Lecture 1 - intro to DevSteR Flashcards
What can we use to study DevSteR?
Model organisms
What is used to study DevSteR?
- model organisms
- key concepts
What is developmental biology?
study of the processes by which animals & plants grow & develop. It also involves the study of tissue homeostasis in adulthood.
What are stem cells?
cells found in the embryo & also in adults. Stem cells are also studied in vitro to aid in regenerative medicine.
What is Regenerative biology?
aims to elucidate (explain) the innate ability of organisms to replace tissues or organs after they have been removed or damaged
What are model organisms used to study DevSteR?
- development of systems involve a range of complex range or interactions within the whole organism.
- genetics (similar/simple)
- surgical accessibility
- low cost
- ethics
- genome sequencing
- shared methods & knowledge worldwide
What type of model organism is expensive to use?
mouse
What type of model organism is inexpensive to use?
drosophila
Why are the ethics of using a vertebrate more problematic compared to those of an invertebrate?
invertebrates are considered to be less neuro-complex
What animal has been studied globally for decades?
drosophila
How long does a zebra fish take to fully form, after fertilisation?
90 days
What are the 6 stages of development in a zebrafish?
- Development of embryo (0-2 hours)
- Cleavage (2-6 hours)
- Gastrulation & epiboly
- Organogenesis
- Hatching
- Adult
What occurs in the cleavage phase during the development of a zebra fish?
- development of sphere stage (1000 cells) - 4 hours
- development of shield stage - 6 hours
What occurs in the gastrulation & epiboly stage during the development of a zebra fish?
- 75% epiboly
- 14 somite stage
What occurs in the organogenesis stage during the development of a zebra fish?
body plan established & major organ visible (16-24hours)
What occurs when a zebra fish hatches?
after 2 days, a zebra fish is free to swim, however it isn’t fully developed.
How long does it occur for a zebra fish to become an adult?
90 days
What are the advantages of using a zebrafish as a model organism?
- vertebrate
- large batches of embryos
- relatively transparent
- external fertilisation
What useful techniques can be carried out using zebrafish?
- mutagenesis/genetics
- cell transplantations
- transgenesis
What are the disadvantages of using a zebrafish as a model organism?
- complex genome with gene duplication
- not inbred (high variation)
How long does it occur for birth to occur in a mouse?
50 days (8 weeks)
Describe the steps involved in the development of a mouse
- Cleavage
- Implantation
- Gastrulation (& turning)
- Organogenesis
- Feral growth & development
- Birth
What are the advantages of using a mouse (Mus musculus) as a model organism?
- it is a mammal
- rapid generation time (8 weeks)
- inbred strains (low variability)
In which useful technique are mice useful as, when using a model organism?
- embryonic stem cells allow for gene knockout
What are the disadvantages of using a mouse (Mus musculus) as a model organism?
- internal embryos have poor access
- small batches of embryos
- expensive
- ethical issues
What are the 2 types of African-clawed frog used as a model organism?
- Xenopus laevis
- Xenopus tropicalis
What are the stages in the development of an African-clawed frog?
- Egg
- Cleavage
- Gastrulation
- Organogenesis
- Metamorphosis
How long does after fertilisation does it take for a tadpole to form in African-clawed frogs?
60 days post-fertilisation
How long is an African-clawed frog an egg for?
1-5 hours
What occurs in the cleavage stage during the development of an African-clawed frog?
Blastula (stage 8) is formed, after 5-10 hours
What occurs in the gastrulation stage during the development of an African-clawed frog?
- Gastrula (stage 12)
- Neurula (stage 16)
10-20 hours
What occurs in the organogenesis stage during the development of an African-clawed frog?
- Tailbud embryo (stage 26)
- Free swimming tadpole (stage 45)
1-4 days
What occurs in the metamorphosis stage during the development of an African-clawed frog?
development into an adult occurs between (4-60 days)
What are the advantages of using an African-clawed frog as a model organism?
