Posted on July 13, 2009 by Oldcola
This is a pre-cteappv Oops and I start wondering how Fleury manage to find journals with so poor review process as to let go to press such mistakes.
This one is from An Elasto-Plastic Model of Avian Gastrulation, Vincent Fleury, Organogenesis 2:1, 6-16, 2005.
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Posted on July 12, 2009 by Oldcola
There is not as much paleontology as one would expect by the title of the chapter. Mostly paleontology is an excuse to further discuss developmental biology, except for subsection 4.1
4.1 Tetrapod origin
If we turn to paleontology, we ﬁnd a description of tetrapods appearance into three main steps. Appearance of chordates, segmentation of lateral fins, appearance of tetrapods.
That’s the shortest version one can get except “pouf they appeared”. Interesting nevertheless the second step, the “segmentation of lateral fins“. This is one of three hypothetical, not exclusive, working models. Not to be used as a granted fact (see below).
Good news, bad news.
Good news are that Fleury abandonned the idea it appeared in one of his conferences announcement, and promoted in fora, that the tetrapods may have appeared suddenly, with all there attributes, specifying suddenly as “in a single generation“.
But he still think that:
These early tetrapods have well formed complex limbs apparently almost “right away”.
Almost right away being an estimate of the time-lapse between Haikouichthys ercaicunensis, presenting a single median fin-fold and tail, to the tetrapodomorph Tiktaalik roseae; almost right-away corresponds to 100 millions years. At least we are not anymore at the “single generation“level.
Progressive modifications are problematic for a model which is based on a suddenly appearing bauplan.
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Posted on July 11, 2009 by Oldcola
I’m greek and during my young years I was feed a lot of geometry. You know how it is, national pride for the ancestors, especially under a military junta. So, I’m quite sensible when one presents geometrical problems incorrectly.
My very first objection concerning Fleury’s model1 was that he described the epiblast cells as contained between two extracellular membranes. When I pointed that his only response was that if there is a single basal membrane that doesn’t affect his model, the flow would be just faster. From that point on you can’t trust the guy with any description.
Filed under: Notes, Oops! | 4 Comments »
Posted on July 1, 2009 by Oldcola
This is an old question which never received an answer. And certainly an answer wasn’t required before the publication of cteappv. As everything in the paper is about clarification and one more particular point remain unclear, I’ll post my question here and maybe Vincent Fleury will be kind enough to provide an answer.
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Posted on June 30, 2009 by Oldcola
By the way “I can has L2/R2″ is not a sentence
Aha! this is not a sentence. I was waiting for this one since I read the paper.
For Dr Fleury first step here, and second one here, both necessary to get the flavor.
For everybody else, a puzzle served below [p22 col2 §1]:
The significance of the reversed flexion of the hindlimb in 10% of the experiments reported in reference  is unclear since the electroporation experiment used to insert Tbx5 in the hindplate prior to hindlimb growth has a polarity in itself. If this experiment would be confirmed, it would be an uncommon case of a chirality, directly induced by a scalar non-chiral field. This would suggest that Tbx5 codes for a chiral molecule.
Maybe Dr Fleury will take the time to provide the solution. Hopefully this will not end as “I can has chirality??“.
While he is visiting lolcats and fails to have an insight about lolchickens I’ll give it a try to prepare a question for him.
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Posted on June 28, 2009 by Oldcola
[p 20, col 2, §3]
Genetic analysis, in relation to evolutionary issues, shows that actually, genes for limbs and for tails are similar, and many are identical ( and references above31, Ref. ). Also, genes which serve to form the true limb skeleton, are actually present in fish fins, in which such skeletal elements are absent  (Fig. 21).
31 “Not only are the same Hox genes expressed in both developing appendages but they are expressed in identical spatial and temporal patterns” in reference .
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Posted on June 27, 2009 by Oldcola
A funny side-effect of PZ Myers “An ontogeny of toilet drain behavior” was to bring Fleury’s theory within the range of one of the famous crackpot detectors, Suzan Mazur.
Filed under: lol, Notes, thankx | 19 Comments »