Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-50883
Dev Biol December 15, 2015; 408 (2): 252-68.

Molecular asymmetry in the 8-cell stage Xenopus tropicalis embryo described by single blastomere transcript sequencing.

De Domenico E , Owens ND , Grant IM , Gomes-Faria R , Gilchrist MJ .


Abstract
Correct development of the vertebrate body plan requires the early definition of two asymmetric, perpendicular axes. The first axis is established during oocyte maturation, and the second is established by symmetry breaking shortly after fertilization. The physical processes generating the second asymmetric, or dorsal-ventral, axis are well understood, but the specific molecular determinants, presumed to be maternal gene products, are poorly characterized. Whilst enrichment of maternal mRNAs at the animal and vegetal poles in both the oocyte and the early embryo has been studied, little is known about the distribution of maternal mRNAs along either the dorsal-ventral or left-right axes during the early cleavage stages. Here we report an unbiased analysis of the distribution of maternal mRNA on all axes of the Xenopus tropicalis 8-cell stage embryo, based on sequencing of single blastomeres whose positions within the embryo are known. Analysis of pooled data from complete sets of blastomeres from four embryos has identified 908 mRNAs enriched in either the animal or vegetal blastomeres, of which 793 are not previously reported as enriched. In contrast, we find no evidence for asymmetric distribution along either the dorsal-ventral or left-right axes. We confirm that animal pole enrichment is on average distinctly lower than vegetal pole enrichment, and that considerable variation is found between reported enrichment levels in different studies. We use publicly available data to show that there is a significant association between genes with human disease annotation and enrichment at the animal pole. Mutations in the human ortholog of the most animally enriched novel gene, Slc35d1, are causative for Schneckenbecken dysplasia, and we show that a similar phenotype is produced by depletion of the orthologous protein in Xenopus embryos.

PubMed ID: 26100918
PMC ID: PMC4684228
Article link: Dev Biol
Grant support: [+]
Genes referenced: dvl2 dvl3 slc35d1 tbx2 vegt wnt11b
GO keywords: axis specification
Morpholinos: slc35d1 MO1

Disease Ontology terms: schneckenbecken dysplasia
OMIMs: SCHNECKENBECKEN DYSPLASIA; SHNKND

Article Images: [+] show captions
References:
Betley, 2002, Pubmed, Xenbase [+]


Xenbase: The Xenopus laevis and X. tropicalis resource.
Version: 4.12.0


Major funding for Xenbase is provided by grant P41 HD064556