- Email: [email protected]
Broken dwarf planet may have scarred the moon
BETTMANN/CORBIS
IN BRIEF The enormous neutrino puzzle
Broken dwarf planet may have scarred the moon THE shattered remnants of a dwarf planet may have bombarded the inner planets in the early solar system, suggests a new analysis of craters on the moon. Several large impact scars on the moon appear to be around 3.9 billion years old, suggesting that the Earth and other objects of the inner solar system were heavily pounded at that time. Most astronomers believe that the bombardment was caused by shifts in the orbits of the giant planets, which destabilised the asteroid belt, hurling giant rocks our way. But the distribution of small and large lunar craters
does not match the numbers of small and large objects in the asteroid belt today, says a team led by Matija Cuk of Harvard University, who spoke at a meeting of the American Geophysical Union in Toronto, Canada, last week. Cuk says one possible alternative is that a dwarf planet or single large asteroid “hundreds or maybe 1000 kilometres across” did the damage after being ripped apart by gravity when it came too close to Earth or another inner planet. It then littered the inner solar system with impactors. Bill Bottke of the Southwest Research Institute in Boulder, Colorado, doubts a shattered 1000-kilometre object can explain all the damage in this period. He thinks the standard picture is closer to the truth but admits: “We still don’t understand the full story.”
Fix genes, then set to mass production ORDINARY cells from people with a genetic disease can be “fixed” by gene therapy and then reprogrammed to be stem cells that will produce a limitless supply of defect-free cells. Juan Carlos Izpisúa Belmonte of the Salk Institute in La Jolla, California, knew that stem cells are more useful for gene therapy than ordinary cells, because they produce multiple daughter cells 16 | NewScientist | 6 June 2009
with the modified genes. However, the body does not have many stem cells for doctors to work with. So Izpisúa Belmonte and his colleagues harvested fibroblasts, which are far more common than stem cells, from the skin of people with the bone marrow disease Fanconi anaemia. The team used viruses to replace the defective genes that cause the anaemia with normal ones, then used a second
virus to insert genes that “reset” the cells to a pluripotent state. The reset cells, known as induced pluripotent stem cells (iPS cells), gave rise to healthy precursors of bone marrow stem cells (Nature, DOI: 10.1038/nature08129). One drawback is that the resetting can trigger cancer. But if efforts to make this step safer succeed, the technique could provide a limitless supply of healthy, personalised iPS cells, says team member Inder Verma.
TALK about misnomers. It seems the particles that Enrico Fermi dubbed neutrinos, meaning “little neutral ones”, might stretch across billions of light years. The big bang produced huge numbers of “relic” neutrinos, which are quantum-mechanical superpositions of three different mass-energy states. In the early universe, all of these states would have moved at close to the speed of light. But according to calculations by George Fuller and Chad Kishimoto of the University of California, San Diego, as the universe expanded, the most massive of these states slowed down in the relic neutrinos, stretching them across the universe (Physical Review Letters, vol 102, p 201303). This raises the possibility that only one of the neutrino’s states could fall into a black hole. It’s unclear what would happen to the others if this occurred, says Fuller.
No bad thing, a few free radicals GENES that protect yeast DNA from oxidising free radicals could one day lead to drugs that prevent cancer and ageing in people. Produced by the body, free radicals damage DNA, so some people take supplements to mop them up. But this could be a bad idea as small doses of free radicals trigger changes in most cells that stop more from entering. Now Trey Ideker at the University of California, San Diego, and colleagues have found genes that control this response in yeast. If similar genes are found in people, drugs that mimic their protective effects could be a better strategy against cancer and ageing than simply mopping up all free radicals (PLoS Genetics, DOI: 10.1371/journal.pgen.1000488).
IN BRIEF The enormous neutrino puzzle
Broken dwarf planet may have scarred the moon THE shattered remnants of a dwarf planet may have bombarded the inner planets in the early solar system, suggests a new analysis of craters on the moon. Several large impact scars on the moon appear to be around 3.9 billion years old, suggesting that the Earth and other objects of the inner solar system were heavily pounded at that time. Most astronomers believe that the bombardment was caused by shifts in the orbits of the giant planets, which destabilised the asteroid belt, hurling giant rocks our way. But the distribution of small and large lunar craters
does not match the numbers of small and large objects in the asteroid belt today, says a team led by Matija Cuk of Harvard University, who spoke at a meeting of the American Geophysical Union in Toronto, Canada, last week. Cuk says one possible alternative is that a dwarf planet or single large asteroid “hundreds or maybe 1000 kilometres across” did the damage after being ripped apart by gravity when it came too close to Earth or another inner planet. It then littered the inner solar system with impactors. Bill Bottke of the Southwest Research Institute in Boulder, Colorado, doubts a shattered 1000-kilometre object can explain all the damage in this period. He thinks the standard picture is closer to the truth but admits: “We still don’t understand the full story.”
Fix genes, then set to mass production ORDINARY cells from people with a genetic disease can be “fixed” by gene therapy and then reprogrammed to be stem cells that will produce a limitless supply of defect-free cells. Juan Carlos Izpisúa Belmonte of the Salk Institute in La Jolla, California, knew that stem cells are more useful for gene therapy than ordinary cells, because they produce multiple daughter cells 16 | NewScientist | 6 June 2009
with the modified genes. However, the body does not have many stem cells for doctors to work with. So Izpisúa Belmonte and his colleagues harvested fibroblasts, which are far more common than stem cells, from the skin of people with the bone marrow disease Fanconi anaemia. The team used viruses to replace the defective genes that cause the anaemia with normal ones, then used a second
virus to insert genes that “reset” the cells to a pluripotent state. The reset cells, known as induced pluripotent stem cells (iPS cells), gave rise to healthy precursors of bone marrow stem cells (Nature, DOI: 10.1038/nature08129). One drawback is that the resetting can trigger cancer. But if efforts to make this step safer succeed, the technique could provide a limitless supply of healthy, personalised iPS cells, says team member Inder Verma.
TALK about misnomers. It seems the particles that Enrico Fermi dubbed neutrinos, meaning “little neutral ones”, might stretch across billions of light years. The big bang produced huge numbers of “relic” neutrinos, which are quantum-mechanical superpositions of three different mass-energy states. In the early universe, all of these states would have moved at close to the speed of light. But according to calculations by George Fuller and Chad Kishimoto of the University of California, San Diego, as the universe expanded, the most massive of these states slowed down in the relic neutrinos, stretching them across the universe (Physical Review Letters, vol 102, p 201303). This raises the possibility that only one of the neutrino’s states could fall into a black hole. It’s unclear what would happen to the others if this occurred, says Fuller.
No bad thing, a few free radicals GENES that protect yeast DNA from oxidising free radicals could one day lead to drugs that prevent cancer and ageing in people. Produced by the body, free radicals damage DNA, so some people take supplements to mop them up. But this could be a bad idea as small doses of free radicals trigger changes in most cells that stop more from entering. Now Trey Ideker at the University of California, San Diego, and colleagues have found genes that control this response in yeast. If similar genes are found in people, drugs that mimic their protective effects could be a better strategy against cancer and ageing than simply mopping up all free radicals (PLoS Genetics, DOI: 10.1371/journal.pgen.1000488).