Simon Silver Department of Microbiology & Immunology University of Illinois Chicago

Bacteria do not leave macrofossils with the visual impact of dinosaur bones or petrified palm fronds. Thus, we do not identify with Precambrian stromatolites. Here is a report of cyanobacterial structures up to 40 meters high, forming off the bottom of a large salt lake near the Turkish-Iraqi and Turkish-Iranian borders. These calcium carbonate bacterial "bones" look similar to structures assigned dates before eukaryotes existed.

S. Kempe, J. Kazmierczak, G. Landmann, et al., "Largest known microbialites discovered in Lake Van, Turkey," Nature, 349, 605-8, 14 February 1991. (University of Hamburg, Hamburg, Germany; Polish Academy of Sciences, Warsaw; et al.)

Specific transport proteins recognizing short sequences as "bar codes" are responsible for moving classes of nascent proteins into the nucleus from their site of cytoplasmic synthesis. Mutations, of course, define the process and the components. The processes are quite general:...

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