sea urchin - cleavage and larval development.pdf

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					sea urchin - cleavage and larval development
     WM 6 ‐ Marinbiologie Seminar 2010 ‐ Johannes Girstmair & Sabine Gufler 
.:01                  introduction



  •    different ways to cleave

        –   radial


        –   spiral


        –   holoblastic


        –   meroblastic


        –   meridional


        –   equatorial


        –   equal


        –   unequal


        –   superficial


        –   discoidal                Fig. 2.1a, 2.2, 3.20c, 4.5a, 4.23 | Müller/Hassel, 2008
.:01                  introduction



  •    different ways to cleave

        –   radial


        –   spiral


        –   holoblastic


        –   meroblastic


        –   meridional


        –   equatorial


        –   equal


        –   unequal


        –   superficial


        –   discoidal                Fig. 2.1a, 2.2, 3.20c, 4.5a, 4.23 | Müller/Hassel, 2008
.:01                  introduction



  •    different ways to cleave

        –   radial


        –   spiral


        –   holoblastic


        –   meroblastic


        –   meridional


        –   equatorial


        –   equal


        –   unequal


        –   superficial


        –   discoidal                Fig. 2.1a, 2.2, 3.20c, 4.5a, 4.23 | Müller/Hassel, 2008
.:01                  introduction



  •    different ways to cleave

        –   radial


        –   spiral


        –   holoblastic


        –   meroblastic


        –   meridional


        –   equatorial


        –   equal


        –   unequal


        –   superficial


        –   discoidal                Fig. 2.1a, 2.2, 3.20c, 4.5a, 4.23 | Müller/Hassel, 2008
.:01                  introduction



  •    different ways to cleave

        –   radial


        –   spiral


        –   holoblastic


        –   meroblastic


        –   meridional


        –   equatorial


        –   equal


        –   unequal


        –   superficial


        –   discoidal                Fig. 2.1a, 2.2, 3.20c, 4.5a, 4.23 | Müller/Hassel, 2008
.:01                  introduction



  •    different ways to cleave

        –   radial


        –   spiral


        –   holoblastic


        –   meroblastic


        –   meridional


        –   equatorial


        –   equal


        –   unequal


        –   superficial


        –   discoidal                Fig. 2.1a, 2.2, 3.20c, 4.5a, 4.23 | Müller/Hassel, 2008
.:02                cleavage state



  •    postfertilization 

        –   membran vibration
        –   thickening of hyaline layer
           radial holoblastic cleavage




                                          Video S3 | Vellutini, 2010
.:02                cleavage state



  •    first & second cleavage 

        –   meridional 
        –   symmetric                                              80 min

        –   4 equal blastomeres




                                     Fig. 5.19 | Wolpert, 2006




                                        Fig. 3 | Vellutini, 2010
.:02                cleavage state



  •    third cleavage

        –   equatorial
        –   symmetric
        –   seperating animal & vegetal blastomeres




                                 Fig. 5.19 | Wolpert, 2006




                                     Fig. 3 | Vellutini, 2010
.:02                cleavage state



  •    isolation experiments

        –   blastomeres of 4‐cell stage                       –   animal & vegetal blastomeres of 8‐
        –   each develop into small larva                         cell stage
                                                              –   animalized/vegetalized larva




                                  Fig. 3.15 | Gilbert, 2006                              Fig. 5.20 | Wolpert, 2006
.:02                  cleavage state



  •    fourth & fifth cleavage

        –   unequal
        –   four small micromeres at vegetal pole                                              180 min

        –   asymmetric micromere division  small & large micromeres




                                                                Fig. 5.19 | Wolpert, 2006




                                                                    Fig. 3 | Vellutini, 2010
.:03                blastula state



  •    blastula

        –   ectodermic cells aquire polygonal shape 
             smaller during division cycles                                                          3-6 hpf

        –   hollow sphere arround central blastocoel (water influx)
        –   mid‐blastula transition  synchrony of divisions ends  new genes become 
            expressed
        –   compactation and tight junctions
        –   cells develop cilia  rotation within fertilization envelope
        –   hatching enzyme  free swimming blastula




                                                                           Fig. 3 | Vellutini, 2010
.:04                gastrula state



  •    gastrulation

        –   vegetal pole cells form vegetal plate
        –   mesoderm cells (red) move inside and endoderm (blue) invaginates                   10 hpf

        –   primary mesenchyme cells form ring around archenteron (gut)
        –   secondary mesenchyme cells  tip of archenteron reaches animal pole




                                                                Fig. 5.19 | Wolpert, 2006




                                                                    Fig. 5 | Vellutini, 2010
.:04                gastrula state



  •    gastrulation

        –   filopodia over basal lamina
        –   primary mesenchyme cells  skeletogenic cells                                          10 hpf




                                                                                      fig. 2.3 | giudice, 1986




                                               Fig. 6 | Vellutini, 2010   Fig. 2 | May Maw Thet et al., 2010
.:05                  organizer center



  •    fate map


            animal region

            • oral mesomeres: ectoderm

            • aboral mesomeres: ectoderm



            vegetal plate

            • veg1: gut and ectoderm

            • veg2: gut and secondary mesenchyme

            • large micromeres: primary mesenchyme 
                  skeletogenic cells 

            • small micromeres: gut induction
                                                       Fig. 5.22 | Wolpert, 2006
.:05                organizer center



