Hormonal regulation of vitellins and yolk proteins:

Vertebrates:  Estrogens acting on a mature liver. 

metamorphosis: 
amphibians-  thyroxin, prolactin acting on the tadpole liver. 
Tata (1993, 1994)
hormone competency 
primary vs. secondary response 
Shapiro (1978); Tata (1978, 1981, 1984)

Estrogen binding proteins 
Vg-gene induction of transcription 
Vg-mRNA stabilization by estrogen 
Shapiro Lab (1976, 1978, 1980, 1982, 1989, 1995)

Arthropods:  Juvenile Hormone (JH) and ecdysone 

Alteration of Vg in Liver/fat body: 

 Vg-mRNA ->  pre-pro-Vg -> CHO, PO₄, lipid addition -> cleavage, dimerization ->secretion 
                Example:  pre-pro-Vg to secretion in Blattella  
Transport: 
serum   ->        pinocytotic vesicle        ->    yolk granule 

Uptake and storage as yolk: 

Vg-dimer  ->      adsobtive endocytosis    ->    vitellin, (lipovitellin-phosvitin) 

Cyclorraphoran Diptera (i.e. Drosophila) vs  Nemataceran (i.e. mosquito)
        Relationship of Drosophilan to Mosquito major yolk protein 

Evolutionary relationship to vitellogenins?

Overt Polarity of oocytes during the oogenic/vitellogenic process: 

     Polarity of the simplest gametes of plants:  Fucus

     Polarity of animal oocytes:
        Sea urchin
 
        Amphibian

        Bird

        Fish

        Insect

Ionic currents and polarity:

Currents measured in and about oocytes
Overheads from class
• wire probe operation
• wire probe callibration
• ion probe operation and callibration
• Periplaneta follicle
  - example of an antero-posterior ion gradient
• Periplaneta, Zootermopsis, Eurycotis follicles
• currents about a Blattella follicle
  - example of a dorso-ventral current
  - ions suggested by ion replacement experiments
• Ionic currents about a cockroach follicle
  - model base on wire probe and ion replacement experiments
• Ionic currents about a cockroach follicle
  - new model based on specific ion electrode measurements