- external fertilisation
- large batches of embryos
- large embryos & cells
What are useful techniques in which an African-clawed frog would be a useful model organism?
- injections
- tissue transplantation & tissue culture
- transgenesis
What are the disadvantages of using an African-clawed frog as a model organism?
- long generation time (1+ years)
- yolky embryo - not transparent
How long does it take after fertilisation for a fully developed chick (Gallus gallus domesticus) to develop?
60 days
What are the different stages of the development of a chick?
- Egg (blastoderm)
- Cleavage
- (Laying) gastrulation
- organogenesis
- Hatching
Where does the development of the Chick egg & cleavage take place?
development occurs within the oviduct
What occurs in the (Laying) gastrulation stage during the development of a chick.
- Stage 4 - Hensen’s node & primitive streak
- Stage 14 (22 somites)
What occurs in the organogenesis stage during the development of a Chick?
stage 30
What occurs after organogenesis in a Chick?
hatching into a chick, then adult chicken (day 60)
What is the advantage of using a chick as a model organism?
- big embryo
- tetrapod
What useful techniques are applicable when using a Chick as a model organism?
- tissue transplantation
- transient genetic manipulation
What is the disadvantage of using a chick as a model organism?
not accessible early, limited genetics
How can we analyse the fate of a cell without watching it for days/weeks?
label the cell fluorescently & see where is fluorescing
What is another reason that you would fluorescently label cells to create a cell fate map?
There are too many cells involved in vertebrates to follow each cell
Describe the steps to creating a fate map
- A dye is injected into 1 of the embryo cells
- This permanent dye labels it
- The animal can then be allowed to develop
- The dyed area can then be said to have developed from that area of the embryo.
This is called linage tracing
What does it mean when a cell is specialised?
This means that a cell can become specified to become a certain part of the body.
What does it mean if a cell is committed?
It is certain to make a certain cell.
How can you test for commitment of a cell?
This can be tested by taking out a cell & placing it in the position of another cell, on another organism.
What can be said about a cell if it has been committed?
It has been DETERMINED by INTRINSIC FACTORS - e.g. transcription factors
What can be said about a cell if it hasn’t been committed?
It has been reprogrammed using cell signalling.
How would you find out what surrounding cells release certain cell signalling involved in the reprogramming of surrounding cells?
The relocation of surrounding cell - e.g. cell D - can lead to the development of a certain cell type to the cell signals induced by cell D,
What is the name given to the cell that provides cell signals that can induce a cell to specialise?
Ectopic signalling source
What is the name given to the area of research which involves physical manipulation of an embryo?
Experimental embryology
What is meant by cell singalling?
Signals are secreted by signalling cells & usually don’t pass through cell membrane
What are needed in order to allow a signal to transduce the signal into the cell?
specific receptors
How should cell B be described if it expresses the right receptor to receive the signal from cell D?
cell B is COMPETENT (receptive) to cell D
What does signal transduction often lead to?
Activation of transcription factors
What are the different activities of signals?
- patterning cells - a signal can cause identical cells to adopt different fates as they develop.
- proliferation
- cause cells to live/die (growth factors)
- allow or block cells from responding to other signals.
- attract or repel cells during migration
- regulate cell metabolism
Signal pathways often can have more than one activity
Why does gene expression analysis take place?
expression analysis tells us about what is happening within a cell or regionally within a tissue.
What does RNA in situ hybridisation do?
stains cells blue/purple if they express the RNA for a particular gene.
What is antibody staining?
a technique that uses antibodies to detect where specific proteins are expressed (can be made to be highly specific and only recognise a specific protein.
What type of fluorescent labels does antibody staining usually use?
fluorescent labels with a very high contrast (everything not labelled is black)
What are FGFs REQUIRED for?
limb development
Why is a mouse a good model for genetic analysis?
As we can do genetic engineering?
What experiment showed that FGFs are SUFFICENT for limb development?
FGF protein placed between limb ducts in chick. This lead to a chick developing with an ectopic arm. As a result it can be said that FGFs are sufficient to induce limb formation.
