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Saturn moon spouts plasma unlike any seen before
Sophie Chivet/Agence VU
THIS WEEK continuing to work as normal cells. The cell computers are more flexible than their electronic counterparts, because both the input molecules and the output proteins can be replaced with other biological signals, while traditional computers are limited to just one signal, the electron. That means a computer could be designed to take a signal from an infection as its input, for instance, and the output would be to deliver an appropriate treatment. Visual signals like the red and green fluorescent proteins used in Fussenegger’s proof of principle experiment could also –Finger-free sums– be used, causing a skin patch to glow red in the presence of an infectious agent, say. Implanted, cell computers could even communicate directly with electronic computers. “Now we have the same logic, we hope that machines can talk better to cells,” says Fussenegger. developed before, but most are “The team have taken this to made of DNA molecules or the next level by showing how bacteria, which would be difficult one can encode decision-making to implant in humans. “In order to logic into cells rather than just be of any therapeutic relevance in producing a response,” says the future, you need to establish Martyn Amos at Manchester these things in mammalian cells,” Metropolitan University, UK. says Fussenegger. It remains to be seen how well Ordinary computers use the their approach scales to larger presence or absence of electrons computational circuits, as the to represent 1s and 0s to encode output from one cell cannot yet information. Fussenegger’s cells be used as the input to another. use two naturally occurring “The next challenge is to engineer molecules: erythromycin, an these devices so that they can antibiotic, and phloretin, a communicate,” says Amos. n substance found in apple trees. These act as inputs, switching a Cells that add reaction within the two types of Cell computers can add up the presence cell on or off. The reaction leads or absence of proteins and give a colourcoded result, mimicking a binary system to the production of a red or green fluorescent protein that signals the result of the calculation (Nature, DOI: 10.1038/ nature11149). For example, in the half adder cell, the presence of 0+0 0 both molecules makes it glow 0+1 1 red (see diagram, right). These reactions take place 1+0 1 without interfering with the cells’ ordinary functions, allowing 1+1 2 them to speak the binary INPUT RESULT SIGNAL language of computers while
Jacob Aron
FORGET smartphones, how about a smart arm? Human cells capable of performing simple arithmetic could one day be implanted in your body as a biological computer to diagnose disease, administer drugs or interface with electronic devices. Martin Fussenegger and colleagues at the Swiss Federal Institute of Technology in Zurich created biological versions of two
“Now we have the same logic, we hope that machines can talk better to cells” key digital circuits inside two sets of embryonic kidney cells: a half adder and half subtractor. As the names suggest, they add or subtract two binary numbers. These are the most complex biological circuits ever created, and could form the building blocks of more advanced computational circuits. Biological circuits capable of simpler computations have been 12 | NewScientist | 9 June 2012
Ph lo r Er eti yt n hr om yc in
Bionic cells do basic arithmetic
Plasma like no other swirls around Saturn A NEW form of matter surrounds Saturn – a plasma put there by Enceladus, the planet’s tiny moon. “It’s a type of charged particle that has never been observed before,” says Tom Hill of Rice University in Houston, Texas. Shortly after it arrived at the Saturn system in 2004, the Cassini spacecraft discovered that the small icy moon Enceladus was spouting a watery geyser. The plume contained water vapour, as well as micrometresized dust grains. Yet in 2009, Cassini saw something else in the plume: nanometre-sized grains that each carried an electric charge. That meant the plume was a powerful source of plasma, a form of matter in which positively and negatively charged particles move around separately. It seems that Enceladus provides most of the plasma in the magnetic bubble, or magnetosphere, surrounding Saturn. But it was unclear how the particles got their charges. Now, after three fly-bys during which Cassini’s plasma detectors could investigate the nanograins, Hill and colleagues think they have an answer. The sun’s ultraviolet light strips electrons from the gas and other material in the plume, creating a cloud of free electrons. As the uncharged nanograins leave Enceladus and move through this charged cloud, they pick up about one electron each to create a plasma. But that means that the structure of the plasma is backwards, says Hill. Most plasmas contain positive ions, which carry mass, and negative free electrons, which carry almost no mass. Here, most of the mass is in the form of negatively charged grains (Journal of Geophysical Research, DOI: 10.1029/2011JA017218). “That changes the basic behaviour of the plasma,” says Hill – although we will have to wait until Cassini next flies by the plume in more than a year to see in what way. Lisa Grossman n
