Intro to Development Flashcards
What three main things does development consist of?
Positional information (cell signalling)
Differentiation (differential gene expression)
Morphogenesis (growth/changes in cell shape/cell movement)
What are the advantages of using nematodes (Caenorhabditis elegans) as a model organism for development?
Transparent (can track individual cells)
Grown in large numbers
Easy to screen for novel drug effects
Useful for study of aging and neural development -> connectivity map of 302 neurons with 7000 synapses exists where functions are known and understood
What are the advantages of using fruit flies (Drosophila melanogaster) as a model organism for development?
Rapid development
Small genome size so easy to understand
Availability of developmental mutants (easy to generate mutants) (for studying gene function)
What are the advantages of using zebrafish (Danio rerio) as a model organism for development?
Small and robust
Transparent (can track individual cells)
Cheaper maintenance than mice
Can lay eggs any time, constant source of embryos (other fish more limited in laying)
->Hundreds of eggs at weekly intervals
What are the advantages of using African clawed toad (Xenopus laevis) as a model organism for development?
Large oocytes
Cell-free extracts rich in protein, DNA, RNA for study
Cell cycle synchrony
Conserved molecular mechanisms with humans
Ease in microinjection
What are the advantages of using mice (mus musculus) as a model organism for development?
99% match with human genome
Easy to generate knock-out or transgenic mice
Easy to tag proteins
Small size -> large scale cost efficient model
Good genetic/molecular toolbox available
Access to embyronic stem cells
What are the advantages of using chicks (Gallus gallus domesticus) as a model organism for development?
Easy to label, transplant and culture cells and tissues
Similar to mammalian development systems (Gestation is same timeframe as mice: 21 days)
Access to egg (by cutting top off shell) for imaging and manipulation (tissue transplants, fluorescent probes, development in-vivo)
What is the name of the pigmented part of the unfertilised Xenopus eggs?
Animal hemisphere
What is the name of the unpigmented part of the unfertilised Xenopus eggs?
Vegetal hemisphere
What stage of embryonic development follows fertilisation in Xenopus?
Cleavage
What stage of embryonic development follows cleavage in Xenopus?
Gastrulation
Describe the structure of a blastula
Epithelium surrounds a more hollow interior
Which organism is most useful for early embryo development study?
Xenopus (frog) due to large eggs
Describe cleavage 1 and 2 in Xenopus embryonic development
Cleavage 1 splits zygote into two, cleavage 2 splits zygote into four. They are perpendicular and equal holoblastic.
The nuclei are displaced and in
animal hemisphere (animal-ward)
Describe cleavage 3 in Xenopus embryonic development
Cleavage 3 is perpendicular/equatorial to 2 and 3.
It is unequal holoblastic (closer to
animal cap, in vegetal region)
What are the two main functions of gastrulation?
Form gut
Form primary germ layers
Which end of where the blastopore begins and ends becomes the mouth and anus of the organism? (Xenopus)
Begins becomes anus
Ends becomes mouth
What are the primary germ layers?
Endoderm
Mesoderm
Ectoderm
What is the blastocoel?
The cavity in the middle of the blastula
What is the blastula?
Stage after the morula, epithelium surrounding hollow interior
What is the morula?
Ball of cells after the 16 cell stage
In vertebrates, what organs does the endoderm go onto form?
Gut, liver, lungs
In vertebrates, what organs does the mesoderm go onto form?
Skeleton, muscle, kidney, heart, blood
In vertebrates, what organs does the ectoderm go onto form?
Skin, nerous system
In insects, what organs does the endoderm go onto form?
Gut
In insects, what organs does the mesoderm go onto form?
Muscle, heart, blood
In insects, what organs does the ectoderm go onto form?
Cuticle, nervous system
Where is the CNS located in vertebrates vs insects?
Vertebrates: Dorsal side
Insects: Ventral side
What position order are the primary germ layers generally in, from outermost to innermost?
Ectoderm -> Mesoderm -> Endoderm
What is an embryo entering the gastrulation stage called?
Gastrula
During development, what can act as inducing signals?
Secreted molecules (as always)
Ligands/molecules bound to surface of other cells (so perceived when cells are in direct contact with each other)
What role in development do signalling pathways involving TGF-Beta receptors usually carry out?
Axis specification
What role in development do signalling pathways involving RTKs usually carry out?
Migration and proliferation
What role in development do signalling pathways involving Wnt receptors usually carry out?
Parasegment boundaries
What role in development do signalling pathways involving Hedgehog receptors usually carry out?
Limb development
What role in development do signalling pathways involving Notch (Delta) receptors usually carry out?
Cell fate decisions in the CNS
What term is given to diffusible molecules that can cause induction at a distance?
Morphogens
Define proximal
Close to the main body
(Eg; Wrist would be proximal, finger tips would be distal)
Define distal
Further point from main body
(Eg; Wrist would be proximal, finger tips would be distal)
Define anterior
Top
(Eg; thumb would be anterior, little finger would be posterior)
Define posterior
Bottom
(Eg; thumb would be anterior, little finger would be posterior)
Define ventral
Front
(Eg; palm would be ventral, knuckles or back of hand would be dorsal)
Define dorsal
Back
(Eg; palm would be ventral, knuckles or back of hand would be dorsal)
What is meant by reciprocal / two-way induction?
One tissue induces another tissue to change fate while this second tissue reciprocally induces the first to adopt another fate
What cell types do kidneys develop from?
Arises from ureteric bud
(epithelium) and metanephric
blastema (mesenchymal tissue)
What does the mesenchyme secrete to induce ureteric bud development?
GDNF morphogen
Knockouts for what prevents ureteric bud from branching?
GDNF, GDNFR or Ret knockouts
