SpNot

Function

SpNot is a transcription factor, ortologue of the vertebrate Not gene.
SpNot may play a role in controlling differentiation and gene expression in larva-specific cell types such as the pigment cells, which at metamorphosis are presumably histolyzed with the aboral ectoderm in which they reside.
SpNot is a single-copy gene (Peterson et al., 1999).

Protein

SpNot open reading frame of 1551 nucleotides encodes a polypeptide of 516 amino acids, the predicted molecular mass of which is 56.8 kDa (Peterson et al., 1999).

Subcellular location

Expression Pattern

Gel blots of RNA show that the SpNot transcripts are present only transiently. Hybridization signals may be present at 12 h of development. By 24 hr (mesenchyme-blastula stage) the signal is greatly enchanced. The high-level expression continues throughout gastrulation (36 hr), but by the end of gastrulation transcripts are no longer detected (48 hr).
This temporal expression pattern is very similar to the Brachyury expression pattern in both H. pulcherrimus and S. purpuratus.
In mesenchyme-blastula stage embryo (24 hr) SpNot expression is localized to the vegetal plate. At 36 hr of development (midgastrula stage) SpNot transcripts are detected by WMISH in the secondary meenchyme cells, are absent in the hindgut region, and are at the process of fading in the midgut region.
SpNot transcripts are abundant by 2 weeks of development. SpNot is expressed in the rudiment, but expression of this gene is limited to the vestibule. No expression occurs in the hydrocoel or any other of the coelomic pouches.
Unlike SpBra, SpNot is detected in three different larval-specific structures: epauletes, pigment cells and blastocoelar cells. Expression can be detected at three weeks of development in the same structures (Peterson et al., 1999).

mRNA level

Temporal accumulation
Method: RNA blot hybridization
Reference: Peterson et al., 1999

Stage	Unfertilized egg	12 hr	24 hr	36 hr	48 hr	60 hr	72 hr
Level	-	-	+	+	-	-	-

mRNA spatial localization
Method: Whole mount in situ hybridization
Reference: Peterson et al., 1999

Stage	24 hr mesenchyme blastula	36 hr midgastrula	2-week larva
Tissue	Vegetal plate	Delaminating secondary mesenchyme cells	Vestibule, epauletes, pigment cells and blastocoelar cells