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| René Magritte: This is not a pipe. It's a painting. But a painting of 'a' pipe--but not 'the' pipe, which doesn't actually exist in the real world. Or does it? |
Saturday, August 04, 2012
LINK: Ooops! The human genome does not exist! Part I. The notion of a type specimen
I am posting this, or rather posting a link to this article because I thought it was fascinating. Hereon I shall sit firmly on the fence, but would be interested in comments from those more qualified than I to judge it. (That means YOU: Doctors Naish, Shuker, Holdsworth etc, and Max if you are reading this...)
Despite many claims to the contrary, that The Human Genome project sequenced the human genome and thus set in motion the most exciting era of fundamental new scientific discovery since Galileo, it has turned out that the HG doesn't exist, after all. It no more exists than does 'the chair' or 'the dog' as Plato once asserted. He said we have dogs and chairs but they are only imperfect instances of the real true dog and chair.
The author here does have a valid point, but is missing the main thrust of the Human Genome Project. When it started DNA sequencing was only just automated and quite a lot of the work involved was done by hand, making the whole process rather slow. Furthermore, the genomes of Drosophilla melanogaster and Caenorhabditis elegans had only just been investigated, so the main thrust of research was to generate a vaguely-correct human genome so that the two known and heavily investigated ones could be cross-compared.
ReplyDeleteThe Human Genome Project's "genome" sequence would never be correct, indeed with chromosome cross-overs during meiosis and the activity of things like transposons and retroviruses there is no way for any genome to be classed as more than "This is the sequence we got for this particular human at this time". This was known at the time, and has never been considered a problem.
What the project did do, which is more important, is allowed us to see just how complex the genome of a mammal is and more importantly, how complex it is not. Humans aren't actually anything special in terms of genome or chromosomes and the like, indeed homeotherms like mammals, archosaurs (that's birds to you) and other dinosaurs are actually a lot simpler in terms of genome than are poikilotherms like frogs, reptiles and so on. This is because poikilotherms need a set of enzymes each optimised to a set of temperatures in order to keep funtioning as their body temperature varies; homeotherms expend vast energies on keeping a stable body temperature with only a limited enzyme set, which in turn needs only a limited set of genes.
No, the major innovations that the Human Genome Project forced were the lab automation systems which permit the rapid sequencing of huge DNA sequences. Hand in hand with this are the new techniques for identifying which regions are activated at any one time, and the computational systems for helping understand all this (up to a few years ago, computing in biology was laughably poor; still is, in parts).
What I predict will happen next is that much, much more research on food plants will ensue. Animals tend to have fairly small, discreet, even streamlined genomes and don't tolerate genetic manipulation or mutation well. Plants by contrast seem to take this sort of thing in their stride, and most modern food-plants are not the beautifully natural creations that most "Green" activists would like to believe that they are. Most plants are diploid; they have two sets of genes per cell (one from the father, one from the mother). Wheat and barley are hexaploid; these plants contain the entire genomes of three different semi-wild grasses and as such, their genomes are absolutely enormous and a right mess to try to understand. Maize is a similarly enormous horror, and even potato genomes aren't simple. The hybridisation events that created modern cereals obviously boosted yields, but actually knowing which genes are turned on in the plants themselves and which are merely baggage along for the ride is actually quite a difficult job; accurate sequences for many different cultivars would help in this respect, which is where the automation comes in.
They are leaving out two elements here: the hyplax and the snorbit. Considerations relevant to the hyperphantasis cannot be regularly disquatulated and the resultant obfuscation of the nargangle is clear for all to see. Further testing of the azuncle (without excluding polynodal considerations)will in time disgrangulate the sorepticity of the entire gastrilarch which should, I feel, clarify matters considerably. This leaves little mystery about the matter.
ReplyDeleteEgo Ronanus. Sir
ReplyDeleteDoes disquatulation,in your opinion give sufficient imputineds for slythy toads to gyre and gimble in the moonlight ?
norman