The centromeres of all four chromosomes of D. melanogaster aggregate to form a chromocenter that consists largely of heterochromatin.

TLS Online TPP Program

#Id: 7408

#Unit 5. Developmental Biology

The engrailed gene is activated in cells that have high levels of the Even-skipped, Fushi tarazu, or Paired & repressed in cells that have high levels of Odd-skipped, Runt, or Sloppy-paired

TLS Online TPP Program

#Id: 7409

#Unit 5. Developmental Biology

The wingless (wg) gene is activated in those bands of cells that receive little or no Even-skipped or Fushi tarazu protein, but which do contain Sloppy-paired

TLS Online TPP Program

#Id: 7410

#Unit 5. Developmental Biology

Once wingless and engrailed expression patterns are established in adjacent cells, this pattern must be maintained to retain the parasegmental periodicity of the body plan.

TLS Online TPP Program

#Id: 7411

#Unit 5. Developmental Biology

TLS Online TPP Program

#Id: 7412

#Unit 5. Developmental Biology

The maintenance of patterns is regulated by reciprocal interaction between neighboring cells: cells secreting Hedgehog protein activate wingless expression in their neighbors, and the Wingless protein signal, which is received by the cells that secreted Hedgehog, serves to maintain hedgehog (hh) expression

TLS Online TPP Program

#Id: 7413

#Unit 5. Developmental Biology

Wingless protein also acts in an autocrine fashion, maintaining its own expression