Study Guides (238,613)
Canada (115,253)
Biology (1,065)
BIOL 303 (47)

EMBRYO SQ 15-16 FULL.docx

7 Pages
Unlock Document

University of Waterloo
BIOL 303
Dragana Miskovic

Study questions for lecture 15, 16 Aaron 1. Define proximal-distal, anterior-posterior and dorsal-ventral limb axis. L15S12 a. Proximal distal axis – 3 segments = stylopod (proximal), zeugopod and autopod (distal) that develop in sequence proximal to distal as cartilage first and then bone in the same order b. Anterior-Posterior axis – small fingers (pinky) are posterior (pp), thumbs are anterior c. Dorsal-ventral: palm is ventral, knuckles and nails are dorsal 2. Is the following statement true or false: Wnt proteins stimulate the degradation of Fgf10 in the lateral plate mesoderm, thereby initiating limb bud formation. Explain your reasoning. S23 False because a. wnt – restrict fgf expression pattern to site of limb bud formation in lateral plate esoderm – act as inhibitor i. result stabilizes fgf expression in hind and forelimb not degrades b. Fgf – secreted by mesenchyme cells of lateral plate mesoderm – inductive signal for limb formation i. Evenly Expressed throughout lateral plate mesoderm until wnt expression ii. Induce AER in competent ectoderm between dorsal, ventral sides iii. Fgf8 from AER maintain mitosis and expression of Fgf10 3. Describe the roles of Fgf10, Fgf8, Wnt2b, Wnt8c and Wnt3a in the initiation of the chicken limb bud formation. How the above molecules interact with each other to signal the formation of the limb bud? S22, S27, S30, P492 Protein Role Interactions Fgf10 -paracrine factor that act as inductive signal for limb -Regulate Fgf8 and Wnt3a formation -Positive loop with Fgf8 -Expressed evenly throughout lateral plate mesoderm (stimulate production of Fgf8) -induce formation of AER from ectoderm -help with maintenance and function of AER -express by AER -Positive loop with Fgf10 Fgf8 -maintain AER mitosis and Fgf10 expression -upregulate wnt3 Wnt2b -assist forelimb bud formation Localize Fgf10 in forelimb area Wnt8c -assist hindlimb bud formation Localize Fgf10 in hindlimb area Wnt3a -assist in Fgf loop by inducing formation of fgf8 -Influenced by Fgf10 1 Study questions for lecture 15, 16 Aaron 4. Describe the roles of FGFs, Tbx5 and Tbx4 during limb bud formation in the chick. Outline the experiments which demonstrated the roles of the above proteins. S24, 25 Protein Role Experiment Fgfs -induce formation of AER and -use of Fgf bead that was put into help maintain mitosis of cells area b/w Tbx genes induced within it formation of chimeric limb -half of limb became hind, half became fore depending on location (affected by Tbx) =show boundary b/w tbx5 & tbx4 Tbx5 Control forelimb specification -use of in situ hybridization – Tbx4 Control hindlimb specification label complementary RNA strand that binds to target RNA (Tbx) which allows coloured location of protein expression -Tbx5 was in forelimb bud area -tbx4 was in hindlimb bud area 2 Study questions for lecture 15, 16 Aaron 5. What is AER? What is PZ? How is the interaction between AER and PZ governing the limb growth? S27, 28 –don’t mention proximal, distal, talk about what does what a. AER = apical ectodermal ridge i. Major signalling centre for all 3 axis ii. Controls mesenchyme cells of progress zone (PZ) iii. Roles 1. Maintain PZ in state of proliferation to allow linear proximal-distal growth of limb 2. Maintain expression of molecules that generate AP axis 3. Interact w/ proteins that specify AP and DV axis to provide cells w/ differentiation info iv. Control when cartilage forms from PZ cells b. PZ = progress zone i. Area underneath AER ii. Contains cells going through mitosis (proliferating distal bud mesenchyme) 1. Proliferation state maintain so limb bud grow and not form cartilage until right time iii. Fgf8 from AER maintain state proliferation 6. Outline the results of grafting experiments which helped defining the interaction between AER and PZ. S29 –talk about polarity (proximal, distal) a. AER removal = limb development stop b. Extra AER graft onto existing limb bud = duplication = mirror image limb c. Leg mesenchyme placed below wing AER = beginning of limb is wing, end of limb is leg d. Limb mesenchyme replace by non-limb mesenchyme below AER = AER regress and limb development stop e. AER replace by Fgf bead = normal limb made b/c AER make Fgfs i. Mesenchyme under AER determine what limb grow into ii. AER responsible for DP growth 3 Study questions for lecture 15, 16 Aaron 7. Outline the experiments which showed that the specificity of the proximal-distal limb axis is determined by the limb mesoderm and not by the AER. S34 a. experimen
More Less

Related notes for BIOL 303

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.