Synthetic biology—loosely defined as the intersection of engineering and biology—is a burgeoning field with the potential to create or alter “non-naturally” occurring organisms using basic biomolecules, or similar molecules not found in living things as we encounter them. A few years ago, Dr. Craig Venter’s group in San Diego synthesized the entire DNA of one species of mycobacterium on a lab bench, added some identifier sequences, and inserted this DNA into the cytoplasm of a mycobacterium of a different, related species, and saw that the new DNA changed the recipient’s phenotype to that of the new DNA’s species.

Today comes the announcement that a different group in San Diego has altered the DNA of E.coli to include two new nucleotides, gene-code “letters,” other than the five that are naturally-occurring nucleic acids. (There are four in DNA, three of which are shared by RNA while the fourth in RNA is different.) Venter’s group recently announced an initiative to create a type of transgenic pigs, altering them so that their lungs could be harvested for transplant into people but, it is hoped, not be rejected by the recipient’s immune system. The drug company Sanofi recently started large scale of production of arteminisin, a plant product that is effective to treat malaria, in a yeast that has been re-engineered to make the drug from sugar. That’s a breakthrough: arteminisin can’t be readily made by standard chemistry, and has to be isolated from plants, and malaria remains a serious worldwide problem.

This week’s issue of Nature is devoted to future directions for “synbio,” which is still getting its sea legs. We need forward-thinking regulation, better communication among scientists from different disciplines, and a re-think of biotechnology patents (including, perhaps, scrapping them in favor of open-source efforts), the writers say.

Wild things have been written. Did Dr. Venter “create life,” or just manipulate it, albeit brilliantly? (My impression is that commentators generally think the latter, as I do.) What extreme applications might we imagine, although they are far, far away from being technically approachable? What ethical issues are raised, and how should we regulate the field?

In 2010, the Presidential Commission for the Study of Bioethical Issues, given a few short months by President Obama to report on “synbio” after the Venter mycobacteria report, did an admirable job getting its arms around a first-pass assessment of the broad ethical issues. As part of that work, ethicists from Johns Hopkins commented that responses to breakthrough biotechnologies cover a spectrum, from “proactive” (enthusiastic about prospects) to “precautionary” (worried about abuses); applications may be considered anywhere from “way cool” to “way gross.”

Much of the work, such as the examples cited above, appear to be small steps that invoke, and are reasonably governed by, existing regulations and precautions that address genetic engineering. (To be sure, the range of ethical issues invoked can be much broader; the Guardian pointed out that Sanofi might put lots of arteminisin farmers out of business, for example.) The new work on E.coli will mainly affect a range of drug discovery and development efforts, although applications in forensics, for one, are also envisioned.

But grasping the implications of synthetic biology is keeping, and will keep, lots of people busy for a while. On the one hand, we don’t need to worry about “aliens taking over Philadelphia” anytime soon, as Dr. Arthur Kaplan was reported as saying. On the other hand, Michael Kalichman of UC San Diego said things might be more challenging “if the researchers were able to produce animals” with the new synthetic nucleotides.

The broad question seems to be, what’s “natural,” and how should we approach it? If Mother Nature got a bit upset about margarine (remember those TV ads?), what sort of boundaries should we consider around synbio? The categories of ethical issues are similar, but, as the editors of a recent book about the ethics of synthetic biology point out, they are raised in new ways, with a twist. Matters for future posts…