Life created in the Lab

If figuring out how to quickly sequence genomes was but the first small step for genetics, Craig Venter has gone ahead and made a giant leap for the discipline. The J. Craig Venter Institute announced today that it has created the world’s first synthetic cell, boasting a completely synthetic chromosome produced by a machine.
"This is the first self-replicating species we’ve had on the planet whose parent is a computer," Venter said in a press conference.
The biological breakthrough could have myriad applications, as it essentially opens the door to engineered biology that is completely manipulated by laboratory scientists. The researchers are already planning to create a specially engineered algae designed to trap carbon dioxide and convert it to biofuel. Other applications could include medicine, environmental cleanup, and energy production.
Though a bacteria cell was the final product in this particular experiment, eukaryotic yeast was a critical player in the process. Venter and company synthesized the genome of the bacterium M. mycoides by taking short strains of DNA (contemporary machines can only assemble short sequences at a time) and inserting them into yeast, whose enzymes have a keen ability to repair DNA and combine the short strains together.
The yeast first linked the shorter snippets (just over 1,000 base pairs each) together into longer 10,000 base pair strands. The longer strands were removed, further combined in groups of ten and put back into yeast to connect 100,000 base pair strands. After three rounds of this, the team had produced the full genome, stretching more than a million base pairs. To distinguish their synthetic genome from those found in nature, special "watermark" sequences were added to the DNA so that it won’t be mistaken for a natural species.
The synthetic genome was then transplanted into another type of bacteria, Mycoplasma capricolum, where the synthetic genome started producing new proteins. The capricolum’s original genome was either destroyed by M. mycoides' enzymes or lost during cell replication. Either way, as the cells multiplied, cells were produced borne solely of the synthesized genome and there it was in the petri dish: the world’s first synthetic cells built from wholly synthesized DNA.
"Every component in the cell comes from the synthetic genome," Venter said. "This cell, its lineage is a computer. But this cell is simply a proof of concept to get to the minimal understanding of the synthetic genome."
Not everyone is thrilled with the achievement, however. Upon the announcement, some researchers questioned the validity of the term "synthetic cell" because though the genome was fabricated by computer, the process merely modified existing life rather than created it from scratch. There are also plenty ethical – and legal – ramifications to such a technological advance that will no doubt be argued in coming months.
What is not up for dispute is that Venter and company have carried out a serious technological feat in stringing together a million nucleotide base pairs to create a complete genome in the lab. Not only that, but they did it accurately enough that the cell accepted the DNA.
"Probably 99% of our experiments have failed," Venter said of the decades-long journey to this point. "This was a debugging, problem solving process from the beginning, because there was no recipe."
Now that there's a recipe, Venter and company want to get cooking. Having strung 1 million base pairs into a coherent genome, Venter said the next step is algae, as algal genomes generally contain just under 2 million base pairs. By comparison, the human genome contains more than 3 billion pairs, so don't look for synthetic mammals any time soon.

Comets and the Origin of Life

STEP by step, the case for an extraterrestrial origin of life has got stronger. But though the case for planetary panspermia - the idea that micro-organisms transfer between planets - is now widely accepted, interstellar panspermia remains controversial.
A key element in the scheme, promoted by Chandra Wickramasinghe and the late Fred Hoyle, are comets, the bodies in which the desiccated bacteria of interstellar space are claimed to come to life before being ferried to planetary surfaces। The recent discovery of amino acids and clays in comets, which could have formed only if comets once had liquid-water interiors, bolsters the case for interstellar panspermia. Yet most scientists require more evidence. Here, the fascinating case that we are all ETs is spelled out in semi-technical rather than popular form.

Amino Acid Found in Stardust Comet Sample

NASA scientists studying the comet samples returned by the Stardust spacecraft have discovered glycine, a fundamental building block of life. Stardust captured the samples from comet Wild 2 in 2004 and returned them to Earth in 2006. "Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet," said Dr. Jamie Elsila of NASA's Goddard Space Flight Center. "Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."Proteins are a major component of all living cells, and amino acids are the building blocks of protein. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins.As Stardust passed through dense gas and dust surrounding the icy nucleus of Wild 2 (pronounced "Vilt-2"), special collection grids filled with aerogel – a novel sponge-like material that's more than 99 percent empty space – gently captured samples of the comet's gas and dust. The grid was stowed in a capsule which detached from the spacecraft and parachuted to Earth on January 15, 2006. Since then, scientists around the world have been busy analyzing the samples to learn the secrets of comet formation and our solar system's history.