John Noto BIO441 Lecture 24 April 2017 Development Development refers to interaction of the genome with the cytoplasm and external environment to produce a programmed sequence of typically irreversible events ID: 593318
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Slide1
embryonic development in the fruit fly
John
Noto
BIO441 Lecture
24 April 2017Slide2
Development
Development refers to interaction of the genome with the cytoplasm and external environment to produce a programmed sequence of typically irreversible events.Differentiation Differentiation refers to the formation of cell types, tissues, and organs through specific gene regulation. A single cell with one genotype produces a variety of specialized tissues and organs.Development and differentiation can be studied at many levels:MorphologyBiochemistryGeneticsSlide3
Development
Development refers to interaction of the genome with the cytoplasm and external environment to produce a programmed sequence of typically irreversible events.Differentiation Differentiation refers to the formation of cell types, tissues, and organs through specific gene regulation. A single cell with one genotype produces a variety of specialized tissues and organs.Development and differentiation can be studied at many levels:MorphologyBiochemistryGeneticsSlide4
Development
Development refers to interaction of the genome with the cytoplasm and external environment to produce a programmed sequence of typically irreversible events.Differentiation Differentiation refers to the formation of cell types, tissues, and organs through specific gene regulation. A single cell with one genotype produces a variety of specialized tissues and organs.Development and differentiation can be studied at many levels:MorphologyBiochemistryGeneticsSlide5
Flies are a great model organismSlide6
Flies are a great model organismSlide7
Flies are a great model organismSlide8Slide9Slide10Slide11
Developmental stages of
Drosophila
(10-12 days)EggLarva (3 instars)PupaAdult
Slide12
EMS Mutation screening
Wieschaus
, Lewis and Nusslein-VolhardNobel Prize, genetics basis of developmentSlide13
EMS MutationSlide14
RecombinationSlide15Slide16
Fertilization and subsequent developmentSlide17Slide18Slide19Slide20Slide21Slide22Slide23Slide24Slide25Slide26Slide27
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide28
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide29
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide30
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide31
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide32
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide33
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide34
Embryonic development in
Drosophila
:Development begins with fertilization.Prior to fertilization, molecular gradients exist within the eggs. Polar cytoplasm occurs at the posterior end---example of maternal effect.2 nuclei fuse after fertilization to form a zygote.9 mitotic divisions occur without cell division, and after 7 divisions, some nuclei migrate to the polar cytoplasm (posterior) creating germ-line precursors.Other nuclei migrate to the cell surface and form blastoderm precursor.4 more mitotic divisions occur and all nuclei are separated by cell membranes.Slide35
Embryonic
development in
Drosophila
.Slide36
Embryonic
development in
Drosophila
.Slide37
Embryonic
development in
Drosophila
.Slide38
Embryonic
development in
Drosophila
.Slide39
Embryonic
development in
Drosophila
.Slide40Slide41
ZEISS Lightsheet Z.1 - Imaging of Drosophila embryo for cell tracking
ZEISS Lightsheet Z.1 - Drosophila cell tracking using a color gradient
https://www.youtube.com/watch?v=FChS4KU5jDMSlide42
DNA
Actin microfilaments
microtubulesCytoskeletal proteins create cytoplasmic islands around nucleiSlide43
Subsequent development depends on two processes
:
Adult segmentation reflect
Embryo segmentation
Anterior-posterior and dorsal-ventral molecular gradients exist in the egg---mRNAs and proteins placed in egg by mother confer maternal effect.
Formation of (1) parasegments and (2)embryonic segments, which give rise to (3) adult segments.Slide44
Subsequent development depends on two processes
:
Adult segmentation reflect
Embryo segmentation
Anterior-posterior and dorsal-ventral molecular gradients exist in the egg---mRNAs and proteins placed in egg by mother confer maternal effect.
Formation of (1) parasegments and (2)embryonic segments, which give rise to (3) adult segments.Slide45
Three major classes of genes control development and differentation
*Mutations identified by presence lethal or abnormal structures during development.
Maternal effect genesSegmentation genesHomeotic genesSlide46
1. Maternal effect genes
Expressed by the mother during egg production; they control polarity of the egg and the thus embryo.
bicoid gene Regulates formation of anterior structures (mutants possess posterior structures at each end).Gene is transcribed during egg production, and expressed after fertilization.nanos gene Regulates abdomen formation (mRNAs collect in posterior of the egg).torso gene
Transcription and translation occur during egg production.
Occurs throughout the eggs, but is only active at the poles.Slide47
1. Maternal effect genes
Expressed by the mother during egg production; they control polarity of the egg and the thus embryo.
bicoid gene Regulates formation of anterior structures (mutants possess posterior structures at each end).Gene is transcribed during egg production, and expressed after fertilization.nanos gene Regulates abdomen formation (mRNAs collect in posterior of the egg).torso gene
Transcription and translation occur during egg production.
Occurs throughout the eggs, but is only active at the poles.Slide48
1. Maternal effect genes
Expressed by the mother during egg production; they control polarity of the egg and the thus embryo.
bicoid gene Regulates formation of anterior structures (mutants possess posterior structures at each end).Gene is transcribed during egg production, and expressed after fertilization.nanos gene Regulates abdomen formation (mRNAs collect in posterior of the egg).torso gene
Transcription and translation occur during egg production.
Occurs throughout the eggs, but is only active at the poles.Slide49
1. Maternal effect genes
Expressed by the mother during egg production; they control polarity of the egg and the thus embryo.
bicoid gene Regulates formation of anterior structures (mutants possess posterior structures at each end).Gene is transcribed during egg production, and expressed after fertilization.nanos gene Regulates abdomen formation (mRNAs collect in posterior of the egg).torso gene
Transcription and translation occur during egg production.
