Transcript of developmental programs

Figure 20.1 Sperm and Egg Differ Greatly in Size
Figure 20.4 Patterns of Cleavage in Four Model Organisms (Part 1)
Figure 20.4 Patterns of Cleavage in Four Model Organisms (Part 2)
Figure 20.5 The Mammalian Zygote Becomes a Blastocyst (Part 2)
Figure 20.7 Twinning in Humans
Two Blastulas
The Primary
Germ Layers
zygote
chordates
brain,
ventral spinal cord,
nerve cord spinal nerves
blastula
lining of
respiratory tract
pharynx
lining of
endoderm
digestive tract
vertebrates
epidermis
gastrula
ectoderm
neural crest
notochord
glands
pancreas, liver
outer covering
of internal organs
mesoderm
integuments
blood, vessels
gonads
lining of
thoracic and
abdominal cavities
circulatory
system
gill arches,
sensory
ganglia,
Schwann cells,
adrenal medulla
heart
somites
kidney
dermis
segmented
muscles
skeleton
Figure 20.8 Gastrulation in Sea Urchins
Figure 20.9 Gastrulation in the Frog Embryo (Part 1)
Figure 20.9 Gastrulation in the Frog Embryo (Part 2)
Figure 20.9 Gastrulation in the Frog Embryo (Part 3)
Neurulation
“For the real amazement, if you wish to be amazed, is this
process. You start out as a single cell derived from the
coupling of a sperm and an egg; this divides in two, then
four, then eight, and so on, and at a certain stage there
emerges a single cell which has as all its progeny the
human brain. The mere existence of such a cell should be
one of the great astonishments of the earth. People ought
to be walking around all day, all through their waking
hours calling to each other in endless wonderment,
talking of nothing except that cell.”
--Lewis Thomas
Figure 20.15 Neurulation in the Frog Embryo (Part 1)
Figure 20.15 Neurulation in the Frog Embryo (Part 2)
Figure 20.16 The Development of Body Segmentation
Figure 20.10 Spemann’s Experiment
Figure 20.11 The Dorsal Lip Induces Embryonic Organization
Figure 20.2 The Gray Crescent
Figure 20.3 Cytoplasmic Factors Set Up Signaling Cascades
Figure 20.12 Molecular Mechanisms of the Primary Embryonic Organizer
dorsal epidermal ectoderm
NT
Wnt
motorneurons
NT-3
Wnt?
dermomyotome
sclerotome
fp
somite
BMP-4
FGF5?
Shh
NC
multiple signals pattern the vertebrate neural
tube and somite
lateral mesoderm
Figure 19.9 Embryonic Inducers in the Vertebrate Eye
Induction in eye development
Figure 19.10 Induction during Vulval Development in C. elegans (Part 1)
Figure 19.10 Induction during Vulval Development in C. elegans (Part 2)
Origami:
sets of instructions
(programs)
to build 3-D models
of organisms out of
paper –
Is this how
developmental
programs work?
The “landscape” of developmental programs:
The determination of different cell types involves
progressive restrictions in their developmental
potentials. When a cell “chooses” a particular
fate, it is said to be determined.
Differentiation follows determination, as
the cell elaborates a cell-specific
developmental program.
Determination
Differentiation
Differentiated
Cell Types
A
B
C D
E
F
G
H
2-D Electrophoresis of proteins extracted from two
different mouse tissues
Mouse Liver Proteins
Mouse Lung Proteins
Sets of gene products
in two cell types
A
A&B
B
Cell types A & B share a common set of
“housekeeping” gene products and a set of
unique “luxury” gene products that
represent the A or B developmental program
Figure 19.2 Developmental Potential in Early Frog Embryos
Figure 19.3 Cloning a Plant (Part 1)
Figure 19.3 Cloning a Plant (Part 2)
Figure 19.4 A Clone and Her Offspring (Part 1)
Figure 19.4 A Clone and Her Offspring (Part 2)
Figure 19.4 A Clone and Her Offspring (Part 3)
Figure 19.5 Cloned Mice
21_41_cloning.jpg
What is a stem cell?
stem cell
determined cell
differentiated cell
21_39_hemopoietic.jpg
Recent breakthroughs in stem cell
research :
- stem cells can be obtained from adults
and embryos/fetal tissue
- stem
cells are multipotent!
-this very likely has theraputic value
The “landscape” of developmental programs:
The determination of different cell types involves
progressive restrictions in cellular developmental
potentials. When a cell “chooses” a particular
fate, it is said to be determined.
Differentiation follows determination, as
the cell elaborates a cell-specific
developmental program.
Determination
Differentiation
Differentiated
Cell Types
A
B
C D
E
F
G
H
Uses of human embryos
• obtain stem cells
• somatic cell transfer, then obtain stem cells
• use stem cells that are coaxed to develop into different
tissues for therapeutic purposes
Figure 20.14 A Human Blastocyst at Implantation
Week 1
Week 2
Week 3
Week 4
Week 5
Figure 19.6 The Potential Use of Embryonic Stem Cells in Medicine (Part 1)
Figure 19.6 The Potential Use of Embryonic Stem Cells in Medicine (Part 2)
Figure 19.7 Asymmetry in the Early Embryo (Part 1)
Figure 19.7 Asymmetry in the Early Embryo (Part 2)
Figure 19.8 The Principle of Cytoplasmic Segregation
Figure 19.9 Embryonic Inducers in the Vertebrate Eye
Figure 19.11 Apoptosis Removes the Tissue between Fingers
Figure 19.12 Organ Identity Genes in Arabidopsis Flowers (Part 1)
Figure 19.12 Organ Identity Genes in Arabidopsis Flowers (Part 2)
Figure 19.13 A Nonflowering Mutant
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Embryo
Hatching larva
Movement of
maternal mRNA
Follicle
cells
Nurse
cells
Posterior
Oocyte
Anterior
Three larval stages
Nucleus
Fertilized egg
a.
c.
Metamorphosis
Syncytial blastoderm
d.
Cellular blastoderm
Nuclei line up along
surface, and membranes
grow between them to
form a cellular blastoderm.
Thorax
Head
Abdomen
Segmented embryo prior to hatching
b.
e.
Egg with maternally-deposited A
mRNA
P
bicoid
nanos
Gradients of informational proteins
encoded by maternal mRNA
Gap Genes
hunchback Krupple
Knirps
Pair RuleGenes
Segment Polarity
Genes
Homeotic
Genes
Figure 19.15 A Gene Cascade Controls Pattern Formation in the Drosophila Embryo
Fig. 19.13
Figure 19.14 Bicoid and Nanos Protein Gradients Provide Positional Information (Part 1)
Figure 19.14 Bicoid and Nanos Protein Gradients Provide Positional Information (Part 2)
hunchback & Krupple - gap class
even skipped - pair rule class
fushi tarazu (ftz) & even skipped (eve) - pair rule class
engrailed - segment polarity class
Fig. 19.17
wild-type
Antennapedia
mutant
Fly heads
Fig. 19.18
wildtype
mouse
Hoxb-4 knockout