Chapter 18 The Genetic Analysis of Development 20-1
20-1 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display The Genetic Analysis of Development The Genetic Analysis of Development Chapter 18
Sections to study18.1Model organisms:Prototypes for developmentalgenetics18.2 Usingmutations to dissect development18.3Analysis of developmentalpathways18.4Acomprehensiveexample:Bodyplan development inDrosophila18.5 How genes help control development20-2
20-2 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Sections to study Sections to study 18.1 Model organisms: Prototypes 18.1 Model organisms: Prototypes for developmental genetics for developmental genetics 18.2 Using mutations to dissect development 18.2 Using mutations to dissect development 18.3 Analysis of developmental pathways 18.3 Analysis of developmental pathways 18.4 A comprehensive example: Body plan development in 18.4 A comprehensive example: Body plan development in Drosophila Drosophila 18.5 How genes help control development 18.5 How genes help control development
Two central challenges for scientists studying developmentNodes,orTo identify which genes areelementscriticalforthe developmentofparticular cell types or organsTo figure out how thesegeneswork together to ensure thateachisexpressedattherighttime, in the right place, and inthe right amount.Edges,orconnectionsA hypotheticalbiological network20-3
20-3 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Two central challenges for scientists studying development Two central challenges for scientists studying development To identify To identify which genes which genes are critical for the development of critical for the development of particular cell types or organs. particular cell types or organs. To figure out To figure out how these genes how these genes work together work together to ensure that to ensure that each is expressed at the right each is expressed at the right time, in the right place, and in time, in the right place, and in the right amount. the right amount. A hypothetical biological network
18.1Model organisms:Prototypesfor developmentalgeneticsPlantArabidopsisthalianaYeastSaccharomyces cerevisiaeNematode (round worm)Caenorhabditis elegansMouseMus musculusFruit flyDrosophilamelanogasterZebrafishDanio rerio20-4
20-4 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 18.1 Model organisms: Prototypes for developmental 18.1 Model organisms: Prototypes for developmental genetics genetics Yeast Saccharomyces cerevisiae Plant Arabidopsis thaliana Nematode (round worm) Caenorhabditis elegans Mouse Mus musculus Fruit fly Drosophila melanogaster Zebrafish Danio rerio
Why study these model organisms?Easeof cultivationRapid reproduction of large numbers of progenyGenomes sequencedEasier for geneticists to identify genes with mutant phenotypesConvenientresources forresearchersCooperative studyamong differentlabsLargecollections of mutants with developmental defectsmaintainedin stockcenters20-5
20-5 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Why study these model organisms? Why study these model organisms? Ease of cultivation Ease of cultivation Rapid reproduction of large numbers of progeny Rapid reproduction of large numbers of progeny Genomes sequenced Genomes sequenced Easier for geneticists to identify genes with mutant phenotypes Easier for geneticists to identify genes with mutant phenotypes Convenient resources for researchers Convenient resources for researchers Cooperative study among different labs Cooperative study among different labs Large collections of mutants with developmental defects maintain Large collections of mutants with developmental defects maintained in stock centers in stock centers
The budding yeast Saccharomyces cerevisiaeCell polarity(Cytoskeleton,vesiculartransportChromosomeorganizationNuclear structureAgeingCell cycleregulationOrganellebiogenesisMitosisMeiosisCytokinesis20-6
20-6 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display The budding yeast The budding yeast Saccharomyces Saccharomyces cerevisiae cerevisiae Cell cycle regulation Mitosis Meiosis Cell polarity (Cytoskeleton, vesicular transport) Cytokinesis Chromosome organization Nuclear structure Ageing Organelle biogenesis
The fruitflyDrosophilaFertilizationmelanogasterOAdultREmbryoPupa31/2-41/2days1dayinpupalstageFirstinstarlarva21/2-3daysDrosophila life cycle1 dayThirdSecondinstarlarva1 dayinstarlarva20-7
20-7 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display The fruitfly fruitfly Drosophila Drosophila melanogaster melanogaster
All living forms arerelated ...Evolution has conserved basic strategies of development acrossmulticellulareukaryotes.The eyes ofinsects and mammals havea common ancestor.eyeless gene in fruit fliesPax-6 gene in miceAniridiageneinhumansommatidiaFig.1.720-8
20-8 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display All living forms are related All living forms are related . ommatidia Fig. 1.7 Evolution has conserved basic strategies of development across Evolution has conserved basic strategies of development across multicellular multicellular eukaryotes. eukaryotes. The eyes of insects and mammals have a common ancestor. The eyes of insects and mammals have a common ancestor. eyeless eyeless gene in fruit flies gene in fruit flies Pax-6 gene in mice gene in mice Aniridia Aniridia gene in humans gene in humans
Wild-typeWild-typefruit flymouse fetuseyeless mutantpax-6 mutantof fruit flyFig.18.220-9
20-9 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display eyeless mutant of fruit fly Wild-type mouse fetus pax-6 mutant Fig. 18.2 Wild-type fruit fly
EctopicredeyetissueWild-typefruitflyEctopicredeyetissueEctopic expression of eyeless gene20-10
20-10 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Ectopic expression of eyeless gene Wild-type fruit fly