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Developmental Biology > Test 3 > Flashcards

Test 3 Flashcards

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1
Q

As a zygote, the organism:

A
  • Consists of one cell of only one type
  • Consists of unrealized genomic potential
  • Operates using stored materials
  • Has “relationships” with no other cells
  • Is relatively homogeneus
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2
Q

True or false, the zygote is polarized to some degree

A

True

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3
Q

What does early development involve

A
  • Development of new “raw materials” for building embryo
  • Establishing new relationships between numerous cells
  • Further polarizing the organism
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4
Q

Steps of early development

A
  1. Cleavage
  2. Establishment of cell fate
  3. Establishment of body axes
  4. Gastrulation
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5
Q

Cleavage

A
  • Cell cycle control

- Rapid cell divisions, division of fertilized egg into many cells

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6
Q

Establishment of cell fate

A

Specification

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7
Q

Establishment of body axes

A

(anterior posterior, dorsal ventral, left right)

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8
Q

Gastrulation

A

Cells undergo displacement, cells move to different parts of the embryo, cells aquire new neighbors

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9
Q

How are cell fates specified during cleavage

A

Cell to cell interactions and asymmetric distribution of morphogenic determinants

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10
Q

What initially controls cleavage

A

Factors stored in the egg

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11
Q

Factors stored in the egg

A

Stored proteins, mRNAs

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12
Q

Mitosis promoting factor

A

Stimulates the cell cycle (initiates cell division during mitosis and meiosis)

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13
Q

Where does MPF come from

A

Mother

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14
Q

What stops division

A

Absence of MPF

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15
Q

Cyclin B

A

Controls cdc2 activity

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16
Q

cdc2

A

Cyclin-dependent kinase

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17
Q

CDK

A

Phosphorylates histones

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18
Q

What happens when cyclin B degrades

A

Cell division stops

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19
Q

What controls the cyclin B presence and degradation

A

Egg cytoplasmic proteins

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20
Q

What happens when the maternal stores are used up

A

Embryonic control of the cell cycle

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21
Q

Mid Blastula Transition

A

Must produce its own proteins

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22
Q

Post MBT

A
  • Cell cycle adds two new G phases
  • New mRNA transcription
  • Cell division becomes asynchronous
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23
Q

How does the cell cycle of blastomeres compare with that of somatic cells

A

Cycle is like somatic cells after MBT

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24
Q

Karyokinesis

A

Mitotic division of cells nucleus

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25
Q

Cytokinesis

A

Division of cytoplasm plus organelles

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26
Q

Mechanical agent of karyokinesis

A

Mitotic spindle

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27
Q

Mechanical agent of cytokinesis

A

Contractile ring

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28
Q

Major protein composition of karyokinesis

A

Tubulin microtubules

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29
Q

Major protein composition of cytokinesis

A

Actin microfilaments

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30
Q

Location of karyokinesis

A

Central cytoplasm

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31
Q

Location of cytokinesis

A

Cortical cytoplasm

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32
Q

Positioning of mitotic spindle and contractile ring relative to eachother

A

Perpendicular

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33
Q

What affects how cleavage occurs

A

Position of centrioles and yolk

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34
Q

Types of cleavage

A
  1. Isolecithal
  2. Mesolecithal
  3. Telolecitithal
  4. Centrolethical
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35
Q

Isolecithal

A

Little yolk, division throughout

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36
Q

Mesolecithal

A

Medium yolk, more division on top

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37
Q

Telolecithal

A

Large yolk, almost all division on top

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38
Q

Centrolethical

A

Division in random spots

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39
Q

First cleavage

A

Meridonial

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40
Q

Second cleavage

A

Meridonial

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41
Q

Third cleavage

A

Equitorial

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42
Q

Fourth cleavage

A

Unequal cleavage between animal and vegital hemispheres

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43
Q

Micromeres

A

Smallest cells

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44
Q

Macromeres

A

Biggest cells

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45
Q

Mesomeres

A

Medium cells

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46
Q

How do the animal and vegetal halves differ

A

Cells on the bottom have different morphogens than on top

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47
Q

7th plus division

A

At 128 cells, divisions become less regular. Forms blastula

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48
Q

How many cells thick is the blastula

A

One (hollow inside)

