First lifeforms to pass on artificial DNA engineered by US scientists

[HuckleB]

Organisms carrying beefed-up DNA code could be designed to churn out new forms of drugs that could otherwise not be made
http://www.theguardian.com/world/2014/may/07/living-organism-pass-down-artificial-dna-us-scientists

"The first living organism to carry and pass down to future generations an expanded genetic code has been created by American scientists, paving the way for a host of new life forms whose cells carry synthetic DNA that looks nothing like the normal genetic code of natural organisms.

Researchers say the work challenges the dogma that the molecules of life making up DNA are "special". Organisms that carry the beefed-up DNA code could be designed to churn out new forms of drugs that otherwise could not be made, they have claimed.

"This has very important implications for our understanding of life," said Floyd Romesberg, whose team created the organism at the Scripps Research Institute in La Jolla, California. "For so long people have thought that DNA was the way it was because it had to be, that it was somehow the perfect molecule."

...

Romesberg said that organisms carrying his "unnatural" DNA code had a built-in safety mechanism. The modified bugs could only survive if they were fed the chemicals they needed to replicate the synthetic DNA. Experiments in the lab showed that without these chemicals, the bugs steadily lost the synthetic DNA as they could no longer make it.

..."


FYI. Of interest.

[Warren DeMontague]

1. Cue entirely predictable freakout in 5....4....3...

[nadinbrzezinski]

2. Hmm. Just hope

They don't escape to the wild otherwise fascinating

[Erich Bloodaxe BSN]

3. The built-in safety mechanism

actually reminds me a lot of the 'built in safety mechanism' from the movie Jurassic Park. Makes you wonder who will be the Jeff Goldblum character to say 'Life finds a way'.

[Warpy]

4. They've used E. coli to make human insulin for years.

At first they only gave it to patients who were resistant or allergic to pork or who refused pork products on religious grounds. Now production is adequate to give most domestic diabetics human insulin.

E. coli is the favorite bug to modify because it dies when exposed to UV light. Sunlight will do the job.

This study shows that true FrankenBugs with huge artificial genomes aren't particularly likely to become much of a threat.

[BainsBane]

5. Wrong. The first synthetic life form was created 67 yrs ago.

[HuckleB]

9. +1

[PADemD]

12. Duzy!

[Prophet 451]

6. Why do I get the feeling...

...that we just came a step closer to a zombie apocalypse?

[arcane1]

7. A third base pair... that's pretty damned fascinating.

It will be interesting to see what, if anything, comes of it. But wow!! Too cool!!

Thanks for posting!

[HuckleB]

10. It is definitely that!

Fascinating, I mean.

[mindwalker_i]

11. I'd like to see whether the extra DNA "letters"

allow evolution to do anything that isn't hasn't been able to do with the standard four. So instead of specifying "strings" in four characters, they can be expressed in five, which means fewer characters would be required to hold the same amount of information. Could shorter strands of DNA then be able to specify the same genetic diversity as a regular, longer genome?

[DetlefK]

13. The genetic alphabet has 4 letters, but a genetic word has 3 letters.

First, a DNA-sequence for a protein gets copied. The copy is m-RNA (messenger). The cell-plasma contains pieces of t-RNA (transfer) bonded to a particular kind of amino-acid. A t-RNA is shaped like a drop: 3 bases protruding from its loop and the amino-acid hanging on the pointy end.

The m-RNA gets clamped into a ribosome and then the sequence is processed. One after one, a matching t-RNA finds its place on the m-RNA, and the sequence of t-RNAs turns into a sequence of amino-acids, a protein.


With only four letters, 4^3 = 64 combinations are possible. (Already abundant: The human organism needs only about 20 different kinds of amino-acids.)
With six letters, 6^3 = 216 combinations are possible, effectively tripling the variety of possible amino-acids the cell can handle.

[Thor_MN]

15. It's been a long time since biology class but IIRC, only 40 unique codons for normal DNA.

ex. AAC would be the same as CAA. 16 palindromes, 24 pairs of reversible sequences. Probably why nature only uses 20, some of the reversible codons might present the amino acid in a less than useful orientation.

However, tripling is true, 126 unique codons for enhanced DNA.

[Thor_MN]

14. "So instead of specifying "strings" in four characters, they can be expressed in five,"

Not sure what you mean by that... With the addition of an artificial base pair, there would be 6 characters.

The short answer to your question is No, due to the way that three nucleotide base codons pull together amino acids to form a protein.

In creating proteins, sequences of three bases (codons) code each amino acid that, strung together, make a protein. So with four bases, there are 64 possible codon sequences. Of those, there are 16 that are palindromes (same forward as back) and 24 that have a backwards "twin", leaving 40 unique codons.

There are only 20 amino acids used in making proteins, although many more amino acids naturally exist. If you consider amino acids to be the letters of protein words, nature only uses/needs about a half of the potential alphabet. Stated another way, normal DNA can code lots of proteins that have no use.

With 6 bases, there are 216 codons sequences, 36 palindromes, 90 pairs of reversible sequences, leaving 126 unique codons. This opens the door to creating enormous numbers of proteins.

The trick is in finding a string of amino acids that has a purpose. One could create any random string of amino acids that one wishes, but unless it has a use, it's just a very expensive(high initial cost), largish compound molecule.



.

[GeorgeGist]

8. Evolution will prove Romesberg wrong.