2. Chapter 8 - Early Development in invertebrates The next chapters examine early development in several models, including invertebrates (Ch. 8-9) amphibians (ch 10) and then vertebrates (ch. 11) 1 frog egg becomes ______ cells in __ hours! Fig. 8.1

3. 1._____- One cell is subdivided into many cells to form a blastula 2. ___________- Extensive cell rearrangement to form endo-, ecto- and meso-derm 3. ___________- Cells rearranged to produce organs and tissue 4. ________________- produce germ cells (sperm/egg) Note: Somatic cells denote all non-germ cells General Animal Development Recall from lecture 1

4. How does egg undergo cleavage without increasing it’s ____? Answer- it abolishes ___ and ___ phases of ________. Do you need a cell cycle primer?? Four cell cycle phases M- _________ G1- ________ __- DNA Synthesis ___- Gap 2 a. Cleavage

5. Reminder- mitosis occurs in __ phase, DNA replication in ____________ From Mol. Biol of the Cell by Alberts et al, p864 a. Cleavage

6. _________________ (cdk, cdc) drive the cell cycle But ________ (e.g cyclin A, B…) regulate cdk (cdc) activity ___________ __________ _________ (MPF= cyclin B+cdc2) Example- MPF a. Cleavage

7. Again, how does egg undergo cleavage without increasing it’s size? Answer- it abolishes __ and___ phases of cell cycle Cyclins are _________ in eggs Cyclins are _________ S phase M phase a. Cleavage

8. What actually drives the _______ process? Answer- Two processes- 1. _________________ (mitotic division of the nucleus) The mitotic spindle (microtubules composed of tubulin) does this 2. __________ (mitotic division of the cell) ___________ “pinch off” (microfilaments composed of actin) Fig. 8.3 _____________ prevents cytokineses a. Cleavage

9. 1.Cleavage- One cell is subdivided into many cells to form a blastula 2. __________- Extensive cell rearrangement to form endo-, ecto- and meso-derm 3. Organogenesis- Cells rearranged to produce organs and tissue 4. Gameteogenesis- produce germ cells (sperm/egg) Note: Somatic cells denote all non-germ cells General Animal Development Recall from lecture 1

10. Gastrulation- cells of blastula are dramatically _______________ Three germ layers are produced Five types of _____________ 12 3 b. Gastrulation

11. Gastrulation Five types of movements 45 b. Gastrulation

12. Axis formation Three axes must be determined- ___________________ (head-tail) ________________ (back-belly) ______________ (right side-left side) Fig. 8.7 b. Gastrulation

13. Now let’s take a look at one beast- the ____________ Cleavages 1 and 2 are through ______________ poles Cleavage 3 results in four ________ and four ______cells 12 3 Fig. 8.8 Cleavage 8 _______ (animal pole) plus 4 _________ and 4 ____________ (vegetal pole) 4 1. Cleavage

14. Post cleavage 5Fig. 8.9 Cell fate map

15. _______________ signal other cells via  to influence fate Micromere cell fate is _____________- these become ____________ tissue if placed in a dish All other cells have ____________specification Example- Transplant micromeres to animal pole at ___________ stage Micromeres cause a second __________ Animal pole cells become _______cells Fig. 8.13

16. Sea urchin (continued) Egg Late _______ ________ Later stages Fig. 8.16 Sea urchin development 2. Gastrulation Note-micromeres produce ______ _________ which will become larval _______

17. How do __________ cells know to migrate inside ________? Answer- changing cell ________________ ___________ Extracellular matrix Basal _____ Primary __________ cell ___________ 98% decrease in ________ affinity 100-fold increase in _____________ affinity Fig. 8.19

18. How does __________ occur? Terms- Invagination region is called _________ Opening created is called the ___________ Answer- swelling of inner _______ layer Inner layer Outer layer _______ cells secrete chondroitin sulfate proteoglycan, causing inner layer to swell and cause _________ ________

19. Now let’s take a look at another creature- the nematode C. elegans ___cells at maturity ____ long Produces eggs and sperm (___________) Transparent __ hours from egg to hatch Entire genome sequences- ___________ genes What a great model! 1mm

20. Mature eggs passes through the ________ on the way to the _______ Germ cells undergo ______, then begin meiosis as travel down _________ Oviduct Cleavage C. elegans 1. Cleavage

21. Cleavages 1 produces _______ cell (AB) and ______ cell (P1) Cleavage 2 results in three _______ cells and one ______ cell (P2) 12 3 Remaining cleavages result in a __________ cell and more founder cells Fig. 8.42 C. elegans

22. How is the ____________ _______ axis determined? Answer- ___________- ribonucleoprotein complexes ________ always stay associated with the “P” cell Fig. 8.43 C. elegans 1 3 5 ____ proteins- these specify ______, cell ________ and cytoplasmic __________. What directs the __________?

23. C. elegans 1. Cleavage P1 develops ________________ AB does not (thus is ____________) What drives P1 lineage? P granules? No, these do not enter ________! Other possibilities _____- a bZIP family transcription factor that control EMS cell fate ______ - a transcription factor required for P2 lineage ______- inhibits SKN-1 and PAL-1 in P2

24. Yes- P2 produces a signal that tells ABp to only _______ and ________ cells, not pharynx like ABa _____ is the receptor on ABp, and _____ is the ligand on P2 GLP-1 is a ____family protein APX-1 is a _____family protein Does P2 dictate fate of _________ cells? An example of _________ signaling