Introductory Lecture

Question 1

What is DevSteR?

Answer 1

Study of the process by which animals and plants grow and develop
Involves the study of:
- Tissue homeostasis in adulthood
-Stem cells in vitro (to aid in regenerative biology)

Question 2

What is the aim of studying regenerative biology?

Answer 2

To elucidate innate ability of organisms to replace tissues or organs after they have been removed or damaged

Question 3

Why do we use in vivo model organisms to study DevSteR?

Answer 3

• Complex interactions within the whole organism
• Genetics
• Surgical accessibility
• Low cost
• Ethics ~ restricted for vertebrates
• Genome sequencing
• Shared methods and knowledge worldwide

Question 4

Vertebrate models of development - Zebra Fish

Answer 4

Yolk as food source
Single cell egg is formed which then divides through cleavage
Starts to form a body but still has yolk sack

Question 5

Vertebrate models of development - Mouse

Answer 5

Cells divide by cleavage to form a blastocyst
Problem as blastocyst implants into womb and to get access to embryos normally have to kill mother (ethical issue)
Cannot look at single cell as embryo is large and not transparent
Born 2 weeks post fertilisation and then dependent on mother’s milk

Question 6

Vertebrate models of development - Frog

Answer 6

Two species of frogs normally used, Xenopus laevis and Xenopus tropicalis (don’t forget to write in italics)
Develop into a tadpol in about a day, very quick but then takes a year to become sexually mature

Question 6

Vertebrate models of development - Chick

Answer 6

Internal fertilisation
Egg layed after 16 hours, can’t study early development
Scientists put little window in egg shell to observe embryonic development, and to do genetic manipulation
Experiments only occurring on embryos atm, not on chicks once they hatch

Question 7

Advantages of using Zebra fish

Answer 7

• Vertebrates
• Large batches of embryos
• Relatively transparent
• External fertilisation

Question 8

Advantages of using Mice

Answer 8

• Mammal
• Rapid generation time (8 weeks)
• Inbred strains (low variability)

Question 9

Advantages of using Frogs

Answer 9

• External fertilisation
• Large batches of embryos
  LArge embryos and cells

Question 10

Advantages of using Chicks

Answer 10

• Big embryo
• Tetrapod

Question 11

Useful techniques when using Zebra fish

Answer 11

• Mutagenesis/genetics
• Cell transplantations
• Transgenesis (introduce foreign gene to embryo to see effect)

Question 12

Useful technique when using mice

Answer 12

• Embryonic stem cells allow for gene knockout

Question 13

Useful techniques when using frogs

Answer 13

• Injections
• Tissue transplantation
• Tissue culture transgenesis

Question 14

Useful techniques when using chicks

Answer 14

• Tissue transplantation
• Transient genetic manipulation

Question 15

Disadvantages of using zebra fish

Answer 15

• Complex genome with gene duplication
• Not inbred (high variation)

Question 16

Disadvantages of using mice

Answer 16

• Internal embryos ~ poor access
• Small batches of embryos
• Expensive
• Ethical issues

Question 17

Disadvantages of using frogs

Answer 17

• Long generation time (1+ year)
• Yolk embryo ~ not transparent

Question 18

Disadvantages of using chicks

Answer 18

• Not accessible early in development
• Limited genetics

Question 19

Key Concept - Cell fate maps

Answer 19

Cell all initially look the same but are already fated to give rise to certain structures or cell type
Sometimes can just wait and watch what the cell and following offspring form (C. elegans)
But sometimes need to label cell so we can follow it for however long we need to

Question 20

Terms used to describe cell fate

Answer 20

Similar to family ancestry
- Daughter cells
- Cell lineage
- Descendants

Question 21

Key concept: Cell fate commitment and plasticity

Answer 21

Ectopic - when you put the cell in the wrong place, e.g. B into C’s place
Reprogramming - when you move a cell to a different position and it now forms something different
Committed - when you move a cell to a different position and it still forms the same thing, the cell has been determined by intrinsic factors, e.g. a transcription factor

Question 22

Key concept: Induction (instructive) signals

Answer 22

Experimental embryology - Experiments that involve physical manipulation of the embryo
Ectopic signalling source - when a cell signals to cells around it to form something specific, and if you move this cell it will just form the same thing just in a different place e.g. an eye

Question 23

Cell signalling

Answer 23

Signals are secreted by signalling cell, don’t normally pass through the cell membrane
Specific receptors required to be present on cell membrane to conduct signal into the cell
If a cell is competent it means it is receptive to receive the signal
signal transduction often results activation of transcription factor
there are often exception to these rules

Question 24

Other key techniques: gene expression analysis

Answer 24

Expression analysis tells whats happening in cell or regionally in tissue
RNA in situ hybridisation stains cells blue/purple if express RNA for particular gene
Antibody staining related techniqueuses gene specific antibodies to detect where proteins are expressed
actin staining shows cytoskeleton of cells

Question 25

Other key techniques: genetic and ectopic expression analysis

Answer 25

Since mutations that remove FGF genes result in limbless mice, know that FGFs are required for limb development
Mouse good model for genetic analysis because can do genetic engineering
if implant bead soaked in FGF between limb buds in chick embryo results in ectopic limb
shows FGF sufficient induce limb formation