The analysis reveals how the cross-regulatory network is able to establish sharp gene expression boundaries (among target genes that, if expressed in isolation, would have a graded or uniform expression profile).
At all stages analyzed, barhl2 and atoh7 expressions appear mostly mutually exclusive (examples are highlighted with asterisks in Figure 4I-J, N-O), although few cells co-expressing both genes are always visible at the expression boundaries (as indicated by arrows in Figure 4D-E, and 4N-O).
UK laws outlaw hate speech and criminalise grossly offensive expression, but because there have been very few court cases over artistic expression, boundaries are often controlled by non-judicial considerations such as public opinion and taste, Index notes.
Using an engineered transcriptional repressor gradient, we demonstrate that overlapping repressor and activator binding sites provide more robust repression and sharper expression boundaries than non-overlapping sites.
Their initial expression takes place shortly after the establishment of the primitive streak, in the posterior-most part of the mouse embryo and is a determinant step for setting up the definitive Hox expression boundaries along the antero-posterior body axis.
Furthermore, Nereis and Platynereis lack spatial colinearity of anterior expression boundaries, and only two larval segments have corresponding Hox gene expression boundaries (Figure 15, [11]).
Nereis and Platynereis lack posterior Hox gene expression boundaries, consistent an absence of morphological boundaries.
In larvae and juveniles, the anterior expression boundaries of CapI-lox2 and CapI-Post2 mark the thoracic abdominal boundary.
As expression patterns mature during late larval and early juvenile stages, posterior expression boundaries appear anterior to the growth zone.