Occurs throughout the eggs, but is only active at the poles.Slide50
Distribution
of
bicoid
mRNA and protein in the egg
A = Anterior
P = PosteriorSlide51
Distribution
of
bicoid
mRNA and protein in the egg
A = Anterior
P = PosteriorSlide52
Distribution
of
bicoid
mRNA and protein in the egg
A = Anterior
P = PosteriorSlide53
Bicoid
proteinSlide54
mRNA
Protein
Bicoid proteinSlide55Slide56Slide57
2. Segmentation genes:
Determine the segments of the embryo and adult, and thus divide the embryo into regions that correspond to the adult segmentation patterns.
Gap genes Subdivide the embryo along the anterior-posterior axis.Mutation results in the deletion of several adjacent segments.Pair rule genesDivide the the embryo into regions, each containing parasegments.Mutations cause deletions of the same part of a pattern in every other segment.Segment polarity genes
Determine regions that become segments of larvae and adults
Mutants possess parts of segments replaced by mirror images of adjacent half segments.Slide58
2. Segmentation genes:
Determine the segments of the embryo and adult, and thus divide the embryo into regions that correspond to the adult segmentation patterns.
Gap genes Subdivide the embryo along the anterior-posterior axis.Mutation results in the deletion of several adjacent segments.Pair rule genesDivide the the embryo into regions, each containing parasegments.Mutations cause deletions of the same part of a pattern in every other segment.Segment polarity genes
Determine regions that become segments of larvae and adults
Mutants possess parts of segments replaced by mirror images of adjacent half segments.Slide59
2. Segmentation genes:
Determine the segments of the embryo and adult, and thus divide the embryo into regions that correspond to the adult segmentation patterns.
Gap genes Subdivide the embryo along the anterior-posterior axis.Mutation results in the deletion of several adjacent segments.Pair rule genesDivide the the embryo into regions, each containing parasegments.Mutations cause deletions of the same part of a pattern in every other segment.Segment polarity genes
Determine regions that become segments of larvae and adults
Mutants possess parts of segments replaced by mirror images of adjacent half segments.Slide60
2. Segmentation genes:
Determine the segments of the embryo and adult, and thus divide the embryo into regions that correspond to the adult segmentation patterns.
Gap genes Subdivide the embryo along the anterior-posterior axis.Mutation results in the deletion of several adjacent segments.Pair rule genesDivide the the embryo into regions, each containing parasegments.Mutations cause deletions of the same part of a pattern in every other segment.Segment polarity genes
Determine regions that become segments of larvae and adults
Mutants possess parts of segments replaced by mirror images of adjacent half segments.Slide61
2. Segmentation genes:
Determine the segments of the embryo and adult, and thus divide the embryo into regions that correspond to the adult segmentation patterns.
Gap genes Subdivide the embryo along the anterior-posterior axis.Mutation results in the deletion of several adjacent segments.Pair rule genesDivide the the embryo into regions, each containing parasegments.Mutations cause deletions of the same part of a pattern in every other segment.Segment polarity genes
Determine regions that become segments of larvae and adults
Mutants possess parts of segments replaced by mirror images of adjacent half segments.Slide62Slide63
Functions
for segmentation genes defined by mutations.Slide64
3. Homeotic genes
:
Homeotic genes specify the body part to develop at each segment.Adult body parts develop from undifferentiated larval tissues called imaginal discs.Homeotic mutants develop a different body part at a particular segment (imaginal disc) than the usual body part.Different homeotic gene groups share similar sequences of ~180 bp called homeoboxes that code proteins.Homeoboxes regulate development and produce proteins that bind upstream of the gene units.Homeotic gene complexes are abbreviated Hox.
Hox
genes also specify body plans in vertebrates and plants.Slide65
Homeotic genes: HOX genesSlide66
Fig. 19.21, Locations of homologous imaginal discs in larva and adult.Slide67
Fig. 19.21, Locations of homologous imaginal discs in larva and adult.Slide68
Examples of homeotic
Drosophila
mutant with the bithorax mutationWhat is wrong with one of
these flies?Slide69
Antennapedia
and
aristapedia
mutantsSlide70
antennapediaSlide71
antennapediaSlide72
AristapediaSlide73
Ectopic expression: Dpp
>eyelessSlide74
Fig. 19.28,
Organization of
bithorax
homeotic genes in a 300kb region of the
Drosophila
genome.
T = thoracic
A = abdominalSlide75
Fig. 19.29
Homologous Hox gene clusters occur in
Drosophila
and the mouse.Slide76
How do development biologists study differential expression of genes during development and differentiation?
Immunofluorescene assays that bind to specific mRNAs and proteins.Slide77
How do development biologists study differential expression of genes during development and differentiation?
Quantitative real-time RT-PCR of cDNA from mRNA transcripts. Slide78
How do development biologists study differential expression of genes during development and differentiation?
Quantitative real-time RT-PCR of cDNA from mRNA transcripts. Slide79
http://www.nature.com/nbt/journal/v28/n5/full/nbt0510-421.html
RNA-SeqSlide80
Ribosome Profiling – sequencing of ribosome-bound mRNAsSlide81
How do development biologists study differential expression of genes during development and differentiation?
Gene knockout using transformation or transduction, or other gene silencing techniques like RNAi.Slide82
http://ja.wikipedia.org/wiki/RNAi
RISC = RNA-induced silencing complexSlide83
How do development biologists study differential expression of genes during development and differentiation?
CRISPR/Cas9 DNA editing tools---snip DNA and replace
“clustered regularly interspaced short palindromic repeats” present in bacteria
1. CRISPR tell Cas9 where to snip the DNA
2. Cas9 recognizes sequences about 20 bp long
3. Guide RNA to match target sequence