Research at Ames...
I'm going to sort of briefly, in a couple of bullet items, summarize what I did my first five or six years at Ames. My interest since I've been at Ames, which has been for about eleven years, has been to try to model the Precambrian a day in the life of the Precambrian, if you will. There's only so much you can get from the fossil record but if you say, what did organisms do at 10:00 in the morning 3 billion B.C.., there's no way you can get that from a fossil record. What you need to do is take modern analogs and try to grow them up under Precambrian conditions and see if they will give you some clue to the way things were working then.
What happens to photosynthesis in a Precambrian day?
So this is what I did my first five years at NASA. I looked particularly at photosynthesis; what happens if you take some of these analogs of these very early communities, follow them through a day in terms of their photosynthesis. What happens if you can start increasing the amount of carbon dioxide, because the modelers tell us there was much more carbon dioxide in the ancient earth. What happens if you start to look at their DNA synthesis, what happens if you start to look at their isotope fractionations. I mentioned before that the radio of carbon-12 to carbon-13 is a very important thing to deduce from the fossil record.
Just to summarize, we have done some of that and we've looked to see how we can raise carbon dioxide in the modern analog and how that affects its isotope fractionation. And the answer is, if you give the modern analogs more carbon dioxide, there's an even greater isotope fractionation. We've looked at their carbon fixation during the course of the day: what happens to the fixed carbon, what happens in terms of nitrogen metabolism. The nitrogen bit is actually not my work, that's my husband's work--molecular biology with a little bit of nucleic acid synthesis. I'll be talking much more about that in a few minutes.