Gene regulation in Drosophila melanogaster Genetic studies One of the best understood developmental...
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Transcript of Gene regulation in Drosophila melanogaster Genetic studies One of the best understood developmental...
Gene regulation in Drosophila melanogaster
Genetic studiesOne of the best understood developmental systems13,600 genes
Axis determinationSignaling pathwayTranscriptional and translational regulation
The genetics of axis specification in Drosophila
Chang-Gung UniversityDr. Li-Mei Pai
The Chapter 9 of Developmental Biology by Scott Gilbert, 7th edition
Targeted ectopic expression of the Eyeless gene--induce eyes to develop in locations such as legs and antennae
Closely related genes initiate the development program for the same organ in animals separate by 500 million years of evolution
Life cycle of Drosophila 4 stages: embryo, larva, pupa, adult
Culture condition: 250C and 60% humidity
Science, 297, 2270-2275, 2002
Comparison of Larval and Adult Segmentation in Drosophila
Body patterning of fly
One cell to an organism
Laser Confocal Micrographs of Stained Chromatin Showing Superficial Cleavage in a Drosophila Embryo
Early development of Drosophila
Rapid division8 mins/division9 divisions
13 divisions
Single cell
asynchronous
Formation of the Cellular Blastoderm in Drosophila
Transgenic flies
One single epithelial layer –all tissuesMesoderm—muscle, connective tissuesEndoderm---midgut (foregut and hidgut-Ectoderm)Ectoderm---nervous tissue and epidermis
Gastrulation
Figure 9.5(1) Gastrulation in Drosophila
Figure 9.5(2) Gastrulation in Drosophila
Germ band extention
Figure 9.5(3) Gastrulation in Drosophila
Germ band retraction
The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis
Localized mRNA and ProteinsTranslated after fertilization—
Positional information to activate zygotic genes
parasegment
Pattern in the segment
Segment identities
Temporal sequence
The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis
The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis
Maternal effect genes—( do not damage mother)preformed mRNA and proteins in the egg
Zygotic genes—embryo nuclei
Three classes of mutants affect the anterior, posterior, and terminal development
head and thoracic
abdominal
acron and telson
Polarization of the body axes during oogenesis
each egg chamber: 3 types of cellsOocyte with nucleus (germinal vesicle-GV)Connected to 15 nurse cells }---germ-lineSurrounded by a monolayer of about 1000 somatic follicle cells
Polarization of the body axes during oogenesis
Polarization of the body axes during oogenesis
Three independent Genetic Pathways Interact to Form theAnterior-Posterior Axis of the Drosophila Embryo
Three independent Genetic Pathways Interact to Form the Anterior-Posterior Axis of the Drosophila Embryo
Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis
Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis
Protein kinase A orients the microtubules
Gradient of Bicoid Protein in the Early Drosophila Embryo
bicoid mRNA in the anterior tip of the embryo3’ untranslated regionExuperantia and Swallow proteins link bicoid to dynein ATPasesFertilization-receives a longer polyadenylate tail-trnaslated
Gradient of Bicoid Protein in the Early Drosophila Embryo
concentrated in the nuclei
Experiments Demonstrating that the bicoid Gene Encodes the Morphogen Responsible for Head Structures in Drosophila
Gradient of Caudal Protein in the Syncitial Blastoderm of aWild-type Drosophila Embryo
Activates genes responsible for the invagination of the midgutBicoid binds to its 3’UTR and prevents its translation
Anterior-Posterior Pattern Generation by the DrosophilaMaternal Effect Genes
Control of hunchback mRNA Translation by Nanos Protein
Anterior-Posterior Pattern Generation by the DrosophilaMaternal Effect Genes
Bicoid stimulates hunchback transcription
All transcription factors
maternal
zygotic
Formation of the Unsegmented Extremities by torso Signaling
torso-receptor tyrosine kinaseDistinction A/P is bicoid
Groucho –transcriptional inhibitortailless, huckebein
Model of Drosophila Anterior-Posterior Pattern Formation
Maternal effect genes
Zygotic genesSyncytial blastoderm
Cellular blastoderm
Conversion of Maternal Protein Gradients into Zygotic Gap Gene Expression
Transcription factor