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49
Q

What do the cells of the blastula adhere to

A
  1. Hyaline layer (outside)
  2. Basal membrane (inside)
  3. Neighboring cells
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50
Q

What develops on the blastula

A

Cilia

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51
Q

What is initiated at the animal pole of the blastula

A

Hatching (hatches out of fertilization envelope)

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52
Q

What changes the osmotic pressure of the blastula

A

Sodium influx

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53
Q

What fills the cavity of the blastula

A

Proteinaceous fluid fills cavity

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54
Q

What expands the blastocoel

A

Osmotic pressure

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55
Q

Mechanisms for establishing asymmetry (in regards to splitting cytoplasmic determinants)

A
  1. Patterning molecules bound to egg cytoplasm
  2. Molecules actively transported along the cytoskeleton (made of microtubules in secretory vesciles)
  3. Molecules become associated with one centrosome, and then follow that centrosome into one of the two mitotic sister cells
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56
Q

What happens when asymmetry is established

A

One cell can specify another and participate in reciprocal inductions

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57
Q

Notochord

A

Induces spinal cord formation

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58
Q

Where is the animal pole located

A

Top

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59
Q

Mesenchyme

A

Loosely packed, unconnected, mesoderm, neural crest origin

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60
Q

Coelom

A

Internal body wall, mesoderm origin

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61
Q

What type of specification do micromeres undergo

A

Autonomous

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62
Q

60 cell stage

A

Specified but not committed. Blastomeres mostly undergo conditional specification

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63
Q

What cells trigger early induction events

A

Micromeres

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64
Q

What do micromeres have enough information to do

A

Induce recognizable larvae and secondary axis

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65
Q

____ plays a role in micromere specification

A

B-catenin

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66
Q

What activates B-catenin

A

Wnt signal transduction pathway

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67
Q

What cell fates does B-cateni accumulate in

A

Endoderm and mesoderm

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68
Q

What do veg2 cells with B-catenin become

A

Endomesoderm

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69
Q

______ causes accumulation of B-catenin in every cell

A

LiCl, transforms presumative ectoderm into endoderm

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70
Q

What will animal cells become if they have B-catenin

A

Endoderm

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71
Q

What micromere protein activates the notch pathway in adjacent veg2 cells

A

Delta

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72
Q

What does notch pathway activation result in

A

Secondary mesanchyme

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73
Q

What is Wnt8 made of

A

Micromeres and endoderm cells

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74
Q

What signal are endomesoderm cells not recieving

A

Delta

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75
Q

What type of signal does Wnt8 act as

A

Autocrine signal

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76
Q

What does Wnt8 boost specification in

A

Veg2 endoderm and micromeres

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77
Q

Invagination

A

Infolding region of the cells

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78
Q

Ingression

A

Migration of individual cells from the interior surface layer into the interior of the embryo (cells become mesencymal and migrate independently)

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79
Q

Involution

A

In turning or inward movement of an expanding outer layer spreads over the internal surface of the external cell layer

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80
Q

Delamination

A

Splitting one cellular sheet into two parallel sheets

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81
Q

Epiboly

A

Epithelial sheets spread and enclose deeper layers of the embryo

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82
Q

Intercalation

A

Two rows become one

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83
Q

How does ingression work

A

Cells lose cadherin and migrate up the blastocoel to a spot

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84
Q

What gradients move cells in ingression

A

VEGF and FGF (growth factors)

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85
Q

What does invagination of the vegetal plate form

A

Archenteron (primative digestive tract)

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86
Q

How does the forgut move to the top

A

Invagination, involutes inwards

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87
Q

What appears to be responsible for the initial invagination that occurs during gastrulation

A

Osmotic gradient

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88
Q

How are cells freed from the hyalin layer to be able to move upward

A

Changing osmotic gradient

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89
Q

What do cells do during formation of the archenteron

A

Cells intercalate and move forward at the same time (results: thin tube)

