Development L 17 Notes

Question 1

What is developmental biology?

Answer 1

• Developmental Biology:
- Study of:
 Growth of an organism from a fertilised egg to an adult organism
 How that organism reproduces
 How it repairs & replaces cells or tissues after injury or under normal homeostatic conditions.

Question 2

Why is developmental biology important?

Answer 2

• Importance of Developmental Biology:
- Better undertstanding of underlying basis -> congenital birth defects.
- Dev. of more effective treatments for human diseases Eg. Regenerative medicine.
- Cannot understand evolution without understanding development
 Selection acts upon phenotype

Question 3

What does LECA stand for?

Answer 3

• LECA:

 Last Eukaryotic Common Ancestor

Question 4

Describe why Arabiopsis thaliana is used as a model organism / the benefits

Answer 4

• Arabidopsis thaliana (Thale Cress)

• Small
• Easy to grow
• Short generation
• Flowering plant
• Embryology
• Good imaging
• Genetics
• Sequenced genome
• Trasngenesis
• Agrobacterium -> Make transgenic plants

Question 5

Describe why Dictyostelium discoidum is used as a model organism / the benefits

Answer 5

•	Dictyostelium discoidum
-	Chemotaxis 
-> Moves towards signals sent by other molecules (CAMP) to aggregate & form 
    fruiting body under stressful conditions.  
-	Genetics
-	Multicellularity 
-> Single amoeba cell which can aggregate to form fruiting body understressful 
     conditions. 
-> Low food conditions -> form spores. 
-	Good imaging
-	Sequenced genome
-	Transgenesis
-	Social behaviour
-	Cheating & altruism
-	Chemotaxis toward cAMP

Question 6

Describe why Hydra are used as model organisms / the benefits

Answer 6

•	Hydra
-	Metazoans -> Animals
-	Radial symmetry
-	Diploblastic 
Ectoderm & Endoderm
-	Small 
-	Easy to grow
-	Sexual & Asexual reproduction
-	High regenerative capacity

Question 7

Describe why Planaria are used as model organisms / the benefits

Answer 7

•	Planaria:
-	Bilateral symmetry 
-	Triploblastic
Ectoderm, mesoderm & endoderm
-	RNAi knockdown technology
-	Adult stem cells
-	Sexual & Asexual reproduction
-	High regenerative capacity

Question 8

Describe why Caenorhabditis elegans are used as model organisms / the benefits

Answer 8

•	Caenorhabditis elegans
-	Short Generation time 
-	Sexual & self-reproduction 
-	Males & hermaphrodites
Hemaphrodites produce eggs & sperm 
   --> Can self-fertilise & perform genetic cross -> One organism. 
-	Genetics
-	RNAi knockdown technology 
-	Sequenced genome 
-	Study -> Aging 
-	Lineage of all cells known 
-	Imaging
-	Provided most knowledge -> Cell death

Question 9

Describe why Ciona intestinalis: (Sea urchins, starfish, sea cucumbers) (Amphipod crustacean) are used as model organisms / the benefits

Answer 9

• Ciona intestinalis:

• Basal chordate
• Transgenesis
• Genetics
• Sequenced genome
• Imaging
• Develop notochord in dev. after 1 day

Question 10

Describe why Brachiostoma Ianceolatum are used as model organisms / the benefits

Answer 10

• Danio rerio: (Zebrafish)

• Genetics
• Sequenced genome
• Transgenesis
• Imaging
• Transparent embryos
• Regeneration capacity
• External development
• Vertebrate

Question 11

Describe why Xenopus (Frogs) are used as model organisms / the benefits

Answer 11

Xenopus:
- Embryos produced -> Large nos
- External development
- Rapid development
- Cell division
- Transparent tadpoles
- Easy -> production of explants & transplants
Can cut embryos -> albino & pigmented. Attach different halves -> rapid effective healing -> produce half albino & half pigmented individuals.
- Generation of transgenic embryos
-  Promoter elements / regulatory proteins of other organisms
-> Mouse elastase-GFP transgenic embryo -> insertion of other organism
-> Mouse Tie2-GFP transgenic tadpole -> Circulatory system
- Rapid, effective wound healing
Imaging
- Regeneration of appendages -> tadpoles
- Tetrapods

Question 12

Describe why Gallus gallus (Chicks) are used as model organisms / the benefits

Answer 12

• Gallus gallus (Chick)

• Transplantation experiments
• Sequenced genomes
• Overexpression & knockdown experiments
• Imaging
• Development of embryo outside cell

Question 13

Describe why Mus musculus: (Mice) are used as model organisms / the benefits

Answer 13

• Mus musculus: (Mouse)

• Mammal
• Strong genetics
• Sequenced genome
• Mammal
• Pluripotent embryonic stem cells
• Short generation time

Question 14

Describe why Homo sapiens are used as model organisms / the benefits

Answer 14

• Homo sapiens

• Genetics
• Sequenced genome
• Mammal
• Induced pluripotent stem cells
• Large population
• Large no. mutated genes

Question 15

Describe the benefits of Developmental Biology Studies:

Answer 15

• Developmental Biology studies:
- Rich source of information -> variety of model organisms
- Enable better understanding -> Biodiversity
-> Congenital disease
- Investigation -> mechanisms leading to tissue formation , repair & regeneration
 Enable clinical interventions
-> improving healing, transplant & regeneration of tissues following injury /
aging process.