Daily Archives: June 1, 2010

A Nudge Goes Deeper

Previously, I explored a pattern that echoes front-loading:

However, note from the phylogenetic tree above that the researchers propose the origin of the writer  just prior to the split between choanoflagellates and metazoans.  This is not a big problem for front-loading, as it would be easy to front-load the appearance of this writer by endowing life forms with serine/threonine kinases.  Nevertheless, the case for front-loading would be stronger is the tyrosine kinases were much older and closer to the original cells.  What’s more, way back in 2002, I predicted:

my working hypothesis (just recently being seriously entertained) is that the original cells were front-loaded to make it more likely that multicellular states would evolve. These leads me to predict that we will find remnants or “fossils” of such front-loaded distributed among protozoa. Specifically, we will find various pieces of information, necessary for multicellular life, not necessary for single-celled existence, yet still present in many single-celled organisms. {emphasis added)

So are the researchers correct in dating the origin of tyrosine kinases just prior to the split between choanoflagellates and metzoans?  Or was yours truly correct in expecting them to be older, and thus more widely distributed?

And as we saw it turned out the tyrosine kinase circuit long predated the choanoflagellates.  Now it looks the FLE expectation has also born out with regard to another system long considered to be strictly metazoan specific:

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