astronomers interpret star formation in more distant galaxies.
Ron Austing/FLPA
ABANDON the rat race at your peril. Naked mole rat colonies contain just one sexually active male – and the lack of competition has left its sperm shrivelled and sluggish. Liana Maree of the University of the Western Cape in Bellville, South Africa, and colleagues took sperm from captive naked mole rats and subjected them to a battery of tests. Only 7 per cent of the sperm actually moved, and they swam at around 35 micrometres per second – possibly the slowest sperm of any mammal (BMC Evolutionary Biology, in press). “The reason they swim so slowly is there is no sperm competition,” says Maree. Naked mole rats live in colonies dominated by the queen, who chooses one male at a time to mate with. She suppresses the reproductive instincts of every other male in the colony. The chosen male has exclusive mating rights, so he can afford to produce listless sperm. “The naked mole rat is actually a very good model for what happens in humans,” Maree says. Previous studies have found faster sperm in more promiscuous species. Humans are relatively monogamous, so sperm competition is fairly low and abnormalities are common. About 60 per cent of human sperm are motile, compared with 95 per cent in more promiscuous species.
18 | NewScientist | 10 December 2011
Blue eyes? You can run but you can’t hide from IrisPlex POLICE with no leads can now predict the eye colour of their suspect from DNA recovered at the crime scene. It’s the first time such a tool has been available. Manfred Kayser at Erasmus University Medical Centre in the Netherlands and colleagues have developed IrisPlex, which can predict with 94 per cent accuracy whether a person has blue or brown eyes from a sample of DNA. The Dutch Ministry of Security and Justice is expected to approve the kit in the coming weeks, while the UK could use it immediately.
It is the first validated tool to help police home in on a possible suspect by predicting a visible trait, says Kayser. This could be useful in cases where police have DNA from a crime scene, but can’t find a match on a DNA database. It is not accurate enough to secure convictions in court, however. IrisPlex examines six singleletter variations in DNA, known as single nucleotide polymorphisms (SNPs), which have been strongly linked to eye colour, and categorises them as blue, brown or “undefined” – an intermediate
colour such as green, grey, or a mix of colours. Tests of the kit, carried out on populations from seven different European countries, confirm that it can predict blue or brown eye colour with a high degree of accuracy (Forensic Science International: Genetics, DOI: 10.1016/j.fsigen.2011.07.009). The identification of three new SNPs may soon enable IrisPlex to predict the shade as well as colour. A different kit that combines both eye and hair colour is also being tested. JPl archive/nasa
The worst sperm – no competition
For new stories every day, visit newscientist.com/news
My love nest is bigger than his… IF YOU thought estate agents knew how to sell a house, take a look at male Emei music frogs. They attract a mate by singing the praises of the burrows they have dug. Other than humans, they are the only animal known to advertise their homes in their calls. Males of the species Babina daunchina are famous for their musical call, which sounds like an ascending scale. They live on the fringes of ponds in central China, where males dig nests. Yezhong Tang of the Chinese Academy of Sciences in Chengdu and his team found that males calling from inside a nest used lower and longer calls than usual. When the researchers recorded typical calls and “nest calls”, and played both back to females, they found that over 70 per cent of females moved towards the nest calls (Biology Letters, DOI: 10.1098/rsbl.2011.1091). Carl Gerhardt of the University of Missouri in Columbia says that in most species males don’t advertise resources like nests in their calls, perhaps because doing so would attract the attention of other males with the strength to take the nest from them.
Voyagers see outsider’s view of galaxy TALK about distance bringing perspective. The twin Voyager probes are so far from the sun that they can see a kind of light from the Milky Way that we on Earth cannot. The Voyagers, which were launched in 1977 and are about 100 times as far from the sun as Earth is, have detected a kind of light called Lyman-alpha emission from our galaxy for the first time. The light is useful because it is a trace of star formation. We are blind to it when it originates in our own galaxy: it is emitted in the ultraviolet range of the spectrum and so
becomes lost in the glare of the sun’s emissions. It can be seen coming from other galaxies, however, because it enters the detectable visible range after being stretched out by the expansion of space on its journey across the universe. Now Rosine Lallement of the Paris Observatory in France and her colleagues have confirmed that the Voyagers have seen through the solar haze into star-forming regions in the Milky Way (Science, DOI: 10.1126/science.1197340). This could help astronomers interpret star formation in more distant galaxies.