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‘Living’ liquid crystals may show infections in motion
NORBERT ROSING/National Geographic Creative
in Brief Liquid crystal puts bacteria on display
Thawing Arctic is even worse news for greenhouse Earth MELTING ice is cooking the planet. Shrinking Arctic sea ice means the ocean is absorbing more energy from the sun, and it’s now clear the effect is twice as big as thought – adding significantly to heating from greenhouse gases. Arctic temperatures have risen 2 °C since the 1970s, leading to a 40 per cent dip in the minimum summer ice coverage in the Arctic Ocean. Open water soaks up more sunlight than ice, so as the ice retreats the ocean absorbs more energy, warming it and causing even more melting. To measure the effect, Ian Eisenman of the Scripps Institute of Oceanography in La Jolla, California, and
colleagues turned to data from NASA’s CERES satellite. They found that the Arctic Ocean’s albedo – the fraction of sunlight it reflects back into space – dropped from 52 per cent in 1979 to 48 per cent in 2011. That may not seem like much, but it means a big rise in energy absorbed – equal to 25 per cent of that trapped by the rise in atmospheric CO2 over the same period (PNAS, DOI: 10.1073/pnas.1318201111). “That is big – unexpectedly big,” says Eisenman. “Arctic sea ice retreat has been an important player in the global warming that we’ve observed during recent decades.” “It reaffirms that albedo feedback is a powerful amplifier of climate change, maybe even more so than is simulated by the current crop of climate models,” says Mark Flanner of the University of Michigan in Ann Arbor.
Tiny rod reels cancer cells to their death LET’S go fishing… for cancer cells. Glioblastoma is the most common and aggressive adult brain cancer, and as the tumours can be large and form deep in the brain, they are difficult to treat. Rather than engineer more toxic drugs to kill glioblastomas, Ravi Bellamkonda at Emory University School of Medicine in Atlanta, Georgia, and his team wondered if they could 18 | NewScientist | 22 February 2014
move the tumours, which latch on to nerves and blood vessels, to a more accessible location. They created a hollow rod 6 millimetres long. Inside, they put a film that mimics the shape of nerves and blood vessels. At the top of the rod is a gel containing a drug that kills the tumour cells. The idea is that the cells mistake the rod for a nerve or blood vessel, travel up it and meet their death.
To test the design, the team grafted human glioblastoma tumours into rat brains. They inserted the polymer rod into the tumour, with the gel sitting above the skull. After 15 days, the majority of the tumour cells had migrated along the rod (Nature Materials, doi.org/rhj). The method won’t banish the cancer, but it could keep tumours at a non-lethal size or move them to where they can be surgically removed, Bellamkonda says.
POPPING bacteria into a pool of liquid crystals could be just what the doctor ordered. The material makes it easier to see bacteria in motion, which could lead to better medical sensors for monitoring infections. Liquid crystals flow like liquids, but their molecules are aligned with each other, as they are in solid crystals. Their unique optical properties make them popular for use in electronic display screens. Igor Aronson at Argonne National Laboratory in Illinois and his colleagues added swimming bacteria to a water-based liquid crystal and found that they could see the waves made by their wiggling “limbs” under an optical microscope (PNAS, doi.org/rgg). These limbs are only tens of nanometres wide, so normally their motion cannot be seen easily. The team could even constrain the bacteria’s movement by varying conditions in the liquid.
Crazy ants use acid as venom antidote THE xenomorphs in Alien have nothing on tawny crazy ants. They often attack fire ants, though fire ant venom can kill small animals. But tawny crazy ants have a nifty way to detox: an acid bath. Edward LeBrun of the University of Texas in Austin watched the ants fight. If a crazy ant (Nylanderia fulva) was hit with fire ant venom, it ran off and then, like a cat cleaning its fur, washed itself with its own acid venom. LeBrun found that a dab of this acid saved Argentine ants, which normally succumb to the fire ant venom (Science, doi.org/rgj). The acid may neutralise the potent enzymes in the venom. Fire ants are a major pest in the US, but tawny crazy ants are no better, as they invade houses.