Conversion of Maternal Protein Gradients into Zygotic Gap Gene Expression
Model of Drosophila Anterior-Posterior Pattern Formation
Maternal effect genes
Zygotic genesSyncytial blastoderm
Cellular blastoderm
Specific Promoter Regions of the even-skipped (eve) Gene Control Specific Transcription Bands in the Embryo
Division cycle 13
the 2nd parasegmentthe expression of eve
Bicoid and hb activate eveKruppel and giant repress eve
Hypothesis for the formation of the Second Stripe of Transcription from the even-skipped Gene
Hypothesis for the Formation of the Second Stripe of Transcriptionfrom the even-skipped Gene
6 sites
3 sites5 sites
3 sites
Cis-regulatory enhancer elementsTrans-regulatory gap gene proteins
Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)
Reinforce the PSCell-cell signaling
Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)
Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)
gradients
Homeotic Gene Expression in Drosophila
thoracic
head
3rd thoracic
abdomen
Homeotic complex
A Four-winged Fruit Fly Constructed by Putting Together Three Mutations in cis Regulators of the Ultrabithorax Gene
Homeotic mutants
Ultrabithorax gene is deletedT3 to T2 transformation
Effect of Mutations Affecting the Distribution of the Dorsal Protein
Translocation of Dorsal Protein into Ventral, but not Lateral or Dorsal, Nuclei
The Generation of Dorsal-Ventral Polarity in Drosophila
Conserved Pathway for Regulating Nuclear Transport of TranscriptionFactors in Drosophila and Mammals
Zygotic genes pattern the early embryoDorsal protein activates twist and snail represses dpp,zen, tolloid
Rhomboid----neuroectodermRepressed by snail (not most ventral)
Binding sites for dorsal protein in their regulatory regions
Model for the subdivision of the dorso-ventral axis into different regions by the gradient in nuclear dorsal protein
Patterns of Gene Expression During Drosophila Mesoderm Development
Eileen E. M. Furlong, Erik C. Andersen, Brian Null,Kevin P. White, Matthew P. ScottScience, 293, 1629, 2001
Goals of ExperimentsSuggestions, opinions
Subdivision of the Dorsal-Ventral Axis by the Gradient ofDorsal Protein in the Nuclei
TABLE 1. Cancer-related genes in Drosophila melanogaster
Fly genes homologous to mammalian oncogenes
Fly genesarmadilloD. AblD. AktaurorahomothoraxDcblDcrkcicyclin DRasD.retsmoothened smoSrc42A, Src64Bstringtrithorax ALL-1D.TCFtorpedo
Mammalian gene or productb-cateninc-ablAktaurora 1, aurora 2, AIM-1 Meis1c-cblc-crkGli1, Gli2, Gli3cyclin D/ PRAD1RasretSmoc-srccdc25All1TCFc-erbB-2
TABLE 1. Cancer-related genes in Drosophila melanogaster
Fly genes homologous to mammalian tumor suppressor genes
Fly genesD-APCcaudalfrazzledgigashaywireklumpfussmedeamei-41MerlinD.NF1patchedPP2A-29BD.PTEND.p16RbfspellcheckerD.XpaD.XPD
Mammalian gene or productAPCCDX2DCCTSC2ERCC3WT-1DPC4ATMNF2NF1ptchPPP2RIBPTEN/ MMACp16(INK4a)/ MTS1pRBhMSH2XPAXPD/ERCC2
FLP(flippase)/FRT(target site) system-mitotic recombination
Large tumor suppressor (Lats), human gene rescue fly mutant
Climbing test: Negative geotactic response, monitor aging-related changes
A30P—day 23 to 45
elav-GAL4/
UAS--synuclein
Premature loss of climbing abilityIn -synuclein transgenic flies
A Drosophila model of Parkinson’s disease Nature(2000) , 404, 394-398
Retinal degeneration
Exam retinal pseudopupil: sensitive to disruption in the normal architecture
Generation of second site modifiers and pharmacological manipulations to modify this degeneration
Gmr-GAL4/+ Gmr-GAL4/+UAS-wt -synuclein
Steroid Control of Longevity in Drosophila melanogaster
Anne F. Simon, Cindy Shih, Antha Mack, Seymour Benzer*
Science, Vol. 299, P1407-1410, 2003
Extension of lifespan in an ecdysone receptor heterozygous mutant
Information : a. Books
The making of a fly (Peter Lawrence; Blackwell Scientific, 1992). The development of Drosophila melanogaster (ed. Bate & Martinez-Arias; Cold Spring Harbor Press, 1993) Fly pushing: The Theory and Practice in Drosophila genetics (Ralph Greenspan ; Cold Spring Harbor Press, 1997)
Drosophila: A practical approach (ed. DB Roberts; IRL Press, 1998).
Drosophila Protocols (ed. Sullivan, Ashburner, and Hawley; Cold Spring Harbor Press, 2000)
The genome of Drosophila melanogaster (by Dan L. Lindsley and Georgianna G. Zimm; Academia Press,1992)
b. The Flybase
http://flybase.bio.indiana.edu http://flybase.nhri.org.tw http://www.bdgp.org/ http://homophila.sdsc.edu/