Monday, October 8, 2007
Junkyard and/or 'hardware superstore'?
GMO Pundit aka David Tribe has a post about yet another story of an ancient mammalian TE co-opted for gene regulation. The study, just published in PLoS Genetics and led by Marcelo Rubinstein, an HHMI International Scholar from the Institute for Research on Genetic Engineering and Molecular Biology and the University of Buenos Aires in Argentina, demonstrates that an ancient SINE (short interspersed nuclear element) has donated an enhancer DNA element, conserved in all mammals examined, that directly contributes to the expression of the propiomelanocortin (POMC) gene in hypothalamic neurons. The POMC gene is involved in the production of neuropeptides controlling functions as diverse as the stress response, skin and hair pigmentation, analgesia, and the regulation of food intake and energy balance. It is tempting to speculate that the acquisition of the neuronal enhancer from the SINE was a key step in the functional evolution of POMC in mammals and the advent of mammalian-specific evolutionary innovations.
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The "and/or" is important, and I'm glad you included it. It is entirely possible for most of the genome to be non-functional or even parasitic, and yet occasionally contribute components that are critical for some major evolutionary transition. In fact, I devoted half a chapter in The Evolution of the Genome to discussing the influence of "non-standard genetic processes" (i.e., things other than small-scale mutations in protein-coding genes, especially TEs and introns) to major events in our lineage. I suspect that many more will be identified in the future, but of course it makes no sense to suggest that these elements are there "so that" they will have these consequences. Anyway, glad to see the number of posts increasing!
Hope I didn't drop a 'so that' in any of my posts so far... I realize I'm being closely watched! I am usually pretty careful at avoiding these, especially in writings. But it is often much harder to avoid these in conversations or even during talks (especially to a general audience), and I found myself often guilty of doing so.
I too am shocked to read quotes from eminent scientists pulling out the 'so that' explanation, including in journals such as Nature or Science. But I tend to give these scientists the benefit of the doubt, unless I have witnessed myself the interview. We all know too well that the blame should often go to poorly qualified science writers for mis-interpreting or over-simplifying what scientists tell them or what they write in the papers.
The reverse is probably true as well. I bet we are fortunate that they are some talented science writers out there (Zimmer is one example) that can actually correct and protect us from some of the awkward-to-outrageous things that scientists can say when they try to publicize their work over the phone!
Well, the product is very cheap in Actfind.com, anybody know Actfind.com is a believable or not?
Its all in the manual they make you read before they download your being into those tiny bodies in those dark wombs.
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