Vertebrate limb bud formation is initiated by localized epithelial-to-mesenchymal transition

Vertebrate limbs first emerge as small buds at specific locations along the trunk. Although a fair amount is known about the molecular regulation of limb initiation and outgrowth, the cellular events underlying these processes have remained less clear. We show that the mesenchymal limb progenitors arise through localized epithelial-to-mesenchymal transition (EMT) of the coelomic epithelium specifically within the presumptive limb fields. This EMT is regulated at least in part by Tbx5 and Fgf10, two genes known to control limb initiation. This work shows that limb buds initiate earlier than previously thought, as a result of localized EMT rather than differential proliferation rates.

Gros J, Tabin CJ.

Science 14 March 2014:  Vol. 343 no. 6176 pp. 1253-1256, doi:10.1126/science.1248228


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Arnold Munnich

Dans Le Point du 17 octobre 2013, p 74-75, une mise au point d’Arnold Munnich (responsable du département de génétique de l’hôpital Necker-Enfants malades à Paris), titrée « La médecine n’est pas le tiercé ». Les propos sont recueillis par Jérôme Vincent qui signe également l’encadré de la p 75 sur « ce qui est autorisé, ce qui est interdit ». Excellent pour une prise de bec !
NB le dossier du Point est à lire, les autres intervenants semblent avoir les pieds sur Terre, aux kiosques !

D’abord, cartes sur table, je travaille pour Portable Genomics Inc., une société américaine, démarrée par des francais éxilés aux USA (à cause de l’ineptie qu’est la loi bioéthique française), et dont le business est lié cet espace de la génétique et de la génomique personnelle.

Avant une dissection en règle de cette mise au point deux choses que je souhaite clairs :

– Effectivement, la médecine, ce n’est pas le tiercé. Je suis entièrement d’accord.
– La génétique personnelle n’est pas le tiercé non plus; elle demande des médecins capables d’exploiter les connaissances actuelles et justement, pour éviter le tiercé,  je ne laisserai jamais un médecin comme Munnich s’occuper de moi ou des gens auxquels je tiens.

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D8133A5D-40AA-4536-9B15-29FCFF1514BC.jpgNDE have been used as proof of the existence of souls in a large set of stupid arguments.
Following this trend, it seems that prophet Sir Terry Pratchett revealed that rats have souls, managed by the DEATH of Rats of course, in his novels.
Now scientific evidence come to support either:

  • the existence of rats’ souls, or
  • the non-supernatural, quite materialistic, explanation of NDE.

Jimo Borjigin, UnCheol Lee, Tiecheng Liu, Dinesh Pal, Sean Huff, Daniel Klarr, Jennifer Sloboda, Jason Hernandez, Michael M. Wang, and George A. Mashour
Surge of neurophysiological coherence and connectivity in the dying brain

PNAS 2013 ; published ahead of print August 12, 2013, doi:10.1073/pnas.1308285110

The brain is assumed to be hypoactive during cardiac arrest. However, the neurophysiological state of the brain immediately following cardiac arrest has not been systematically investigated. In this study, we performed continuous electroencephalography in rats undergoing experimental cardiac arrest and analyzed changes in power density, coherence, directed connectivity, and cross-frequency coupling. We identified a transient surge of synchronous gamma oscillations that occurred within the first 30 s after cardiac arrest and preceded isoelectric electroencephalogram. Gamma oscillations during cardiac arrest were global and highly coherent; moreover, this frequency band exhibited a striking increase in anterior–posterior-directed connectivity and tight phase-coupling to both theta and alpha waves. High-frequency neurophysiological activity in the near-death state exceeded levels found during the conscious waking state. These data demonstrate that the mammalian brain can, albeit paradoxically, generate neural correlates of heightened conscious processing at near-death.

Illustration by ~Smaggers

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Just for Hits – Richard Dawkins

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A Switch Between Topological Domains Underlies HoxD Genes Collinearity in Mouse Limbs

Guillaume Andrey, Thomas Montavon, Bénédicte Mascrez, Federico Gonzalez, Daan Noordermeer, Marion Leleu, Didier Trono, François Spitz, Denis Duboule

Science 7 June 2013: Vol. 340 no. 6137 dpi: 10.1126/science.1234167

Editors Summary

During limb development, the time and place of Hox transcription are fixed by respective gene position within the gene cluster. Andrey et al. (p. 1234167; see the Perspective by Rodrigues and Tabin) found that this enigmatic property results from the opposite and successive actions of two large regulatory landscapes located on either side of the mouse Hox locus. In the early phase, one of these topological domains regulates transcription in the proximal limb until a switch occurs toward the other topological domain, which takes over the regulation in the distally developing digits. As a side effect of this antagonistic regulatory strategy, cells in-between have lessened Hox transcription, which generates the wrist.


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Sequencing of the sea lamprey (Petromyzon marinus) genome provides insights into vertebrate evolution

Sequencing of the sea lamprey (Petromyzon marinus) genome provides insights into vertebrate evolution

Smith JJ, Kuraku S, Holt C, Sauka-Spengler T, Jiang N, Campbell MS, Yandell MD, Manousaki T, Meyer A, Bloom OE, Morgan JR, Buxbaum JD, Sachidanandam R, Sims C, Garruss AS, Cook M, Krumlauf R, Wiedemann LM, Sower SA, Decatur WA, Hall JA, Amemiya CT, Saha NR, Buckley KM, Rast JP, Das S, Hirano M, McCurley N, Guo P, Rohner N, Tabin CJ, Piccinelli P, Elgar G, Ruffier M, Aken BL, Searle SM, Muffato M, Pignatelli M, Herrero J, Jones M, Brown CT, Chung-Davidson YW, Nanlohy KG, Libants SV, Yeh CY, McCauley DW, Langeland JA, Pancer Z, Fritzsch B, de Jong PJ, Zhu B, Fulton LL, Theising B, Flicek P, Bronner ME, Warren WC, Clifton SW, Wilson RK, Li W.

Nat Genet. 2013 Apr;45(4):415-21, 421e1-2. doi: 10.1038/ng.2568. Epub 2013 Feb 24

Sea lamprey mouth (Photo: T. Lawrence, GLFC)

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Macrophages are required for adult salamander limb regeneration

Macrophages are required for adult salamander limb regeneration

James W. Godwina, Alexander R. Pinto, and Nadia A. Rosenthal

Published online before print May 20, 2013, doi: 10.1073/pnas.1300290110

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Enquête sur les Créationnismes

par Cyrille Baudouin et Olivier Brosseau

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Neural Decoding of Visual Imagery During Sleep

Neural Decoding of Visual Imagery During Sleep

T. Horikawa, M. Tamaki, Y. Miyawaki, Y. Kamitani

Science 3 May 2013: Vol. 340 no. 6132 pp. 639-642 doi: 10.1126/science.1234330

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Emergence and Diversification of Fly Pigmentation Through Evolution of a Gene Regulatory Module

Laurent Arnoult, Kathy F. Y. Su, Diogo Manoel, Caroline Minervino, Justine Magriña, Nicolas Gompel, and Benjamin Prud’homme

Science 22 March 2013: 339 (6126), 1423-1426. doi: 10.1126/science.1233749

Capture d’écran 2013-03-22 à 20.11.43.JPG

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