The Bottleneck Years

Artificial Biology, April 19, 2056

I was beginning to feel like things were slipping out of control. I don't know that they had ever been in control, but before Edie started Neurolin, before the Group 2 disaster and before Rhamaposa started talking about conventions of idiots, I had felt I had a handle on what was going on. Now I realized I was at a loss. What effect would the drug have on Edie? What good would the Group 6 cloud makers do? The Group 5 sun shade project was at best speculative. On top of which the numbers coming in from greenhouse gas monitoring stations around the world were rising ominously. How were we going to fix this? Things were not looking good.

Once when dad was in a dark mood, he said, "It's so unalterably simple. Thou shalt not destroy thy life support system. And yet we do it. Over and over. When will we learn?"

I was flailing about looking for direction. I needed a focus and it occurred to me that the most useful thing I could do was apply myself more forcefully in my research. I began to lean in that direction. Anna, Edie, UNGETF, Carman, the students and other aspects of my life, such as it was, clamoured for attention, but the research became my default activity. What I always fell back to when I was otherwise doing nothing.

And what was my research?

Studying the miracle of photosynthesis. Plants take light, carbon dioxide and water vapour and give us oxygen, while creating carbohydrates for themselves. They make all animal life possible.

One funny thing about photosynthesis is how little of the incident sunlight is actually used --- less than 1%. That was the first aspect of the problem space I investigated.

There were some extremophiles, exotic plants that aborbed a slightly wider bandwidth of sunlight, but other aspects of the process moved at cellular speeds and that could not be easily accelerated. All in all, the process of photosynthesis was remarkably uniform among plants and single cell creatures.

That recognition led me to consider an artificial biology. What did I want? A non-propagating plant-like material that absorbed a lot of carbon dioxide and turned it into a hopefully useful solid. Wouldn't it be cool to make a plant that grew diamonds. That would liven up UNGETF meetings. I began to design my first carbon capture membrane.

I envisioned a layer of leaf like material: a dark surface, possibly black, stretched over supports that supplied water and other nutrients. The membrane would use sunlight as in normal photsynthesis to generate a thin film of carbon fiber, perhaps a crystallite layer of graphite, that would peel away from the bottom of the membrane and accumulate below. I would keep the diamond idea in the back of my mind in case something turned up while I worked on the more practical graphite. The precise composition of the carbon film would vary according to what?

There were a lot of questions. How much CO2 would it capture? Would it be practical? How could I make the membrane? Could I design the life form?
Getting bacterial genes to produce food, fuel, drugs and so on was relatively straightforward; had been since the time of the Synthetic Biologists at the turn of the millennium.
Controlling patterns of growth in higher organisms was several orders of complexity more difficult.

I got to work.

As I envisioned it, there would be two stages, a growing stage and a carbon capture stage, with a distinct chemical switch between the two.

The carbon capture stage was the real problem, so I focused on it. It occurred to me that once cracked, the carbon capture stage could be propagated in any broad leaf plant. But it had to be under control which took me back to the membrane.

Photosynthesis could happen in all the cells, but if there was no mechanism to exude carbonaceous materials, it wouldn't work. That was the nut of it. How to direct the photosynthesis of the carbon capture stage to deposit carbonaceous material in a film on the underside?

Maybe just the immediately adjacent layers of cells needed to switch into the second type of photosynthesis, P2. How could I control that? Most of the photosynthesis happened within the surface layer exposed to sunlight, not at the base where only higher frequency wavelengths penetrated. Maybe I could devise a frequency sensitive mechanism. P1 inhibits P2 as long as it is active, but when it is not, P2 dominates the chemical pathways.

I was talking myself in circles.

How to crack this nut?

Make the whole membrane grow upwards at the surface but change into a film as it is deprived of light? How could I arrange that? Have a lack of P2 chemical byproducts act as a trigger to flip the genes into a desiccation process? I began to look more closely at the candidate chemicals and consider the plant structure that would support the process. Then I needed to convert that into gene sequences. The layeredness was essential and not at all straightforward. It would have to arise from the cell geometry in the growing phase.

I pulled up the modelling software and started looking through gene libraries that were potentially useful.

I had a lot of work to do.

Excerpted from _The Bottleneck Years_ by H.E. Taylor

For further information see:
A Gentle Introduction.

Last modified April 30, 2013