As we finish up another jam-packed summer term in 2013, this hit the news feed on Scientific American. Looking at the image, I can’t quite tell if it’s a eukaryote–I don’t see a really distinct nucleus or membrane-bound organelles, but it’s a FOSSIL. What do you expect? A map?
The size looks pretty promising, though: it’s in line with a lot of eukaryotic cells (and most that I’ve seen). For reference, the human dermal fibroblasts I work with are about 25 um in diameter on average (when they’re all detached from each other and floating in media; when they’re spread out and adhered to a surface, it’s harder to measure). The shape looks rather more geometric than I expect for cells, too, but again, fossil. That might just be an artifact from the rock (planes in crystal structures).
They dated the rock this was found in to 3 million years old using carbon dating. If you’ve been in my class, I would have told you to laugh at me and demand another explanation, because carbon dating isn’t effective in this range; you get a usable maximum of maybe 100,000 years. That’s true for 14C (Carbon-14). In this case, they used 13C (Carbon-13) for dating. Carbon-13 is not radioactive. The levels of this form of carbon are different in plants than in the atmosphere or in the water. If accurate, this pushes back when the last universal common ancestor (LUCA) is expected to have lived–and the origins of complex eukaryotic life itself.
Interesting that the enzyme works best at a high temperature and relatively high pH: weren't those conditions long ago?That would make an interesting post.
Oddly, yes; check out http://www.ncbi.nlm.nih.gov/pubmed/18027102That might be a neat option for a future post!
Interesting. Could there possibly be a Exosymbiotic theory? Ha