Friday, March 20, 2015

Genetic Engineering: Birds Do It, Bees Do It. Let's Modify Our Embryos!

David Baltimore wants a moratorium on CRISPR/Cas9 technology and likens it to the voluntary moratorium on recombinant DNA declared at the Asilomar conference in 1975. Paul Berg, one of the signatories back then, is one of the signatories now.  They feel that the technique could be used for 'germline' genetic modification, even though the current uses are for 'somatic' (non-inheritable) genetic changes. And germline engineering - inheritable changes to DNA - would be bad.

It's interesting that it's taken literally 40 years to go from OMG we can do what to bacteria? through OMG we're adding what genes to tomatoes? to OMFG we can do what to human babies? I think once we got past Asilomar, people thought the timelines would be shorter.

An image of DNA.

Anyway, according to Genomeweb (which you may have to sign up for to read; it's free and doesn't send you spam), Ye Olde Concernede Scientists are making another principled stand against the possibility of the Frankenstein thing. They've published two editorials, one in Science and one in Nature, which is the strongest stance scientists can take. (It's equivalent to ordinary mortals saying "I say Good Day to you Sir, Good Day!" and walking out.) You can't read the one in Science because it's beyond a paywall (because science) but the Nature one is free to air, or whatever it's called in sciency terms.

The Nature piece describes CRISPR as:
The newest addition to the genome-editing arsenal is CRISPR/Cas9, a bacteria-derived system that uses RNA molecules that recognize specific human DNA sequences. The RNAs act as guides, matching the nuclease to corresponding locations in the human genome. CRISPR/Cas9 is the simplest genome-editing tool to work with because it relies on RNA–DNA base pairing, rather than the engineering of proteins that bind particular DNA sequences.
The CRISPR technique has dramatically expanded research on genome editing.
And Zinc Finger Nucleases as:
For instance, ZFNs are DNA-binding proteins that can be engineered to induce a double-strand break in a section of DNA. Such molecular scissors enable researchers to ‘knock out’ specific genes, repair a mutation or incorporate a new stretch of DNA into a selected location.
Scientists could use these powers for good:
Genome-editing technologies may offer a powerful approach to treat many human diseases, including HIV/AIDS, haemophilia, sickle-cell anaemia and several forms of cancer.
Or use the powers for evil:
In our view, genome editing in human embryos using current technologies could have unpredictable effects on future generations. This makes it dangerous and ethically unacceptable. Such research could be exploited for non-therapeutic modifications.  

Admittedly that doesn't sound very evil. I think what they're really concerned about is this (the next sentence):
We are concerned that a public outcry about such an ethical breach could hinder a promising area of therapeutic development, namely making genetic changes that cannot be inherited.
In other words, people might find out about it and stop them.

In the article that is pointed to by the Science editorial, entitled Embryo Engineering Alarm, Gretchen Vogel points out:
Rumors are rife that scientists in China have already used CRISPR on human embryos.
If the Chinese are creating supersoldiers who can withstand boiling lava and nuclear explosions, I sense what we actually have is an embryo engineering gap, and we should move full steam ahead!


Anyway, if we won't genetically engineer our own embryos, the bugs will do it for us. That's the gist of  another article in Genomeweb this week called Genome Analysis Reveals Horizontal Gene Transfer Events in Vertebrates. It shows that a number of genes that vertebrates bear actually come from other organisms, transferred there 'horizontally' which is to say by being transferred physically into cell nuclei where they cause a permanent change, rather than 'vertically', which describes genes that get there from your mother and father.

The authors say:
"This is the first study to show how widely horizontal gene transfer occurs in animals, including humans, giving rise to tens or hundreds of active 'foreign' genes," Cambridge's Alastair Crisp said in a statement. "Surprisingly, far from being a rare occurrence, it appears that HGT has contributed to the evolution of many, perhaps all, animals and that the process is ongoing, meaning that we may need to re-evaluate how we think about evolution."
But that's not really what the overall article says:
To place the timing of these HGT events, Crisp and his colleagues mapped the foreign ortholog groups for each taxon to their phylogenetic trees. For Drosophila and Caenorhabditis, the branch length corresponded with the number of HGT events along those branches, suggesting that HGT is both old and ongoing in these species.
Which is to say for fruit flies and a type of roundworm, the horizontal gene transfer has been going on for a long time and still occurs.
However, the pattern was different for primates, as most of the foreign groups mapped to the base of the phylogenetic tree, indicating that the HGT events occurred in the span of time between the common ancestor of Chordata and the common ancestors of primates.
So for us and our cousins, these HGT occurred half a billion years ago. If they hadn't said that, I would assume the whole paper simply existed to give credence to Big Ag's contention that genetic engineering occurs naturally, and therefore the more fish genes they can stuff into tomatoes, the more natural they are. Crisp's statement above about "ongoing" HGT is right in line with that thinking.

And also note this, also from the Genomeweb article:
The researchers also noted that they couldn't fully rule out the possibility that these foreign genes were inherited by vertical descent and then lost from other metazoan species.
Well then.

Personally, I'm still more worried that, as the original Asilomar team thought, someone will genetically engineer anthrax or some minor tick-borne disease to become untreatable or more  easily spread. And I'm more worried that Monsanto will continue to add weird genes in random spots on the genome of world-wide crop plants, as the Greens fear. I'm not particularly worried that Mr. and Mrs. Ritchie Rich of the Hamptons will want their kid to have green eyes or agouti hair. All that would happen is, instead of people saying, "Hahaha -she's called Skylar. She must have been born in the twenty-teens!" people will say, "Hahaha - he's got six fingers. He must have been born in the twenty-teens!"

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