Synthetic biologists have discovered that six other molecules  can could store genetic information and pass it on. A host of alternative nucleic acids have been made in labs over the years, but no one has made them work like DNA. Until now, everyone thought we were limited to RNA and DNA. This is the first time artificial molecules have been made to pass genes on to their descendants. The finding is a proof of principle that life needn't be based on DNA and RNA.

The ability to copy information from one molecule to another is fundamental to all life. Organisms pass their genes to their descendants, often with small changes, and as a result life can evolve over the generations. Barring a few exceptions, all known organisms use DNA as the information carrier."This unique ability of DNA and RNA to encode information can be implemented in other backbones," says Philipp Holliger of the MRC Laboratory of Molecular Biology in Cambridge, UK.

Holliger's team focused on six XNAs (xeno-nucleic acids). DNA and RNA are made of a sugar, a phosphate and a base. The XNAs had different sugars, and in some of them the sugars are replaced with completely different molecules. Synthetic XNA, with its different sugar backbone to natural DNA, can mimic many of the properties of the real thing.

Holliger and his team engineered enzymes that helped the six types of XNA to assemble and replicate genetic messages. The enzymes transcribed DNA into the various XNAs, then back into new DNA strands — with 95% accuracy or more.

A major challenge for the team was to create enzymes that could copy a gene from a DNA molecule to an XNA molecule, and other enzymes that could copy it back into DNA. Once they had created these enzymes, they were able to store information in each of the XNAs, copy it to DNA, and copy it back into a new XNA. In effect, the first XNA passed its information on to the new one – albeit in a roundabout way. "The cycle we have is a bit like a retrovirus, which cycles between RNA and DNA," Holliger says. Because the XNAs can do this, they are capable of evolution.

Genetic transmission over successive DNA-to-XNA cycles allowed researchers to select for only those XNAs that attached to certain target proteins from a pool of random samples — a process akin to evolution over multiple generations.

“For the first time, this confirms that replication, heredity and evolution are possible in these alternative backbones,” says Holliger.."This is very interesting with respect to the origin of life," says Jack Szostak of Harvard University in Boston, Massachusetts. Many biologists suspect that the first life-forms used RNA, and DNA was adopted later. But we don't know why those two molecules were chosen: are they the best possible storage media, or were they simply the only things available?

Holliger suspects RNA was an opportunistic choice. "Clearly, there is no overwhelming functional imperative to use DNA and RNA," he says. Instead, life may have started with RNA simply because it was made in large quantities on the early Earth.

Most biologists think life on Earth began with RNA because it can both store information and catalyse useful reactions. In his latest experiment, Holliger has now shown that one of his XNA's – 1,5-anhydrohexitol nucleic acid, or HNA – can fold into a 3D shape and bind to specific target molecules. This is the first step in becoming an enzyme. The same thing had previously been done for threose nucleic acid (TNA).

This suggests XNAs might form the basis of life on other planets, where different environments led to different chemistry. "I would be surprised if we find truly extraterrestrial life that was based on DNA and RNA," Holliger says. "There might have been an XNA-world on a different planet."

Source

Nero, I think the reason for making these discoveries is to help stretch the minds and discover other forms and kinds of life. It is simple to say that life can exist any other way, but there would be doubts as too how different and the limits to any "infinite" possibilities. If you went up into the clouds and looked for "life," you could consider the clouds themselves life, or likewise the ocean, consider every bit of waste life. Not because you are an idiot, but because there is no defining property that claims "life." When you take samples from other ecosystems not like your own, you must start with what you know, or you will get nowhere; how do you know what other life looks like? If you don't know, how will you find it? They don't mean to simply say "Oh my, life can be different?" but "This is another way we can look at life." With that new idea, it becomes easier to locate where life can be. Obviously not all life is the same, and these scientists are usually very well aware of that.

Another point for your last sentence: It is not impossible for life to exist in these places, but highly unlikely. What creates the membrane in the first pieces of life is something fluid to mix it and create the "bubbles" with the pieces inside. Not necessarily water, but it works best, as other fluid chemicals are either too spaced or too reactive. Liquid hydrogen, for example, would prove disasterous to keep anything together; it would react with every part and rip it to shreds (as hydrogen, by itself, is an acid with attached hydrogen to everything, ripping other bonds -- the bonds in "genes" of any kind much be fairly loose to be able to create new codes, reproduce, create nRNA and rRNA, and able to open and close with polar molecules to create the proteins (or any other body-building materials), and if it is not reproduction would be difficult and structure building nearly impossible, as even the bodies would be ripped apart -- anything chemically heavy enough to "thrive" would either fall apart or be too reactive or not reactive enough to stay together -- this is a chemistry thing, not biological). It is possible for life to exist without light, of course, but there must be a source of energy, and without understanding what kinds of sources can be used without the organism being unable to thrive, there is no way to find it.

This article focused more on chemistry than biology -- this is because chemistry is a universal concept, unlike what people  feel about biology. Even "alien metals" can be produced in labs, as the process is predictable, but most of these fall apart or decay in seconds. Life that only lives for a few seconds or less, though possible (and proven), is difficult to define. In fact, these experiments were funded by people who agreed that not all life is the same; to say so would mean no funding. There was never a time when people though all life was the same. And, technically, the definition of life was never told in "carbon, H20, air, &c.," but rather, "it consumes energy, it reproduces, &c.," though I do agree that the definition of life is very vague and needs improving. According to it, a donkey is not alive if does not reproduce. But, anyway, this experiment was carried to help determine other ways life can exist. Anyone who thinks all life is the same is probably not very informed, and is not a scientist.


Thanks for the article, Owlscrying!