C8545 Developmental Biology Lesson 2 Early Development of Drosophila Jan Hejátko Laboratory of Molecular Plant Physiology, Department of Functional Genomics and Proteomics, and Functional Genomics and Proteomics of Plants CEITEC Masaryk University, Brno, Czech Republic hejatko@sci.muni.cz, www.ceitec.eu Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation  Early embryogenesis  Gastrulation  Video of gastrulation in Drosophila  Overview of metamorphosis  Introduction into genetic and molecular mechanisms of the early embryogenesis in Drosophila Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video) Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video) Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video) Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis Semená schránka (receptaculum seminis) Spermatéka Ovariola Vajíčka Děloha Laterální vejcovod Společný vejcovod  Video of sperm size and behavior Ovaries Vaječníky 03_02 Nurse cells Výživové (podpůrné) buňky Oocyte Oocyt 8days 03_03 Prstencový kanál Cysta Cystoblasty (Cystocyty) Cystoblast Nurse cells Výživové (pomocné) buňky Terminal follicle cells Terminální folikulární buňky Main follicle cells Hlavní folikulární buňky Polar follicle cells Polární folikulární buňky Egg cell cytoplasm Cytoplasma vaječné buňky Egg cell nucleus Jádro vaječné buňky Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation Huynh and Johnston., Curr Biol (2004) Anterior Posterior Oogonium Cystoblast Huynh and Johnston., Curr Biol (2004) Ring canals Prstencové kanály Pro-oocytes Pro-oocyty Oocyte Oocyt Fuzom Synaptonemální komplex Anterior Posterior Follicle cells Folikulární buňky spectrosome cytoplasmic proteins, mRNAs and mitochondria centrosomes microtubules Repolarization of cytoplasmic contents (proteins, mRNAs and mitochondria) Synaptonermal complex Fusome Synaptonemal complex Lateral elements Transverse elements Longitudinal elementsRecombination nodule Chromatin of sister chromatids Kinetochores Recombination nodule Huynh and Johnston., Curr Biol (2004) Spectrosome (actin, spectrin, adducin-like protein) Cystoblast (Cystocyte) Centrosomes Mitotic spindle Mitotické vřeténko Fusome plug Fuzómová zátka The same centrosome inherited through the cell division 1-4 Fusome always marks the anterior of cystocyte 1 Anterior Posterior Ring canal Prstencový kanál Anterior Posterior Anterior Posterior Stage 1 Stage 2a Stage 2b Early stage 3 Stage 3 Stage 3 Cox and Spradling., Development (2003) Mitochondria (stained by anti-ATP synthase) Balbiani bodies-like structures Ring canal actin Fusome Anterior pole of the oocyte Cox and Spradling, Development (2003) OSK •mRNA stability, •Oocyte microtubule cytoskeleton polarization •Oogenesis ORB •mRNA translation, •mRNA polyadenylation Stage 2a Stage 2b Stage 3 Repolarization in stage 3 ANTERIOR POSTERIOR Huynh and Johnston., Curr Biol (2004) actin Synaptonemal complex Orb centrosomes fusome Initial polarity of fusome regulates several parallel processes involved in oocyte cell identity nucleus Huynh and Johnston., Curr Biol (2004) Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation  Early embryogenesis 03_06 Pole cells – the first true cells Pólové buňky-první pravé buňky Cellular blastoderm Buněčný blastoderm Blastula formation mRNA-binding proteins Synchronized nuclear divisions in the early Drosophila embryo 03_08_01 DAH protein localization 03_08_02 Sulivan et al., Development (1993) 03_09 Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation  Early embryogenesis  Gastrulation 03_11 Embryonální vývoj kopinatce Change in position Cell differentiation Epitel Mesenchym Epithelium Mesenchyme Hyalinní (sklovitá, kloubní) chrupavka 03_11_01 Ventral furrow/Ventrální rýha Zárodečný proužek a jeho konvergentní extenze umožňující další invaginaci zadního střeva Stomodeum formation and invagination (via convergent extension)…and progression of hindgut invagination Archenteron Mesoderm Visceral/viscerální Somatic/somatický Tvorba a invaginace předního střeva (stomodea – primitivní ústní jamky) MesodermEctoderm Endoderm Secondary invagination Primary invagination Ventral side neurons/ neural supporting cells 03_11_02 Anterior and posterior middgut elongation Retraction of germ band brings the posteror midgut opening posteriorly Anterior and posterior midgurt fusion (endoderm) Segmentation becomes obvious Foregut (ectoderm) Hindgut (ectoderm) Stomodeum (ectoderm) Secondary invagination Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation  Early embryogenesis  Gastrulation  Video of gastrulation in Drosophila Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation  Early embryogenesis  Gastrulation  Video of gastrulation in Drosophila  Overview of metamorphosis 03_13 03_14 Imaginal discs in Drosophila larva 08_05 Under control of ecdyson and juvenile hormone Morphogenic movements during metamorphosis Predetermined cell fate Adult structures Outline of Lesson 2 Early Development of Drosophila  Introduction into Drosophila  Life cycle (video)  Anatomy (video)  Mating (video)  Oogenesis  molecular mechanisms of the early axis formation  Early embryogenesis  Gastrulation  Video of gastrulation in Drosophila  Overview of metamorphosis  Introduction into genetic and molecular mechanisms of the early embryogenesis in Drosophila Different levels of morphogens Klaus Sanders experiments in Germany, 1960’s Eric F. Wieschaus The Nobel Prize in Physiology or Medicine 1995 Christiane Nüsslein-Volhard The Nobel Prize in Physiology or Medicine 1995 Position-dependent rescue of the bcd/bcd phenotype using cytoplasm from bcd/BCD or BCD/BCD oocyte bcd/BCD or BCD/BCD ectopic formation of anterior structures rescue A A P P 03_17 SWALLOW-, EXUPERANTIA- and STAUFEN-dependent BCD localization 03_18 03_18b protein 03_18c 03_17 Maternal tissue as a source of asymmetry in the early Drosophila formation 03_20b GURKEN (TGFα) signal perceived via TORPEDO unknown feed-back signal to the nucleus and microtubule reorganization Reorganization of the cytoskeleton and anteroposterior axis formation GURKEN signal induces dorsal specification via inhibition of X complex formation Key Concepts  Axis formation is based on the asymmetrical distribution of molecular determinants, mostly proteins and RNAs. Processes ensuring the asymmetrical distribution of those process occur very early in the oogenesis.  The cytoplasm may contain factors (TFs) that regulate the expression of target genes in the nucleus as shown in pole plasm transplatation experiments.  During early development, the developmental potential of cells or group of cells changes.  Gastrulation comprises a suite of coordinated cell divisons and movements that results into movement of specific cells from the surface to the interior.  The cytoplasm of embryo in Drosophila and almost all other animal embryos is heterogenic in terms of the distribution of factors that regulate developmental fate of adjacent cells. The origin of this heterogeneity is in the maternal tissue and its mutual interaction with the oocyte.