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Eat a little less, remember more
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G. DAVID JOHNSON/DONAL HUGHES/BRUCE ROBINSON
IT IS the very opposite of family resemblance: three groups of strikingly different-looking fish that turn out to be males, females and young of the same family. Tapetails (top picture) live in shallow waters and are named for the long streamers that trail behind them. Whalefish and bignoses are both deep-sea fish, but while whalefish (middle) lack scales and have huge jaws, bignoses (bottom) have long nasal organs and immobile jaws, and live off energy stored in their gigantic livers. Nobody thought these groups were related. “The differences were so extreme,” says marine biologist David Johnson of the Smithsonian Institution in Washington DC. Then a study found that whalefish and tapetail mitochondrial DNA is virtually identical, prompting Johnson to re-examine museum specimens. This revealed one in the process of changing from a tapetail into a whalefish. Specimens intermediate between tapetails and bignoses were collected in 2007, and together with more DNA analysis this proved that the three families are really one (Biology Letters, DOI: 10.1098/rsbl.2008.0722). A “tapetail” larva grows up to be a “whalefish” female or “bignose” male. Johnson claims this is the most extreme metamorphosis ever seen in a vertebrate.
Leaky membranes may be key to Parkinson’s disease THE origin of the mysterious filaments that clog the brains of people with Parkinson’s and other neurodegenerative diseases may have been identified. It seems that the barrier enclosing the nucleus inside cells grows leakier with age, admitting proteins from outside. One, called tubulin, forms long filaments that clog up the nucleus and may damage chromosomes. Lead researcher Martin Hetzer of the Salk Institute for Biological Sciences in La Jolla, California, says that in people with Parkinson’s,
tubulin filaments abound in the substantia nigra, the part of the brain affected by the disease. Finding a way to reverse nuclear “leakiness” could lead to new treatments as well as slowing ageing more generally, he says. The barrier between nucleus and cytoplasm is usually policed by nuclear pore complexes, molecular sentinels regulating passage of molecules in and out. Hetzer and his colleagues investigated the fate of these complexes as cells age. They showed that Caenorhabditis
elegans, a roundworm whose cells do not divide in adulthood, retains the same complexes for life. This was also true in nondividing rat neurons (Cell, DOI: 10.1016/j.cell.2008.11.037). But these pore scaffolds gradually break down with age, admitting proteins. “We think the age-dependent deterioration of pores might lead to defects in nuclear function,” Hetzer says. “We are now investigating the possibility of plugging the leaky pores and preventing breakdown of cell compartmentalisation.” SHAROW L. JONZ/WORKBOOK STOCK/JUPITER
A shape-shifting fishy trinity
Eat a little less, remember more EATING less doesn’t just boost physical health. In elderly people, it seems to improve memory, too. As well as extending lifespan in mice, restricting calorie intake has been shown to boost cognitive ability in elderly animals. To see if the cognitive benefit held for people, Agnes Flöel and colleagues at the University of Münster in Germany tested the short-term memory of 50 people, with an average age of 60. The people were overweight, but not obese, and one-third of them were instructed to eat 30 per cent fewer calories than normal each day. After three months, the dieters scored 20 per cent higher on the word-based memory test than they had before dieting, recalling on average 12.5 out of 15 words, compared to 10.5. “Two words may not seem like much, but it’s more than the difference between people under 30 and above 50,” says Flöel. Those who did not go on the diet showed no change (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0808587106). The dieters had lower levels of glucose and insulin in their blood, which previous studies have linked to improved brain function.
Born to follow the beat BRAIN activity in babies listening to a drum beat suggests they are born with a keen sense of rhythm. The finding might help to spot abnormal brain development at an early age. Babies under a year old often clap or bounce to a rhythm, but whether they are born with the ability to recognise a beat, or learn it later, was unclear. To find out, a team led by István Winkler from the Institute for Psychology in Budapest, Hungary, and Henkjan Honing from the University of Amsterdam in the Netherlands placed electrodes on the scalps of sleeping babies just two or three days old, while playing
them a rock drum rhythm. When the rhythm stopped briefly and then restarted out of sync with the original beat, the babies’ brains produced electrical activity known to be associated with the violation of sensory expectations (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0809035106). This didn’t happen after the rhythm merely missed a single beat. “Beat perception is there right from birth,” Winkler concludes. He now plans to investigate whether poor beat perception in newborns is a sign of speech and communication problems to come.
