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Life Swap: Switching genomes converts bacteria
In a step toward creating artificial microbes, scientists have managed to replace the entire genome of one kind of bacterium with the DNA of a related species. After the transplant, the recipient took on all the traits of the donor, effectively transforming into the donor's species.
The researchers say they hope to use this new technique to swap a bacterium's DNA for an artificial genome that they will assemble from scratch, thus creating the first synthetic life form. As well as helping scientists explore fundamental cell biology, such custom-made microbes could eventually be designed to produce biofuels and medicines efficiently, says study coauthor John I. Glass of the J. Craig Venter Institute in Rockville, Md.
"As you understand better how a cell works, it makes it possible to rationally design more-complicated [synthetic] organisms that meet some of the needs of humanity," Glass says.
Implanting an artificial genome into a cell would be tricky, however, because DNA molecules longer than about 50,000 genetic units are prone to breaking. In the recent study, the ring-shaped DNA molecules from the donor bacteria were more than a million genetic units long. "You have to be very gentle," Glass says. "Humpty Dumpty can't be put back together again."
Ape Aid: Chimps share altruistic capacity with people
Many researchers have asserted that only people will assist strangers without receiving anything in return, sometimes at great personal cost. However, a new study suggests that chimpanzees also belong to the Good Samaritan club, as do children as young as 18 months of age.
Without any prospect of immediate benefit, chimps helped both people and other chimps that they didn't know, and the 18-month-olds spontaneously assisted adults they'd never seen before, say psychologist Felix Warneken of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues.
The roots of human altruism reach back roughly 6 million years to a common ancestor of people and chimps, the researchers propose in the July PLoS Biology.
"Learning and experience are involved in altruistic helping, but our claim is that there is a predisposition [in chimps and people] to develop such behavior without explicit training," Warneken says.
His team conducted three experiments with adult chimps living on an island sanctuary in Uganda and two experiments with 18-month-old German children. In the chimp version of the first experiment, 36 animals watched one at a time from a barred enclosure as an experimenter in an adjacent room-who had had virtually no prior contacts with the animals-reached through the bars for a stick on the other side. The stick was within reach of only the observing chimp.
Most chimps snatched the stick and gave it to the experimenter, whether or not the experimenter offered a piece of banana as a reward. No assistance came if the experimenter didn't first reach in vain for the stick.
A similar trial with 36 youngsters yielded comparable altruistic behavior, regardless of whether the experimenter offered toys as a reward.
The second round of experiments included 18 chimps and 22 infants who had helped at least once in the first experiment.
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A Gemstone's Wild Ride
Thanks to their hardness, durability, and rarity, diamonds are symbols of eternal love and wealth. A new analysis of how these gems emerge from the depths where they were forged billions of years ago suggests that they should also evoke images of diamond-studded fountains of gas and rock.
Almost all diamonds come from volcanic deposits called kimberlites. Tens of thousands of such deposits, some more than a kilometer across, have been found protruding through Earth's surface. However, only one in every 200 of them contains gem-quality diamonds. Increasingly, scientists are looking at kimberlites' odd mix of geological characteristics to discern how diamond deposits get there in the first place.
With or without diamonds, kimberlites are enigmatic, says James W. Head III, a planetary geologist at Brown University in Providence, R.I. The carrot-shaped deposits, which can extend to depths of 2.5 kilometers, are clearly volcanic in origin, but areas around them aren't marked by large amounts of lava. Furthermore, kimberlites contain large numbers of glass spherules that typically form from airborne droplets of molten rock. Locked within kimberlites, however, the spherules apparently never make it above ground. Finally, as much as half the jumbled rocks in kimberlite deposits comes from Earth's mantle, the hot, viscous material that lies below depths of 35 km.