Spatiotemporal gene regulation during development
So, the eve gene is regulated by bicoid, hunchback, kruppel, and giant – but how do those transcription factors end up expressed in exactly the right place? And how does it relate to the homeotic mutants we saw at the beginning of this chapter? They are all interdependent.
In the next section, we will look at five different classes of genes that play a role in building body structures along the anterior-to-posterior axis of the embryo.
- Maternal effect genes (like bicoid)
- Gap genes (like hunchback, kruppel, and giant)
- Pair-rule genes (like eve)
- Segment polarity genes
- homeotic genes (like antennapedia and ultrabithorax)
These genes are all part of a larger regulatory network that leads to the differentiation of cells in the embryo. Each gene encodes a protein factor that influences the expression of other downstream genes, either directly or indirectly. Many are transcription factors, but others are signaling molecules that indirectly affect transcription. Some of these mechanisms are discussed later in this chapter. We see that expression is controlled over time and in different spaces within the embryo – spatiotemporal gene regulation. Although this section focuses on anterior-posterior patterning, similar factors influence dorsal-ventral patterning as well.
