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BMS 109 > Developmental Revision > Flashcards

Developmental Revision Flashcards

1
Q

4 developmental problems

A
  • Regional specification - generation of a pattern
  • Cell differentiation
  • Morphogenesis - movement of cells and tissues
  • Growth
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2
Q

Mutation in single copy of PAX6?

Mutation in both copies of PAX6?

A
  • Aniridia (loss of iris)

- Eyes are completely absent with severe brain defects (lethal)

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3
Q

Is PAX6 function sufficient and required fro eye development?

A

Yes, PAX6 is both sufficient and required for eye development

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4
Q

What is both sufficient and required for egg activation after fertilisation?

A

Increase in Ca2+

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5
Q

Organisms that undergo holoblastic cleavage?

- 4 organsims

A
  • C. Elegans
  • Xenopus
  • Mouse
  • Humans
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6
Q

Organisms that undergo meroblastic cleavage?

- 2 organsims

A
  • Chick

- Zebrafish

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7
Q

Organism that undergoes superficial cleavage?

A

Drosophila

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8
Q

4 things that drive tissue rearrangements?

A
  • Cell shape changes
  • Localised cell proliferation
  • Localised cell death
  • Change in expression of cell-surface receptors
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9
Q

8 types of tissue rearrangements (explain them)

A
  • Condensation
  • Epithelium to mesenchymal transition
  • Mesenchymal to epithelium transition
  • Involution
  • Invagination
  • Cavitation
  • Epiboly
  • Convergent extension
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10
Q

Useful techniques of C. Elegans

A
  • Cell ablation

- Mutagenesis

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11
Q

Cell ablation in C. Elegans

A
  • If anchor cell is removed there is no vulva formation
  • If anchor cell is mutated there is no vulva or multivulva formation
  • Shows anchor cell is involved in vulva formation
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12
Q

Useful techniques of Zebrafish

A
  • Mutagenesis
  • Cell transplantation
  • Injections
  • Transgenesis
  • Targeted knockouts
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13
Q

What is a transgenic organism?

  • Unstable transgenic
  • Stable transgenic
A
  • An organism carrying a gene that has been incorporated into its genome using recombinant DNA
  • Unstable - extrachromosomal expression
  • Stable - permanently integrated into genome
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14
Q

Useful techniques of mouse?

A
  • Mutagenesis

- Targeted knockouts via ES cells

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15
Q

Useful techniques of Drosophila?

A
  • Mutagenesis
  • Transgenesis
  • Clonal analysis
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16
Q

Pole cell transplantation in Drosophila

A
  • Cells taken from posterior end of one embryo and transplanted to anterior end of second embryo
  • Cells retained pole cell function
  • Cells then transplanted into posterior end of third embryo and adult fly develops with germ cells with genotype of second embryo amongst its own
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17
Q

2 types of genes that affect development of Drosophila egg (imaginal discs)

A
  • Maternal effect genes - determine polarity of egg (bicoid)

- Zygotic genes - responsible for body plan of embryo

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18
Q

Useful techniques of Xenopus

A
  • Injections
  • Transgenesis
  • Tissue transplantation
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19
Q

Useful techniques of Gallus Gallus?

A
  • Tissue transplantation
  • Retroviral injection
  • Electroporation
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20
Q

Cell fate

A

Is what a cell will normally become in development

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21
Q

Fate maps are used to…

A

Identify the normal fates of cells

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22
Q

4 methods of producing a fate map?

A
  • Observation
  • Natural pigmentation
  • Label/Marker - look for progeny of original cell that have label/marker
  • Orthotopic transplantation - cells taken from labelled organism and implanted in similar place in another embryo
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23
Q

Commitment - Specification is…

A

Reversible

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24
Q

Commitment - Differentiation is…

A

Irreversible

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25
Q

Comparison of fate map with specification map shows that…

A

Cells need to receive signals as they are not specified at the blastula stage

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26
Q

Mosaic development

A

Cells are determined early

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27
Q

Autonomous and Non-autonomous mechanism of Regulative development

A
  • Autonomous mechanism - intrinsic factors make cells different e.g. segregation of cytoplasmic contents
  • Non-autonomous mechanism - extrinsic factors make cells different e.g. signalling molecules
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28
Q

How does the french flag model account for regulative development?

A
  • If length of line varies (more or less cells) the pattern will regulate
  • If the line is cut in half the system will regenerate
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29
Q

What is induction?

A

Signalling from one cell type to another, with a change in specification of the receiving cell

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30
Q

What was the Amphibian Organiser experiment?