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90
Q

When is the anterior posterior axis formed

A

Very early on with the animal vegetal axis

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91
Q

What does the vegetal region have that is necessary for posterior development

A

Maternal components

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92
Q

When is the dorsal ventral axis established

A

After fertilizatio

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93
Q

Another name for the dorsal ventral axis

A

Oral-aboral

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94
Q

Where is the dorsal ventral axis

A

Approx. 45 degrees clockwise from the first cleavage plane

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95
Q

What promotes oral fates

A

Nodal

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96
Q

What promotes aboral fates

A

BMP2/4

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97
Q

When is the left right axis established

A

After oral-aboral

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98
Q

The left right axis has ____ expression of the nodal gene

A

Asymmetric

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99
Q

What sets up the axis in amphibians

A

The organizer

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100
Q

What is the organizer analogous to in sea urchins

A

Mircomeres

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101
Q

Inductions of the organizer

A
  • Dorsal ventral axis
  • Mesoderm
    _Ectoderm
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102
Q

Where does fertilization occur

A

Anywhere on the animal pole

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103
Q

Cortical rotation

A

Contents in egg shift

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104
Q

Where are cytoplasmic determinants shifted to

A

Gray crescent

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105
Q

Where is the gray crescent located

A

Directly diagonal to the site of sperm entry

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106
Q

How many degrees does the egg rotate

A

30

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107
Q

What does the first cleavage plane cut in half

A

Gray crescent

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108
Q

Where is the dorsal located

A

Opposite sperm entry

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109
Q

Where does gastrulation begin

A

Gray crescent

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110
Q

What does cortical rotation relocate

A

Maternal factors

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111
Q

What is the dorsal most and vegetal most region

A

Nieukoop Center `

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112
Q

Yolk classification of amphibians

A

Mesolecithal

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113
Q

What pole is the yolk in for amphibians

A

Vegetal pole

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114
Q

Where do more cells develop in the amphibian embryo

A

Animal pole

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115
Q

What type of cleavage occurs in amphibians

A

Displaced radial

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116
Q

Holoblastic

A

Complete cleavage

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117
Q

Meroblastic

A

Incomplete cleavage

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118
Q

Is amphibian cleavage holoblastic or meroblastic

A

Holoblastic

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119
Q

Major functions of blastocoel

A
  1. Permits cell migration during gastrulation
  2. Prevents cells beneath it from interacting prematurely with cells above it (cells on top are different from bottom cells)
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120
Q

What type of movement forms the archenteron

A

Invagination

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121
Q

Beginning of frog gastrulation

A

Formation of dorsal lip
Vegetal rotation
Invagination of bottle cells
Involution of marginal zone cells

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122
Q

Dorsal blastophere lip

A

Site where gastrulation begins (cells stream through the opening)

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123
Q

What happens to the blastocoel during gastrulation

A

Will eventually go away and be replaced

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124
Q

What does gastrulation form

A

3 germ layers

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125
Q

Where is archenteron located

A

Blastopore

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126
Q

What is the yolk plug

A

Spot not yet covered

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127
Q

What are axes specified by

A

Events triggered at fertilization and realized during gastrulation

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128
Q

What is the mesoderm determined by

A

Transcription factors and paracrine factors from the vegetal region

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129
Q

What is the only tissue in the xenopus pre-gastrula that has its fate determined

A

Dorsal lip of the blastopore

130
Q

What will the dorsal lip determine the fates of

A

Notochord and head endomesoderm

131
Q

What decides if it will be ventral or dorsal mesoderm

A

Nodal

132
Q

Both cells have equal amount of gray crescent

A

Normal development

133
Q

One cell has entire gray crescent

A

Normal development of one, only belly piece in other

134
Q

Gray crescent

A

Future dorsal lip of the blastopore (future site of gastrulation)