in Brief Liquid crystal puts bacteria on display
Thawing Arctic is even worse news for greenhouse Earth MELTING ice is cooking the planet. Shrinking Arctic sea ice means the ocean is absorbing more energy from the sun, and it’s now clear the effect is twice as big as thought – adding significantly to heating from greenhouse gases. Arctic temperatures have risen 2 °C since the 1970s, leading to a 40 per cent dip in the minimum summer ice coverage in the Arctic Ocean. Open water soaks up more sunlight than ice, so as the ice retreats the ocean absorbs more energy, warming it and causing even more melting. To measure the effect, Ian Eisenman of the Scripps Institute of Oceanography in La Jolla, California, and
colleagues turned to data from NASA’s CERES satellite. They found that the Arctic Ocean’s albedo – the fraction of sunlight it reflects back into space – dropped from 52 per cent in 1979 to 48 per cent in 2011. That may not seem like much, but it means a big rise in energy absorbed – equal to 25 per cent of that trapped by the rise in atmospheric CO2 over the same period (PNAS, DOI: 10.1073/pnas.1318201111). “That is big – unexpectedly big,” says Eisenman. “Arctic sea ice retreat has been an important player in the global warming that we’ve observed during recent decades.” “It reaffirms that albedo feedback is a powerful amplifier of climate change, maybe even more so than is simulated by the current crop of climate models,” says Mark Flanner of the University of Michigan in Ann Arbor.
Tiny rod reels cancer cells to their death LET’S go fishing… for cancer cells. Glioblastoma is the most common and aggressive adult brain cancer, and as the tumours can be large and form deep in the brain, they are difficult to treat. Rather than engineer more toxic drugs to kill glioblastomas, Ravi Bellamkonda at Emory University School of Medicine in Atlanta, Georgia, and his team wondered if they could 18 | NewScientist | 22 February 2014
move the tumours, which latch on to nerves and blood vessels, to a more accessible location. They created a hollow rod 6 millimetres long. Inside, they put a film that mimics the shape of nerves and blood vessels. At the top of the rod is a gel containing a drug that kills the tumour cells. The idea is that the cells mistake the rod for a nerve or blood vessel, travel up it and meet their death.
To test the design, the team grafted human glioblastoma tumours into rat brains. They inserted the polymer rod into the tumour, with the gel sitting above the skull. After 15 days, the majority of the tumour cells had migrated along the rod (Nature Materials, doi.org/rhj). The method won’t banish the cancer, but it could keep tumours at a non-lethal size or move them to where they can be surgically removed, Bellamkonda says.
POPPING bacteria into a pool of liquid crystals could be just what the doctor ordered. The material makes it easier to see bacteria in motion, which could lead to better medical sensors for monitoring infections. Liquid crystals flow like liquids, but their molecules are aligned with each other, as they are in solid crystals. Their unique optical properties make them popular for use in electronic display screens. Igor Aronson at Argonne National Laboratory in Illinois and his colleagues added swimming bacteria to a water-based liquid crystal and found that they could see the waves made by their wiggling “limbs” under an optical microscope (PNAS, doi.org/rgg). These limbs are only tens of nanometres wide, so normally their motion cannot be seen easily. The team could even constrain the bacteria’s movement by varying conditions in the liquid.
Crazy ants use acid as venom antidote THE xenomorphs in Alien have nothing on tawny crazy ants. They often attack fire ants, though fire ant venom can kill small animals. But tawny crazy ants have a nifty way to detox: an acid bath. Edward LeBrun of the University of Texas in Austin watched the ants fight. If a crazy ant (Nylanderia fulva) was hit with fire ant venom, it ran off and then, like a cat cleaning its fur, washed itself with its own acid venom. LeBrun found that a dab of this acid saved Argentine ants, which normally succumb to the fire ant venom (Science, doi.org/rgj). The acid may neutralise the potent enzymes in the venom. Fire ants are a major pest in the US, but tawny crazy ants are no better, as they invade houses.