A
  • Blastopore lip was grafter onto the ventral side of another embryo
  • This induced formation of a second axis in the embryo and the tissue was derived from the host not the graft
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31
Q

What is competence?

A
  • The ability to respond to a signal

- More cells are competent to respond than actually do so

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32
Q

Xenopus Animal Cap Assay

A
  • Animal cap cells are induced by vegetal tissue

- Animal cap is competent to respond to this induction and become mesoderm

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33
Q

Cap cells are

  • Fated to become…
  • Specified to become…
  • Induced to become…
A
  • Fated to become neural cells
  • Specified to become epidermis
  • Induced to become muscle cells
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34
Q

Bicoid gradient in drosophila embryo?

A
  • Highest at anterior end and decreases towards posterior end
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35
Q

Bicoid codes for transcription factor that activates…

What does this activate

A
  • Hunchback transcription

- Activates cascade of of gene expression and leads to segmentation

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36
Q

Is MyoD sufficient and required to direct muscle fate?

A
  • MyoD is sufficient to direct muscle fate - fibroblasts differentiate into muscle when transfected with MyoD
  • MoD is NOT required to direct muscle fate - mice lacking MyoD still develop skeletal muscle, Myf5 acts redundantly with MyoD
37
Q

What is redundancy?

A

When one gene takes over from dominant gene to undertake same job

38
Q

Forward genetic analysis

A
  • Starts with a mutant phenotype to identify the mutated gene
  • In homozygous recessive
39
Q

Reverse genetic analysis

A
  • Starts with a gene sequence to identify what phenotype arises
  • In homozygous recessive
40
Q

Semi-dominant

A

An intermediate phenotype between dominant and recessive phenotypes seen in a heterozygote

41
Q

Haplosufficient

A

One wild type allele is sufficient for normal development

42
Q

Haploinsufficient

A

One wild type allele is insufficient for normal development

43
Q

Embryonic lethal

A
  • Causes death in the homozygote

- Phenotype common in homozygous knockout mice

44
Q

Null (amorph) mutation

A

Complete loss of protein function

45
Q

Hypomorph mutation

A

Partial loss of protein function

46
Q

Hypermorph mutation

A
  • Overexpression of gene

- Gain in protein function

47
Q

Dominant negative (antimorph) mutation

A

Mutant copy interferes with function of wild type protein function

48
Q

Neomorph mutation

A

Protein acquires new function

49
Q

Process of Mutagenesis

A
  • Expose adult male to mutagen
  • Breed mutations through homozygosity
  • Screen for interesting phenotypes
  • Complementation testing to assign mutations to loci
  • Maintain stock of heterozygous carriers
50
Q

Complementing mutations are in…

A

Different genes

51
Q

Non-complementing mutations are in…

A

The same gene

52
Q

In a complementation test, when 2 different mutants are crossed:

  • If no mutant phenotypes are seen, the genes…
  • If 25% show the mutant phenotype, the genes…
A
  • No mutant phenotype = Complement each other

- 25% mutant phenotype = Do not complement each other

53
Q

Steel mutant

A

No steel factor produced = no pigment cell produced

54
Q

Kit mutant

A

No steel factor receptor produced = no pigment cell produced

55
Q

Epistasis analysis

A
  • Cross between heterozygote mutants to examine the double mutant
  • Phenotype of one mutant masked by the other = recessive epistasis
  • Can be used to determine the order in which genes act
  • Epistatic genes usually act downstream
56
Q

Phenotype of

  • Hh mutants
  • Smoothened mutants
  • Wingless mutants
A

All loss of naked cuticles

57
Q

Phenotype of

- Patched mutants

A

Excess naked cuticles

58
Q

Cell fates in Drosophila

- Dorsal ectoderm express

A

dpp gene

59
Q

Cell fates in drosophila

- Neuroectoderm express

A

rhomboid gene

60
Q

Cell fates in drosophila

- Mesoderm express

A

Twist and Snail

61
Q

Dorsalised mutants

  • Excess of dorsalised material
  • Decreased ventralised material
A
  • Toll, Spätzle and Dorsal mutants
  • Dorsal cannot enter nucleus to activate mesodermal genes (twist, snail and rhomboid)
  • Zygotic gene (dpp) is expressed throughout embryo and all cells adopt a dorsal fate
62
Q

Ventralised mutant

  • Decreased dorsalised material
  • Excess of ventralised material
A
  • Cactus mutant
  • Dorsal enters nucleus of all cells across DV axis to activate mesodermal genes (twist, snail and rhomboid) throughout the embryo
  • Zygotic gene (dpp) is repressed throughout embryo and all cells adopt a ventral fate
63
Q

