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39 Cards in this Set
- Front
- Back
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Who named and found mRNA and pioneered use of C. elegans as a model organism for developmental biology? |
Sydney Brenner |
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What is Type One Embryogenesis? - 3 characteristics - give 2 example animals |
Type One Embryogenesis
Ex. Sea Urchin and C. elegans |
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Why is C. elegans a good model organism? 5 things |
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What Genes and Signalling pathways does C elegans have? 4 What is it lacking? |
1) Hox genes 2) TGF-B 3) Wnt pathway 3) Notch pathway DOES NOT HAVE HEDGEHOG |
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Describe C. elegans Development - Development? - Specification - Cleavage |
INVARIANT Embryonic development AUTONOMOUS Specification (usually) - can also see conditional specification and regulatory development ROTATIONAL HOLOBLASTIC Cleavage NO PLASTICITY |
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C. elegans is a Hermaphrodite, how does fertilization occur? |
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Where do C elegans eggs undergo cellularization? |
They undergo cellularization as they move down the ovary - NO MITOSIS OR CYTOKINESIS |
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What type of cleavage does C. elegans undergo? Cleavage divisions are symmetrical or asymmetrical ? |
ROTATIONAL HOLOBLASTIC - Holoblastic = complete cleavage - Rotational = 2 blastomeres divide in different planes (meridonally or equatorially) ASYMMETRICAL |
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Divisons of blastomeres produces what two types of cells? |
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When is the A/P Axis established and what event establishes it? |
FIRST DIVISION - entry of sperm = POSTERIOR end - Sperm derived centriole initiates cytoplasmic movement and pushes sperm pronucleus to the nearest end => made the Posterior |
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What are PAR genes, what do they do? |
Partition Defective Genes - maternally loaded into oocyte - act as MECHANISM that ESTABLISHES POLARITY |
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In early zygote, how are PAR genes distributed? |
All PAR proteins enriched near or at cortex - adopt asymmetrical localization pattern as cell polarization develops |
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C. elegans ONE CELL stage is polarized by what? Where are the diff types of PAR proteins concentrated |
Polarized by CONTRACTION OF ACTOMYOSIN CORTEX to Anterior side of cell PAR-3 & PAR-6 = concentrated in ANTERIOR PAR-1 & PAR-2 = concentrated in POSTERIOR |
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What two putative signs does the sperm give to induce the actomyosin contraction? |
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Described the oocyte and PAR protein distribution before Fertilization |
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Described the zygote and PAR protein distribution after Fertilization - what role does the centrioles play? - what do microtubules do |
Sperm contributes 2 centrioles to zygote = KEY TO SETTING UP POLARITY
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How does the ACTIN-MYOSIN CONTRACTION occur? - what does it establish |
Polarization & Establishment of A/P Axis depends on the CYTOSKELETON
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What are GTP- binding proteins (GTPases) / G-Proteins considered as? |
MOLECULAR SWITCHES - phosphorylation of proteins either activates or inactivates them |
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What is Rho? - what does it do, regulate, activate, affect? |
Rho is a G-Protein - regulates aspects of actin dynamics - affects actin-myosin organization - cytoskeletal movement - activates myosin based contractility - cell shape |
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What is CYK-4? |
RhoGap => Locally Inactivates Rho on one side of the cell - inhibits contractility of actin-myosin on side of sperm entry |
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What produce the asymmetrical distribution of PAR-3 & PAR-6 proteins in the Anterior and PAR-1 & PAR-2 proteins in the POSTERIOR? |
Combo of:
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What happens to eggs that are fertilized with sperm that has CYK-4 knockdown? |
Eggs do not polarize and they die |
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What do PAR proteins localize? |
P-Granules |
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What are P-Granules |
Ribo-nucleo- PROTEIN COMPLEX that SPECIFIES GERM CELLS - have specific translation regulators - Maternally loaded mRNA & protein complex |
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Where are P-Granules located - before fertilization - after fertilization |
Before: found throughout embryo After: LOCALIZED IN POSTERIOR |
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What cells inherit P-Granules? What do these cells form later? What trans factor do they also inherit that is required for them to form? |
P1 Cells - P-Lineage cells - descendants form the germline Inherit PIE-1 = trans factor required for germ cell fate ** P cell behaves as a stem cell |
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How do we know P- Granules are localized by microfilaments (actin) ONLY ? what experiment was performed |
Treated eggs with CYTO-CHA-LASIN D: - drug that disrupts microfilaments - P Granules NOT localized in posterior Treated eggs with COL-CHI-CINE: - drug that disrupts microtubules - P Granules LOCALIZED in posterior |
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The inheritance of P-Granules and PIE-1 trans factor which then specifies the germ cell fate is an example of what? |
AUTONOMOUS SPECIFICATION - no cell -cell interaction |
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In TWO CELL STAGE we see both autonomous and conditional specification. How was autonomous specification shown? |
Isolated P1 Cell
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In TWO CELL STAGE we see both autonomous and conditional specification. How was conditional specification shown? |
Isolate AB Cell
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When is the Dorsal/Ventral Axis established in C. elegans and how is it specified? |
4 CELL STAGE through CONDITIONAL SPECIFICATION |
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Dorsal/Ventral Axis relates to the division of which cell? How is the dorsal and ventral sides determined? |
AB Cell
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What is another example of Conditional Specification to do with the EMS cell? What happens if you switch the side for the EMS cell? |
At 4 Cell Stage, EMS divides to produce - MS Cell = future mesoderm - E Cell = future endoderm * Without P2 cell = EMS produces TWO MS Cells - No endoderm Changing the side for EMS reverses the normal polarity (D/V axis) |
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What is another example of Conditional Specification at 4 Cell stage of ABp cell? - what cell is required for successful production of ABp cell descendants? - what cell does ABp have to be in contact with at 4 cell stage and why? - does anything happen if you switch the ABa and ABp positions? |
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ABp specified by P2 cell how? what is the signalling pathway |
Juxtacrine Cell-Cell Interaction ABp has a GLP-1 protein = NOTCH RECEPTOR P2 has a APX-1 protein = DELTA LIGAND |
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What signal results in the polarizing of the EMS cell to E & MS? What does this signal instruct EMS to make? |
An inductive signal from P2 - P2 signal = MOM-2 (~Wnt) - EMS Receptor = MOM-5 (~Frizzled) MOM-2 signal instructs EMS tof form gut structures (E Cells) ` |
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When does the Left/ Right specification occur? |
In the 3rd Cleavage Division - 6 Cell stage * Conditional Specification |
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When does C. elegans Gastrulation begin? |
Right after the generation of the P4 Cell ~ 24 cell stage |
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What are the steps for C. elegans gastrulation? |
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