time is telling

A few days ago Dr Fleury wrote me a quite short message, with just the subject line “time is telling” and a paper attached :

Who moves whom during primitive streak formation in the chick embryo, Manli Chuai and Cornelis J. Weijer, HFSP J. 2009 April; 3(2): 71–76. Published online 2009 March 31. doi: 10.2976/1.3103933.

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Just posted this to Pharyngula at the “An ontogeny of toilet drain behavior” thread

Very nice from Dr Fleury to finally inform us of what L2/R2 could be. Never late to do well. The funny thing is that he commented here but haven’t send me a message about it! That’s weird. I’m asking for evidence concerning L2R2 since august 2007.

Let’s see what we have here anyway.

The first pair of vortices Fleury claims as R1L1 are shown by CuiC et al [Dev Biol. 2005 Aug 1;284(1):37-47. doi:10.1016/j.ydbio.2005.04.021, during stages ~1-3+.

For more than 2 years the presence of the R2L2 vortices was assumed to be visible during the same developmental period and modeled as the result of a single phenomenon.

The second pair of vortices Fleury claims as R2L2, presumably shown here, are situated between stages ~8-9+. They traveled in time!

Assuming that we have evidence for R2L2, the model presented by Fleury describing simultaneously the two pairs, R1L1 and R2L2, must be wrong and he should recall his paper (doi: 10.1051/epjap/2009033) and clarify this point (along with correcting everything else) before submitting it again.

Unfortunately, it seem’s that the cell trajectories are manually spotted, the green color must not mislead anybody to confuse it as GFP expression, which is the case with Weijer’s lab experiments. Manual spotting is not the best technique to follow a particular cell population during a process where everything is moving in 3D. Not even ink or membrane dyes were used!

The first gif file even as annotated by Fleury don’t show any vortex.

The second gif file is even worse, it is obvious that the 2D depiction of the vortices is just false, sorry Dr Fleury, the cells/tissues movement is in 3D, you can’t just get a projection in 2D and try to make it look as you would like it to be. This seems to be a recurrent problem. The animation starts when the 8th pair of somites is forming at stage 9+, always faraway in time.

Let me summarize Dr Fleury:

IF those are the R2L2, the vortices contributing to the formation of the hindlimbs THEN

the previous positioning at stages 1 through 3+ was false, as I have argued the last 2+ years


the published models are false [cteappv (2009) & epmag (2005)]

AND that have nothing to do anymore with a 2D flow you claim to be at the origin of the tetrapods.

Now, we don’t really think we have evidence from a 2D manual projection of a 3D moving structure, in the absence of a tissular marker.

And I wonder what you will prefer, drop your model which assumes a (almost) 2D cellular layer and a hyperbolic flow forming simultaneously the four vortices, or try to get more consistent evidence (if any available).