Received: by alpheratz.cpm.aca.mmu.ac.uk id MAA19960 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Tue, 23 Jan 2001 12:44:37 GMT Message-ID: <A4400389479FD3118C9400508B0FF230010D1A65@DELTA.newhouse.akzonobel.nl> From: "Gatherer, D. (Derek)" <D.Gatherer@organon.nhe.akzonobel.nl> To: "'memetics@mmu.ac.uk'" <memetics@mmu.ac.uk> Subject: RE: ....and the beat goes on and on and on... Date: Tue, 23 Jan 2001 13:40:07 +0100 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset="iso-8859-1" Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Chris:
An intersting 'discovery' lately has been that the zebrafish has left/right
hemisphere processing like we do i.e. KNOWN (left bias) vs UNKNOWN (right
bias) IOW these patterns are possibly in fundamental neurology PRE
amphibians/reptiles development.
(oops almost forgot the ref: Liang, J.O. et al (2000) Asymmetric nodal
signaling in the zebrafish diencephalon positions the pineal organ "
Development 127, 5101-5112)
Derek:
But is that what this paper really says? The abstract is:
_________
The vertebrate brain develops from a bilaterally symmetric neural tube but
later displays profound anatomical and functional asymmetries. Despite
considerable progress in deciphering mechanisms of visceral organ
laterality, the genetic pathways regulating brain asymmetries are unknown.
In zebrafish, genes implicated in laterality of the viscera (cyclops/nodal,
antivin/lefty and pitx2) are coexpressed on the left side of the embryonic
dorsal diencephalon, within a region corresponding to the presumptive
epiphysis or pineal organ. Asymmetric gene expression in the brain requires
an intact midline and Nodal-related factors. RNA-mediated rescue of mutants
defective in Nodal signaling corrects tissue patterning at gastrulation, but
fails to restore left-sided gene expression in the diencephalon. Such
embryos develop into viable adults with seemingly normal brain morphology.
However, the pineal organ, which typically emanates at a left-to-medial site
from the dorsal diencephalic roof, becomes displaced in position. Thus, a
conserved signaling pathway regulating visceral laterality also underlies an
anatomical asymmetry of the zebrafish forebrain
________
There's no evidence that zebrafish have 'left/right
hemisphere processing like we do'. All that this paper says is that
zebrafish anatomical brain asymmetry is dependent on the nodal signalling
pathway.
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