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William



    Posts: 3564
  • Darwins +92/-2

I was not aware of this. Mind giving me more info? Why would the same genes be expressed differently in species that, while different, share a common ancestor and DNA?

Moving a gene from a plant to an animal may just work - but more likely it will be similar to lifting the engine directly out of a VW beetle and trying to bolt it into a Trabant without modification. Some parts may look similar and even have the same function - but the 3D 'fit' is different and the controls are in the wrong places.

'Genes' are often not neat little discrete self-contained packages that can be cut and pasted from one genome to another.  They consist of areas that code for amino acids (building blocks of proteins) and areas involved in regulation.  These areas are sometimes not contiguous.  Some finished functional proteins are actually assemblies derived from several amino acid coding areas in different parts of the genome.  The DNA involved in regulation is sometimes vast - much of it was once termed "junk DNA" before we understood it better - and some of it depends on complex interactions with other proteins not coded for by the "genes" of interest.  All of it is diverging in different species and has evolved in the context of other molecules within that same species - it's a 3D molecular environment optimised to work with itself. 

The genetic code is said to be "universal" but there are indeed a few tiny differences e.g. [UGA] is normally a 'stop' codon, but in the mitochondria of Drosophila it's the code for tryptophan.  Also, there is substantial degeneracy in the universal code. There are 64 codons, 61 of them code for only 20 amino acids  (the other three are stop codes). With all this 'slack' in the coding system, different species have evolved codon usage biases - for which they are now optimised - so they may not code efficiently if moved into the 3D cell apparatus of another species.

One way to overcome some of this complexity would be to study the plant protein of interest and how it gets assembled or folds into the right shape to function properly, then try to reverse engineer that into synthetic DNA and splice it into a well known regulation mechanism such as the machinery of a virus that splices itself into the human genome.  The risks are fairly obvious :police: 

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