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Light limits lake productivity
MARK DEEBLE&VICTORIA STONE/OSF/PHOTOLIBRARY
IN BRIEF The upside of psychosis genes
Punting along the river, hippo style THEY might be ungainly on land, but in water it’s a different story – hippos glide gracefully along the river bed using their feet as punts. As they spend relatively long periods “in flight” between punts, their movements resemble those of astronauts in microgravity. Frank Fish and Brittany Coughlin of West Chester University in Pennsylvania spent hours filming a pair of captive hippos at the Adventure Aquarium in Camden, New Jersey. Contrary to popular belief, they saw no evidence that hippos actually swim. Instead, they spent most of their
time “punting” along the bottom, usually using one or both of their front feet as the punt. When they needed air, they launched themselves to the surface with their hind feet (Journal of Mammalogy, vol 90, p 675). Fish says that the weight and bone density of the hippos is an asset underwater because, coupled with the buoyancy of the water, it gives them momentum to spring forward. The findings also give a clue to how hippo-like creatures may have given rise to cetaceans, with whom hippos share a common ancestor. “First, they may have walked on the bottom and foraged,” says Fish. “It’s a compelling idea that bottom-walking might have preceded all-out swimming in all lineages,” says John Hutchinson of the Royal Veterinary College in Hertfordshire, UK.
Lazy gene favours adventurous choices IN A restaurant, do you order the dish you know you love or try a new one, in case you like it better? The level of the reward chemical dopamine you have in a brain region may determine your reply. The COMT gene codes for an enzyme that breaks down dopamine in the prefrontal cortex. People with a less efficient version of COMT have more dopamine in this region, and 16 | NewScientist | 25 July 2009
this makes them good at storing multiple ideas in the short term. To see if COMT affects decisionmaking too, Michael Frank and colleagues at Brown University in Providence, Rhode Island, asked volunteers to stop a stop-clock hundreds of times in exchange for points. Sometimes stopping it early garnered most points, while at other times a late response did best. This forced volunteers to
keep changing their strategies. When people were clocking up points, and so could be fairly confident in their current strategy, those with the inefficient version of COMT were more likely than people with the active version to switch strategies to try to do even better (Nature Neuroscience, DOI: 10.1038/nn.2342). The team concludes that high levels of dopamine in the prefrontal cortex make people more adventurous, even when the status quo is fine.
A GENE linking schizophrenia and psychosis to creativity could help explain why genes that up the risk of mental illness have been preserved in human evolution. Szabolcs Kéri of Semmelweis University in Budapest, Hungary, genotyped 200 adults who replied to adverts for creative volunteers. He tested their creative thinking and scored them according to creative achievements, such as filing a patent or writing a book. Those with two copies of a mutation in the NRG1 gene, linked to psychosis, scored higher on creativity than volunteers with one or no copies of the mutation (Psychological Science, DOI: 10.1111/j.1467-9280.2009.02398.x). Other variations in NRG1 slightly up the risk of schizophrenia. Kéri speculates that the mutation dampens a brain region that modulates mood and behaviour, unleashing creativity in some and psychosis in others.
Light’s the key for a lake full of life ADD nutrients and a lake’s ecosystem flourishes – or so the thinking goes. But new work suggests that light, rather than food, is the key to lake productivity. The idea that productivity is limited by the availability of nutrients is based mainly on studies in surface waters. So when Jan Karlsson from Umeå University in Sweden and his colleagues studied 12 lakes in Sweden, they measured the productivity of the whole ecosystem, from deepwater algae to fish. Light levels dropped sharply with depth in the lakes but they all contained enough nutrients to be highly productive. However, the less the light penetrated, the less productive the lake was (Nature, DOI: 10.1038/nature08179).
IN BRIEF The upside of psychosis genes
Punting along the river, hippo style THEY might be ungainly on land, but in water it’s a different story – hippos glide gracefully along the river bed using their feet as punts. As they spend relatively long periods “in flight” between punts, their movements resemble those of astronauts in microgravity. Frank Fish and Brittany Coughlin of West Chester University in Pennsylvania spent hours filming a pair of captive hippos at the Adventure Aquarium in Camden, New Jersey. Contrary to popular belief, they saw no evidence that hippos actually swim. Instead, they spent most of their
time “punting” along the bottom, usually using one or both of their front feet as the punt. When they needed air, they launched themselves to the surface with their hind feet (Journal of Mammalogy, vol 90, p 675). Fish says that the weight and bone density of the hippos is an asset underwater because, coupled with the buoyancy of the water, it gives them momentum to spring forward. The findings also give a clue to how hippo-like creatures may have given rise to cetaceans, with whom hippos share a common ancestor. “First, they may have walked on the bottom and foraged,” says Fish. “It’s a compelling idea that bottom-walking might have preceded all-out swimming in all lineages,” says John Hutchinson of the Royal Veterinary College in Hertfordshire, UK.
Lazy gene favours adventurous choices IN A restaurant, do you order the dish you know you love or try a new one, in case you like it better? The level of the reward chemical dopamine you have in a brain region may determine your reply. The COMT gene codes for an enzyme that breaks down dopamine in the prefrontal cortex. People with a less efficient version of COMT have more dopamine in this region, and 16 | NewScientist | 25 July 2009
this makes them good at storing multiple ideas in the short term. To see if COMT affects decisionmaking too, Michael Frank and colleagues at Brown University in Providence, Rhode Island, asked volunteers to stop a stop-clock hundreds of times in exchange for points. Sometimes stopping it early garnered most points, while at other times a late response did best. This forced volunteers to
keep changing their strategies. When people were clocking up points, and so could be fairly confident in their current strategy, those with the inefficient version of COMT were more likely than people with the active version to switch strategies to try to do even better (Nature Neuroscience, DOI: 10.1038/nn.2342). The team concludes that high levels of dopamine in the prefrontal cortex make people more adventurous, even when the status quo is fine.
A GENE linking schizophrenia and psychosis to creativity could help explain why genes that up the risk of mental illness have been preserved in human evolution. Szabolcs Kéri of Semmelweis University in Budapest, Hungary, genotyped 200 adults who replied to adverts for creative volunteers. He tested their creative thinking and scored them according to creative achievements, such as filing a patent or writing a book. Those with two copies of a mutation in the NRG1 gene, linked to psychosis, scored higher on creativity than volunteers with one or no copies of the mutation (Psychological Science, DOI: 10.1111/j.1467-9280.2009.02398.x). Other variations in NRG1 slightly up the risk of schizophrenia. Kéri speculates that the mutation dampens a brain region that modulates mood and behaviour, unleashing creativity in some and psychosis in others.
Light’s the key for a lake full of life ADD nutrients and a lake’s ecosystem flourishes – or so the thinking goes. But new work suggests that light, rather than food, is the key to lake productivity. The idea that productivity is limited by the availability of nutrients is based mainly on studies in surface waters. So when Jan Karlsson from Umeå University in Sweden and his colleagues studied 12 lakes in Sweden, they measured the productivity of the whole ecosystem, from deepwater algae to fish. Light levels dropped sharply with depth in the lakes but they all contained enough nutrients to be highly productive. However, the less the light penetrated, the less productive the lake was (Nature, DOI: 10.1038/nature08179).