Reprogrammed Bacterium Speaks New Language of Life 141
wabrandsma writes "New Scientist reports that 'A bacterium has had its genome recoded so that the standard language of life no longer applies. Instead, one of its words has been freed up to impart a different meaning, allowing the addition of genetic elements that don't exist in nature. ... The four letters of the genetic code are usually read by a cell's protein-production machinery, the ribosome, in sets of three letters called codons. Each codon "word" provides instructions about which amino acid to add next to a growing peptide chain. Although there are 64 ways of combining four letters, only 61 codons are used to encode the 20 amino acids found in nature. ... The three combinations left over, UAG, UAA and UGA, act like a full stop or period – telling the ribosome to terminate the process at that point. ... A team of synthetic biologists led by Farren Isaacs at Yale University have now fundamentally rewritten these rules (abstract). They took Escherichia coli cells and replaced all of their UAG stop codons with UAAs. They also deleted the instructions for making the release factor that usually binds to UAG, rendering UAG meaningless. Next they set about assigning UAG a new meaning, by designing molecules called tRNAs and accompanying enzymes that would attach an unnatural amino acid – fed to the cell – whenever they spotted this codon."
Re:4^4 (Score:5, Informative)
64 ways of combining four letters taken 3 at a time to form a codon.
Re:4^4 (Score:4, Informative)
Codons are sets of three letters. Every creature has its own unique codon table - every three letters (GATC) make up one codon, so there are 64 possibilities.
Almost. Every species has its own take on tRNA codong, but there is a lot of similarity up to the Kingdom level [wikipedia.org]
But the fun thing is that many codons actually code for the same amino acid, but take different times to complete the process. Either because some molecular rotation is taking place or just because it's a time delay to allow folding to complete elsewhere. Then sometimes the sequence is used in reverse order (creating a back-to-front version of whatever is made) and sometimes even the sequence of letters is read with an offset of one or two letters, so essentially one group of letters can code for six different chains of amino acids.
Uh, no...not molecular rotation or time delay....this is actually more of a planned overlap [wikipedia.org]. Pretty neat how nature planned this one. And as for mRNA being converted to a protein using tRNA (tranlation [mcgraw-hill.com]), it is strict one-way encoding (5' to 3' IIRC). dsDNA (but not ssDNA) (transscription [mcgraw-hill.com]) may be read in either direction, but mRNA not so (is is very much like ssDNA)
Re:labeling food food (Score:4, Informative)
Ok.
First of all: it's been debunked:
http://academicsreview.org/reviewed-content/genetic-roulette/section-1/1-2-gm-tomatoes-proven-safe/
1. No real differences were seen between groups of animals in the study. Contrary to Smith’s claims, expert pathologists stated that mild gastric erosions were seen at similar levels in both GM and non-GM fed rats (European Commission 2000, FDA 1994).
2. There is no evidence of animal deaths. The numbers and details given by Smith about rats fatalities appear to be factually incorrect, Smith may have confused the words necrosis and dead cells with animal deaths. Careful reading reveals that the regulatory record does not mention any animal deaths which surely would have been of concern had they occurred.*
Second of all: there's nothing about feeding pigs GM food in that paper.
Finally, the publisher of that article (Bentham Open) is on Beall's list of predatory publishers which charge authors to publish their papers without actually conducting any peer review to speak of. If you heard about the recent sting on predatory journals the other week*, the Open Neutraceutical Journal's sister publication, The Open Bioactive Compounds Journal, was quite willing to publish an utterly bogus cancer article, one constructed to be obviously fake to anyone with experience in the field.
With sections titles that say "GENETICALLYY MODIFIED ANIMALS AND HUMAN NUTRITION" I don't think they spend anything on copy editing either.
*Who's Afraid of Peer Review?
http://www.sciencemag.org/content/342/6154/60.full [sciencemag.org]