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18 | NewScientist | 26 November 2011 Heart condition? Try pregnancy WHY wait to be born to develop a healing hand? Mouse fetuses will give up stem cells to repair their mother’s heart. The discovery could explain why half the women who develop heart weakness during or just after pregnancy recover spontaneously. Hina Chaudhry of the Mount Sinai School of Medicine in New York City mated normal female mice with males genetically engineered to produce a green- fluorescing protein in all their body cells. Half the resulting fetuses also produced the protein, making it easy to spot any fetal tissue in the mother. Chaudhry’s team inflicted a heart attack on the pregnant mice and then two weeks later examined their hearts at post-mortem. They found some fluorescent cells in the mothers’ damaged heart tissue, where they had accelerated repair by changing into new heart cells, including beating cardiomyocytes and blood vessel cells (Circulation Research, DOI: 10.1161/circresaha.111.249037). Chaudhry says that the phenomenon is an evolutionary mechanism: the fetus promotes its own survival by protecting its mother’s heart. Unruly neurons set the stage for synaesthesia THE mysterious mechanisms that lie behind synaesthesia could be explained by hyperactive neurons. In grapheme-colour synaesthesia an individual’s sense of numbers or letters is associated with colours. Devin Terhune at the University of Oxford studied the brains of six people with this kind of synaesthesia using a non-invasive technique called transcranial magnetic stimulation. He found that neurons in the primary visual cortex were more active than expected. Suspecting that these hyperactive neurons played a role in synaesthesia, Terhune used transcranial direct current stimulation to damp down their activity. Surprisingly, this actually intensified the synaesthetic experience (Current Biology, DOI: 10.1016/j.cub.2011.10.032). Terhune thinks that makes sense if you think of the hyperactive neurons as noise that drowns out the synaesthetic experience. But the overexcited neurons may still be key to the development of synaesthesia in the first place. Since the condition SPIDER tartare would make a juicy feast for an army of ants, if only they could make it onto their webs. It seems some arachnids build anti- ant shields into their silken abodes. Mark Elgar at the University of Melbourne, Australia, and Daiqin Li at the National University of Singapore analysed the webs of 21 batik golden web spiders (Nephila antipodiana), which are found in south-east Asia and live alongside many ant species. They detected 2-pyrrolidinone on the silk. The chemical has been found on the webs of other spiders, but its function was unclear. Next, the team created three bridges each made of a single thread of N. antipodiana silk. Two were stripped of chemicals, while a third was left intact. Ants were lured across the bridges with a dead fly. En masse, they crossed the stripped silk, but not the natural thread (Proceedings of the Royal Society B: DOI: 10.1098/rspb.2011.2193). Pouring the chemical on a stripped thread deterred ants from following a trail of food back over it. “It either tastes or smells really awful to them,” says Elgar, who wonders if it could be used as an insecticide. Back off ants, my web stinks AMIR RIDHWAN tends to run in families, Terhune thinks that people with synaesthesia may be predisposed to hyperactive neurons from birth. As the brain develops through early childhood, the enhanced neural activity may cause connections to form between areas of the brain that are not normally paired. “Hyperactivity [of neurons] at an early developmental stage might contribute to atypical binding of neurons associated with graphemes and colour,” he says. Penicillin’s true identity revealed THE discovery of penicillin triggered the antibiotic revolution. But a forensic-style investigation of the lab in which Alexander Fleming discovered the fungus suggests it has been misidentified for 80 years. Daniel Henk and Matthew Fisher at Imperial College London looked at fungal samples still preserved in Fleming’s lab in London, and even swabbed his old notebook. They then compared them with samples from around the world. Fleming thought his bacteria- killing fungus was Penicillium chrysogenum, but genetic analysis of the samples showed that they comprised three previously unknown species as well as P. chrysogenum. The antibiotic fungus was one of the new species, and seems the most common of the four. “It’s likely among the most common multicellular organisms on the planet,” says Fisher (Molecular Ecology, DOI: 10.1111/j.1365-294x.2011.05244.x). The work could help others find new antibiotics. “When the US Department of Agriculture was looking for fungi with antimicrobial properties, it was sampling randomly,” says Henk. His analysis suggests that doing so will throw up Fleming’s species most of the time. In future it will be possible to use the DNA sequences to confirm that wild samples carry something truly new and worth investigating. DR JEREMY BURGESS/SCIENCE PHOTO LIBRARY IN BRIEF For new stories every day, visit newscientist.com/news
