More Science Pickings
by MikeGeneIt's becoming increasingly clear that the eukaryotic nucleus is not a bag of soup whose function is the product of nothing more than randomly diffusing transcription factors, RNA, and DNA. Another study has documented the importance of location within the nucleus.
as red blood cells mature, the beta globin locus progressively moves away from the nuclear periphery, towards the interior. Furthermore, they found that efficient relocalization is dependent upon the locus control region (LCR). Contrary to the existing dogma, this finding demonstrates that gene transcription precedes relocalization "“ establishing the nuclear periphery as the new hot spot.
Changing topics, Robert Shapiro has published another paper on the origin of life. I have not read it, but it looks like he outlines the fundamental flaw in the quest for the elusive self-replicator (Conway Morris, relying on Shapiro, also outlines this reason in his recent book). Shapiro clearly opts for the "metabolism first" school of thinking that has been around for years:
Shapiro outlines how replicator theories, though they have been supported by "prebiotic" syntheses carried out by chemists using modern apparatus and purified reagents, are highly unlikely. The creation of a molecule that can self-replicate requires the combination of diverse chemicals in a long sequence of reactions in a specific order, interspersed by complicated separations, purifications, and changes in locale.
Instead, Shapiro introduces the idea of a "driver" reaction, linked to a free energy source, that helps convert an unorganized mixture into a organized, self-regulated metabolic network.
"If we wish a more plausible origin of life, then we must work with the assumption that life began, somehow, among one of the mixtures of simple organic molecules that are produced by abiotic processes," writes Shapiro. "Nature will be instructing us, rather than we attempting to impose our schemes onto it."
May 22nd, 2006 at 9:09 am
Meanwhile, many readers of this blog (I'll not single out the culprits) scoff at the notion that things like hurricanes can inform us about life.
Does the transition from "slow" to "fast" (a transition in chemistry that is necessary for the OOL) inevitably lead to self-replicators, or are there parallel tracks ("speed" and "replicators") that merge?
That's a pretty serious anti-ID swipe there.
Comment by Art — May 22, 2006 @ 9:09 am
May 22nd, 2006 at 12:54 pm
Culprit #1 here, reporting for duty. Hey, go for it, Shapiro! I think it's implausible. But I understand why people like Art and Shapiro think ID is implausible, too. But now I'll have to go get that Bruce Alberts' article on molecular machines (Cell, vol. 92, February something, I think). If I read it right, a hurricane was the old model of understanding what goes on in the cell.
Comment by Bilbo — May 22, 2006 @ 12:54 pm
May 22nd, 2006 at 1:05 pm
Hi Bilbo,
"But now I'll have to go get that Bruce Alberts' article on molecular machines (Cell, vol. 92, February something, I think)."
Pages 291-294, if you're a stickler for details.
Comment by Krauze — May 22, 2006 @ 1:05 pm
May 22nd, 2006 at 1:24 pm
Thanks, Krauze. I didn't realize it was online. That saves me a trip across town, photocopying, etc. Would you say my interpretation of Alberts' opening remarks are correct? And that the hurricane model is the old one?
Comment by Bilbo — May 22, 2006 @ 1:24 pm
May 24th, 2006 at 8:26 pm
By the way, Art, Shapiro takes a pretty serious anti-RNA world swipe there, wouldn't you say?
Comment by Bilbo — May 24, 2006 @ 8:26 pm
May 27th, 2006 at 9:11 am
Yeah, I'd say that Shapiro doesn't like the idea that RNA came before metabolism (I use the term metabolism in a very loose sense, to mean any sort of collection of linked chemical reactions driven by flow thru the system). But he's non-commital (in the review, at least) about the existence of the RNA World at some point in the progression from his first baby steps to full-fledged LAWKI.
And he doesn't really do or say much to tip the balance one way (RNA shaped the metabolic landscape of the prebiotic world) or the other (the metabolic landscape shaped the nature of the RNA World).
Comment by Art — May 27, 2006 @ 9:11 am