Dorsal

A

Transcription factor

  • Activates transcription of mesodermal genes (Twist, Snail and Rhomboid)
  • Represses transcription of zygotic genes (dpp)
  • Acts a morphogen
64
Q

Homeotic transformation (2 examples)

A

One structure is replace by another

  • Recessive mutations in Ubx gene cause transformation of 3rd Thoracic segment (haltere) into 2nd Thoracic segment (wings)
  • Recessive mutations in Abd-B gene cause transformation of abdominal segments A4, A5, A6 into A4, A4, A5
65
Q

Autonomous function

A

Mutations that affect the cells in which it is present

66
Q

Non-autonomous function

A

Mutations that affect other cells

67
Q

Selector genes

A
  • Cells in different segments interpret positional information differently due to activity of selector genes
  • Ubx acts as selector gene to direct cells down 3rd thoracic segment pathway
68
Q

Homeobox

A

Codes for a homeodomain which is a sequence specific DNA binding motif

69
Q

Bithorax Complex (BX-C)

A
  • Consists of Ubx, Abd-A and Abd-B
  • Arrangement of genes reflects order in which they function along AP axis
  • Contain homeobox (highly conserved DNA sequence)
  • Expression of Bithorax is spatially restricted
70
Q

Antennapaedia Complex (ANT-C)

A
  • Contains homeobox genes that control development of head and thorax
  • Antennapedia gene is expressed in T2 segment
  • Dominant mutation in Antennapedia gene causes transformation of antenna to legs
71
Q

HOX genes

A
  • Specify segment identity in animals with segmented body plan
  • E.g. determine site of limb bud formation
72
Q

Site of limb bud determined by…

A

HOX genes

- HoxB5 knockout mouse forelimbs develop at a more anterior level

73
Q

HOX genes restrict expression of…

Where is expression restricted to?

A
  • Fibroblast Growth Factors (FGFs)

- Limb forming regions

74
Q

Is FGF sufficient and required for limb bud formation?

A
  • FGF signalling is required - FGFR knockout mice embryos lack limb buds
  • FGF signalling is sufficient - Local application of FGF4 protein results in ectopic limb buds
75
Q

3 regions of limb bud and function

A
  • Apical Ectodermal Ridge (AER) - maintains the progress zone
  • Progress Zone (PZ) - length of time spent in PZ determines cell fate
  • Zone of Polarising Activity (ZPA) - patterns AP axis of limb
76
Q

Manipulation of AER

A
  • Removal of AER results in truncated limbs

- AER can be replaced with beads soaked in FGFs to give normal development

77
Q

Manipulation of PZ

A
  • Length of time spent in PZ determines cell fate

- Cells that are first to leave PZ form proximal parts of limb

78
Q

Manipulation of ZPA

A
  • When transplanted from posterior limb bud to under anterior AER, results in symmetrical duplications of normal limb
  • Shh is expressed in ZPA
  • ZPA can be replaced with beads soaked in Shh to give normal development
79
Q

Proneural cluster cell fates

A
  • One cell becomes a neuroblast (primary cell fate)

- Other cells become epidermal cells (secondary cell fate)

80
Q

In a pro neural cluster:

  • Cell displaying lots of Delta becomes…
  • Cells displaying lots of Notch become…
A
  • One cells displays lots of Delta -> Neuroblast

- Other cells display lots of Notch -> Epidermis

81
Q

Recessive mutations in Delta or Notch result in…

A

Lots of neuroblasts and no epidermis

82
Q

How do neuroblasts form neurones?

A
  • Neuroblasts delaminate from neuroectoderm and undergo asymmetrical division to form another neuroblast and a ganglion mother cell
  • Ganglion mother cell divides again to form cells that differentiate into neurones
83
Q

Short range cues for axon growth cone…

Long range cues for axon growth cone…

A
  • Short range - cell-cell contacts (surface markers)
  • Long range - diffusible molecules
    Can be attractive or repulsive signals
84
Q

4 cells of sensory bristle

A
  • Hair cell
  • Sheath cell
  • Socket cell
  • Neurone
85
Q

What cell gives rise to cells of sensory bristle?

Where do they arise from?

A
  • Sensory Organ Precursor (SOP) cells

- SOP cells are singled out in pro neural clusters

86
Q

How does numb and notch interact?

A

Numb inhibits notch function

87
Q

Loss of Notch function results in…

A

4 neurone cells

88
Q

Loss of Numb function results in…

A

4 socket cells

BMS 109 (8 decks)

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