Upload
augustus-gibbs
View
219
Download
0
Tags:
Embed Size (px)
Citation preview
Molecular and Organismal Development
Chapter 21: pp 411-429
Chapter 47: pp 992-1008
Topics in Development• 1. totipotency: development depends on selective expression of
the whole genome present in every cell.
• 2. blastula to gastrula: comparative analysis yields insights into the general nature of development
• 3. the three fundamental processes:
– cell division (differential rates of division are critical, programmed cell death is significant)
– cell differentiation (changes in integration and shape are critical; targeting cells with signals is a critical part of the process)
– morphogenesis of tissues and organs (includes defining the individual’s polarities, dividing the organism into segments, and – in animals -- migration of cells in tissue origin)
Figure 21.2 Some key stages of development in animals and plants
Figure 21.5 Test-tube cloning of carrots
Figure 21.8 Working with stem cells
Topics in Development• 1. totipotency: development depends on selective expression of
the whole genome present in every cell.
• 2. blastula to gastrula: comparative analysis yields insights into the general nature of development
• 3. the three fundamental processes:
– cell division (differential rates of division are critical, programmed cell death is significant)
– cell differentiation (changes in integration and shape are critical; targeting cells with signals is a critical part of the process)
– morphogenesis of tissues and organs (includes defining the individual’s polarities, dividing the organism into segments, and – in animals -- migration of cells in tissue origin)
Figure 47.6 Cleavage in an echinoderm (sea urchin) embryo
Figure 47.9 Sea urchin gastrulation (Layer 3)
Figure 47.8x Cleavage in a frog embryo
Figure 47.8d Cross section of a frog blastula
Figure 47.10 Gastrulation in a frog embryo
Figure 47.12 Gastrulation in a
frog embryo
Figure 47.12 Cleavage, gastrulation, and early organogenesis in a chick embryo
The cells in the three germ layers have defined fates in the adult:
Topics in Development• 1. totipotency: development depends on selective expression of
the whole genome present in every cell.
• 2. blastula to gastrula: comparative analysis yields insights into the general nature of development
• 3. the three fundamental processes:
– cell division (differential rates of division are critical, programmed cell death is significant)
– cell differentiation (changes in integration and shape are critical; targeting cells with signals is a critical part of the process)
– morphogenesis of tissues and organs (includes defining the individual’s polarities, dividing the organism into segments, and – in animals -- migration of cells in tissue origin)
Figure 21.4 Cell lineage in C. elegans
C. elegans cell targeting
C. elegans cell targeting
Figure 47.14 Organogenesis in a frog embryo
Figure 47.16 Change in cellular shape during morphogenesis
Apoptosis in development
Topics in Development
4. Homeotic genes a. the determination of appendage identity on fruitfly segmentsb. the evolution of form in segmented animals
4. Morphogenesis in Plants5. Organ identity genes in flower development
Figure 21.11 Key developmental events in the life cycle of Drosophila
Figure 21.12 The effect of the bicoid gene, a maternal effect (egg-polarity) gene Drosophila
Figure 21.13 Segmentation genes in Drosophila
Figure 21.13 Homeotic mutations and abnormal pattern formation in Drosophila
The homeodomain - 60 amino acids of the homeotic gene product that remain very similar in all proteins made by homeotic genes.
Homeotic genes:the DNA sequence of the gene (blue) contains a 180 bp sequence—the homeobox—(red) that
is highly conserved.
Figure 17.7 The initiation of transcription at a eukaryotic promoter
control of transcription in C.elegans lin-3
|tctctccctattcaatgcacctgtgtattttatgctggttttttcttgtgaccctgaaaactgtacacacaggtgttcttaccaatgtctcaggcatttttggaaaagtaatattaagaaaattatacatattttcttgaatacgaaaaatttaaATGTTCGGTAAATCGATTCCTGAACGACTTCTAGTCGCATT
T
HLH-2 binding siteNHR binding site
EXON is in uppercase letters.
Figure 19.10 Three of the major types of DNA-binding domains in transcription factors
The homeobox is relatively constant because it has a precise job.
The homeobox is relatively constant because it has a precise job.
Figure 21.14 Homologous genes that affect pattern formation in a fruit fly and a mouse
Topics in Development
4. Homeotic genes a. the determination of appendage identity on fruitfly segmentsb. the evolution of form in segmented animals
4. Morphogenesis in Plants5. Organ identity genes in flower development
Serial Homology of the Lobster
CRUSTACEANS COMPARED - EVOLUTIONARY HOMOLOGY
CRUSTACEANS COMPARED: EVOLUTIONARY TRANSFORMATION
LOBSTERROCK CRAB
Figure 33.28 Horseshoe crabs, Limulus polyphemus
Figure 33.27 A trilobite fossil
Figure 33.x1 Insecta: beetle
Figure 32.8 Animal phylogeny based on sequencing of SSU-rRNA
lophophore
Figure 32.13x Burgess Shale fossils
Figure 32.13 A sample of some of the animals that evolved during the Cambrian explosion
Porifera and Cnidaria are prominent in the Burgess Shale
Annelid worms in the Burgess shale
Anomalocaris hunts
so are arthropods!!
Figure 26.8 The Cambrian radiation of animals
Causes of the radiation:
1. Atmospheric oxygen reaches sufficient levels.
2. Predator-prey relationships originate.
3. Homeobox genes evolve.
(Ediacaran)
525BurgessShale
PLPL PL
PE
DD
RP
Evolutionary changes in the timing of homeobox genes yield morphological change.
Artemia, the brine shrimp
Another representation of the sequence of homeotic gene expression in an arthropod.
Notice the continued prominence of Antp, Ubx, and Abd paralogs.
Timing of expression of the homeobox genes Antp, Ubx, and AbdA. Fading lines indicate weaker expression later
in development.
Number of homeobox paralogs increases in arthropods.
This illustration also shows
change in timing of gene expression.
Dm - FruitflyTc - BeetleJc - ButterflyAk - Onycho- phoran
Amino acid sequences compared for the homeotic gene Ubx
insects
arthropods
Decides six legs versus more
Topics in Development
4. Homeotic genes a. the determination of appendage identity on fruitfly segmentsb. the evolution of form in segmented animals
4. Morphogenesis in Plants5. Organ identity genes in flower development
Figure 35.13 Morphology of a winter twig
Goethe’s inspiration - the European Fan Palm at the Padua Botanical
GardenJohann Wolfgang von Goethe1749 - 1832
Padua Botanical Garden
SERIAL HOMOLOGY - GOETHE’S PALM
Figure 35.17 The terminal bud and primary growth of a shoot
Figure 21.20a Organ identity genes and pattern formation in flower development: Normal flower development
from Campbell, 6th edition
A set of homeotic genes, in different combinations, yield the different floral organs.
A CB E
Figure 21.20b Organ identity genes and pattern formation in flower development: In situ hybridization
from Campbell, 6th edition
The evolutionary determination of sepal and petal.
A CB2
B1
B3
Topics in Development
4. Homeotic genes a. the determination of appendage identity on fruitfly segmentsb. the evolution of form in segmented animals
4. Morphogenesis in Plants5. Organ identity genes in flower development