  •    inductive action

        –   organizing center in vegetal region
        –   micromeres implanted into side of 32‐cell embryo
        –   induction of second gut
        –   maternal –catenin accumulation in micromere nuclei (16–64 cell state)




                                                  fig. 5.23 | wolpert, 2006
.:06                  prism state



  •    pluteus prisma

        –   archenteron reached animal pole and is bent toward the ventral side
        –   red pigmented cells differentiate on vegetal pole                                              19 hpf

              •   regulatory role  trigger gastrulation

              •   might participate on prism formation / axis specification

        –   larva covered by cilia




                           Fig. S | Vellutini, 2010                           fig. 2.2p,q, giudice, 1985
sea urchin - larval development
WM 6 ‐ Marinbiologie Seminar 2010 ‐ Johannes Girstmair & Sabine Gufler 
.:07                 larval development




   radial symmetric embryo




                                                         pentameric juveline




                             bilateral planctonic form
                                     (Pluteus)
.:08              pluteus


  Pluteus larva with 2 arms
.:08              pluteus


  Pluteus larva with 4 arms
.:08              pluteus


  Pluteus larva with 6 arms
.:08              pluteus


  Pluteus larva with 8 arms
.:09                  organogenesis


  development of organanlagen:
   -   formation of 2 coelomic sacs   (3:2)
.:09                organogenesis


  migration of coelomic sacs
   -   along esophagus
.:09                organogenesis


  migration of coelomic sacs
   -   along esophagus
   -   towards stomach
.:09                 organogenesis


  migration of coelomic sacs
   -   along esophagus
   -   towards stomach
   -   some cells remail on the esophagus  axocoel
.:09                  organogenesis


  migration of coelomic sacs
   -   coelomic cells on left side continue migration
.:09                      organogenesis


  migration of coelomic sacs
   -   coelomic cells on left side continue migration
   -   differentiation:              stone channel
.:09                      organogenesis


  migration of coelomic sacs
   -   coelomic cells on left side continue migration
   -   differentiation:              stone channel
                                     hydrocoel vesicle
.:09                      organogenesis


  migration of coelomic sacs
   -   coelomic cells on left side continue migration
   -   differentiation:              stone channel
                                     hydrocoel vesicle   induces ectodermal invagination
.:09                 organogenesis


  imaginal disc (ventral)
   -   ectodermal vestibulum & mesodermal hydrocoel
.:09                 organogenesis


  imaginal disc (ventral)
   -   ectodermal vestibulum & mesodermal hydrocoel




                                              ventral
.:09               organogenesis


  variations in the development of coelomic sacs



        situs inversus




        normal                          ventralized   dorsalized
.:09                 organogenesis


  C. subdepressus
   -   formation of two coelomic sacs



                                                48 hpf


                           48 hpf       3 dpf
.:09                   organogenesis


  C. subdepressus
   -   formation of two coelomic sacs
   -   mouth opens
   -   gut: not functional
                                                48 hpf


                             48 hpf     3 dpf
.:09                  organogenesis


  C. subdepressus
   -   stomach grows, its epithelium becomes thinner
   -   functional gut  larvae begin to feed

                                                               3 dpf


                            48 hpf                     3 dpf
.:09                  organogenesis


  C. subdepressus
   -
   -   C fusion of invagination
       A vestibule vestibule and left coelom
   -   B vestibule reaching left coelomic sac

                                                4-5 dpf
.:09                   organogenesis


  C. subdepressus
   -
   -   A
       C   fusion of invagination
           Vestibulevestibule and left coelom
   -
   -   B
       D   Vestibule reaching left coelomic sac
           well developed rudiment (podia, spines)

                                                     4-5 dpf
.:10                  metamorphosis


  competent Pluteus
   -   swimming near bottom
   -   exposing rudiment (moving arms)
   -   touching substrate
.:10                  metamorphosis


  metamorphosis
   -   fully evert rudiment by opening arms 180° posteriorly
   -   larvae attach bottom
   -   regression of larval tissue & accumulation on aboral surface
.:10                  metamorphosis


  post-metamorphic juvenile
   -   larval tissue  globoid structure
                                           aboral surface of rudiment
.:11                   juvenile


  Juvenile
   -   resorption of larval tissue
   -   rudiments of lantern of Aristotle are visible  teeth
.:11                   juvenile / adult


  Juvenile
   -   resorption of larval tissue
   -   rudiments of lantern of Aristotle are visible  teeth
   -   mouth opened 7 dpm  juveniles begin to feed
a sea biscuit‘s life
.:12                           references



  Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter
  Molecular Biology of the Cell
  Garland Science, 5th edition, 2008

  Gerhard Czihak
  Sea urchin embryology in the sixties
  Int. J. Dev. Biol. 40, 1996

  Scott F. Gilbert
  Developmental Biology
  Sinauer Associates Inc.,8th edition, 2006

  Giuduce
  The Sea Urchin Embryo – A Developmental Biological System
  Springer-Verlag, 1986

  Müller/Hassel
  Entwicklungsbiologie
  4. Auflage, Springer, 2006

  Bruno C.Vellutini , Alvaro E. Migotto
  Embryonic, Larval, and Juvenile Development of the Sea Biscuit Clypeaster subdepressus (Echinodermata:Clypeasteroida)
  PLoS ONE, vol5, 2010

  Lewis Wolpert, Thomas Jessell, Peter Lawrence, Elliot Meyerowitz, Elisabeth Robertson, Jim Smith
  Priciples of Development
  Third Edition, Oxford University Press, 2007

				
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