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Terminal buzz gives bats their hunting edge
dietmar nill/minden/flpa
IN BRIEF Corals adapt to warmer waters
Terminal buzz gives bats their hunting edge BATS owe their hunting prowess to superfast muscles in their larynx, which allow them to make a series of increasingly rapid calls as they home in on their prey. Most bats use echolocation to find prey. After a bat spots an insect it calls more frequently to get more information about the speed and direction of its prey, eventually calling up to 160 times a second (160 hertz). This final sequence of calls is known as the terminal buzz. The muscles that Myotis daubentoni uses to create the buzz move so quickly that they are classed as “superfast”, says Coen Elemans of the University of
Southern Denmark in Odense (Science, DOI: 10.1126/ science.1207309). The bats’ muscles are among the fastest known to exist, able to contract and relax at frequencies up to 200 Hz. Elemans knew that songbirds have superfast muscles to enable them to sing complex songs. Hummingbird wings, by comparison, can clock only around 40 Hz. “When bats evolved about 50 million years ago, the skies were full of night-flying insects that nobody was eating,” Elemans says. Echolocation by itself would not have been enough to hunt fast-moving insects in the dark, but the addition of superfast muscles and the terminal buzz could have given bats the advantage. “Most bats that echolocate with their larynx probably have these muscles,” he says.
Brain tweak makes wimps mighty DOMINANT mice can be humbled and wimps made mighty by altering the strength of electrical connections in their brain. The work may reveal mechanisms that dictate social standing in people. Crucial brain connections directing a mouse’s place in the social hierarchy sit in the medial prefrontal cortex. To investigate the mPFC’s role in social ranking, Hailan Hu of the Chinese Institute 16 | NewScientist | 8 October 2011
of Neuroscience in Shanghai and colleagues first worked out the hierarchy within a group of mice through challenges between pairs in tubes. When the mice came face to face, the subordinate animal would back out of the tube. The team then injected a virus into some of the mice that inserts a gene into mPFC neurons. The gene amplifies transmission of electrical signals – a key step in
strengthening connections. When the tests were repeated, previously subordinate mice that had received the virus became dominant. Likewise, implanting a gene that reduced the strength of connections caused previously dominant mice to become subordinate (Science, DOI: 10.1126/science.1209951). Hu says that the strengthened connections probably enable mice to exert more control over anger, emotion and aggression.
TANTALISING evidence suggests coral can be trained to withstand rising sea temperatures. Mauricio Rodriguez-Lanetty at the University of Louisiana at Lafayette found that Acropora millepora coral, which typically lives at 21 to 22 °C, experienced significant bleaching when held at 31 °C for eight days. But the coral could survive without bleaching if first held at 28 °C for 10 days. Some researchers think that coral might adapt to hotter water by switching its algae or symbiotic bacteria to heat tolerant types – but that would take more than 10 days. Rodriguez-Lanetty used genetic sequencing to show no such changes occurred (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2011.1780). However, it’s unclear whether the heat tolerance is permanent. “Corals still face a gloomy future unless we stop global warming,” says Rodriguez-Lanetty.
Harassed fish bait their friends PITY the friends of a sexually harassed female guppy – they are likely to feel her anger. Males of the species Poecilia reticulata regularly harass females for sex. Safi Darden of the University of Exeter, UK, has now found that harassed females become more aggressive. In her lab, female guppies were more likely to chase and nudge other females after exposure to a male (Biology Letters, DOI: 10.1098/rsbl.2011.0807). Darden thinks harassed females of other species may react in the same way. Female guppies are not ordinarily very aggressive towards each other, says Penny Watt of the University of Sheffield, UK. “I’m surprised they got quite so grumpy.”
IN BRIEF Corals adapt to warmer waters
Terminal buzz gives bats their hunting edge BATS owe their hunting prowess to superfast muscles in their larynx, which allow them to make a series of increasingly rapid calls as they home in on their prey. Most bats use echolocation to find prey. After a bat spots an insect it calls more frequently to get more information about the speed and direction of its prey, eventually calling up to 160 times a second (160 hertz). This final sequence of calls is known as the terminal buzz. The muscles that Myotis daubentoni uses to create the buzz move so quickly that they are classed as “superfast”, says Coen Elemans of the University of
Southern Denmark in Odense (Science, DOI: 10.1126/ science.1207309). The bats’ muscles are among the fastest known to exist, able to contract and relax at frequencies up to 200 Hz. Elemans knew that songbirds have superfast muscles to enable them to sing complex songs. Hummingbird wings, by comparison, can clock only around 40 Hz. “When bats evolved about 50 million years ago, the skies were full of night-flying insects that nobody was eating,” Elemans says. Echolocation by itself would not have been enough to hunt fast-moving insects in the dark, but the addition of superfast muscles and the terminal buzz could have given bats the advantage. “Most bats that echolocate with their larynx probably have these muscles,” he says.
Brain tweak makes wimps mighty DOMINANT mice can be humbled and wimps made mighty by altering the strength of electrical connections in their brain. The work may reveal mechanisms that dictate social standing in people. Crucial brain connections directing a mouse’s place in the social hierarchy sit in the medial prefrontal cortex. To investigate the mPFC’s role in social ranking, Hailan Hu of the Chinese Institute 16 | NewScientist | 8 October 2011
of Neuroscience in Shanghai and colleagues first worked out the hierarchy within a group of mice through challenges between pairs in tubes. When the mice came face to face, the subordinate animal would back out of the tube. The team then injected a virus into some of the mice that inserts a gene into mPFC neurons. The gene amplifies transmission of electrical signals – a key step in
strengthening connections. When the tests were repeated, previously subordinate mice that had received the virus became dominant. Likewise, implanting a gene that reduced the strength of connections caused previously dominant mice to become subordinate (Science, DOI: 10.1126/science.1209951). Hu says that the strengthened connections probably enable mice to exert more control over anger, emotion and aggression.
TANTALISING evidence suggests coral can be trained to withstand rising sea temperatures. Mauricio Rodriguez-Lanetty at the University of Louisiana at Lafayette found that Acropora millepora coral, which typically lives at 21 to 22 °C, experienced significant bleaching when held at 31 °C for eight days. But the coral could survive without bleaching if first held at 28 °C for 10 days. Some researchers think that coral might adapt to hotter water by switching its algae or symbiotic bacteria to heat tolerant types – but that would take more than 10 days. Rodriguez-Lanetty used genetic sequencing to show no such changes occurred (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2011.1780). However, it’s unclear whether the heat tolerance is permanent. “Corals still face a gloomy future unless we stop global warming,” says Rodriguez-Lanetty.
Harassed fish bait their friends PITY the friends of a sexually harassed female guppy – they are likely to feel her anger. Males of the species Poecilia reticulata regularly harass females for sex. Safi Darden of the University of Exeter, UK, has now found that harassed females become more aggressive. In her lab, female guppies were more likely to chase and nudge other females after exposure to a male (Biology Letters, DOI: 10.1098/rsbl.2011.0807). Darden thinks harassed females of other species may react in the same way. Female guppies are not ordinarily very aggressive towards each other, says Penny Watt of the University of Sheffield, UK. “I’m surprised they got quite so grumpy.”