135
Q

Transplantation in early gastrula

A

Conditional specification

136
Q

Transplantation in late gastrula

A

Autonomous specification

137
Q

Spemann and Mangolds experiment

A

Dorsal blastopore transplanted to another embryo, secondary axis forms

138
Q

What is the conclusion of the spemann and mangold experiment

A

The dorsal lip is the organizer

139
Q

What does the organizer do in spemann mangold experiment

A
  • induces the host ventral tube and dorsal mesodermal tissue such as somites
  • organized host and donor tissue into secondary embryo with a clear a-p and d-v axis
  • organize dorsal ectoderm into neural tube and transform flaking mesoderm into anterior posterior body axis
140
Q

Induction

A

Signal from one group of cells

141
Q

The mesoderm is induced to be dorsal, intermediate or ventral based on _______

A

Location

142
Q

Dorsal signal

A

B-catenin

143
Q

B-Catenin

A
  • anchor for cadherins

- nuclear transcription factor in wnt

144
Q

B catenin in sea urchins

A

specifies micromeres and endomesoderm

145
Q

B catenin in xenopus

A

specifies dorsal structures

146
Q

Where is B catenin initially

A

Spread throughout the embryo

147
Q

Where does B catenin become accumulated in

A

Dorsal cells

148
Q

Where is B catenin concentarted

A

Nieukoop center and organizer

149
Q

Dorsalization of B catenin accomplished by

A
  • Protecting B catenin in the dorsal area

- Degrading B catenin anywhere else

150
Q

What causes accumulation of B catenin only on dorsal side of the embryo

A

Cortical rotation

151
Q

What happens to B catenin without Wnt

A

It is broken down

152
Q

GSK3 distrubution

A

Distributed throughout the embryo

153
Q

What marks B catenin for degradation

A

GSK3

154
Q

Dishevled (Dsh)

A

Blocks GSK3 activity

155
Q

Where is Dsh localized

A

Cytoplasmic cortex at the vegetal pole

156
Q

GSK3 present

A

No B catenin, ventral

157
Q

No Gsk3

A

B catenin present (Dsh blocked GSK3), dorsal

158
Q

Dsh present

A

B catenin present, dorsal

159
Q

GBP

A

GSK3 binding protein

160
Q

Kinesin

A

Motor protein

161
Q

How is Dsh moved

A

Moved on microtubules. Hitches a ride on GBP. Kinesin helps it move

162
Q

Where is beta catenin present after GSK3 acts

A

Marginal area opposite the point of sperm entry (ie. future dorsal lip)

163
Q

What transcirption factor does B catenin act with

A

Tcf3

164
Q

What do B catenin and Tcf3 do

A

Stimulate expression of dorsalizing genes

165
Q

Dorsalizing genes

A

Siamois and Twin proteins, Goosecoid and Xlim1

166
Q

Siamois and Twin

A

Tracription factors to turn on more dorsalizing genes

167
Q

Gooseoid and Xlim1

A

Specify dorsal mesoderm

168
Q

B catenin pathway (organizer induction)

A

B catenin –> nodal related high –> organizer (dorsal)

169
Q

VegT, Vg1 pathway (mesoderm or organizer induction)

A

VegT, Vg1 –> nodal related high –> organizer (dorsal)
OR
VegT, Vg1 –> nodal related low –> ventral mesoderm

170
Q

Summary of mesoderm induction

A
  1. Maternal RNAs tethered to the vegetal cortex

2. Gardient of nodal (TGFB family protein) signal

171
Q

Maternal RNAs thethered to vegetal cortex

A
  • Vg (TGFB family protein)

- VgT (transcription factor)

172
Q

Role of VgT

A

Instruct endoderm to express another TGFB family activin, derriere and nodal

  • Induce to express Xbra or goosecoid
  • induce mesodermal development
173
Q

Gradient of nodal signal

A

Nodal gradient is formed by expression of VgT and B-catenin in endoderm

174
Q

What does nodal gradient induce

A

Mesoderm formation

175
Q

Less nodal

A

Ventral mesoderm

176
Q

Intermediate nodal

A

Lateral mesoderm

177
Q

Highest nodal

A

The organizer (dorsal)

178
Q

Functions of the organizer

A
  1. Can self differentiate dorsal mesoderm
  2. Can dorsalize the surrounding mesoderm into paraxial mesoderm
  3. Can initiate the movement of gastrulation
  4. Can dorsalize the ectoderm to induce neural tube
179
Q

