1. A Fly by Any Other Name …

2. Segmentation of Larvae

3. Three Classes of Segmentation Genes mutant wild type

4. Gradients of Maternal Effect Gene Products Direct Subsequent Patterning Gap gene expression is regulated by bcd, hb, & cad Gap genes in turn regulate pair-rule & segment polarity genes and autoregulate themselves

5. Expression of Gap Genes Ems, btd, otd – expression pattern similar to hb activated by bcd

6. Interaction of Maternal Effect & Gap Genes

7. Gap Genes as Txn Regulators Eve txn reg sequences

8. Transgenic Analysis of Eve Expression

9. Expression of Pair-rule Genes Expressed in 7 vertical stripes corresponding to parasegments Expression is at border of segments

10. Refinement of Pair-rule Gene Expression Ftz expression (brown) in 7 stripes corresponding to even numbered parasegments co-stained for eve expression (blue) in odd numbered parasegments

11. Segment Polarity Genes Pair-rule genes define every other parasegment In turn, pair-rule genes regulate segment polarity genes

12. Segment Polarity Genes Expressed in a single column of cells at the posterior/anterior border of every parasegment PA

13. Segment Polarity Genes wg, hh, en signaling specify individual cell types within parasegment

14. Gradients of Wg & Hh

16. Homeotic Genes Gap genes & pair-rule genes initiate homeotic gene expression in proper domains Segment polarity genes confine homeotic gene expression to appropriate parasegments Homeotic genes regulate their own expression

17. Homeotic Selector Genes

18. Autoregulation of Homeotic Genes Each homeotic gene is negatively regulated by the more posteriorly expressed homeotic genes Antp txn is repressed by Ubx LOF mutations in homeotic genes causes anterior transformation GOF mutations in homeotic genes causes posterior transformation

19. Ultrabithorax LOF Mutation

20. Dominant Antennapedia Mutation