THIS WEEK continuing to work as normal cells. The cell computers are more flexible than their electronic counterparts, because both the input molecules and the output proteins can be replaced with other biological signals, while traditional computers are limited to just one signal, the electron. That means a computer could be designed to take a signal from an infection as its input, for instance, and the output would be to deliver an appropriate treatment. Visual signals like the red and green fluorescent proteins used in Fussenegger’s proof of principle experiment could also –Finger-free sums– be used, causing a skin patch to glow red in the presence of an infectious agent, say. Implanted, cell computers could even communicate directly with electronic computers. “Now we have the same logic, we hope that machines can talk better to cells,” says Fussenegger. developed before, but most are “The team have taken this to made of DNA molecules or the next level by showing how bacteria, which would be difficult one can encode decision-making to implant in humans. “In order to logic into cells rather than just be of any therapeutic relevance in producing a response,” says the future, you need to establish Martyn Amos at Manchester these things in mammalian cells,” Metropolitan University, UK. says Fussenegger. It remains to be seen how well Ordinary computers use the their approach scales to larger presence or absence of electrons computational circuits, as the to represent 1s and 0s to encode output from one cell cannot yet information. Fussenegger’s cells be used as the input to another. use two naturally occurring “The next challenge is to engineer molecules: erythromycin, an these devices so that they can antibiotic, and phloretin, a communicate,” says Amos. n substance found in apple trees. These act as inputs, switching a Cells that add reaction within the two types of Cell computers can add up the presence cell on or off. The reaction leads or absence of proteins and give a colourcoded result, mimicking a binary system to the production of a red or green fluorescent protein that signals the result of the calculation (Nature, DOI: 10.1038/ nature11149). For example, in the half adder cell, the presence of 0+0 0 both molecules makes it glow 0+1 1 red (see diagram, right). These reactions take place 1+0 1 without interfering with the cells’ ordinary functions, allowing 1+1 2 them to speak the binary INPUT RESULT SIGNAL language of computers while
Jacob Aron
FORGET smartphones, how about a smart arm? Human cells capable of performing simple arithmetic could one day be implanted in your body as a biological computer to diagnose disease, administer drugs or interface with electronic devices. Martin Fussenegger and colleagues at the Swiss Federal Institute of Technology in Zurich created biological versions of two
“Now we have the same logic, we hope that machines can talk better to cells” key digital circuits inside two sets of embryonic kidney cells: a half adder and half subtractor. As the names suggest, they add or subtract two binary numbers. These are the most complex biological circuits ever created, and could form the building blocks of more advanced computational circuits. Biological circuits capable of simpler computations have been 12 | NewScientist | 9 June 2012
Ph lo r Er eti yt n hr om yc in
Bionic cells do basic arithmetic
Plasma like no other swirls around Saturn A NEW form of matter surrounds Saturn – a plasma put there by Enceladus, the planet’s tiny moon. “It’s a type of charged particle that has never been observed before,” says Tom Hill of Rice University in Houston, Texas. Shortly after it arrived at the Saturn system in 2004, the Cassini spacecraft discovered that the small icy moon Enceladus was spouting a watery geyser. The plume contained water vapour, as well as micrometresized dust grains. Yet in 2009, Cassini saw something else in the plume: nanometre-sized grains that each carried an electric charge. That meant the plume was a powerful source of plasma, a form of matter in which positively and negatively charged particles move around separately. It seems that Enceladus provides most of the plasma in the magnetic bubble, or magnetosphere, surrounding Saturn. But it was unclear how the particles got their charges. Now, after three fly-bys during which Cassini’s plasma detectors could investigate the nanograins, Hill and colleagues think they have an answer. The sun’s ultraviolet light strips electrons from the gas and other material in the plume, creating a cloud of free electrons. As the uncharged nanograins leave Enceladus and move through this charged cloud, they pick up about one electron each to create a plasma. But that means that the structure of the plasma is backwards, says Hill. Most plasmas contain positive ions, which carry mass, and negative free electrons, which carry almost no mass. Here, most of the mass is in the form of negatively charged grains (Journal of Geophysical Research, DOI: 10.1029/2011JA017218). “That changes the basic behaviour of the plasma,” says Hill – although we will have to wait until Cassini next flies by the plume in more than a year to see in what way. Lisa Grossman n