AUTHOR=Merchán Paloma , Bardet Sylvia M., Puelles Luis , Ferran José L.

TITLE=Comparison of Pretectal Genoarchitectonic Pattern between Quail and Chicken Embryos

JOURNAL=Frontiers in Neuroanatomy

VOLUME=5

YEAR=2011

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2011.00023

DOI=10.3389/fnana.2011.00023

ISSN=1662-5129

ABSTRACT=<p>Regionalization of the central nervous system is controlled by local networks of transcription factors that establish and maintain the identities of neuroepithelial progenitor areas and their neuronal derivatives. The conserved cerebral Bauplan of vertebrates must result essentially from conserved patterns of developmentally expressed transcription factors. We have previously produced detailed molecular maps for the alar plate of prosomere 1 (the <italic>pretectal region</italic>) in chicken (Ferran et al., <xref ref-type="bibr" rid="B25">2007</xref>, <xref ref-type="bibr" rid="B24">2008</xref>, <xref ref-type="bibr" rid="B23">2009</xref>). Here we compare the early molecular signature of the pretectum of two closely related avian species of the family Phasianidae, <italic>Coturnix japonica</italic> (Japanese quail) and <italic>Gallus gallus</italic> (chicken), aiming to test conservation of the described pattern at a microevolutionary level. We studied the developmental pretectal expression of <italic>Bhlhb4</italic>, <italic>Dbx1</italic>, <italic>Ebf1</italic>, <italic>Gata3</italic>, <italic>Gbx2</italic>, <italic>Lim1</italic>, <italic>Meis1</italic>, <italic>Meis2</italic>, <italic>Pax3</italic>, <italic>Pax6</italic>, <italic>Six3</italic>, <italic>Tal2</italic>, and <italic>Tcf7l2</italic> (<italic>Tcf4</italic>) mRNA, using <italic>in situ</italic> hybridization, and PAX7 immunohistochemistry. The genoarchitectonic profile of individual pretectal domains and strata was produced, using comparable section planes. Remarkable conservation of the combinatorial genoarchitectonic code was observed, fundamented in a tripartite anteroposterior subdivision. However, we found that at corresponding developmental stages the pretectal region of <italic>G. gallus</italic> was approximately 30% larger than that of <italic>C. japonica</italic>, but seemed relatively less mature. Altogether, our results on a conserved genoarchitectonic pattern highlight the importance of early developmental gene networks that causally underlie the production of homologous derivatives in these two evolutionarily closely related species. The shared patterns probably apply to sauropsids in general, as well as to more distantly related vertebrate species.</p>