Avian hairy Gene Expression Iden4fies a Molecular Clock Linked to Vertebrate Segmenta4on and Somitogenesis

Transcription

1 Avian hairy Gene Expression Iden4fies a Molecular Clock Linked to Vertebrate Segmenta4on and Somitogenesis Pourquie, et. al., 1997 Swetha Mummini, Victoria Fong What is a somite? Defini4on: Segmental block or ball mesoderm formed from paraxial mesoderm adjacent to notochord, form the axial skeleton (vertebrae, ribs), skeletal muscle, dorsal dermis, tendons, joints, and dorsal aor4c cells. Chick somite every 90 minutes 1

2 Clock & wavefront model 2

3 What is c hairy1? Member of the pair rule genes/segmenta4on genes Promotes produc4on of somites Expressed in presomi4c mesoderm (PSM) What does this paper explore? Turning c hairy1 off and on in individual cells during somite forma4on expression of c hairy1 in somite forma4on Autonomy of c hairy1 expression 3

4 What does the clock & wavefront model predict about gene expression in somite forma4on? Is c hairy1 expression in cells oscilla4ng in a pa]ern consistent with the c&w model? Are cells really oscilla4ng or it is a result of cell movement? Is this kind of gene expression a result of relay signaling? Is this gene expression autonomous? c hairy1 gene oscillates once per cell/per wave 4

5 Is c hairy1 expression in cells oscilla4ng in a pa]ern consistent with the c&w model? Figure 3 Is c hairy1 expression in cells oscilla4ng in a pa]ern consistent with the c&w model? Figure 4 5

6 What does the clock & wavefront model predict about gene expression in somite forma4on? Is c hairy1 expression in cells oscilla4ng in a pa]ern consistent with the c&w model? YES Are the cells really oscilla4ng or is it a result of cell movement? Is this kind of gene expression a result of relay signaling? Is this gene expression autonomous? Figure 5 6

7 What does the clock & wavefront model predict about gene expression in somite forma4on? Does gene expression move in a wave like pa]ern? YES Are the cells really oscilla4ng or is it a result of cell movement? NO Is this kind of gene expression a result of relay signaling? Is this wave like gene expression autonomous? Figure 6 A C 7

8 What does the clock & wavefront model predict about gene expression in somite forma4on? Does gene expression move in a wave like pa]ern? YES Are the cells really oscilla4ng or is it a result of cell movement? NO Is this kind of gene expression a result of relay signaling? NO Is this gene expression autonomous? Is this wave like gene expression autonomous? Figure 6 D F 8

9 What does the clock & wavefront model predict about gene expression in somite forma4on? Does gene expression move in a wave like pa]ern? YES Are the cells really oscilla4ng or is it a result of cell movement? NO Is this kind of gene expression a result of relay signaling? NO Is this gene expression autonomous? YES Figure 8 9

10 Summary & conclusions for c&w model in c hairy1 Expression is not due to cell migra4on through PSM it is individual oscilla4ons within cells Individual oscilla4ons within cells are not due to relay signaling it is autonomous within the PSM The molecular clock of c hairy1 con4nues to be debated whether c hairy1 is a central component or if its expression is an output of the molecular clock Discussion 1. How does c hairy1 fit with somitogenesis and the c&w model? 2. When do PSM cells know when to group together and form a somite? 3. Why does it even ma]er? 10

11 Your Ques4ons/Notch & Wnt Vast majority of your ques4ons involved other genes involved in the molecular clock What is Notch? 11