L19 - key concepts in dev bio

Question 1

whats the name of the important chordate used in experimental dev bio - looks like jellyfish

Answer 1

ciona intestinalis
or a tunicate

Question 2

What type of development is seen in tunicate embryos

Answer 2

mosaic development

Question 3

describe briefly the experiment that proved cytoplasmic determinents for what the cells turns into

Answer 3

needle pushed throught the devleoping embryo
pushes the muscle-forming cytoplasm into a different region

the diff region starts making muscle cells

Question 4

whats the name of the mRNA in insect (drysophila specicially) embryos that makes the anterior structures

Answer 4

bicoid mRNA
when this mRNA is transplanted into different oarts of the embryo, it starts growing anterior structures

Question 5

in the specification map for the frog embryo, which structures aren’t formed

Answer 5

no nervous system
no heart and stuff

Question 6

what is the grey crescent

Answer 6

important bit in embryo that determines orientation in the growing embryo

Question 7

what was roux’s experiment and why was it flawed

Answer 7

at the 2 cell stage
he destroyed half of the cell to see what would happen to the other half
and he jsut got a normal half embryo
so the development of the other half wasn’t affected

but flawed design since, it was kept in the same environemtn
the other half of the cell was still there, just dead
results werent accurate

Question 8

how did they fix this experiment to get more accurate results

Answer 8

actually seperated the 2 cells
So a lot more like a specification experiment
and got 2 identical twins that developed fine

shows regulative development

But inheritence of the grey crescent VERY impotant for normal develpoment of both twins

Question 9

basic overview of the organiser experiment

Answer 9

transplanted the organiser bit (that is responsible to form the notochord and thus other structures) into the ventral side of another embryo

Formed conjoined twins

Notochord formed as it normally would, even in the transplanted location, but found that the cells around it would start forming muscle cells and nerve cells

Question 10

general process of the 4 signal model of induction of events

Answer 10

VEGETAL POLE induces middle bit to become MESODERM

DORSAL VEGETAL POLE induces cells in dorsal side to become organise

ORGANISER forms the notochord and induces nerve cells and muscle tissue

and then the rest doesnt make sense he didnt explain it

Question 11

descriptive embryology

Answer 11

just describing the process
can be shown in a fate map
no explanation or mechanisms

Question 12

experimental embryology

Answer 12

doing experiments to figure out the mechanisms underlying descriptive embryology

Question 13

mosaic developmetn

Answer 13

autonomous specification of a cell’s fate
instead of depending on cell-cell interactions, are determined by cytoplasmic factors contained within the cell itself

If the cells are removed from the embryo they should, develop according to their intrinsic instructions and differentiate into the appropriate part of the embryo even if the rest of the embryo is not there.

if it is taken out, then it’s noo easily replaced or fixed
the whole things just kinda ruined

Question 14

regulative development

Answer 14

cell-cell signaling interactions determinet the fate of the cell
removed part can be repaired, or even separated blastomeres can form identical twins

If the cells are removed from the embryo they should not fulfill their normal fate because they lack the necessary interactions.

But the gaps left behind are regulated and no change is observed

Question 15

Fate map

Answer 15

descriptive embryology
shows the fate of cell
basically shows what happens if left undisturbed in the emvryo

Question 16

specification map

Answer 16

assessment of what cell/group of cells form if they’re removed from the embryonic environment

part of experimental bio
requires tissues or cells being removed from embryos

Question 17

definition of determined

Answer 17

a cell or tissue is determined if it will still develops according to its fate, even when transplanted into another site in the embryo
Example: the dorsal lip of the
blastopore (organiser) is fated to become notochord and will become notochord even when environemnt is changed as seen in organiser experiments

Question 18

definition of competence

Answer 18

A cell or tissue may be competent to give rise to many cell types that it would not normally be specified to form

eg. the animal cap cells from blastula stage frog embryos, which, although they are specified and fated to give rise only to ectodermal tissues, are competent to form any cell type in the embryo, given the appropriate signals

Question 19

definition of induction

Answer 19

a cell or group of cells emit signals to its neighbouring cells, and influence them to change their fate

e.g. the induction of neural ectoderm by dorsal mesoderm at the gastrula stage (organizer experiment)