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A hormone-free contraceptive pill? hormones?
In brief–
JIM ZIPP/SPL
FROGS learn the scent of danger before they hatch, which may give tadpoles a head start in evading predators. Animals learn that a smell or sound is a warning if it accompanies something dangerous. Maud Ferrari at the University of Saskatchewan in Saskatoon, Canada, and her team tested whether wood frog eggs could be primed to detect a predator’s scent. The team bathed the eggs in water that had previously contained fire-bellied newts. Half the eggs were also given a whiff of danger, in the form of an infusion of crushedup tadpoles, whose death is marked by chemical signals. After the eggs hatched, the researchers gave the tadpoles a second burst of newt odour. Tadpoles whose experience of newt had been accompanied by the odour of dead tadpoles froze in place – a classic defence against predators. Those that had not had this training continued swimming as normal (Proceedings of the Royal Society B, vol 275, p 2603). In a second study, Ferrari’s team showed that without encountering the “smell of danger” while frogspawn, frogs deem the newt odour as safe and are unable to associate it with danger thereafter (Biology Letters, DOI: 10.1098/ rsbl.2008.0641). The studies are the first to show that animals can learn the smell of a predator as embryos. The team has preliminary evidence that fish can do it too – suggesting the ability may be widespread.
16 | NewScientist | 6 December 2008
Bacterial mix and match is the key to good digestion WITHOUT the “good” bacteria in our guts, we could not digest food. You might expect that we would all have the same set of bacteria to provide the chemical machinery that does the job. But this turns out to be only half true. Knowing that gut bacteria are key to digestion and metabolism, Jeffrey Gordon of Washington University School of Medicine in St Louis, Missouri, and his colleagues went in search of a core group of bacterial species that aid digestion. They expected to find these species living in the
guts of most healthy people. When the researchers analysed faeces from 154 people this turned out not to be so. The subjects did, however, all possess the same core group of bacterial genes needed for digestion, albeit from different species (Nature, DOI: 10.1038/nature07540). It is this combination of genes, rather than any particular species, that is necessary for a healthy gut, says Gordon. “We’ve learned that you can have different collections of species, yet the gene functions represented in these
collections are broadly shared.” The analysis also flagged up differences between the bacterial genes of obese and lean people. Obese individuals had a greater proportion of genes for digesting fat, protein and carbohydrates, which might make them better at extracting and storing energy from food. Gordon hopes that a better knowledge of these genes might suggest new ways of combating obesity. Interestingly, participants who were related shared similar gut bacteria species as well as genes.
Where dogs have led, humans follow
began to plateau. Denny thinks this is because these animals reached a peak speed for their species, perhaps because selective breeding had created an optimum body type. Women sprinters began to plateau in the 1970s, with rarer and smaller improvements since then, but female marathon runners and male runners in general are still speeding up. Using these records, Denny has created a model which predicts that men will eventually achieve a peak time of 9.48 seconds for the 100-metre sprint, 0.21 seconds better than Usain Bolt’s current world record, while women will slice 2 minutes 44 seconds off Paula Radcliffe’s current marathon record of 2 hours, 15 minutes, 25 seconds.
DAVID BROOKOVER/AMANA/GETTY
Frogspawn knows how death smells
A hormone-free contraceptive pill? A PROTEIN that plays a crucial role in conception could be the key to creating a contraceptive that doesn’t tinker with a woman’s hormones. The coating of mammalian eggs contains a protein called ZP3, which sperm must bind to if they are to burrow through the coating and fertilise the egg. Female mice engineered to lack ZP3 do not have this coating, making them infertile, while women with abnormal ZP3 may also suffer fertility problems. Luca Jovine at the Karolinska Institute in Huddinge, Sweden, and his colleagues have used X-ray crystallography to work out the chemical structure of a stretch of mouse ZP3 that gives the protein its structural properties (Nature, DOI: 10.1038/nature07599). As the equivalent stretch of human ZP3 is likely to be similar in structure, Jovine says it may be possible to design drugs that bind to ZP3, thereby preventing the coating from forming and rendering women temporarily infertile. Such a drug might avoid some of the side effects of today’s oral contraceptives, which disrupt hormone production throughout the body.