What does the organizer develop into

A
  1. Pharangyeal ectoderm (frontal ectodermal cells)
  2. Head mesoderm (frontal mesodermal cells)
  3. Dorsal mesoderm (notochord)
  4. Dorsal blstopore lip
180
Q

What does anterior posterior axis development come after

A

Dorsal ventral axis development

181
Q

What do the first migarting endomesodermal cells become

A

Anterior part

182
Q

What do later migrating mesoderm cells become

A

Ventral lips (form posterior structures)

183
Q

Organizer inductions

A
  • Mesoderm
  • Dorsal/ventral axis
  • Ectoderm and neural tissue
184
Q

What does ectoderm usually want to become

A

Neural tissue

185
Q

How does ectoderm become epidermis

A

Needs signa (BMP)

186
Q

BMP inhibitors

A

Noggin, Chordin, Follistatin

187
Q

What activates BMP inhibitors

A

Smad 2/4 and Siamois/Twin

188
Q

What do BMP inhibitors do

A

Stop BMP and make neural tissue

189
Q

Where are BMP inhibitors located

A

Dorsal side

190
Q

Where is more BMP located

A

Ventral side

191
Q

What happens as levels of noggin increase

A

More neural structures develop

192
Q

Nuclear proteins

A

Remain within the cell

193
Q

Where are noggin, chordin and follistati found

A

Organizer

194
Q

Epidermal inducers

A

BMP4, BMP2, BMP7

195
Q

Job of BMPs

A

Repress genes involved in forming neural tissue while activating other genes involved in epidermal specifiaction

196
Q

Add BMP to embryp

A

No dorsal structures, no neural tube

197
Q

Blocked BMP in embryo

A

Spread to ventral side and form more neural tissue than they were supposed to

198
Q

Proneural gene

A

Neurogenin

199
Q

Making sure parts of the brain are made in the right spot

A

Regional specification of the neural structures that are produced

200
Q

FrzB

A

Binds to Wnt and prevents it from binding to receptor on cell and activating it (acts as receptor)

201
Q

What is FrzB secreted from

A

Organizer (dorsal)

202
Q

Where is Wnt secreted from

A

Ventral

203
Q

FrzB blocks _____ from dorsal region

A

Xwnt8

204
Q

When is d-v axis set up

A

At ferilization

205
Q

When is a-p axis set up

A

Established by gatsrulation movements across the dorsal lip of the blastopore

206
Q

L-R axis establishment

A

Nodal expression on left, not righrt

207
Q

Gene that expressed eft right axis

A

Xnr1

208
Q

How is xnr1 expression limited to the left side

A

Process involving cortical rotation and Vg1

209
Q

What happens if Xnr1 is blocked

A

Random gut coiling and heart looping

210
Q

What direction does the heart loop (normal)

A

Left

211
Q

What direction is gut coiling (normal)

A

Counter clockwise

212
Q

What happens if nodules are mutated

A

No left or right axis

213
Q

Yolk amount in mammals

A

Isolethical

214
Q

How do mammals gastrulate

A

Gastrulate as if there is a lot of yolk `]

215
Q

What is the blastula called in mammals

A

Blastocyst

216
Q

When is the first mammalian cleavage

A

1 day after fertilization

217
Q

How far apart are cleavages in mammals

A

12-24 hrs

218
Q

Cleavage type mammals

A

Rotational

219
Q

Rotational cleavage

A

Not happening with all cells at the same time, no MBT

220
Q

Compaction

A

8 cell stage, tight junctions between outside cells (e-cadherin), seal off inside of sphere

221
Q

What will ICM form

A

Embryo proper

222
Q

What will trophoblast form

A

Extraembryonic structures

223
Q

What secretes hormones to cause the uterus to retain the fetus

A

Trophoectoderm

224
Q

Cavitation

A

Trophoblast secretes fluid into the morula (with Na+ pumps, `creates blastocoel and pushes ICM to one side)

