&Cell biology perspective opportunity, throughout-

Microtubules and motorsCalcium mediated Membrane fusions Cell-Cell interaction – First example

Gametogenesis

and Fertilization Unit

Gametogenesis (Germ cell specification and maturation)

• Germ line specification (g.l. stem cells first)

• Germ line migration to the gonads

• Meiosis

• Gamete maturation

Figure 2.1 Developmental History of the Leopard Frog, Rana pipiens

Set aside as quiescent cells.“Pole cells”, with “pole plasm” Transcription & Diff. to Ecto,Meso, Endo blocked

For All Bilaterians (here, ecto-meso-endo specifics for tetrapods)

Set aside as quiescent cells. These express Vasa in all bilaterians. & Nanos, Piwi. . .

For All Bilaterians:

For All Bilaterians:

For All Bilaterians:

For All Bilaterians: In addition ‘placement’ in the proper positions - -

These molecules are transported on microtubules (made of Tubulin)

as cargo on molecular motors:

see Movies: Kinesin_Transport_Protein.MOV

Dynenin: to -Kinesin: to +

For All Bilaterians:

Vasa and Nanos- RNA binding proteins

In flies and many others:

Figure 2.21 Major Evolutionary Divergences in Extant Animals

Gametogenesis (Germ cell specification and maturation)

• Germ line specification (g.l. stem cells first)

• Germ line migration to the gonads

• Meiosis

• Gamete maturation

Mammalian

Zebrafish

Fruitfly Drosophila melanogaster

Gametogenesis (Germ cell specification and maturation)

• Germ line specification (g.l. stem cells first)

• Germ line migration to the gonads

• Meiosis

• Gamete maturation

Gametogenesisoogenesis spermatogenesis

After fertilization, the zygote will essentially be an activated egg

Frog oocyte

Table 19.2 Cellular components stored in the mature oocyte of Xenopus Laevis

ComponentApproximate excess over amount in larval cells

Mitochondria100,000

RNA polymerases60,000 - 100,000

DNA polymerases100,000

Ribosomes200,000

tRNA10,000

Histones15,000

Deoxyribonucleoside triphosphates2,500Note Yolk –vitellegenin –from liver

Laskey 1979

Table 19.2 Cellular components stored in the mature oocyte of Xenopus Laevis

ComponentApproximate excess over amount in larval cells

Mitochondria100,000

RNA polymerases60,000 - 100,000

DNA polymerases100,000

Ribosomes200,000

tRNA10,000

Histones15,000

Deoxyribonucleoside triphosphates2,500Yolk –vitellegenin FROM LIVER

Laskey 1979 2 .Micro-pinocytosis – vesicle delivery from other cells

1 .Oocytes’ massive bio-synthesis of macromolecules

Fruitfly Drosophila melanogaster

Gametogenesis/Fertilization Unit

OPPORTUNITY TO FOCUS ON MICROTUBULES

Microtubles in mitosis/meiosis

Movie1Life of cell 2

http://biolog-e.ls.biu.ac.il/faculty/wides/80-557/movies/MCB1803ActinMyosin.MOV

Kinesins towards+ Dyenins towards-

http://www.youtube.com/watch?v=4TGDPotbJV4Kinesin walk

Attachment later by vegetal Cortex microfilaments

Transport viaMicrotubules-Assymetric placementof cytoplasmiccomponents (RNA)

Microtubles in oogenesis, creating assymetry in cytoplasm

Figure 2.1 Developmental History of the Leopard Frog, Rana pipiens

Gametogenesisspermatogenesis

oogenesis

First: Microtubles and the flagellum

9+2 micorotuble arrangement - in motile cilia -including most metazoans’ sperm flagella

9 dimer microtubules

+2 monomer microtubules

- primary cilia ineukaryotic cells:

9 :stationary- secondary cilia,

including flagella:9+2 :movement Can see: http://www.youtube.com/watch?v=n40VTfWvh1Y

http://www.youtube.com/watch?v=vQ3CdSiVzUkcilia

Flagellum structure:Sperm and most eukaryotic

flagella

http://www.youtube.com/watch?v=5rqbmLiSkpk

Centriole-> flagellumAcrosomeMitochondria to axonemeCytoplasm

Figure 6 By-the-way: Flagella in Eubacteria,) and in Archea ,(are Analogous,

NOT homologous

Fertilization

Figure 2.21 Major Evolutionary Divergences in Extant Animals

Attraction of sea urchin sperm to egg in Sea water:

Swimming along the gradient of the RESACT peptide

Gametogenesis

and Fertilization Unit

Opportunity: Microtubules and motors

1. Calcium mediated Membrane fusions (3)

Cell-Cell interaction – First example2. Extracellular matrix (ECM) introduction

Vade Mecum Sea Urchin Fertilization

_Zona Pellucida

Ovum

Cumulus