CSB328H1 Study Guide - Final Guide: Transgene, Ac Propulsion Ebox, Oct-4
8 Jun 2018
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Department
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CBS328 DEVOLPMENTAL BIOLOGY
LECTURE 1
What is development?
- Women only able to reproduce eggs @
certain stage after puberty
- Men don’t lose reproductive ability
Developmental processes
- Child: growth, changes in body
production, brain development
- Puberty: changes in production of sex
hormones
o Changes in body shape
o New organ: breast
o Specific skin areas: hair prod.
o Production of mature germ cells
(differentiation of egg and
sperm)
- Young adults: homeostasis through
regeneration of tissues (stem cells)
- Senescence: menopause, shift from
muscle to fat production, cancer
(=developmental disease)
Brain develops continuously, our body
undergoes changes throughout our life
development never stops
Human embryogenesis
- All starts with a single cell 9 months
later, highly complex organism
- Embryonic development at 8 week –
start of a human
- Week 4 human embryo forms a tail –
tail disappears after time
- Week 4-8 organ development and
limb/are development begins
Developmental processes during embryogenesis
- Axis formation (anterior-posterior,
dorsal-ventral, proximal-distal, right-
left)
- Specification of cells: decide cell fate
- Differentiation of cells: acquire a
particular cell morphology +physiology
- Growth (cell growth and division):
regulation of cell, tissue, and organ size
- Regulation of the number of structures
(e.g. vertebrae, toes)
- Organogenesis: formation and
differentiation of organs
- Morphogenesis: cell movements define
spatial organization of cells + tissues
To understand how the complexity of a
multicellular organism develops, we need
organisms that allow us to study embryogenesis
1. Life observation of development
- Follow cell division and cell movements
2. Experiments
- Physical manipulations (cell ablation,
tissue transplantation, injections)
- Genetic manipulations (reduce increase
activity of developmental genes)
Good model organisms
o Drosophila
o Zebra fish
o C. elegans
- Large eggs – physical manipulations
(e.g. injections, tissue transplantations)
- Clear eggs – live observation & physical
manipulations
- Egg production throughout the year –
experiments at any time
- Production of a large number of eggs –
examine different stages of
development – repeat experiments to
check reproducibility, check statistical
significance – conduct experiment with
negative and positive controls
- Rapid embryonic development – rapid
experimental results
- Short life cycle – allows genetics
- Small organisms with cheap and easy
maintenance & breeding in the
laboratory
external
development
allowing for
physical
manipulation
LECTURE 2
Chicken egg
- People learn to cut window into egg
shell and look under microscope to see
development of embryo
- Forms blood vessels to yolk and shell
Xenopus (frog eggs)
- Hundreds of eggs laid simultaneously
- Eggs and embryo not transparent
- External development (independent of
mother
- Rapid embryonic development (4 days)
- Life cycle (egg adult 60 days, sexual
maturity at 6 months)
- Excellent model for physical
manipulation
- Easy genetic manipulation but limited
to early development (no transmission
genetics)
C. elegans
- Small transparent eggs, transparent
embryo
- External development
o Limited amount of nutrients
- Rapid embryonic development ( 15
hours)
- Life cycle very rapid (egg adult 3
days)
- Cheap and easy to breed
- Physical manipulations limited
- Highly developed genetics easy
genetic manipulation
o Embryo itself does not grow –
maintain size
o Cell division – each smaller than
smaller
o Egg shell confine embryo
Xenopus and C. elegans
- Early embryonic cell divisions =
Cleavage division
- Early embryonic cells that undergo
cleavage divisions = Blastomeres
Frog egg (Xenopus)
Animal pole- involve a lot of movements of cell
Vegetal pole- not much movements
Egg coated by vitelline membrane and
gelatinous coat
When egg is fertilized, egg separates from
membrane
- Eggs will have same orientation –
brown side up
- Dark side up to protect embryo from UV
light
1st cleavage division goes along animal-vegetal
pole
2nd cleavage division goes 90o along animal-
vegetal pole
300 eggs in 2 weeks
sperm entry point, only occurs
on animal pole (important
when the yolk and embryo
rotate)
holoblastic
cleavage,
meaning all of it
divides
16-64
128 cell
128
(blastomeres)
bisects the animal
pole
- small cells at animal pole and larger
cells at vegetal pole
Notochord – provide structure
Somites —later give rise to skeletal muscle and
back bone
Fate map
- Stain various regions of the egg
- Dip agar in dye (vital dye—not harmful
to embryo) (Nile blue)
- Watch where dye goes to figure out
where cells end up
- Experiment done with newt
- Morphogenesis – embryo undergo
movement under development
- Certain structure start to be seen on
embryo which look like hoofs
o Observed some stain cell
disappear into hoof and into
interior of embryo
o Dived inside ( gastration)
Fate map – determine where each part come
form blastula
LECTURE 3
“A fate map is a diagram which shows what will
become of each region of the embryo in the
course of normal development:
- Where it will move,
- How it will change shape, and what
structures it will turn into”
CON: not precise, don’t know which cells will
take up
- Limit of how far can follow dilute
with each divide
PRO: 100 years ago this was really advance
Fate mapping with photo-activatable GFP
- UV light cause decarboxylation
expose protein to blue light emit
green light – used for fate mapping
Zebra fish embryo contains PA-GFP transgene
- All cell make the PA-GFP but green
fluorescence only visible in those cells
where PA-GFP was activated (GFP is a
very stable protein)
Make trans-line that expose PS-GFP
- Get eggs let develop to right stage
- Shine UV light laser on specific cells to
activate shine blue light to follow
cells
- GFP – long lasting protein – allows us to
track cells over long period of time
cavity filled
with fluid
remaining yolk
missing some organs
1929 vogt
newt embryo
agar chips with dye
placed it on the embryo
surface
(placed it in different positions
all along the surface )
the cells absorbed the dye
and therefore can be
identified (answering:
where does this
cell end up?) when
embryo development
continues
* inverted smiley dorsal lip (shortly)
fate map
6,7,8,9 are engulfed through the dorsal lip of the blastopore
notochord anlage= prospective notochord
fate map
:deterministic, and non random
same area turns into the same part of the frog everytime
Document Summary
Women only able to reproduce eggs @ certain stage after puberty. Child: growth, changes in body production, brain development. Puberty: changes in production of sex hormones: changes in body shape, new organ: breast, specific skin areas: hair prod, production of mature germ cells (differentiation of egg and sperm) Young adults: homeostasis through regeneration of tissues (stem cells) Senescence: menopause, shift from muscle to fat production, cancer (=developmental disease) Brain develops continuously, our body undergoes changes throughout our life development never stops. All starts with a single cell 9 months later, highly complex organism. Embryonic development at 8 week start of a human. Week 4 human embryo forms a tail tail disappears after time. Week 4-8 organ development and limb/are development begins. Axis formation (anterior-posterior, dorsal-ventral, proximal-distal, right- left) Specification of cells: decide cell fate particular cell morphology +physiology. Growth (cell growth and division): regulation of cell, tissue, and organ size. Regulation of the number of structures (e. g. vertebrae, toes)
