Bio 580, Developmental Biology.  Wednesday, April 25, 1997

Gametogenesis:  Female (continued)

4. Other donations to the developing oocyte of interest
a.  Ribosomes
      Nurse cells, follicle cells.
            - massive processes-
                - rDNA amplification
                        - widespread in animal kingdom.
                - dumping of cytoplasm by accessory germ cells or somatic cells.
                        - nurse cells (some insects)
                        - follicle cells (vertebrates?)
 
b.  Calmodulin
                Sea urchin
                African clawed toad, Xenopus laevis 
                Cockroach, Blattella germanica 
  1) Structure and function

  2) Role in early germ cells?


c.  Yolk protein (vitellin or lipovitellin) (Vitellogenesis)
            Tissue sources of vitellin


Hormonal regulation:

    Vertebrates:  Estrogens acting on a mature liver.
            metamorphosis:
                amphibians-  thyroxin, prolactin acting on the tadpole liver.
                hormone competency
                            primary response
                            secondary response
                            Estrogen binding proteins
                            Vg-gene induction of transcription
                            Vg-mRNA stabilization by estrogen

    Arthropods:  Juvenile Hormone (JH) and ecdysone
             - alternation of vitellogenesis and molting

Liver/fat body:

 Vg-mRNA ->  pre-pro-Vg -> CHO, PO₄, lipid addition -> cleavage, dimerization ->secretion

Transport:
               serum    ->        pinocytotic vesicle        ->    yolk granule

Uptake and storage as yolk:
            Vg-dimer  ->      adsobtive endocytosis    ->    vitellin, (lipovitellin-phosvitin)

Cycloraphoran Diptera i.e. Drosophila

        Yolk Proteins

        Evolutionary relationship to vitellogenins?

Polarity of oocytes during the oogenic/vitellogenic process: