intro to DevSteR Flashcards
(12 cards)
what’s Developmental biology
-the study of the process by which animals and plants grow and develop
-It also involves the study of tissue homeostasis in adulthood (mechanisms important in embryo are maintained in adult hood)
what are stem cells
-found in the embryo and also in adults. Stem cells are also studied in vitro to aid in regenerative medicine
-highly studied- cultured in petri-dish and differentiate into different cells
-produce progeny with different cell type
what does The study of regenerative biology aim to do
-aims to make clear of the natural ability of organisms to replace tissues or organs after they have been removed or damaged
why are model organisms used in DevSteR studies
- complex interactions within the whole organism
- genetics
- surgical accessibility- doesn’t kill animal but you can surgically look at it
- low cost
- ethics - restricted for vertebrates
- genome sequencing- so you can look at sequence of protein for its function
- shared methods and knowledge worldwide - without this= very slow progress
what are Cell fate maps
-what essentially that cell will turn into
- Early on in the embryo, cells all look the same.
- But they may already be fated to give rise to a certain structure or cell type
- Sometimes we can watch patiently for days to follow a cell and its offspring to see what it forms (C.elegans)- label cells with dye put embryo away then look later to see what the cell gives rise to- about 1000 cells
- Otherwise, we need to label the cell so that we can follow the cells for days, weeks or longer
what are Fate maps
-8 cells in embryo
-inject dye into cell B
-B is specified to become muscle in the tail of fish
-signal received by cell telling it to be muscle or does it already know to be muscle (committed irreversibly)
-inject dye into cell C
-C is specified to become eye cells
-lineage tracing
whats Cell fate commitment and plasticity
-take dyed b cell from one embryo and place it in the place of c of another
-2 b cells
-B remains committed to muscle fate. B has been determined by intrinsic factors such as a transcription factor.
-Perhaps the fish would have extra muscle and less eye tissue
-or B has been reprogrammed to C’s cell fate.
This suggests that cell signalling is taking place so that the transplanted cell knows its position- cell signalling in place C
what are Induction (instructive) signals
-dyed D cell put into another embryo in place of A cell- ectopic signalling source
-duplicated D cell
- The fish has less muscle and an extra eye
- This suggests that D is a signalling cell that induces eye cell fate
- These types of experiments that involve physical manipulation of the embryo are called embryology
What do we mean by cell signalling?
- Signals (ligands) are secreted (as proteins) by signalling cells and usually do not pass through the cell membrane
- Specific receptors need to be present on the cell membrane to transduce the signal into the cell
- In this example B and C are competent (receptive) to receive the signal from D because they both express the receptor
- Signal transduction often results in activation of a transcription factor
- There are many exceptions to these rules
-C cell has very specific recs
-lots of signals made by D cells which can’t pass through membrane to neighbouring cell (can’t bind to recs)
how can cell signals have different activities
-patterning cells: a signal can cause identical cells to adopt different fates as they develop - cells are similar and not differentiated therefore adopt different cell fates
-cause cells to proliferate (eg FGF Lecture 3)
-cause cells to live or die (eg Growth Factors)
-allow or block cells from responding to other signals (eg permissive signals)
-attract or repulse cells during migration (eg chemoattractants)
-regulate cell metabolism (eg insulin) etc
-Signal pathways often can have more than one activity
whats Gene expression analysis
- Expression analysis tells us about what is happening within a cell or regionally within a tissue
-all have same genes, its which ones are activated which make it different
-RNA in situ hybridisation stains cells blue/purple if they express the RNA for a particular gene - Antibody staining is a technique that uses antibodies to detect where specific proteins are expressed
-The edge of the limb bud expresses FGF4 which is a signal- drives proliferation
-Actin staining (in green) shows the cytoskeleton of these two cells- Fluorescent labels give very high contrast
whats Genetic and ectopic expression analysis
-Since mutations that remove FGF genes result in limbless mice, we know that FGFs are required for limb development. Mouse is a good model for genetic analysis because we can do genetic engineering.
-implant a bead soaked in FGF protein between the limb buds
-This results in a chick embryo with an ectopic limb. This shows that FGFs are sufficient to induce limb formation (in the flank of the embryo).
