What are the limits of genetic engineering

[Lucanus cervus]

I've been wondering for quite some time now, how broad is the phylogenetic range to which genes can be transferred among organisms (by natural occurring horizontal gene transfer or by means of genetic engineering)

For example, recently I read a paper about some entomopathogenic nematodes that were used to try to control some foliage feeding pests (The goal was that the nematodes would kill the invertebrates that were eating the crops). But the experiment failed because the nematodes were unable to cope with dessication stress.

So I immediately wondered whether it would be possible to insert a gene that protects against dessication stress, and would it for example be possible to use a gene found in Antarctic cyanobacteria (which are able to cope with dessication), or will the gene not be compatible?

I can imagine a gene that protects against dessication in micro-organisms, does not necessarily protects against dessication in multicellular organisms because its protein's function is not relevant to a multicellular organism

[Cat]

Usually, pathways are involved. That means transferring not 1 but a host of genes because unrelated organisms are unlikely to have any of them.

Take a look at this pathway:

http://potatometabolicpathways.webs.com ... ponses.pdf

[Lucanus cervus]

Ok thank you for your answer!

So I guess the more distantly related the organisms are, the harder it becomes to transfer a certain property?

[Cat]

Yes. It's like adding a book in the foreign language (one you don't know) to your library - useless.

[Lucanus cervus]

Then a last question, does this then fall under "metabolic engineering"? That they engineer a whole pathway, with all the enzymes etc, to yield an organism that is able to cope with dessication. Or is metabolic engineering only used in industrial biotechnology to increase the efficiency of production of certain metabolites?

[JackBean]

So I guess the more distantly related the organisms are, the harder it becomes to transfer a certain property?

Not really. If you tried to produced e.g. caffeine in Arabidopsis, you would had to transfer all the genes involved, although it would be from one plant into other, but if you tried to express toxin from Bacillus into any plant, you are fine only with one gene. My point it, that it doesn't matter that much on the distance of the two species, but rather, what trait you want to introduce. If it is something special, you will have more work that with something, what is either more common or what is coded by only one gene.

[JackBean]

However, other thing is compatibility of the introduced gene with the new species. As you probably know, most amino acids are coded by more than one codon and each species (or rather kingdom) prefers other codon usage, thus the expression of some gene may be limited by unavailability of some tRNA. But nowadays it's not such a big problem to get your gene optimized from some commercial company

[Cat]

Then a last question, does this then fall under "metabolic engineering"? That they engineer a whole pathway, with all the enzymes etc, to yield an organism that is able to cope with dessication. Or is metabolic engineering only used in industrial biotechnology to increase the efficiency of production of certain metabolites?

More like the latter. It's more of a fine-tuning a pathway rather than introducing a new one.

[Lucanus cervus]

Thank you both for the answers! This is very interesting stuff

I have just chosen my dissertation subject and I'm going to explore bacterial biodiversity on Antarctica by means of pyrosequencing and other techniques, and one of the goals is to find genes that code for valuable properties (resistance to radiation, drought, salinity, cold, new antibiotics, enzymes). So that's why I was wondering what the possibilities are once interesting things are found in the genomes of my bacteria.

[allenePanek]

Genetic engineering works because there is one language of life: human genes work in bacteria, monkey genes work in mice and earthworms. Tree genes work in bananas and frog genes work in rice. There is no limit in theory to the potential of genetic engineering.