31 January 2009 | NewScientist | 15
G. DAVID JOHNSON/DONAL HUGHES/BRUCE ROBINSON
IT IS the very opposite of family resemblance: three groups of strikingly different-looking fish that turn out to be males, females and young of the same family. Tapetails (top picture) live in shallow waters and are named for the long streamers that trail behind them. Whalefish and bignoses are both deep-sea fish, but while whalefish (middle) lack scales and have huge jaws, bignoses (bottom) have long nasal organs and immobile jaws, and live off energy stored in their gigantic livers. Nobody thought these groups were related. “The differences were so extreme,” says marine biologist David Johnson of the Smithsonian Institution in Washington DC. Then a study found that whalefish and tapetail mitochondrial DNA is virtually identical, prompting Johnson to re-examine museum specimens. This revealed one in the process of changing from a tapetail into a whalefish. Specimens intermediate between tapetails and bignoses were collected in 2007, and together with more DNA analysis this proved that the three families are really one (Biology Letters, DOI: 10.1098/rsbl.2008.0722). A “tapetail” larva grows up to be a “whalefish” female or “bignose” male. Johnson claims this is the most extreme metamorphosis ever seen in a vertebrate.
Leaky membranes may be key to Parkinson’s disease THE origin of the mysterious filaments that clog the brains of people with Parkinson’s and other neurodegenerative diseases may have been identified. It seems that the barrier enclosing the nucleus inside cells grows leakier with age, admitting proteins from outside. One, called tubulin, forms long filaments that clog up the nucleus and may damage chromosomes. Lead researcher Martin Hetzer of the Salk Institute for Biological Sciences in La Jolla, California, says that in people with Parkinson’s,
tubulin filaments abound in the substantia nigra, the part of the brain affected by the disease. Finding a way to reverse nuclear “leakiness” could lead to new treatments as well as slowing ageing more generally, he says. The barrier between nucleus and cytoplasm is usually policed by nuclear pore complexes, molecular sentinels regulating passage of molecules in and out. Hetzer and his colleagues investigated the fate of these complexes as cells age. They showed that Caenorhabditis
elegans, a roundworm whose cells do not divide in adulthood, retains the same complexes for life. This was also true in nondividing rat neurons (Cell, DOI: 10.1016/j.cell.2008.11.037). But these pore scaffolds gradually break down with age, admitting proteins. “We think the age-dependent deterioration of pores might lead to defects in nuclear function,” Hetzer says. “We are now investigating the possibility of plugging the leaky pores and preventing breakdown of cell compartmentalisation.” SHAROW L. JONZ/WORKBOOK STOCK/JUPITER
A shape-shifting fishy trinity
Eat a little less, remember more EATING less doesn’t just boost physical health. In elderly people, it seems to improve memory, too. As well as extending lifespan in mice, restricting calorie intake has been shown to boost cognitive ability in elderly animals. To see if the cognitive benefit held for people, Agnes Flöel and colleagues at the University of Münster in Germany tested the short-term memory of 50 people, with an average age of 60. The people were overweight, but not obese, and one-third of them were instructed to eat 30 per cent fewer calories than normal each day. After three months, the dieters scored 20 per cent higher on the word-based memory test than they had before dieting, recalling on average 12.5 out of 15 words, compared to 10.5. “Two words may not seem like much, but it’s more than the difference between people under 30 and above 50,” says Flöel. Those who did not go on the diet showed no change (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0808587106). The dieters had lower levels of glucose and insulin in their blood, which previous studies have linked to improved brain function.
Born to follow the beat BRAIN activity in babies listening to a drum beat suggests they are born with a keen sense of rhythm. The finding might help to spot abnormal brain development at an early age. Babies under a year old often clap or bounce to a rhythm, but whether they are born with the ability to recognise a beat, or learn it later, was unclear. To find out, a team led by István Winkler from the Institute for Psychology in Budapest, Hungary, and Henkjan Honing from the University of Amsterdam in the Netherlands placed electrodes on the scalps of sleeping babies just two or three days old, while playing
them a rock drum rhythm. When the rhythm stopped briefly and then restarted out of sync with the original beat, the babies’ brains produced electrical activity known to be associated with the violation of sensory expectations (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0809035106). This didn’t happen after the rhythm merely missed a single beat. “Beat perception is there right from birth,” Winkler concludes. He now plans to investigate whether poor beat perception in newborns is a sign of speech and communication problems to come.
31 January 2009 | NewScientist | 15