FOOD
Bugs: They’re what’s for dinner Edible insects could supply as much dietary iron as meat Move over, meat. Beetle larvae consumed as food in some parts of the world deliver as much iron to cells, gram per gram, as beef (J. Ag. Food Chem. 2016, DOI: 10.1021/acs. jafc.6b03286). Gladys O. Latunde-Dada of King’s College London wanted to study the nutrient content of invertebrates because insect farming releases less greenhouse gas than does livestock farming. “If we are going to eat insects, we’ll need to see if they have enough iron,” she says. Widespread iron deficiency exists among populations that eat little or no meat. That’s because humans absorb much less iron from plant-based foods than from meat, Latunde-Dada says. Meat-based iron is easy to absorb because it’s in the form of heme, an iron-carrying cofactor found in blood. Insects don’t have heme, but are part of diets in many parts of the world. Latunde-Dada’s team 0 studied four common food insects—grasshoppers (Sphenarium
purpurascens), crickets (Gryllus bimaculatus), mealworms (Tenebrio molitor), and buffalo worms (Alphitobius diaperinus)—and compared their total iron content to sirloin
beef. Crickets had the most—12.91 mg/100 g, just shy of beef’s 15.47 mg/100 g. To test how much iron from insects humans can actually absorb, the researchers first mixed ground insect powder with digestive enzymes at low pH to imitate condiThe buffalo worm, a type of beetle tions in the stomach, then added bile-panlarva, has more bioavailable iron than creatic extract at neutral pH to mimic the sirloin steak. small intestine. They then incubated the digested samples with human epithelial cell cultures and measured how much ferritin—a protein that stores iron—the cells Grasshopper contained. In this test, iron uptake from buffalo worms, a type Cricket of beetle larvae, was the clear winner, besting sirloin beef. “I was a bit surprised at how Mealworm well some of the insects did in comparison to the sirloin,” says Buffalo worm Darja Dobermann, a graduate researcher at the University of Beef sirloin Nottingham who is studying how insects can combat malnu20 40 60 80 100 trition.—ERIKA GEBEL BERG,
Bugs, not beef
Iron uptake, ng ferritin/mg protein
special to C&EN
NEUROSCIENCE
How our brains repurposed a bone gene
CREDIT: J . AG . FO O D C H E M . /C&EN (CHART); NAT URE (NEURONS)
Gene expressed in muscle and bone in mice could regulate neuronal connections in primate brains Millions of years of evolution separate us and primates more generally, evolve our from our last common ancestor with mice. cognitive abilities,” says Justine Kupferman In that time, our brains, and those of other of Columbia University, who, along with primates, have picked up some impressive Franck Polleux, wrote a perspective accomcognitive abilities. panying the new report. A team of neurobiologists now report an example of genetic tinkering that helped this Cultured human neurons (left) show happen. They found that a handful of DNA increased dendrite growth (right) when base pair changes allowed a gene normally OSTN expression is decreased. expressed in the muscle and bone of mice to turn on in primate brains when neurons fire (Nature 2016, DOI: 10.1038/nature20111). Because this gene gets expressed in response to brain activity, the researchers think that it plays a role in how our brains develop during childhood as we process inputs from the world around us. 30 µm The work “gets at this underlying question of how did we as a species,
The research team, including Bulent Ataman, Gabriella L. Boulting, and Michael E. Greenberg of Harvard Medical School, pinpointed this gene by subjecting cultured human neurons to conditions that mimic what happens when neurons receive input from other cells in the brain. One gene active in human cells but not in mouse cells, OSTN, codes for the protein osteocrin. Further experiments showed that, when turned on in neurons, OSTN helps regulate the growth and shape of dendrites, the spiny structures the cells use to connect with their neighbors during development, learning, and memory. Besides beginning to show how primate brains developed such complexity, Boulting says the findings point to profound differences in how human and mouse neurons behave, suggesting researchers should think past mouse models of what happens in our brains.—MICHAEL TORRICE NOVEMBER 14, 2016 | CEN.ACS.ORG | C&EN
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