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Crime-scene DNA extracted from single hair
lance-modis/terra/nasa
IN BRIEF Single hair reveals crime-scene DNA
Acidifying ocean added to the hurricane’s long rap sheet AS IF tropical storms didn’t get enough of a bad press, it now seems they can ramp up ocean acidification, putting the world’s coral reefs under even greater pressure. Seawater is becoming less alkaline as it absorbs ever more atmospheric carbon dioxide, levels of which are rising owing to fossil fuel use. As a result, seawater holds less calcium carbonate, so corals, molluscs and other creatures that use it to make their shells will struggle. Corals were thought less at risk because they live in tropical seas rich in calcium carbonate, says Derek Manzello of the Atlantic Oceanographic and
Meteorological Laboratories in Miami, Florida. But hurricanes could render them vulnerable. Manzello and colleagues were monitoring two reefs off Florida when tropical storm Isaac swept through in August last year. The team found that the seawater’s pH fell from 8.0 to around 7.8 as the storm moved through, and stayed at that level for a week afterwards. As a result, the water was significantly less rich in calcium carbonate over the same period. The main cause seems to have been rainfall and water runoff from the land. With climate models predicting increased ocean acidification, Manzello calculates that by 2100, every hurricane will briefly push calcium carbonate levels so low that coral skeletons will begin dissolving (Journal of Geophysical Research: Oceans, doi.org/npg).
Better dads have smaller testicles MEN with smaller testicles tend to be more involved as fathers, a new study suggests. James Rilling’s team at Emory University in Atlanta, Georgia, used MRI scans to measure the testicle volume of 55 fathers. The researchers asked the men – and the mothers of their children – a series of questions to determine how involved they are as fathers. They also used fMRI to look at the 16 | NewScientist | 14 September 2013
brain activity of the men as they viewed photos of their kids. Men with smaller testicles got the best parenting scores in the questionnaires. When looking at pictures of their children, these men also showed more activity in regions of the brain associated with empathy and motivation to care for offspring than men with bigger testes, which suggests they are more caring (PNAS, DOI:
10.1073/pnas.1305579110). Rilling does not know how smaller testicles might make men better fathers. The relationship could work the other way: “It could be that when men become more involved as caregivers, their testes shrink,” he says. Bigger testicles tend to produce more and higher-quality sperm. There may be a trade-off between the amount of energy a man invests in reproduction and parenting, the team says.
YOU wouldn’t expect forensic teams to waste valuable evidence. But it happens all the time, though perhaps not for much longer. Standard DNA profiling grabs DNA from inside cells, copies it many times, and then looks for unique sequences to compare with those of a suspect. But much DNA is lost in the extraction, so tiny samples are often unusable. Now, Adrian Linacre of Flinders University in Adelaide, Australia, and his colleagues have targeted “free” DNA – the stuff floating loose in material such as sweat and hair – in trace samples, copying it directly using a standard lab kit, bypassing the extraction step altogether. The team is the first to reliably get full profiles from single hairs (Forensic Science, Medicine, and Pathology, doi.org/nq2). They also got a profile from sweat left after touching fabric for just 15 seconds.
Impregnate me, and make it quick FOR humans sex can be just for fun. For the male Bahamas mosquitofish it is a matter of survival. It seems that these tiny fish have evolved genitalia that are adapted for the quickie. Justa Heinen-Kay at North Carolina State University and her team caught fish from atolls in the Bahamas. Roughly half came from a group that is prey to larger fish; the rest had few predators. Males with many predators had significantly smaller gonopodia – the modified fins used for copulation – with longer, bonier tips (Journal of Evolutionary Biology, doi.org/nqg). The small size lets them swim away faster, whereas the rigid tip boosts their accuracy. All in all, it makes for a faster, more productive session.
IN BRIEF Single hair reveals crime-scene DNA
Acidifying ocean added to the hurricane’s long rap sheet AS IF tropical storms didn’t get enough of a bad press, it now seems they can ramp up ocean acidification, putting the world’s coral reefs under even greater pressure. Seawater is becoming less alkaline as it absorbs ever more atmospheric carbon dioxide, levels of which are rising owing to fossil fuel use. As a result, seawater holds less calcium carbonate, so corals, molluscs and other creatures that use it to make their shells will struggle. Corals were thought less at risk because they live in tropical seas rich in calcium carbonate, says Derek Manzello of the Atlantic Oceanographic and
Meteorological Laboratories in Miami, Florida. But hurricanes could render them vulnerable. Manzello and colleagues were monitoring two reefs off Florida when tropical storm Isaac swept through in August last year. The team found that the seawater’s pH fell from 8.0 to around 7.8 as the storm moved through, and stayed at that level for a week afterwards. As a result, the water was significantly less rich in calcium carbonate over the same period. The main cause seems to have been rainfall and water runoff from the land. With climate models predicting increased ocean acidification, Manzello calculates that by 2100, every hurricane will briefly push calcium carbonate levels so low that coral skeletons will begin dissolving (Journal of Geophysical Research: Oceans, doi.org/npg).
Better dads have smaller testicles MEN with smaller testicles tend to be more involved as fathers, a new study suggests. James Rilling’s team at Emory University in Atlanta, Georgia, used MRI scans to measure the testicle volume of 55 fathers. The researchers asked the men – and the mothers of their children – a series of questions to determine how involved they are as fathers. They also used fMRI to look at the 16 | NewScientist | 14 September 2013
brain activity of the men as they viewed photos of their kids. Men with smaller testicles got the best parenting scores in the questionnaires. When looking at pictures of their children, these men also showed more activity in regions of the brain associated with empathy and motivation to care for offspring than men with bigger testes, which suggests they are more caring (PNAS, DOI:
10.1073/pnas.1305579110). Rilling does not know how smaller testicles might make men better fathers. The relationship could work the other way: “It could be that when men become more involved as caregivers, their testes shrink,” he says. Bigger testicles tend to produce more and higher-quality sperm. There may be a trade-off between the amount of energy a man invests in reproduction and parenting, the team says.
YOU wouldn’t expect forensic teams to waste valuable evidence. But it happens all the time, though perhaps not for much longer. Standard DNA profiling grabs DNA from inside cells, copies it many times, and then looks for unique sequences to compare with those of a suspect. But much DNA is lost in the extraction, so tiny samples are often unusable. Now, Adrian Linacre of Flinders University in Adelaide, Australia, and his colleagues have targeted “free” DNA – the stuff floating loose in material such as sweat and hair – in trace samples, copying it directly using a standard lab kit, bypassing the extraction step altogether. The team is the first to reliably get full profiles from single hairs (Forensic Science, Medicine, and Pathology, doi.org/nq2). They also got a profile from sweat left after touching fabric for just 15 seconds.
Impregnate me, and make it quick FOR humans sex can be just for fun. For the male Bahamas mosquitofish it is a matter of survival. It seems that these tiny fish have evolved genitalia that are adapted for the quickie. Justa Heinen-Kay at North Carolina State University and her team caught fish from atolls in the Bahamas. Roughly half came from a group that is prey to larger fish; the rest had few predators. Males with many predators had significantly smaller gonopodia – the modified fins used for copulation – with longer, bonier tips (Journal of Evolutionary Biology, doi.org/nqg). The small size lets them swim away faster, whereas the rigid tip boosts their accuracy. All in all, it makes for a faster, more productive session.