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#egg jelly

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Regeneration -ll

Egg jelly in sea urchins primarily functions in:

Egg jelly is thick layer of sulfated fucan polysaccharides and glycoproteins surrounding vitelline envelope, deposited during oocyte growth and containing embedded chemotactic peptides resact and speract. Its primary adaptive functions are attracting sperm from distance via diffusion gradients ensuring fertilization in dilute seawater and inducing acrosome reaction through fucose-sulfate ligands that raise sperm calcium and pH. Jelly also contributes to species-specific agglutination of sperm. Polyspermy block is achieved by fertilization envelope elevation and hardening after cortical reaction, nutrient supply comes from yolk platelets, and embryonic genome activation depends on calcium and pH changes inside egg not jelly components.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Egg jelly functions - chemotaxis and acrosome induction.

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Sea urchin -l

Egg jelly in sea urchins primarily functions in:

Egg jelly is thick gelatinous extracellular mucoid coat outside vitelline envelope composed of sulfated fucan polysaccharides intermingled with small peptides such as resact and speract. Its principal biological functions include long-range sperm chemoattraction and preparation for fusion. Diffusible peptides establish chemotactic gradient guiding motile sperm toward egg, while polysaccharides interact with sperm receptors inducing Ca2+-dependent acrosomal reaction ensuring membrane fusogen bindin becomes exposed precisely before reaching vitelline membrane. Although it contributes to species filtering, core specificity arises later at bindin-receptor binding step. It does not block polyspermy nor supply metabolic nutrition; polyspermy prevented by electrical shift and fertilization envelope.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Egg jelly role - sperm attraction and acrosome induction.

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Sea urchin -lll

Sperm attraction peptides released from sea urchin egg jelly are:

Sea urchin egg jelly contains diffusible peptides that attract sperm via chemotaxis. Purified factors Resact from Arbacia punctulata and Speract from Strongylocentrotus purpuratus are small 10-14 amino acid sulfated peptides. They bind receptors on sperm flagellum activating membrane guanylate cyclase, increasing cGMP, calcium influx, and altering flagellar beating to orient toward gradient source. This chemotaxis enhances encounter rates in seawater where dilution is extreme. Bindin and Hyalin are structural adhesion proteins, acrosin is acrosomal protease, not chemoattractants, leaving Resact and Speract as established sperm attraction peptides guiding fertilization.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Resact Speract chemotaxis peptides sea urchin fertilization.

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