What sequences of DNA around the GataE gene in sea urchins control it’s expression in the embryo?
The gatae gene in sea urchins is expressed in the endoderm and mesoderm of early embryos and later in the gut (endoderm). Scientists isolated a large piece of DNA containing the coding sequences and surrounding DNA. They inserted ad Green fluorescent protein (GFP) gene into the first exon of the gatae gene. This created a reporter gene that can be used to identify what sequences are necessary to express the gatae gene properly. Cells expressing the reporter will fluoresce green. When inserted into the embryo, this entire construct caused first mesoderm and endoderm to fluoresce, then endoderm.
The scientists then compared this sequence between two sea urchin species to identify conserved sequences. These were then individually fused to the GFP reporter (Basal promoter, first bit of exon 1, then GFP). They were injected into embryos and GFP expression was assayed. The results are below.
Gatae BAC is the whole piece of DNA with GFP. 10 and 24 are pieces of DNA that showed GFP expression. What can you say about how this gene is transcriptionally regulated?
The spatial and temporal expression of the 10-GFP reporter are shown below. What does this tell you?
The spatial and temporal expression of the 24-GFP reporter are shown below.
If you take the whole BAC reporter with all the sequences and delete just piece 10, you get what is shown below. The whole BAC is shown in blue. The reporter where piece 10 has been deleted is shown in red. What does this mean?
A similar deletion of piece 24 is shown below.
Create a model of how this gene is transcriptionally regulated.