225
Q

Zona pellucida

A

Prevents adhesion to uterine wall

226
Q

Why does adhesion to the uterine wall need to be prevented

A

Must hatch out for adhesion, premature adhesion = eptopic pregnancy

227
Q

What is formed when trophoblast attaches to the uterine wall

A

Chorion

228
Q

Chorion

A

Embryonic portion of the placenta

229
Q

What is secreted by the trophoectoderm and why

A

Proteases

  • Digests uterine ECM
  • Blastocyst implants
230
Q

What does ICM form besides embryo proper

A

Yolk sac, allantois, amnion

231
Q

What does the allantois turn into

A

Part of the bladder

232
Q

Which is a stem cell, ICM or trophoectoderm

A

ICM

233
Q

Cells of the blastocyst

A

ICM and trophoectoderm

234
Q

What does ICM become

A

Epiblast and Hypoblast

235
Q

Epiblast

A

Forms embryo proper

236
Q

Hypoblast

A

forms extraembryonic membrane - yolk sac

237
Q

What are the epiblast and hypoblast together callled

A

Bilaminar germ disc

238
Q

Cytotrophoblast

A
  • adheres to endometrium
  • proteolyze uterine wall
  • secretes paracine factors to attract maternal blood vessels
  • displaces vascular tissue
239
Q

Syncytiotrophoblast

A

Digests uterine tissue (move further into uterine wall)

240
Q

Extraembryonic endoderm

A

Gives rise to the yolk sac

241
Q

Extraembryonic mesoderm

A

Gives rise to blood vessels and umbilical cord

242
Q

Job of paracrine factors

A

Recruit maternal blood vessels towards embryo

243
Q

Decidua

A

Maternal portion of the placenta

244
Q

What does the epiblast become

A

Amniotic ectoderm or embryonic epiblast

245
Q

Embryonic epiblast division

A

Embryonic ectoderm of primative streak (which will become embryonic endoderm or embryonic mesoderm, sometimes extraembryonnic mesoderm)

246
Q

What does the hypoblast become

A

Hypoblast –> extraembryonic endoderm –> yolk sac –> (extraembryonic mesoderm sometimes)

247
Q

What does the trophoblast become (pathway)

A

Trophoblast –> cytotrophoblast –> syncytiotrophoblast

248
Q

What does the chorion surround

A

Embryonic membrane

249
Q

What is the cloud around the fetus

A

Blood vessels, part of the chorion

250
Q

Cells that form yolk sac

A

hypoblast, blastodisc cells

251
Q

Function of yolk sac

A

No nutritional function (vestigial), important for blood cell formation

252
Q

What is the amnion formed by

A

Epiblast… ectodermal and mesodermal cells complete amnion

253
Q

Amniotic fluid purpose

A

Cushions embryo or fetus

254
Q

Allantois formation

A

Begins as outpocket of endoderm near yolk sac base, endodermal and mesodermal cells form stalk attaching to blastocyst wall

255
Q

Purpose of allantois before it becomes the bladder

A

Vestigial respiratory organ

256
Q

What is the chorion formed from

A

Mesoderm and trophoblast near allantois

257
Q

How does the chorion get nutrients

A

Chorion vili invade endometrium

258
Q

Placenta purpose

A

Primary embryo support, oxygen and nutrients exchanged for carbon dioxide and wastes

259
Q

What do umbilical arteries carry

A

Deoxygenated blood from fetus

260
Q

What do umbilical veins carry

A

Oxygenated blood to fetus

261
Q

Early twin separation

A

2 chorions, 2 amnion

262
Q

Middle twin separation

A

1 chorion, 2 amnion

263
Q

Late twin separation

A

1 chorion, one amnion

264
Q

Evidence that ICM generate any cell type

A

Twin formation (ICM split and both halves can become a whole embryo)

265
Q

Where does human gastrulation begin

A

Primative streak

266
Q

Movement of primative streak

A

Posterior to anerior, back posterior and disappears

267
Q

What is the primative streak analogous to in amphibians

A

Blastopore (where movement first starts)

