Gene Networks Database
purpuratus Genes in Development: Transcription Factors
SpBra is a transcription factor, ortologue of the vertebrate Brachyury gene.
This gene appears to be an excellent marker for the progeny
of the set-aside cells of the sea urchin embryo.
SpBra is a single-copy gene (Peterson et al., 1999).
RNA gel blot hybridization showed that the SpBRA signal is easily
observed by hatching blastula stage and the gene is then odwnregulated
In mesenchyme-blastula stage embryo (24 hr) SpBra expression is localized
to the vegetal plate.
At 36 hr of development (midgastrula stage) SpBra transcripts are detected by WMISH
in the delaminating secondary mesenchyme cell population, consistent with the
report for the H. pulcherrimus Brachyury (HpTa) gene
(Harada et al., 1995).
The early spatial pattern suggests that the SpBra gene could be involved in
some initial function of the vegetal plate and that its later expression
is downstream of the process by which endodermal precursors are segregated
from secondary mesenchyme precursors, to which
the expression of this gene in the embryo is ultimately confined.
At the 2-week larva SpBra is abundantly but specifically expressed in
both the vestibule and left hydrocoel.
Expression begins with the initial invagination of the vestibule and continues
through contact and flattening of both structures.
SpBra is also expressed in the right axohydrocoel.
The expression is not seen in the somatocoels nor in any larva-specific
structures outside the rudimant from which the adult body plan forms.
SpBra is again undetectable by WMISH by 3 weeks of development (Peterson et al., 1999).
mRNA spatial localization
Method: Whole mount in situ hybridization
Reference: Peterson et al., 1999
||24 hr mesenchyme blastula
||36 hr midgastrula
||Delaminating secondary mesenchyme cells
||Vestibule, left hydrocoel and right axohydrocoel
- HpTa Hemicentrotus pulcherrimus
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