Tópico: O flagelo do "desenho inteligente"

[Buckaroo Banzai]

A Complex Tail, Simply Told

By Jennifer Cutraro
ScienceNOW Daily News
17 April 2007
One of evolutionary biology's greatest challenges is deciphering the origins of complex structures. Now, scientists have unraveled the steps in the evolution of the bacterial flagellum, a tiny, whiplike structure used in swimming and host invasion. A new study shows the flagellum is the result of successive duplications of a single gene in the ancestor of today's bacteria, a finding that not only answers an important question about the evolution of complex structures but also provides additional ammunition to counter arguments from evolution's foes.

[...] evolutionary biologist Howard Ochman and postdoc Renyi Liu of the University of Arizona, Tucson, obtained the complete genomes of 41 flagellated bacteria species and identified 24 flagella-related genes common to all the microbes.

In each species, the 24 genes were very similar to each other but not to any other genes in the genome. This finding, coupled with the observation that this complete set of genes exists in all flagella-bearing bacteria, suggests the genes arose by duplication of a single gene in the ancestor of all bacteria, Ochman says. Slight changes in the genes then generated new functions. Each gene is responsible for a different aspect, such as producing the proteins that make up the flagellar motor, filament, and other structural components. In addition, an evolutionary tree constructed by the researchers suggests that the order in which the genes appeared matches the sequence of steps in the assembly of the flagellum.

http://sciencenow.sciencemag.org/cgi/content/full/2007/417/3?rss=1

[Dbohr]

Muto inteligente o jogo de palavras do título da notícia e deste tópico!

E vamos ver como a turma do ID responde essa...

[Buckaroo Banzai]

Críticas (não criacionistas) ao artigo:

I read the new paper and looked for some comments. I email Nick Matzke, a co-author of an earlier paper on this topic. He wasn't impressed. To register his displeasure, he wasn't content just to send me a grousing email. He blogged at length on Panda's Thumb. Commenters threw in their own two cents. Meanwhile, another source-turned-blogger, Ryan Gregory (whom I wrote about in an article on dinosaur genomes), wrote about the study as well, to which Larry Moran, himself a blogger as well as University of Toronto biochemist, responded harshly in the comments, saying that the paper should never have been published. (Moran, Matzke, and others complain about the methods the ASU scientists used to identify related genes.)

(excerto de um post do Carl Zimmer no seu blog, em que dá links para as discussões mencionadas)


No Pharyngula, do PZ Myers:

There is considerable interest in a recent paper in PNAS that purports to have found some rather substantial homologies in the proteins that make up the bacterial flagellum. That would be extremely interesting if it were true, but it looks like there are massive methodological problems in the work. Matzke has put up a preliminary criticism; the gang at PT are working on a much more detailed analysis, and if half of what I'm hearing about the paper is true … well, it's going to be rather thoroughly sunk.

If you are arguing against ID's favorite example, the flagellum, do not use the data in this paper. It's about to go kablooieee. Sorry, everyone, but that self-correcting stuff is the way science is supposed to work (and letting error-filled papers make it to press is not supposed to happen, but it does all too often anyway.)

http://scienceblogs.com/pharyngula/2007/04/uhohpoor_science_alert.php

(novamente com links no post)