268
Q

Ectoderm

A

Nonmigrating superficial blastodisc cells

269
Q

Endoderm

A

Cells facing yolk sac

270
Q

Mesoderm

A

Poorly organized cells between two other germ layers

271
Q

What day does gastrulation occur in humans

A

12-15

272
Q

What germ layer is created first in humans

A

Endoderm

273
Q

Where will the brain form

A

Neural plate

274
Q

How does the neural tube form

A

Primative streak loops

275
Q

Where does the neural plate form

A

In the ectoderm along embryo posterior

276
Q

What forms CNS cavities

A

Neural folds

277
Q

Week 3

A

Head fold
Chorionic vili
Heart starts beating
Allantois forms

278
Q

Week 4

A

Body stalk
Yolk stalk
Other organs form

279
Q

Body stalk

A

Between the embryo and chorion. Forms carrying blood to and from the placenta

280
Q

Yolk stalk

A

Narrow connection between endoderm and yolk sac

281
Q

When does embryonic folding occur

A

4 weeks

282
Q

Week 5

A

Umbilical stalk

283
Q

What forms the umbilical stalk

A

Body and yolk stalks

284
Q

Week 6

A

Brain waves, mouth and lips, fingernails, limbs lengthen, skull bones form

285
Q

When does it become a fetus

A

9 weeks

286
Q

Week 10

A

Bones replace cartilage. Fetus is connected to placenta by umbilical cord
Amniotic cavity fills uterine cavity

287
Q

What is the umbilical cord made of

A

Allantois, blood vessels, remnants of yolk stalk

288
Q

Carnegie stages

A

Stage based on level of development, regardless of time passed

289
Q

Anterior posterior patterning mammals

A

BMP, Wnt, RA, Hox genes

290
Q

Dorsal ventral patterning mammals

A

Mystery

291
Q

Left right patterning mammals

A

Cilia, Hedgehog, RA, FGF

292
Q

Mammalian organizer

A

AVE and Node

293
Q

AVE

A

Anterior visceral endoderm, secretes anterior markers

294
Q

Node

A

(same as spemann organizer in amphibians), creates all body and neural features

295
Q

Anterior patterning

A

BMP and Wnt antagonists (some RA)

296
Q

Posterior patterning

A

Wnt, BMP, FGF, RA

297
Q

Retinoic acid gradient

A

Posterior –> high, anterior–> low

298
Q

How is the anterior determined

A

Blocking posterior signals

299
Q

What determines A-P axis patterning

A

Hox genes

300
Q

What activates hox genes

A

Cdx1,2,4

301
Q

What activates cdx family

A

RA, Wnt3a, fgf8

302
Q

Homeotic selector genes

A

Determine segment identity

303
Q

Where are hox genes expressed

A

Along the dorsal axis

304
Q

How is the level of body along the A/P axis determined

A

Most posterior hox gene expressed

305
Q

What does hox knockout do

A

Shifts vertebrae

306
Q

What are hox genes sensitive to

A

RA

307
Q

Direction of RA gradient

A

P-A

308
Q

Where does hypoblast form

A

Side of ICM exposed to blastocyst fluid

309
Q

Where does dorsal axis form

A

From ICM cells in contact with trophoblast and amniotic cavity

310
Q

Levels of regulation for left right

A

Organ specific

Global

311
Q

Organ specific

A

IV gene

Mutations cause randomized LR asymmetry for each organ, can be fatal

312
Q

Global

A

Inversion of Inv gene

Mutations cause asymmetrical organs to be reversed, usually not a large problem

313
Q

Active genes on left side

A

Nodal and Pitx2

314
Q

LR mechanism frog

A

Vg1 placement

315
Q

LR mechanism chick

A

Suppression of sonic hedgehog

316
Q

LR mechanism mouse

A

Asymmetirc distribution of Shh

317
Q

Dynein

A

Motor protein

318
Q

What cells are ciliated for LR

A

Node

319
Q

NVP

A

Nodal vesicular parcels

Contain Shh and RA

320
Q

What happens if parcels are not secreted

A

LR asymmetry fails to establish

321
Q

What are cilia powered by

A

Dynein and ATPase

322
Q

What do iv genes code for

A

Dynein protein

Developmental Biology (5 decks)

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