WHAT do greyhounds, horses and women sprinters have in common? They may all have hit peak performance, while female marathon runners and men running over all distances are still getting faster. So says Mark Denny of Stanford University in California. He analysed records from athletics events and greyhound and horse races since the 1920s to see if they revealed limits on the speeds that animals and humans can run (The Journal of Experimental Biology, DOI: 10.1242/jeb.024968). Winning greyhounds and horses got faster until the 1970s, when they
www.newscientist.com
JIM ZIPP/SPL
FROGS learn the scent of danger before they hatch, which may give tadpoles a head start in evading predators. Animals learn that a smell or sound is a warning if it accompanies something dangerous. Maud Ferrari at the University of Saskatchewan in Saskatoon, Canada, and her team tested whether wood frog eggs could be primed to detect a predator’s scent. The team bathed the eggs in water that had previously contained fire-bellied newts. Half the eggs were also given a whiff of danger, in the form of an infusion of crushedup tadpoles, whose death is marked by chemical signals. After the eggs hatched, the researchers gave the tadpoles a second burst of newt odour. Tadpoles whose experience of newt had been accompanied by the odour of dead tadpoles froze in place – a classic defence against predators. Those that had not had this training continued swimming as normal (Proceedings of the Royal Society B, vol 275, p 2603). In a second study, Ferrari’s team showed that without encountering the “smell of danger” while frogspawn, frogs deem the newt odour as safe and are unable to associate it with danger thereafter (Biology Letters, DOI: 10.1098/ rsbl.2008.0641). The studies are the first to show that animals can learn the smell of a predator as embryos. The team has preliminary evidence that fish can do it too – suggesting the ability may be widespread.
16 | NewScientist | 6 December 2008
Bacterial mix and match is the key to good digestion WITHOUT the “good” bacteria in our guts, we could not digest food. You might expect that we would all have the same set of bacteria to provide the chemical machinery that does the job. But this turns out to be only half true. Knowing that gut bacteria are key to digestion and metabolism, Jeffrey Gordon of Washington University School of Medicine in St Louis, Missouri, and his colleagues went in search of a core group of bacterial species that aid digestion. They expected to find these species living in the
guts of most healthy people. When the researchers analysed faeces from 154 people this turned out not to be so. The subjects did, however, all possess the same core group of bacterial genes needed for digestion, albeit from different species (Nature, DOI: 10.1038/nature07540). It is this combination of genes, rather than any particular species, that is necessary for a healthy gut, says Gordon. “We’ve learned that you can have different collections of species, yet the gene functions represented in these
collections are broadly shared.” The analysis also flagged up differences between the bacterial genes of obese and lean people. Obese individuals had a greater proportion of genes for digesting fat, protein and carbohydrates, which might make them better at extracting and storing energy from food. Gordon hopes that a better knowledge of these genes might suggest new ways of combating obesity. Interestingly, participants who were related shared similar gut bacteria species as well as genes.
Where dogs have led, humans follow
began to plateau. Denny thinks this is because these animals reached a peak speed for their species, perhaps because selective breeding had created an optimum body type. Women sprinters began to plateau in the 1970s, with rarer and smaller improvements since then, but female marathon runners and male runners in general are still speeding up. Using these records, Denny has created a model which predicts that men will eventually achieve a peak time of 9.48 seconds for the 100-metre sprint, 0.21 seconds better than Usain Bolt’s current world record, while women will slice 2 minutes 44 seconds off Paula Radcliffe’s current marathon record of 2 hours, 15 minutes, 25 seconds.
DAVID BROOKOVER/AMANA/GETTY
Frogspawn knows how death smells
A hormone-free contraceptive pill? A PROTEIN that plays a crucial role in conception could be the key to creating a contraceptive that doesn’t tinker with a woman’s hormones. The coating of mammalian eggs contains a protein called ZP3, which sperm must bind to if they are to burrow through the coating and fertilise the egg. Female mice engineered to lack ZP3 do not have this coating, making them infertile, while women with abnormal ZP3 may also suffer fertility problems. Luca Jovine at the Karolinska Institute in Huddinge, Sweden, and his colleagues have used X-ray crystallography to work out the chemical structure of a stretch of mouse ZP3 that gives the protein its structural properties (Nature, DOI: 10.1038/nature07599). As the equivalent stretch of human ZP3 is likely to be similar in structure, Jovine says it may be possible to design drugs that bind to ZP3, thereby preventing the coating from forming and rendering women temporarily infertile. Such a drug might avoid some of the side effects of today’s oral contraceptives, which disrupt hormone production throughout the body.
WHAT do greyhounds, horses and women sprinters have in common? They may all have hit peak performance, while female marathon runners and men running over all distances are still getting faster. So says Mark Denny of Stanford University in California. He analysed records from athletics events and greyhound and horse races since the 1920s to see if they revealed limits on the speeds that animals and humans can run (The Journal of Experimental Biology, DOI: 10.1242/jeb.024968). Winning greyhounds and horses got faster until the 1970s, when they
www.newscientist.com