A big step towards an artificial yeast genome

BIOLOGY’S biggest division is not between plants and animals, nor even between multicellular and single-celled creatures. It is between prokaryotes and eukaryotes. Prokaryotes—bacteria are the most familiar sort—are simple. Their DNA is an unadorned circular molecule between 500,000 and 10m genetic “letters” long. As such, it is fairly easy to replicate from off-the-shelf chemicals.

The DNA of eukaryotes—animals, plants, fungi and so on—is both more abundant and more complex than that. It may have hundreds of millions, even billions, of letters and it is organised into several elongated chromosomes inside a cell’s nucleus. Synthesising a eukaryote’s genome is thus a far harder task than creating its prokaryote equivalent. But if biology is ever to be brought within the realm of technology in the ways that physics and chemistry have been, it is an essential task.

This week has seen a big step towards that achievement, with the publication in Science of recipes for five artificial chromosomes for yeast cells. Yeast, a fungus, is one of the workhorses of eukaryotic genetics. The chefs who have devised…Continue reading
Source: Economist

Building from the atom up

A second quantum revolution is happening at the atomic level. What will it mean for the future of computers? Also: a new battery based on aluminium provides up to ten times the power. And why yellow taxis are much less likely to get into accidents. Kenn Cukier hosts.<param name="playerID"…Continue reading
Source: Economist

Two putative human sex pheromones turn out not to be

FOR several decades biologists have pondered the question of whether men and women produce pheromones. A pheromone is a chemical signal from one animal to another. Often, though not always, such chemicals indicate sexual availability—and when it comes to human mating signals in particular, those looking into the matter have a couple of specific molecules in mind.

Androstadienone (AND) and estratetraenol (EST) are derived, respectively, from male and female hormones and are exuded in sweat. The idea that they are pheromonal is thus worth investigating. The results of such investigations as have been made so far, though, are contradictory. Some experiments have found that these molecules make opposite-sex faces, or photographs thereof, appear more attractive to heterosexual volunteers. Others discern no such effect.

Unfortunately, most of these studies were done with groups of volunteers too small for clear conclusions to be drawn, or using less-than-rigorous experimental methods. (That has not stopped businesses taking up the idea: several brands of “pheromone perfume” based on EST and, especially, AND are available for hopeful…Continue reading
Source: Economist

Yellow cabs are less likely to crash than blue ones

IN 1907 John D. Hertz, the owner of a taxi firm in Chicago, asked some academics at the University of Chicago to do a piece of research for him. He wanted to know what colour he should paint his cabs in order to make them stand out among the sea of black vehicles that then inhabited American city streets. The researchers’ conclusion was: yellow. Now, more than a century later, a group of researchers at a different university have concluded that yellow was a wise choice for other reasons, too. In a study just published in the Proceedings of the National Academy of Sciences, Ho Teck Hua of the National University of Singapore and his colleagues show that yellow taxis are less likely to be involved in accidents.

Dr Ho’s research made use of a merger that took place, in 2002, between two Singaporean taxi companies. One of the precursor firms had a yellow fleet. The other’s was blue. The merged concern has continued that bichromatic tradition to this day. At the moment it owns 4,175 yellow taxis and 12,525 blue ones. All are the same model (a Hyundai Sonata) and all undergo the same maintenance schedules. Any differences in safety between…Continue reading
Source: Economist

A machine-learning census of America’s cities

“WOULD it not be of great satisfaction to the king to know, at a designated moment every year, the number of his subjects?” A military engineer by the name of Sébastien le Prestre de Vauban posed this question to Louis XIV in 1686, pitching him the idea of a census. All France’s resources, the wealth and poverty of its towns and the disposition of its nobles would be counted, so that the king could control them better.

These days, such surveys are common. But they involve a lot of shoe-leather, and that makes them expensive. America, for instance, spends hundreds of millions of dollars every year on a socioeconomic investigation called the American Community Survey; the results can take half a decade to become available. Now, though, a team of researchers, led by Timnit Gebru of Stanford University in California, have come up with a cheaper, quicker method. Using powerful computers, machine-learning algorithms and mountains of data collected by Google, the team carried out a crude, probabilistic census of America’s cities in just two weeks.

First, the researchers trained their machine-learning model to recognise the make, model…Continue reading
Source: Economist

A memory chip that can compute

Resistance for change

ELECTRONICS has long relied on a division of labour. At the heart of myriad devices, from computers and smartphones to drones and dishwashers, a microprocessor can be found busily crunching data. Switch the power off, though, and this chip will forget everything. Devices therefore contain other, different sorts of chips that work as a memory. That is inefficient, because shuffling data between the two types of chip costs time and energy. Now, though, a group of researchers working in Singapore and Germany think they have found a way to make a single chip work as both a processor and a memory.

