Molecular asymmetry in the 8-cell stage Xenopus tropicalis embryo described by single blastomere transcript sequencing
Elena De Domenico
Nick DL Owens
Ian M Grant
Rosa Gomes-Faria
Michael J Gilchrist
10779/crick.12666863.v1
https://crick.figshare.com/articles/journal_contribution/Molecular_asymmetry_in_the_8-cell_stage_Xenopus_tropicalis_embryo_described_by_single_blastomere_transcript_sequencing/12666863
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.
2020-07-17 10:59:03
Cortical rotation
Dorsal determinants
Molecular asymmetry
Polar enrichment of mRNAs
Spatial distribution of maternal mRNAs
Xenopus tropicalis
Animals
Blastomeres
Body Patterning
Female
Gene Knockdown Techniques
Humans
Male
Models, Animal
Monosaccharide Transport Proteins
Mutation
RNA, Messenger
Transcription, Genetic
Xenopus
Xenopus Proteins
Gilchrist U117597137
AS-ack
Developmental Biology
06 Biological Sciences
11 Medical and Health Sciences