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The Story of Ur-Genes:
the Genetics of the First Organism

..... In the early 1960's, Kimball C Atwood, MD, who was the graduate school advisor of the owner of this web-site, dreamed up the word "ur-gene" to deal with the genetics involved at the time of the earliest evolution of living matter. .. Maybe a theme - a big-picture theme - is the word 'biology' - the study of life - whatever 'life' is! ..What is the quality of livingness? ..This is no small question to, for example, NASA. .. How would be recognize life elsewhere in the universe?

..... One of the earliest questions of modern bacteriology was posed: whether or not bacteria were living things. ..Quickly it was found that bacteria possessed the quality of genetic heritability. .. Then it was wondered if genetic recombination was also a part of it. ..Soon many people were demonstrating that two strains of Bacillus coli (now E.coli) could 'mate,' and so arose the most commonly used branch in the E.coli family: .. E.coli K-12 with its F-plasmid, Hfr's, etc.

..... Atwood (at the Univ. of Illinois) then wondered what genes were universal. ..Such universality would indicate that those genes preceeded all of those phyla, kingdoms, whatever overriding taxons one might invent - such as Carl Woese's 'domains'. ..(And remember that Atwood and Woese were very close buddies at the Univ. of Illinois. Woese was also on the graduate committee of this author.)

..... So while Woese was interested in the molecular determinants that out of chemical necessity paired one type of codon with its amino acid, Atwood was thinking about what genes were universal so as to get a handle on what the primordial organism looked like - at least genetically.

..... "Ur" is the German prefix for 'primordial' or 'the first ever.' So he coined 'ur-genes'. ..As far as I know, he never published anything on it, it was just talked up a lot with other of Atwood's friends, including Dobzansky (sp?). .. Ur-functions must include DNA-replication, transcription, all the translation factors, most of the glycolytic pathway components. ..You might develop a list of the individual components and then the list of their governing genes.

..... Of course, the list is long. ..How could so many functions suddenly come into existence to make that 'first' organism? .. Something must have gone on before. ..That was where Woese came in with the theme of molecular determinism. .. In essence, life anywhere in the universe, if developed on the basis of carbon, would have to look like this which we see around us. ....So Woese set out to look to see if there was any hint of other life-forms on earth. ..Interestingly, one of his Univ. of Illinois colleagues, H.O.Halversen was an enthusiast of an odd set of halophiles. ..Soon evidence hinted that much of the halophiles' codon assignments were different from those of E.coli and all other bacteria. ..Then it was discovered that mitochondria had the same codon assignments as the halophiles, and not like those of the nucleus. .. But, to the delight of Woese, the t-RNA's had very similar structures - hence supporting his hypothesis of molecular determinism. .. And what of the codon assignments that were the same in both domains? .. Molecular determinism? .. Was there enough "wobble" in molecular determinism to allow some codons to be different? .. But others had no possibility of wobble?

.....That's a brief history of the ur-gene coinage and the archebacteria discovery also. ..So many discussions on this went on around the picnic bench at the back of the Spudnut Shop down at the corner a few hundred feet from the lab.

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