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CO2 makes crops less nutritious
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IN BRIEF Crop nutrition falls as CO2 rises
Dawn and dusk dives help tuna find their way home TUNA dive fast and deep twice a day because they use an internal compass to navigate, a new study suggests. It has long been known that tuna dive around dawn and dusk but no one has been quite sure why. To find out, Jay Willis at the University of Tasmania in Hobart, Australia, and colleagues attached tags to 21 southern blue fin tuna (Thunnus maccoyii) and used them to monitor water temperature, time, depth and light levels for 135 days (Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-009-0818-2). The team found that the tuna initiated
these “spike dives” when the sun was precisely 6 degrees below the horizon, 30 minutes before dawn and 30 minutes after sunset. At this time of day magnetic interference created by the solar wind is at its lowest. Since some fish can detect and navigate using magnetic fields, Willis thinks that diving at this time may help tuna to get a clearer magnetic signal. As surface wind and waves also cause interference, Willis suggests that they dive deep to “fine-tune their personal compass”. Others are not so sure. “There may be other reasons besides geolocation at work here, namely keeping track of food,” says Molly Lutcavage of the University of New Hampshire in Durham. She points out that tuna’s prey migrate to depth at around the same time.
Planets found orbiting backwards YOU wait years to find an extrasolar planet orbiting in the opposite direction to its star’s spin, then two come along at once. The two planets, WASP-17b and HAT-P-7b, are both “hot Jupiters” – gas giants that orbit very close to their stars. HAT-P-7b, which is 1.4 times as wide as Jupiter and 1.8 times as massive, is smaller and heavier than WASP-17b, which may be the biggest and least dense 14 | NewScientist | 22 August 2009
exoplanet found so far. The planets are about 1000 light years from us. David Anderson of Keele University, UK, and colleagues found WASP-17b using a telescope array at the South African Astronomical Observatory near Sutherland. HAT-P-7b was discovered by two independent teams, one led by Joshua Winn of the Massachusetts Institute of Technology, and
the other by Norio Narita at the National Astronomical Observatory of Japan. They both used the Japanese Subaru telescope atop Mauna Kea in Hawaii. Although both teams agree that HAT-P-7b is orbiting backwards, its orbit is tilted with respect to its star’s equator, and the two teams disagree on the degree of tilt. “We’re catching so many planets these days, we’re bound to see some of the oddballs,” says Adam Burrows of Princeton University.
RISING carbon dioxide levels may increase future crop yields but there is a catch: food will be less nutritious. We already know that wheat exposed to higher CO2 has a lower protein content. To see whether it affects concentrations of trace elements and toxins, Petra Högy from the University of Hohenheim in Germany and colleagues grew wheat under CO2 concentrations expected by 2050. The team found an 8 per cent drop in iron and a 14 per cent increase in lead (Plant Biology, DOI: 10.1111/ j.1438-8677.2009.00230.x). On the upside, levels of the heavy metal cadmium dropped by 14 per cent. “This study brings into sharp focus the effects on wheat – one of the largest sources of nutrients for humans,” says Irakli Loladze of the University of Nebraska in Lincoln, who predicted the negative effects of rising CO2 on micronutrients seven years ago.
Tone-deaf people need connections PEOPLE who struggle to distinguish musical notes have fewer brain connections in an area involved in language and speech. They were already known to have abnormalities in brain areas responsible for perceiving and producing sounds. Now Psyche Loui of Harvard Medical School, and colleagues, have found that in tone-deaf volunteers, these areas are less well-connected than in people with normal sound perception (The Journal of Neuroscience, DOI: 10.1523/ jneurosci.1701-09.2009). These brain connections are also used for speech and language, so “rehabilitation strategies for tone-deafness may also help with speech and language disorders”, says Loui.
IN BRIEF Crop nutrition falls as CO2 rises
Dawn and dusk dives help tuna find their way home TUNA dive fast and deep twice a day because they use an internal compass to navigate, a new study suggests. It has long been known that tuna dive around dawn and dusk but no one has been quite sure why. To find out, Jay Willis at the University of Tasmania in Hobart, Australia, and colleagues attached tags to 21 southern blue fin tuna (Thunnus maccoyii) and used them to monitor water temperature, time, depth and light levels for 135 days (Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-009-0818-2). The team found that the tuna initiated
these “spike dives” when the sun was precisely 6 degrees below the horizon, 30 minutes before dawn and 30 minutes after sunset. At this time of day magnetic interference created by the solar wind is at its lowest. Since some fish can detect and navigate using magnetic fields, Willis thinks that diving at this time may help tuna to get a clearer magnetic signal. As surface wind and waves also cause interference, Willis suggests that they dive deep to “fine-tune their personal compass”. Others are not so sure. “There may be other reasons besides geolocation at work here, namely keeping track of food,” says Molly Lutcavage of the University of New Hampshire in Durham. She points out that tuna’s prey migrate to depth at around the same time.
Planets found orbiting backwards YOU wait years to find an extrasolar planet orbiting in the opposite direction to its star’s spin, then two come along at once. The two planets, WASP-17b and HAT-P-7b, are both “hot Jupiters” – gas giants that orbit very close to their stars. HAT-P-7b, which is 1.4 times as wide as Jupiter and 1.8 times as massive, is smaller and heavier than WASP-17b, which may be the biggest and least dense 14 | NewScientist | 22 August 2009
exoplanet found so far. The planets are about 1000 light years from us. David Anderson of Keele University, UK, and colleagues found WASP-17b using a telescope array at the South African Astronomical Observatory near Sutherland. HAT-P-7b was discovered by two independent teams, one led by Joshua Winn of the Massachusetts Institute of Technology, and
the other by Norio Narita at the National Astronomical Observatory of Japan. They both used the Japanese Subaru telescope atop Mauna Kea in Hawaii. Although both teams agree that HAT-P-7b is orbiting backwards, its orbit is tilted with respect to its star’s equator, and the two teams disagree on the degree of tilt. “We’re catching so many planets these days, we’re bound to see some of the oddballs,” says Adam Burrows of Princeton University.
RISING carbon dioxide levels may increase future crop yields but there is a catch: food will be less nutritious. We already know that wheat exposed to higher CO2 has a lower protein content. To see whether it affects concentrations of trace elements and toxins, Petra Högy from the University of Hohenheim in Germany and colleagues grew wheat under CO2 concentrations expected by 2050. The team found an 8 per cent drop in iron and a 14 per cent increase in lead (Plant Biology, DOI: 10.1111/ j.1438-8677.2009.00230.x). On the upside, levels of the heavy metal cadmium dropped by 14 per cent. “This study brings into sharp focus the effects on wheat – one of the largest sources of nutrients for humans,” says Irakli Loladze of the University of Nebraska in Lincoln, who predicted the negative effects of rising CO2 on micronutrients seven years ago.
Tone-deaf people need connections PEOPLE who struggle to distinguish musical notes have fewer brain connections in an area involved in language and speech. They were already known to have abnormalities in brain areas responsible for perceiving and producing sounds. Now Psyche Loui of Harvard Medical School, and colleagues, have found that in tone-deaf volunteers, these areas are less well-connected than in people with normal sound perception (The Journal of Neuroscience, DOI: 10.1523/ jneurosci.1701-09.2009). These brain connections are also used for speech and language, so “rehabilitation strategies for tone-deafness may also help with speech and language disorders”, says Loui.