Saturday, June 7, 2014

Students Build the First Eukaryotic Chromosome from Scratch

The feat is a landmark achievement in synthetic biology






Credit: Science Source
In March undergraduate students in Johns Hopkins University's Build a Genome course announced they had made a yeast chromosome from scratch—and history, too. It is the first time anyone has synthesized the chromosome of a complex organism, a landmark achievement in the field of synthetic biology. It is also a triumph for the movement known as DIY biology.
The target was chromosome 3, which controls the yeast's sexual reproduction and has 316,617 base pairs of the DNA alphabet—A for adenine, G for guanine, C for cytosine and T for thymine. To synthesize it, the students took a shortcut: they built only the sections considered essential or nonrepetitive. The resulting chromosome had a more manageable 272,871 base pairs. And as reported in Science, the yeast with the new genes thrived just as well as regular yeast did in terms of size and growth.
“They are going strong,” says biologist Jef Boeke of New York University, who helped lead the research as part of the Synthetic Yeast 2.0 project—an effort to build a synthetic genome for yeast that would give scientists nearly complete control of it. Boeke and others plan to grow this batch for thousands of generations over the next several years to see how they evolve over time, which will give scientists a better understanding of fundamental biology, from the role of “junk DNA” to the absolute minimum of genetic code necessary for survival. “The questions are endless,” Boeke says.
The current work is just 3 percent of the way toward creating an entirely synthetic yeast genome (there are 16 chromosomes in total) and will take many more years to finish. If finished, synthetic yeast could be second on the list of organisms with genomes built from scratch—the J. Craig Venter Institute built a bacterium's genome in 2010.
It could also be a breakthrough in humanity's millennia-long cohabitation with Saccharomyces cerevisiae, which is responsible for bread and wine. Yeasts today churn out human proteins for medicines, biofuels and other specialty products. Being able to fine-tune the microscopic fungus's genetics could lead to better beer or sustainable chemicals, according to Boeke. And after yeast? “The fruit fly? The worm? We're not sure what is next.”

 

Students Build the First Eukaryotic Chromosome from Scratch

"Beast" Asteroid to Fly by Earth on Sunday

What might be the effects if a large asteroid collided with Earth?


The orbit of near-Earth asteroid 2014 HQ124, first discovered on April 23, 2014, is shown in this NASA graphic. The asteroid will fly by Earth Sunday, June 8, at a safe distance of three times the Earth-moon distance.NASA/JPL-Caltech
 

Humanity should be thankful "The Beast" doesn't have Earth in its crosshairs.


This Sunday (June 8), the near-Earth asteroid 2014 HQ124—which some observers have nicknamed "The Beast"—will give the planet a relatively close shave, coming within 777,000 miles (1.25 million kilometers) at its closest approach, or about 3.25 times the distance from Earth to the moon.
There is no chance of an impact on this pass, researchers stress. But at 1,100 feet (335 meters) wide, 2014 HQ124 could do some serious damage if it slammed into us. [
Potentially Dangerous Asteroids (Images)]
"This one would definitely be catastrophic if it hit the Earth," asteroid impact expert Mark Boslough, of Sandia National Laboratories in New Mexico, said during a June 5 webcast produced by the online
Slooh community observatory that previewed 2014 HQ124's upcoming flyby.
"If it hit a city, it would definitely wipe out an entire metropolitan area," Boslough added.
Asteroid 2014 HQ124 is currently traveling about 31,000 mph (50,000 km/h) relative to Earth, Boslough said. But if the asteroid were on a collision course, our planet's gravity would boost its speed up to about 40,000 mph (64,000 km/h) at the time of impact.
If 2014 HQ124 is one solid piece of rock—its composition isn't known for certain—the strike would unleash an explosion with a yield of about 2,000 megatons, Boslough added. For comparison, the atomic bomb the United States dropped on the Japanese city of Hiroshima during World War II packed about 15 kilotons. (One megaton is equivalent to 1,000 kilotons.)
"You'd end up with a crater about 3 miles across," Boslough added. "An event like that would break windows over 100 kilometers away."
Asteroid 2014 HQ124 was discovered on April 23, just six weeks ago—not nearly enough time to deflect the asteroid if it were on a collision course with Earth. But that doesn't mean the
asteroid would kill millions of people if it struck New York City or Tokyo.
"Once it's within radar distance, the precision is remarkably good on its position and speed," Boslough said. "So the folks at JPL [NASA's Jet Propulsion Laboratory] would be able to predict its impact point to within the nearest kilometer and its time to within the nearest second."
There would thus probably be plenty of time to organize an effective evacuation campaign if 2014 HQ124 were headed straight for us. But that isn't always always the case, as some (smaller) space rocks slam into the planet without ever being detected.

In February 2013, for example, a 65-foot-wide (20 m) asteroid detonated without warning in the sky above the Russian city of Chelyabinsk, shattering thousands of windows and
injuring more than 1,200 people. And there are many more objects out there like the Chelyabinsk asteroid—small space rocks cruising unnamed through the dark depths of space.
Scientists estimates that they've found about 95 percent of the potential "civilization-enders" out there—mountain-size asteroids at least 0.6 miles (1 km) across. But there are probably more than 1 million near-Earth asteroids at least 100 feet (30 m) wide, and less than 1 percent of them have been discovered.
Originally published on Space.com.

"Beast" Asteroid to Fly by Earth on Sunday

 
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