Both sorts of existing chip rely on transistors. These are tiny electronic switches, the ons and offs of which represent the ones and zeroes of the digital age. In the quest for speed, a processor’s transistors need to be able to flip rapidly between those two states. This speed is bought, however, at the cost of the forgetfulness that makes a separate memory essential. Meanwhile, the non-forgetful transistors used in a computer’s permanent form of memory are too slow to make useful processors. To make a chip which…Continue reading
Source: Economist

The 48 uses of dragon’s blood

MYTHOLOGY is rich with tales of dragons and the magical properties their innards possess. One of the most valuable bits was their blood. Supposedly capable of curing respiratory and digestive disorders, it was widely sought. A new study has provided a factual twist on these fictional medicines. Barney Bishop and Monique van Hoek, at George Mason University in Virginia, report in The Journal of Proteome Research that the blood of the Komodo dragon, the largest living lizard on the planet, is loaded with compounds that could be used as antibiotics.

Komodo dragons, which are native to parts of Indonesia, ambush large animals like water buffalo and deer with a bite to the throat. If their prey does not fall immediately, the dragons rarely continue the fight. Instead, they back away and let the mix of mild venom and dozens of pathogenic bacteria found in their saliva finish the job. They track their prey until it succumbs, whereupon they can feast without a struggle. Intriguingly, though, Komodo dragons appear to be resistant to bites inflicted by other dragons.

Most animals—not just Komodo dragons—carry simple proteins…Continue reading
Source: Economist

A new fossil could push back the start of life on Earth

SCIENTISTS have a pretty good idea of how the Earth formed: it condensed, around 4.6 billion years ago, from the same cloud of dust and interstellar gas that gave birth to the sun and the rest of the solar system. They are less sure how and when life got going. Last year a group of researchers found evidence for stromatolites—small, layered mounds produced by photosynthesising bacteria—in rocks from Greenland that are 3.7 billion years old.

Now, though, the date of life’s debut may be pushed back even further. As they report in Nature, a group of researchers led by Dominic Papineau from University College London have found what they think is the signature of living organisms in rocks from Quebec that date back to between 3.8 and 4.3 billion years ago. Intriguingly, the sort of life that Dr Papineau and his colleagues think they have found is very different from the sort that built the stromatolites. This suggests that even very early in its existence, Earth was hosting several different kinds of living organism.

The rock in question is a 3-kilometre-long swathe on the eastern shores of the Hudson Bay…Continue reading
Source: Economist

A new fossil suggests life got started quickly on ancient Earth

SCIENTISTS have a pretty good idea of how the Earth formed: it condensed, around 4.6bn years ago, from the same cloud of dust and interstellar gas that gave birth to the sun and the rest of the solar system. They are less sure how and when life got going. Last year a group of researchers found evidence for stromatolites—small, layered mounds produced by photosynthesising bacteria—in rocks from Greenland that are 3.7bn years old.

Now, though, the date of life’s debut may be pushed back even further. As they report in Nature, a group of researchers led by Dominic Papineau from University College London have found what they think is the signature of living organisms in rocks from Quebec that date back to between 3.8bn and 4.3bn years ago. Intriguingly, the sort of life that Dr Papineau and his colleagues think they have found is very different from the sort that built the stromatolites. This suggests that even very early in its existence, Earth was hosting several different kinds of living organism.

The rock in question is a 3-kilometre-long swathe on the eastern shores of the Hudson Bay called the Nuvvuagittuq Greenstone…Continue reading
Source: Economist

Two races to the moon are hotting up

THE $30m Google Lunar XPRIZE has had a slow time of it. Set up in 2007, it originally required competitors to land robots on the moon by 2012. But the interest in returning to the moon that the prize sought to catalyse did not quickly materialise; faced with a dearth of likely winners, the XPRIZE Foundation was forced to push back its deadline again and again. Now, though, five competing teams have launch contracts to get their little marvels to the moon by the end of this year. And as those robotic explorers head into the final straight, a new contest is opening up.

On February 27th Elon Musk said that SpaceX, his aerospace company, had agreed to send two paying customers around the moon some time in 2018, using a new (and as yet untried) version of its Falcon rocket, the Falcon Heavy. They would be the first people to travel beyond low-Earth orbit since 1972. Two weeks before Mr Musk’s announcement, NASA said it was considering using the first flight of its new rocket, the Space Launch System (SLS), to do something similar, though with astronauts, not paying tourists. The race, it seems, is on.

This is not, though, a simple story of…Continue reading
Source: Economist